Cyto-genetic diversity with special reference to medicinal plants of the Kashmir Himalaya – a review

Abstract

The present paper reviews research conducted on the cytogenetics of the plants of the Kashmir Himalaya. The review discloses that out of the total c.550 cytologically determined plants, there are c.190 genera and c.55 families of angiosperms. Among the cytologically determined species, c.50 species have been reported for the first time at global level along with varied chromosomal reports for c.110 species from the Kashmir Himalaya. The genus Jaeschkea has also been cytologically determined for the first time worldwide from the Kashmir Himalaya. The chromosome numbers in these species vary from 2n = 10 to 2n = 120 with frequency of 2n = 18 (13.73%), 2n = 16 (13.46%), 2n = 14 (7.96%) and 2n = 32 (7.41%). The reported base numbers of x = 7, x = 8, x = 9 are common ones. Most of the genera are polybasic, followed by monobasic and dibasics while tribasic taxa are least represented in the Kashmir Himalaya. New base numbers have been reported for Astragalus (x = 6), Cheiranthus (x = 6), Gypsophila (x = 13), Meconopsis (x = 7) and Saussurea (x = 18) from this region. In all, nearly 65% species are diploids and the rest (35%) are polyploids existing at various polyploid levels, with a preponderance of tetraploids. These plants depict significant level of intraspecific variability not only in chromosome numbers but also for meiotic behaviour and morphology. The knowledge of intraspecific variability of these species point out the existence of genetic diversities. Additionally, it has been observed that molecular marker studies are restricted to few plant species in the geographically diverse the Kashmir Himalaya.

Keywords:

• cytogenetics
• diversity
• the Kashmir Himalaya
• medicinal plants

Introduction

Himalaya is recognized as one of the major biodiversity hotspots. This biodiversity involves a large group of plants with medicinal attributes, being potential sources of new products and bioactive compounds for drug development (Gangwar and Deepali 2010). It has been estimated that 60% of the world population and 80% of the population in developing countries rely on traditional medicine (mostly herbal drugs), for their primary health care needs (Shrestha and Dhillions 2003). In India, nearly 70% of population is dependent on traditional plant based medicines (Gadgil and Rao 1998). Of the 350,000 plant species identified so far, about 35,000 (several estimate it at 70,000) are used worldwide for medicinal purposes and less than about 0.5% of these have been chemically investigated (Comer and Debus 1996). In India, of the 17,000 species of higher plants, about 7500 are known for medicinal uses, which constitute a considerable proportion of the total flowering plants (cf. Gairola et al. 2010). The use of plants for medicinal purposes in India has a long history, and the proportion of medicinal plants in the flora is the highest compared in the world (Kala et al. 2006).

Medicinal plants offer alternative remedies with tremendous opportunities to generate income, employment and foreign exchange for developing countries (Rawat and Uniyal 2004). The global market for these plants and herbal medicine is estimated to be worth US$800 billion a year and the market for Indian traditional systems of medicine is about Rs. 4000 crores per year (Rajasekharan and Ganeshan 2002). India is one of the leading countries in Asia in terms of the wealth of traditional knowledge systems related to herbal medicine and employs a large number of plant species under different medicine systems, including Ayurveda (2000 species), Siddha (1121 species), Unani (751 species) and Tibetan (337 species) (Kala 2002).

The Kashmir Himalaya harbours a rich Angiosperm flora with about 152 species endemic to the Kashmir region (Dar et al. 2006). Among the over 8000 species of flowering plants growing in the Himalaya, about 590 medicinal plant species are found at different altitudes in the Kashmir valley and nearly 40% of the known medicinal plants of the Kashmir Himalaya are used in the Indian pharmaceutical industry alone (cf. Siddique et al. 2004). More than 100 species growing at different altitudes (in Kashmir) are regarded as potential medicinal plants (Iqbal and Siddique 2004). Kashmir has a long history of use of herbal drugs and the tradition of herbal healing is an ever-growing activity. However, large number of species are endemic, and several species have acquired rare, threatened or endangered status, e.g. Aconitum heterophyllum, Arnebia benthamii, Inula racemosa, Picrorhiza kurroa, Podophyllum hexandrum, Rheum emodi and, Saussurea costus.

In order to understand the population dynamics of these species, it is necessary to have a thorough understanding of their genetic potential, including chromosome behaviour, reproductive tactics and breeding strategies. There have been many studies in these areas, especially in cytogenetics. These studies are not only helpful in solving the problems related to inter-species relationships and evolution of plant groups, but are also important in understanding reproductive behaviour and systematics. This is evident from the ever-increasing lists of chromosome numbers of medicinal plants appearing from various parts of the world. Chromosomal features are help elucidate phylogenetic affinities and evolutionary development, and are indicators of appropriate classifications of several plants (Jones 1978). According to Gill and Singhal (1998), chromosomal surveys involving the determination of chromosome numbers and meiotic behaviour are of immense importance in understanding the cytogenetic constitution of species, relationships among taxa and to provide a base for future improvement programmes. This paper draws from literature including the chromosomal atlases by Darlington and Wylie (1955), Fedorov (1974), Kumar and Subramaniam (1986), Khatoon and Ali (1993); indexes by Ornduff (1968, 1969), Moore (1970–1977), Goldblatt (1981–1988), Goldblatt and Johnson (1990–2003); International Association for Plant Taxonomy/International Organization of Plant Biosystematists (IAPT/IOPB) and Society of Cytologists and Geneticists, India (SOCGI) chromosome reports and various journals. An attempt has been made to review the information available in this field so that future research and development can be planned accordingly.

1. Cytology and chromosome numbers

1.1. Indian Himalaya

A detailed assessment of the chromosomal conspectus of Himalayan species reveals that although Johnson (1910) was the first to record a chromosome count of 2n = 32 in Piper betle of Piperaceae (cf. Darlington and Wylie 1955), the first chromosomal study on an Indian Himalayan plant can be attributed to Hakansson (1926) reporting 2n = 34, 36 in Verbascum thapsus (cf. Darlington and Wylie 1955). Earlier (1926–1955) cytological studies on the Indian Himalayan plants were dominated by cytologists from outside India. During this period only a few Indian cytologists worked on Himalayan plants, including Patel and Narayana (1937), Bhalla (1941), Raghavan and Venkatasubban (1943), Pathak et al. (1949), Dutt (1952), Janaki-Ammal and Saunders (1952), Janaki-Ammal (1953), Sharma and Das (1954) and Khoshoo (1955a, 1955b).

The 36-year period from 1955 to 1990 is regarded the as golden era of cytology in Indian Himalaya. In this period, extensive field surveys were carried out to explore the cytogenetic diversity in flowering plants covering both the Eastern and the Western Himalayas. Mehra and his students worked extensively on the cytomorphological diversity of both the Eastern and Western Himalayas. They carried out studies on grasses (Mehra and Kohli 1966; Khosla and Mehra 1973), orchids (Vij and Gupta 1975; Mehra and Kashyap 1986) and tree species (Khoshoo and Tandon 1963; Mehra and Gill 1968; Mehra and Sareen 1969; Khosla and Sareen 1981). Also studied were Alismataceae (Mehra and Pandita 1984), Asteraceae (Mehra et al. 1965), Butomaceae and Hydrocharitaceae (Pandita and Mehra 1984), Balsaminaceae (Khoshoo 1957), Chenopodiaceae (Mehra and Malik 1963), Cyperaceae (Mehra and Sachdeva 1975), Lamiaceae (Gill 1970), Leguminosae (Mehra and Hans 1971; Mehra and Sareen 1973), Ranunculaceae (Mehra and Kaur 1963; Mehra and Remanandan 1972), Rosaceae (Mehra and Dhawan 1966), Rubiaceae (Khoshoo and Bhatia 1963) and monocots (Mehra and Malik 1961). The work on woody taxa was published in the form of a book entitled Cytology of Himalayan Hardwoods (Mehra 1976).

Bir and Gill and their students carried out the cytological work on some of the plants of North-Western Himalaya, central Indian plants of Pachmari hills of Madhya Pradesh as well as some plants of South India. The studies involved trees (Bir et al. 1985), legumes (Bir and Kumari 1975, 1981a, 1981b, 1985; Kumari and Bir 1990) and Acanthaceae (Bir and Saggoo 1980; Saggoo and Bir 1989), Asteraceae (Gill and Gupta 1979; Gupta et al. 1989), Lamiaceae (Saggoo and Bir 1986) and Ranunculaceae (Bir and Thakur 1984).

1.2 The Kashmir Himalaya

The details of different species/ taxa reported for the first time from the Kashmir Himalaya along with chromosome numbers, locality and authorship have been provided in Table 1.

Table 1. List of taxa along with chromosome numbers reported for the first time at global level from the Kashmir Himalaya).

Name of taxon	Chromosome number	Locality/voucher no.	Authors
Aconitum leave Royle	2n = 16	RN 19	Koul and Gohil 1973
Agrimonia eupatoria L.	2n = 84	Sonmarg	Kumar, Jeelani, Rani, Kumari, et al. 2011
	2n = 84 + (0 – 1B)	Chumnai
Alchemilla vulgaris L.	2n = 34	Aru	Jeelani et al. 2012a
	2n = 96	Thajwas
Alliaria petiolata (M.B.) Cav. & Grande.	2n = 14	Gulamarg	Naqshi and Javeid 1976
Allium ampeloprasum L.	2n = 48	RN 3	Koul and Gohil 1973
Allium cepa var. aggregtaum	2n = 16	RN 5	Koul and Gohil 1973
Allium consanguineum Kunth	2n = 16	GS4002	Koul and Gohil 1973
Allium govanianum Wall.	2n = 16	GS 3598	Koul and Gohil 1973
Allium thomsoni Baker	2n = 32	RN 36	Koul and Gohil 1973
Alopecurus nepalensis Trin. ex Steud.	2n = 42	Bijbahara	Kaur, Mubarik, et al. 2011
Amaranthus hybridus L.	2n = 34	Zawoora	Farooq 2013
Anaphalis nubigena DC.	2n = 56	Thajwas	Malik 2012
Anemone obtusiloba Don.	2n = 14, 16	GS 3307	Koul and Gohil 1973
Arabidopsis himalaica (Edgew.) Schulz	2n = 16	Pahalgam	Naqshi and Javeid 1976
Arabidopsis mollissima (C.A. Mey) Busch.	2n = 16	Mahadev	Naqshi and Javeid 1976
Arabidopsis mollissima (C.A. Mey) Busch. var. glaerrima (Hook.f. Thoms.) Naqshi & Javeid	2n = 16	Drass	Naqshi and Javeid 1976
Arabidopsis wallichii (Hook. f. Thoms.) Busch	2n = 18	Shankracharya	Naqshi and Javeid 1976
Arabis amplexicaulis Edgew.	2n = 32	Harwan	Naqshi and Javeid 1976
	2n = 16	Gurez	Jeelani et al. 2012a
Arabis tenuirostris O.E. Schulz	2n = 16	Sonmarg	Naqshi and Javeid 1976
Arenaria kashmirica Edgew.	2n = 40	Thajwas	Jeelani, Rani, et al. 2011
Artemisia cashemirica Kaul & Bakshi	2n = 18	Kashmir	Kaul and Bakhshi 1984
Artemisia glauca Pall. ex Willd.	2n = 27	Kashmir	Kaul and Bakhshi 1984
Artemisia maritima L. ex Hook. f.	2n = 18 + 0 – 2B	Kashmir	Kaul and Bakhshi 1984
Asparagus filicinus Ham.	2n = 20	GS 4030	Koul and Gohil 1973
Astragalus grahamianus Royle.	2n = 16	Beru	Gohil et al. 1981
Astragalus himalayanus Klotzsch.	2n = 16	Sonmarg	Gohil et al. 1981
Astragalus melanostachys Benth. ex Bunge	2n = 12	Meenamarg	Ashraf and Gohil 1988a
Astragalus strobiliferus Royle	2n = 16	Mahadev	Jeelani, Kumari, et al. 2011
Barbaraea intermedia Boreau	2n = 32	Ferozpur Nallah	Jeelani et al. 2013
Caltha alba Jacquem.	2n = 32	Thajwas	Jeelani et al. 2012a
Cardamine loxostemonoides O.E. Schulz	2n = 16	Ratnipora	Jeelani, Kumari, et al. 2011
Cardamine macrophylla Adams.	2n = 32	Mahadev	Gohil et al. 1981
Carduus edelbergii Rech. f.	2n = 40	Pampore	Malik et al. 2011b
Carduus onopordeoides Fisch. ex Bieb.	2n = 40	GS 3824	Koul and Gohil 1973
Chenopodium murale L.	2n = 54	Mashwara	Farooq 2013
Cirsium wallichii DC.	2n = 68	GS 3930	Koul and Gohil 1973
Codonopsis rotundifolia Benth.	2n = 32	Aharbal	Malik 2012
Coleus blumei Benth.	2n = 42	Pulwama	Malik et al. 2011b
Conringia planisilique Fisch. & Mey.	2n = 18	Khalsi	Naqshi and Javeid 1976
Dahlia pinnata Cav.	2n = 36	RN 13	Koul and Gohil 1973
Delphinium denudatum Wall.	2n = 16	GS 1441	Koul and Gohil 1973
Delphinium roylei Munz	2n = 16	Chumnai	Jeelani, Kumari, et al. 2011
Delphinium uncinatum Hook. f. & Thomson	2n = 16	Lower-Munda	Jeelani, Kumari, et al. 2011
Dipsacus mitis D. Don	2n = 18 + 0 – 1B	Gulmarg	Malik 2012
Erysimum altaicum C.A. Mey.	2n = 32	Mahadev	Gohil et al. 1981
Erysimum melicentae Dunn.	2n = 18	Harwan	Naqshi and Javeid 1976
Erysimum perofskianum Fisch. & Mey.	2n = 18	Srinagar	Naqshi and Javeid 1976
Erysimum perowskianum Fisch. & mey.	2n = 36	Srinagar	Gohil et al. 1981
Euphorbia pilosa L.	2n = 20	Harwan	Saggoo and Farooq 2011b
Euphrasia paucifolia Wett.	2n = 44	Amarnath road	Malik 2012
Filipendula vestita (Wall. ex G. Don) Maxim.	2n = 14	Aharbal	Jeelani, Kumari, et al. 2011; Jeelani, Rani, et al. 2011b
Fritillaria roylei Hook.	2n = 24	GS 3610	Koul and Gohil 1973
Habenaria digitata Lindl.	2n = 42	Ramban	Vij and Gupta 1975
Hedysarum cachemirianum Benth. ex Baker	2n = 16	Chumnai	Jeelani, Kumari, et al. 2011
Hieracium vulgatum Fries.	2n = 54	Thajwas	Malik 2012; Malik and Gupta 2013
Impatiens amphorata Edgew.	2n = 14	Hirpora	Jeelani et al. 2012a
Impatiens edgeworthii Hook.f.	2n = 14	Naranag	Gohil et al. 1981
Impatiens racemosa DC.	2n = 12	Gurez	Jeelani et al. 2012a
Impatiens scabrida DC.	2n = 16	Aharbal	Jeelani et al. 2010
Impatiens sulcata Wall.	2n = 16	Aharbal	Jeelani et al. 2010
	2n = 12	Gulmarg	Jeelani et al. 2012a
Jaeschkea gentiannoides Kurz.	2n = 18	GS 3942	Koul and Gohil 1973
	2n = 22	Aharbal	Gohil et al. 1981
Juncus articulatus L.	2n = 80	Srinagar	Bhat et al. 1975
Lactuca decipiens C.B. Clarke	2n = 16	Gurez	Malik 2012
Lavatera cachemiriana Camb.	2n = 28	Tangmarg	Bhat et al. 1975
Leacus lanata Benth.	2n = 30	Srinagar	Bhat et al. 1975
Lignariella obscura (Dunn.) Jafri	2n = 16	Apharwat	Naqshi and Javeid 1976
Lotus corniculatus L. var. minor Baker	2n = 24	Batnoor	Jeelani et al. 2012b
Lychnis indica Benth.	2n = 48	Naranag	Gohil et al. 1981
Marrubium vulgare L.	2n = 54	Pulwama	Malik 2012
Meconopsis latifolia Prain	2n = 14	Razdan	Jeelani et al. 2012a
Mertensia echioides Benth.	2n = 24	Gurez	Malik 2012
Mertensia echioides Benth.	2n = 24	Razdan Pass	Malik et al. 2014
Myriophyllum spicatum L.	2n = 42	Srinagar	Bhat et al. 1975
Nasturtium officinale R. Br.	2n = 16	Ferozpur Nallah	Jeelani et al. 2013
Onosma hispida Wall.	2n = 12	Zabarwan	Gohil et al. 1981
Oxyria digyna Hill.	2n = 14 + 0 – 2B	Lidderwat	Farooq and Saggoo 2014
Papaver macrostomum Boiss.	2n = 14	GS 3370	Koul and Gohil 1973
Parthenocissus semicordata Planch.	2n = 48	Cheshmashahi	Jeelani, Kumari, et al. 2011
Pedicularis pectinata Wall.	2n = 16	Tangmarg	Bhat et al. 1975
Pedicularis pyramidata Royle	2n = 16	Tangmarg	Bhat et al. 1975
Phlomis bracteosa Royle.	2n = 28	Sonmarg	Gohil et al. 1981
Platanus orientalis L.	2n = 42	GS 3451	Koul and Gohil 1973
Pleurospermum densiflorum Benth. ex C.B. Clarke	2n = 22	Mahadev	Jeelani, Kumari, et al. 2011
Polemonium coeruleum L.	2n = 18	Gulmarg	Bhat et al. 1975
Polygonum affine D.Don	2n = 24	GS 342 a	Koul and Gohil 1973
Potamogeton pectinatus L.	2n = 78	Srinagar	Bhat et al. 1975
Potentilla argyrophylla Wall.	2n = 28	Thajwas	Jeelani, Kumari, et al. 2011
Potentilla atrosanguinea Lodd.	2n = 14	Keller	Jeelani, Kumari, et al. 2011
Potentilla nepalensis Hook.	2n = 28	Keller	Jeelani, Kumari, et al. 2011
Potentilla supina L.	2n = 14	Thajwas	Jeelani et al. 2012a
Ranunculus hirtellus Royle	2n = 14	GS 774a	Koul and Gohil 1973
Ranunculus muricatus L.	2n = 32	Srinagar	Jeelani 2012
Ranunculus palmatifidus Riedl	2n = 28	Thajwas	Jeelani et al. 2012a
Rorippa palustris (Leyss.) Bess.	2n = 32	Srinagar	Naqshi and Javeid 1976
Rorippa sylvestris (L.) Bess.	2n = 32	Srinagar	Naqshi and Javeid 1976
Rosa macrophylla var. minor Lindl.	2n = 14	Keller	Jeelani, Kumari, et al. 2011
Rosa pendulina L.	2n = 14	Zabarwan	Jeelani, Kumari, et al. 2011
Rubus caesius L.	2n = 14	Bandzoo	Jeelani, Kumari, et al. 2011
Rumex acetosa L.	2n = 12 + XY1Y2 + 0 – 3B	Kongwattan	Farooq, Lovleen, et al. 2013
Rumex dentatus L.	2n = 42, 120	Devpora	Farooq 2013
Rumex hastatus D.Don	2n = 18 + 0 – 1B	Rambiaa	Farooq 2013
Rumex nepalensis Spreng.	2n = 36, 40, 60, 80, 100, c.108–110	Srinagar and adjacent areas	Farooq 2013
Sarcococca saligna D.Don Muell	2n = 28 + 0 – 2B	Poonch	Saggoo et al. 2011
Saussurea albescens DC.	2n = 34	Thajwas	Malik 2012
Saussurea lappa C.B. Clarke	2n = 36	Gratnar	Siddique and Wafai 1993
Saussurea roylei DC.	2n = 32	Dibjan	Malik 2012
Saussurea taraxacifolia Wall.ex DC.	2n = 16	Apharwat	Malik and Gupta 2013
Saxifraga cernua L.	2n = 16	Thajwas,	Jeelani et al. 2012a
Saxifraga cernua L.	2n = 16	Razdan	Jeelani 2012
Saxifraga filicaulis Wall. ex Ser.	2n = 16	Thajwas	Jeelani 2012
Saxifraga sibirica L.	2n = 32	Thajwas	Jeelani, Kumari, et al. 2011
Scrophularia decomposita Royle ex Benth.	2n = 52	Razdan	Malik 2012
Sedum ewersii Ledeb.	2n = 72	Chumnai	Jeelani, Kumari, et al. 2011
Sedum heterodontum Hook. f. & Thomson	2n = 14	Gurez	Jeelani et al. 2012a
Sedum wallichianum Hook.	2n = 72	Thajwas	Jeelani, Kumari, et al. 2011
Senecio chrysanthemoides DC.	2n = 40	Harwan	Bhat et al. 1975
Silene conoidea L.	2n = 40	Tral	Jeelani, Rani, et al. 2011a
Silene edgeworthii Bocquet.	2n = 24	Pehalgam	Jeelani, Rani, et al. 2011a
	2n = 48	Gulmarg
Silene moorcroftiana Wall.	2n = 48	Aharbal	Jeelani, Rani, et al. 2011a
Silene nepalensis Majumdar	2n = 24	Tral	Jeelani, Rani, et al. 2011a
Sisymbrium orientale L.	2n = 12	Srinagar	Naqshi and Javeid 1976
	2n = 14	Sonmarg	Jeelani, Kumari, et al. 2011
Sium latijugam C. B. Clarke	2n = 24	Lidderwatt	Jeelani et al. 2012a
Stellaria media L.	2n = 26	Aharbal	Jeelani, Rani, et al. 2011a
Stellaria monosperma Buch.	2n = 26	Pehalgam	Jeelani, Rani, et al. 2011a
Stellaria semivestita Edgew.	2n = 26	Sonmarg	Jeelani, Rani, et al. 2011a
Strobilanthes alatus Nees.	2n = 32	Boniyar	Bhat et al. 1975
Swertia ciliata (D. Don ex G. Don) B.L. Burtt.	2n = 26	Aharbal	Malik et al. 2011b
Swertia petiolata Royle	2n = 26	GS 990b	Koul and Gohil 1973
Tanacetum longifolium Wall.	2n = 18	GS 3932	Koul and Gohil 1973
Tauscheria lasiocarpa (Fisch. ex DC.) Boiss.	2n = 14	Bodkharbu	Naqshi and Javeid 1976
Thymus linearis L.	2n = 26	Pampore	Malik et al. 2011b
Tulipa aitchisonii Hall	2n = 24	BW 1	Koul and Gohil 1973
Tulipa stellata Hook.	2n = 24	BW 2	Koul and Gohil 1973
	2n = 48	BW 3
Valeriana hardwickii Wall.	2n = 64	Aharbal	Malik 2012
Verbascum thapsus L.	2n = 34 + 0 – 2B	Pahalgam	Malik et al. 2011b
Veronica cana Wall. ex Benth.	2n = 46	Aharbal	Malik et al. 2011b
Veronica deltigera Wall.	2n = 16	Razdan	Malik 2012
Veronica persica Poir.	2n = 14	Pulwama	Malik 2012
Vicatia coniifolia DC.	2n = 44	Thajwas	Jeelani et al. 2012a
Yucca gloriosa L.	2n = 60	RN 34	Koul and Gohil 1973

1.2.1 The period 1969–1990

The plants of the Kashmir Himalaya were also extensively studied in the Indian Himalaya’s golden era of cytology. Koul and Khan (1969) discussed chromosome numbers of some Himalayan species of the genus Gagea and Koul and Gohil (1970) carried out cytology of the tetraploid Allium ampeloprasum with information on chiasma localization. Koul et al. (1972) made cytomorphological studies on six species of genus Papaver and reported rare chances of aneuploidy in the genus while monosomy and trisomy was displayed in the two species. Gohil and Bali (1973) proposed a new base number (x = 13) for the genus Gypsophila. In the same year, Koul and Gohil (1973) presented a cytological conspectus and recorded the chromosome counts of 101 species belonging to 26 families of angiosperms which include new counts for 23 species and one genus (Jaeschkea gentianoides Kurz). Koul and Wakhlu (1974) proposed a new base number (x = 6) for the genus Cheiranthus L. and in 1975 made cytological studies of Cyathocline lyrata (Koul and Wakhlu 1975). Subsequently, Koul and Wakhlu (1976) described chromosome numbers of 52 dicot species. Bhat et al. (1975) revealed new chromosome numbers for 12 species of angiosperms from different areas of the Kashmir Himalaya. Vij and Gupta (1975) targeted orchids and unravelled the chromosome numbers of Western Himalayan Orchidaceae. Koul, Wakhlu, et al. (1976a, 1976b) evaluated chromosome numbers of some flowering plants of Jammu in the Western Himalaya. Naqshi and Javeid (1976) also explored chromosome numbers of 15 dicot species of which 14 species belong to the family Brassicaceae and one to the family Apiaceae. Jeelani (1977) carried out cytomorphology of the genus Potentilla L. while Koul (1977) investigated cytomorphology of 15 taxa belonging to 13 species and two varieties of genus Iris. Mehra and Sharma (1977) studied the chromosome numbers, morphology and meiotic behaviour of the chromosomes of 30 grass taxa from the Kashmir Himalaya and also the cytological and morphological variability within the species in relation to environment. Wafai (1977) carried out extensive cytoembryological investigations on the species of the genera Tulipa and Fritillaria. Gohil and Kaul (1978) investigated the meiotic behaviour of two species of Papaver (P. somniferum and P. rhoea). Gohil and Koul (1978) revealed structural hybridity in Allium consanguineum. Koul and Wafai (1980) studied chromosome polymorphism and nucleolar organization in species of Fritillaria Linn. In the same year, Ahmad and Koul (1980) examined chromosome numbers of 47 species of Apiaceae. Pandita and Mehra (1981) presented a detailed karyotypic and chromosomal configuration for 13 wild species of Allium of the Kashmir Himalaya. They also described chromosomal polymorphism in A. schoenoprasm. Gohil et al. (1981) reported new chromosome numbers in different species for dicots. Rather (1982) carried out cytology and cytogenetics of some members of Polygonaceae of Kashmir, while Gohil et al. (1983) also studied comparative cytology, growth and grain composition of Western Himalayan buckwheats. Karihaloo and Koul (1983) evaluated cytogenetic studies in two garden varieties of Narcissus poeticus L. Mehra and Pandita (1984) carried out meiotic and karyotypic studies in five species of the family Alismataceae from the Kashmir Himalaya. Later, Pandita and Mehra (1984) continued the cytological studies from the same area on four taxa of the two families (Butomaceae and Hydrocharitaceae). Gohil and Ashraf (1984) revealed chromosome behaviour during micro- and megasporogenesis and the development of embryo sac in Vicia faba L. Jee et al. (1983, 1984, 1985, 1987) described chromosome numbers and cytology of some alpine–subalpine taxa. Kaul and Bakhshi (1984) studied the genus Artemisia in North-West Himalaya and reported chromosome counts for 18 species including new counts 2n = 3x = 27 for A. glauca and 2n = 18 for A. cashemirica. They further noticed diploidy, tetraploidy and hexaploidy in various accessions of A. vulgaris complex and diploidy and tetraploidy in A. roxburghiana complex. Ashraf (1985) studied 24 species of Astragalus collected from different altitudes (1500–4100 m) in Kashmir and Ladakh. Bakhshi and Kichloo (1985) observed B-chromosomes in wild populations of Artemisia maritima L. which also had higher mean chiasma frequency. Singh et al. (1985) made assessment of apple (Malus pumila Mill.) germplasm in Kashmir along with cytology of varieties Lal Farashi, Double Kesri, Hindwand Rakam, Kichhama Trail, Sabe Alif and Tursh Nawabi. Ashraf and Gohil (1986) revealed chromosome numbers of certain species of dicots, and later (Ashraf and Gohil 1989) for the first time investigated meiotic behaviour in 21 diploid species of the genus Astragalus L. Gohil and Rather (1986) carried out cytogenetic studies of members of Polygonaceae of Kashmir including buckwheats and Rheum. Hamal et al. (1986) described the nucleolar organising region (NOR) of chromosomes of Apiaceae. Wafai and Gouk (1986) performed a karyotype analysis of Himalayan tulips and described taxonomic rearrangement within subsection Clusianae. Koul and Gohil (1987, 1988) enumerated chromosome numbers of several species of angiosperms. Singh et al. (1987) studied pollen mother cell meiosis in 58 diploid varieties of apple under cultivation in the Kashmir valley. Later, Gohil and Koul (1988) revealed the cytology of Kashmir grasses with emphasis on morphological and chromosomal polymorphism in Paspalum distichum L. Ashraf and Gohil (1988a, 1988b) studied the cytology of Astragalus melanostachys Benth. ex Bunge with a new base number (x = 6) for the genus; in addition interpopulation differences were found in the karyotypes of three species of Astragalus L. In yet another attempt, Hamal and Koul (1988) made cytotaxonomic analysis of the Himalayan species of the genus Torilis (T. arvensis, T. leptophylla, T. stocksiana and T. japonica). Koul and Gohil (1989a, 1989b, 1989c) published a series of research papers on the cytology of Kashmir grasses. The same authors (Koul and Gohil 1990a, 1990b) described the cytogenetics of Dactylis glomerata, and studied cytomorphological polymorphism in Alopecurus aequalis. Jee, Dhar and Kachroo (1989) and Jee, Dhar, Wafai, et al. (1989) revealed the cytogeography of some endemic taxa of the Kashmir Himalaya, besides cytology of Senecio jacquemontianus of Asteraceae. Gohil and Koul (1990) made cytological studies on some Kashmir grasses with emphasis on cytomixis in three fodder grasses. Koul (1990) studied the chromatin transfer in PMCs of Alopecurus arundinaceus. Siddique et al. (1990) determined the chromosome complement and nucleolar organization in an anticancer drug plant (Podophyllum hexandrum Royle) and described the karyomorphology of the species for the first time.

1.2.2 The period 1991–2006

In this period Gohil et al. (1991) carried out meiotic chromosomes studies in Astragalus tibetanus and Agrostis pilosula. Koul and Gohil (1991a, 1991b) supplemented the cytological data on the tribe level by studying tribes Agrostideae, Festuceae and Paniceae of family Poaceae from the Kashmir Himalaya. They also studied the cytology of Poa trivialis L. Gupta et al. (1991) analysed five species of genus Torilis from the Kashmir Himalaya in order to understand the phylogenetic relationships between different species and the mode of karyotype evolution within the genus. Siddique (1991) made detailed investigation of the population structure, reproductive biology, karyology and pollen mother cell meiosis of three rare and threatened medicinal plants of the Kashmir Himalaya (Podophyllum hexandrum, Aconitum heterophyllum and Sanssurea lappa). Siddique and Wafai (1993) provided a new base number (x = 18) for the genus Saussurea and a new chromosome count, 2n = 36, in S. lappa C. B. Clarke. Ashraf and Gohil (1994) studied cytomixis and chromosome migration in Astragalus subuliformis. Tak and Wafai (1997) conducted chromosome enumeration and pollen mother cell meiosis in some wild and cultivated members of family Ranunculaceae. Lattoo, Khan, Bamotra, et al. (2006) studied how cytomixis impairs meiosis and influences reproductive success in Chlorophytum comosum.

1.2.3 The period 2006–2015

Recently, extensive cytomorphological studies on genus Impatiens from Himachal and the Kashmir Himalaya were conducted by Jeelani et al. (2010). The study included cytological works on some species for the first time as well as reporting aneuploid cytotypes for a few species. Jeelani, Rani, et al. (2011a) reported meiotic chromosome numbers of 50 populations comprising 12 species belonging to five genera of Caryophyllaceae from Western Himalaya. The chromosome numbers in eight species were reported for the first time globally, while those for Lychnis coronaria (n = 12) and Silene vulgaris (n = 24) were investigated for the first time from India. Jeelani, Rani, et al. (2011a) also reported an abnormal course of meiosis leading to reduced pollen fertility and differences in pollen grain size in many species. Jeelani, Kumari, et al. (2011) reported some new and varied chromosome numbers for 20 species from different areas of the Kashmir Himalaya. In yet another study, Jeelani, Rani, et al. (2011b) made extensive cytomorphological studies on Filipendula vestita and reported some morphovariants on the basis of hairiness in the leaves besides authenticating the chromosome number n = 7 for the species. Jeelani (2012) reported the first ever chromosome counts for 14 species along with B-chromosomes in Agrimonia eupatoria. He also reported 29 species (30 taxa) with varied chromosomal counts for the first time worldwide, and 19 species (22 taxa) cytologically investigated for the first time in India. The study further revealed that many taxa exhibited anomalous meiotic behaviour where cytomixis was found to be quite common and associated with various meiotic abnormalities in the meiocytes, ultimately leading to pollen sterility and formation of variable sized pollen grains. Jeelani et al. (2012a) evaluated chromosome numbers of 53 species belonging to 15 families of angiosperms from different high altitudes of Kashmir, while exploring the cytomorphology of Polypetalae of the flowering plants. Jeelani et al. (2012b) investigated male meiosis in Lotus corniculatus from different geographical areas of the Kashmir Himalaya and gave a new chromosome count, 2n = 4x = 24, in one cytotype of var. minor. Jeelani et al. (2012b) also reported abnormal meiosis in the diploid cytotype var. minor, in which, due to cytomixis, a few PMCs have been observed with a double chromatin mass and two nucleoli at diakinesis as well as PMCs double the size of normal ones; this may have played a role in the production of infraspecific polyploidy in the species. In addition, the authors studied detailed meiotic behaviour for 12 species of Brassicaceae from the Western Himalaya (Jeelani et al. 2013). Jeelani et al. (2014) also studied the cytogenetics of four species of genus Berberis.

Rani et al. (2010a) evaluated chromosome numbers of nine species belonging to nine genera and six families of Polypetalae from different areas of Western Himalaya. Rani et al. (2010b) also studied the effect of cytomixis in different populations of Clematis grata L. from the same area. Rani et al. (2011) made population based meiotic studies on several members of Ranunculaceae from selected geographical areas of Kashmir and Himachal Pradesh and reported new chromosome counts in Delphinium roylei (2n = 16) and D. uncinatum (2n = 16); different cytotypes in Caltha alba (2n = 32), Thalictrum foetidum (2n = 16) and T. foliolosum (2n = 28) as well as occurrence of B-chromosomes in Anemone obtusiloba (2n = 14 + 0 – 3B) and Clematis grata (2n = 16 + 0 – 1B) for the first time worldwide. They also reported chromosome numbers for many species for the first time from India, as well as numerous meiotic abnormalities. Rani, Kumar, et al. (2012) investigated 14 species of genus Potentilla L., an important medicinal plant growing in the Western Himalaya. New chromosome numbers were established in nine species for the first time, as well as chromosomal races for many diploid and polyploid cytotypes; the effect of cytomixis on pollen fertility for many of these species was also assessed. In yet another study, Rani et al. (2013) evaluated the cytomorphology of diploid and tetraploid cytotypes of Bupleurum lanceolatum, the tetraploid cytotype being reported for the first time.

Intraspecific cytomorphological diversity in Agrimonia eupatoria L. (Rosaceae) and genus Saxifraga L. from different parts of the Western Himalaya was observed by Kumar, Jeelani, Rani, Kumari, et al. (2011a) and Kumar, Jeelani, Rani, Gupta, et al. (2011b). In this study, a new hexaploid cytotype (2n = 84) for A. eupatoria was reported for the first time from the Kashmir Himalaya and new chromosome numbers for several species of Saxifraga. Cytology of five species of subfamily Papaveroideae was examined from different areas of Western Himalaya by Kumar et al. (2013a), where a new base number x = 7 was proposed for the genus Meconopsis, besides reporting on the occurrence of different meiotic abnormalities in the genera Meconopsis and Papaver. Kumar et al. (2013b) depicted meiosis in some species of the Ranunculus L. from the Western Himalaya, including Kashmir, with more emphasis on the cytomixis and other meiotic abnormalities in these species. Kumar et al. (2014) also made cytological investigations on different species of Apiaceae from Western Himalaya.

Malik et al. (2010) studied the genetic diversity in different population of Artemisia absinthium. The same group (Malik et al. 2011a) carried out exploration of cytomorphological diversity in the family Scrophulariaceae and reported new chromosomal counts for several species. Subsequently, Malik et al. (2011b) also reported new chromosome numbers for many gamopetalous angiosperms. Malik et al. (2012) studied cytomorphology of Elsholtzia ciliata Benth. (Lamiaceae) and revealed certain important morphological differences between the diploid and tetraploid cytotypes of the species. Through male meiosis, Malik and Gupta (2013) investigated some selected gamopetalous species and reported new/varied chromosome reports for 17 species belonging to six families, besides many meiotic abnormalities in such species. Malik et al. (2014) described the first study of the chromosomes of Mertensia echioides Benth. and observed anomalous meiosis as well as formation of 2n pollen grains in different populations of the species.

Farooq and Lovleen (2011) carried out meiotic studies in Phytolacca acinosa; the tetraploid chromosome count 2n = 36 represented a new cytotype for the species from India. Saggoo and Farooq (2011a) described cytology of two species of Rheum (R. emodi and R. webbianum). They reported structural heterozygosity in R. emodi for the first. Saggoo and Farooq (2011b) also investigated structural heterozygosity and varied chromosome numbers in Euphorbia pilosa L. along with other meiotic abnormalities. Saggoo et al. (2011) carried out meiotic studies on two species of Sarcococca from Jammu and Kashmir and Himachal Pradesh. They observed inter-bivalent size difference in both the species. They also reported the phenomenon of cytomixis in S. pruniformis for the first time along with B-chromosomes (0–2 B) for S. saligna. Farooq (2013b) carried out detailed meiotic studies at the population level in the members of Monochlamydeae and reported some new/varied chromosomal reports for certain species. He also carried out the biochemical and molecular analysis of selected cytotypes for Chenopodium album and Rumex nepalensis. Farooq, Lovleen, et al. (2013) investigated meiosis and behaviour of sex chromosomes in different populations of Rumex acetosa L. from the Kashmir and other parts of Western Himalaya. Farooq and Saggoo (2014) carried out cytomorphological investigations in Oxyria digyna Hil on a population basis from high altitudes.

Kaur, Mubarik, et al. (2011) reported new chromosome numbers for some monocots from Kashmir and other parts of the Western Himalaya. The same group (Kaur, Singh, et al. 2011) also carried out cytomorphological studies in some species of Setaria from the same area. Shabir et al. (2012a) reported chromosomal stickiness and breeding behaviour in Inula racemosa, a critically endangered herb of the Kashmir Himalaya. Recently Bala et al. (2015) made cytological observations of the genus Gentiana from Kashmir and other parts of Western Himalaya. Besides reporting meiotic abnormalities, some new chromosome numbers have also been depicted.

As well as cytological, cytomorphological and karyological examinations of plants of the Kashmir Himalaya, additional studies have been conducted by different workers to reveal the genetic relationships among the plants. Koul and Gohil (1970) described the allopolyploid nature of Allium ampeloprasum cultivated in Kashmir and observed that the shift from a multivalent to a bivalent type of pairing is attributed to the localization of chiasmata around the centromere in the species. Gohil and Koul (1973) described some adaptive genetic evolutionary processes accompanying polyploidy in the Indian alliums. The same authors (Gohil and Koul 1977) studied the cause of multivalent suppression in Allium ampeloprasum L. Later (Gohil and Koul 1983), they made detailed cytological studies on Allium tuberosum which was revealed to be an autotetraploid species with 2n = 4x = 32; they also found male meiosis in the progeny plants, which differ markedly in certain aspects from that of the parent plants. Wafai and Koul (1974) investigated the genus Tulipa with emphasis on the nature of triploidy in T. lanata. Koul, Wafai, et al. (1976) studied the genus Gagea, describing early embryology and endosperm development in hexaploid G. stipitata. Cytoembryology of the genus Gageas of Jammu and Kashmir State was studied by Wakhlu (1977). Singh and Wafai (1984) examined intravarietal polyploidy in the apple (Malus pumila Mill.) cultivar Hazratbali. Soodan et al. (1988) evaluated chromosome count, meiotic system and pollen viability of 10 distinct variants of almond and 11 cultivated varieties of peach. Hamal et al. (1986) studied the nucleolar organizing region in Apiaceae and established the exact number of nucleoli in various subfamilies and tribes through studies on the karyotype and nucleolus. Siddique, Wafai, et al. (1998) analysed the breeding system in Himalayan mayapple along with pollen mother cell meiosis and pollen production. They also studied the breeding system of Aconitum heterophyllum of the Kashmir Himalaya as well as cytogenetics, resource allocation and propagation of some important medicinal plants (Siddique, Beigh, et al. 1998). Sex differences in meiosis between Vicia faba L. and its close wild relatives were revealed by Koul et al. (1999). Lattoo et al. (2003) studied breeding behaviour, genetic system and reproductive effort in Sisymbrium irio under cultivation experiments. Lattoo, Khan, Dhar, et al. (2006) evaluated genetics and mechanism of induced male sterility in Andrographis paniculata and its significance. Gohil and Ashraf (2008) studied cytological parameters along with probable modes of evolution in Astragalus. Sharma and Gohil (2011) carried out cytological studies and found differential meiotic associations and additional chromosomes in the embryo-sac mother cells of Allium roylei Stearn from the Bani region of Jammu Province. This study resulted in identification of two variants, having embryo-sac mother cells (EMCs) with more than 16 chromosomes. Rather et al. (2012) examined meiotic behaviour and seed biology in Valeriana jatamansi, a high altitude endangered medicinal plant. They also studied in vitro seed germination and seed viability in the species. Sharma and Gohil (2013) studied the origin and cytology of a novel cytotype of Allium tuberosum.

2. Molecular marker analysis

Recent biotechnological techniques for analysing genetic diversity in plants have been used in a small number of studies of the plants of the Kashmir Himalaya. Verma et al. (2007) studied genetic diversity by using RAPD markers in Eremostachys superba Royle ex Benth. (Lamiaceae), an endangered Himalayan species. Dhar et al. (2008) used inter-simple sequence repeat (ISSR) and Random Amplified Polymorphic DNA (RAPD) markers to facilitate molecular characterization of the Withania germplasm. Lattoo et al. (2008) made a comparative analysis of genetic diversity using molecular and morphometric markers in Andrographis panicualata. Sultan et al. (2008) provided a strong correlation and association of values of morphological characters, phytochemical variables and DNA polymorphism data of Podophyllum hexandrum. They also documented that one accession, PSH–B from Keller, was significantly diverse from the other native genotypes. Kumar et al. (2009) described genetic variability among populations of apricot from Ladakh by using DNA markers. Narzary et al. (2009) investigated genetic variation in natural populations of Indian pomegranate from the Western Himalayan region of Jammu and Kashmir, Himachal Pradesh and Uttarakhand states based on ISSR markers. Characterization of genetic structure of alfalfa (Medicago sp.) from trans-Himalaya using RAPD and ISSR markers was explored by Xavier et al. (2011). According to this study, the pronounced genetic variation in Medicago spp. makes it a good plant for genetic research and there is great potential of breeding in the species for improved forage varieties. Shabir et al. (2012b) studied genetic variability in Inula racemosa using RAPD analysis. Mir et al. (2012) evaluated genetic diversity analysis by using RAPD markers in 24 apricot (Prunus armeniaca L.) genotypes with different geographic origins and revealed genetic relationships among these genotypes. Farooq (2013a) studied genetic diversity in different populations of Chenopodium album, Rumax dentatus and R. nepalensis by using RAPD markers. Genetic diversity in Podophyllum hexandrum and Hypericum perforatum using molecular and morphological markers was also investigated by Farooq (2013a). Somaclonal variations at the genetic level were also studied by using ISSR markers in Artemisia amygdalina – a critically endangered medicinal plant endemic to the Kashmir Himalaya (Khan et al. 2013).

3. Overall assessment

The Western Himalayan region is one of the 12 biogeographic regions of India and includes Jammu and Kashmir, Himachal Pradesh and Uttaranchal. This region comprises an alpine zone, and temperate, humid and warm climatic conditions. The main portion of Western Himalaya lies in Jammu and Kashmir State, comprising 67.5% of total Western Himalaya whereas Himachal and Uttarakhand comprise only about 17% and 15.5% respectively (Singh et al. 2002). The extreme variations in climate (subtropical to alpine cold desert), altitude and habitat have contributed significantly to the great diversity in the flora. Although Western Himalaya is relatively less varied in floristic composition than Eastern Himalaya, particularly in rhododendrons, bamboos, orchids and gymnosperms, it has a greater diversity of high altitude Gentians, Primulas, Saussureas, Saxifragas, etc. (Kumar and Chauhan 2006). There are more than 4500 species of flowering plants in Western Himalaya, the Asteraceae being the largest plant family, represented by c.540 species (Sharma and Singh 2001). Other important plant families include Poaceae, Fabaceae, Cyperaceae, Roasaceae, Lamiaceae, etc.

Himalayas span an area of 750,000 km² and contain about 10,000 plant species; interestingly, the Kashmir Himalaya alone contributes nearly 2000 (20%) of the plant species within just 2.15% (15,948 km²) of the total land area (Dar et al. 2002). It harbours economically, medicinally and ethnobotanically important angiosperms. Of more than 3000 species of angiosperms reported from the area, 467 are endemic to this region (Dhar 2002). The Kashmir Mountains are extremely rich in medicinal and aromatic plant species. In a recent review of floristic diversity in Jammu and Kashmir, Singh et al. (1999) reported 4439 taxa comprising 4252 species in 1220 genera and 189 families of angiosperms. According to Dhar and Kachroo (1983), the number of species in alpine sub-alpine regions of the Kashmir Himalaya is 1610, distributed within 64 families of dicotyledons and monocotyledons, excluding family Gramineae. Among these, Polypetalae is represented by a total of 787 species belonging to 169 genera and 27 families; Gamopetalae includes 804 species of 137 genera in 23 families; and Monochlamydeae contains 161 species including 34 genera and eight families.

Cytology is believed to be a dependable tool for solving taxonomic problems and for elucidating systematic relationships, phylogeny, and evolution of related plant groups. Information including chromosome number, structure, morphology and behaviour during mitotic and meiotic division have been of considerable value in understanding inter relationships and delimitation of taxa (Iwastubo and Naruhashi 1991). Therefore, these factors are used as classificatory criteria in the same manner as the morphological characters, as the chromosomes have direct relation to the genetic system of which they are an integral part (Den Hartog et al. 1979). Information on the cytogenetic system operating in a species can serve as a basis for conclusions on taxonomy and genetic diversity. The chromosome number is known to characterize a species or a group of species and is specific for a given species.

3.1 Chromosome numbers

To date, c.550 species belonging to over c.190 genera and c.55 families of angiosperms have been determined cytologically from the different parts of the Kashmir Himalaya. The chromosome numbers are 2n = 10–120. The frequency of the chromosome numbers vary considerably, with 2n = 18 (13.73%) and 16 (13.46%) found in most of the species followed by 2n = 14 (7.96%), 2n = 32 (7.41%), 2n = 12 (5.49%), 2n = 34 (4.94%), 2n = 28 (4.12%), 2n = 40 (3.84%), 2n = 22 (3.29%), 2n = 24 (3.02%), 2n = 26 (2.74%), 2n = 54 (2.74%), 2n = 56 (2.74%), 2n = 72 (2.19%); while the frequencies of 2n = 28, 42, 120, 30,10, 44, 48 (1.64–1.09%) are low; 2n = 60, 80,100, 46, 52, 84, and 96 are rarely encountered. The present investigation reveals that c.50 species have been cytologically reported for the first time at global level along with varied chromosomal reports for c.110 species from the Kashmir Himalaya. The genus Jaeschkea has also been cytologically determined for the first time worldwide from the Kashmir Himalaya. Of these cytologically determined species, nearly 65% species are diploids and the rest are polyploids.

3.2 Base numbers

Although the base chromosome numbers of angiosperms vary from x = 2 in Haplopappus of Asteraceae to x = 43 in member of Winteraceae, Stebbins (1950) is of the view that only x = 10 or lower numbers are of primary origin and all others are secondary basic numbers. According to Raven and Kyhos (1965), Ehrendorfer et al. (1968), and Raven (1975), the primary base number of angiosperms is x = 7 and all others are of secondary origin. However, Stebbins (1950, 1971) suggested that x = 5–8 are the primary basic numbers for the flowering plants on the whole. According to Grant (1982a, 1982b), x = 7 as the base number for the flowering plants is not supported by the existing chromosomal data because there is high incidence of other numbers as well. However, there is a possibility that x = 8 is an ancestral basic number because of its high frequency of occurrence (Grant 1982a). From the present investigations, it has been observed that new base numbers have been proposed for Astragalus, Cheiranthus, Gypsophila, Meconopsis and Saussurea from the Kashmir Himalaya. The base numbers x = 7 and x = 8 are both common, followed by other numbers (x = 6, 9, 10, 11, 12, etc.) and most of these genera are polybasic, followed by monobasic and dibasic while tribasics are least represented in the Kashmir Himalaya. From these cytological observations, it can be concluded that speciation and co-evolution within this group of plants (angiosperms) in the Kashmir Himalaya have been possible as a result of increase in variability through changes in the base numbers, as well as numerical and structural changes in chromosome numbers. The various cytological phenomena such as protoautoploidy, amphiploidy, ascending and descending dysploid have been suggested as being responsible for variability of basic numbers in these genera. The wide range of chromosome numbers observed in many genera/species marks a significant role of aneuploidy and polyploidy in the evolution of various taxa at the generic and species level.

3.3 Meiotic abnormalities

In past few decades, most of the species from the Kashmir Himalaya have been worked out for their chromosome numbers only. However, as mentioned earlier in this review, recent studies have observed the details of meiotic course for the Kashmir Himalayan species as well. The various meiotic anomalies in these species include cytomixis, chromatin stickiness, interbivalent connections, multivalents, formation of unoriented bivalents, chromosomal bridges and laggards, multipolarity, and non synchronous meiotic divisions as well as micronuclei, monads, dyads, triads or polyads during microsporogenesis. In some cases, it has been observed that all the populations of a particular species are meiotically abnormal, while only some populations of other species depict such anomalous behaviour. The occurrence of different meiotic abnormalities at intra-population level indicates intraspecific genetic diversity among those species. Such genetic differences have been seen in different plant species (Baptista-Giacomelli et al. 2000; Sheidai et al. 2003; Gupta et al. 2009; Kumar and Singhal 2011; Rani, Gupta, et al. 2012) from other parts of the country and world. Among these meiotic anomalies, the chromosomal laggards and bridges persist in most of the species followed by cytomixis. The later has been found to be predominating in the members of Ranunculaceae and Caryophyllaceae, while quadrivalent formation has mostly been observed in the species of Asteraceae and Poaceae. Meiotic abnormalities have been reported for c.200 species with highest frequency of all abnormalities in the members of Aconitum, Anemone, Artemisia, Astragalus, Caltha, Centaurea, Clematis, Delphinium, Filipendula, Lychnis, Meconopsis, Papaver, Ranunculus, Rheum, Saxifraga and,Swertia. However, the members of families Apiaceae, Brassicaceae, Crassulaceae, Fumariaceae and Geraniaceae show minimal abnormalities.

Although most of these meiotic abnormalities have been observed in plants at higher altitudes, meiotic abnormalities do occur among plant species at lower altitudes as well. The effect of these meiotic anomalies on the pollen fertility and pollen grain size of these species has been evaluated (Gupta et al. 2009; Kumar and Singhal 2011; Rani, Gupta, et al. 2012). Cytomixis, along with other meiotic abnormalities, reduces the pollen fertility in most of these species along with the formation of variable sized pollen grains. Such studies have also been carried out in other parts of Western Himalaya (Gupta et al. 2009; Kumar and Singhal 2011; Rani, Gupta, et al. 2012) as well as other parts of the world (Sheidai et al. 2003; Sheidai and Fadaei 2005). The formation of unreduced gametes has also been observed from the Kashmir Himalaya. According to Villeux (1985) unreduced gametes are of evolutionary significance as they can lead to the production of plants with higher ploidy level through polyploidization.

Meiotic abnormalities are cytological manifestations of either chromosomal disparities or the specific genetic effect of mutant genes such as synaptic mutants (Bala et al. 2010). According to these studies, the meiotic abnormalities form an integral part of the meiotic system of these species, particularly for higher altitude species. From other parts of Western Himalaya, Kumar and Singhal (2011) are of the opinion that harsh climatic conditions at higher altitudes in Lahul-Spiti are responsible for various meiotic abnormalities in the majority of the plants of the area, which has affected the genetic constitution and viability of male gametes. Although such statements regarding the meiotic abnormalities of plants of the Kashmir Himalaya are lacking, they are equally applicable to the plants growing at higher altitudes in the Kashmir Himalaya. As per the literature regarding the cause of meiotic abnormalities in the Kashmir Himalaya, genomic factors have been suggested to be responsible for these meiotic abnormalities; a few studies consider environmental factors responsible as well. However, according to other investigations across the world, meiotic abnormalities also occur due to physiological control (Bahl and Tyagi 1988), chemicals and herbicides (Haroun 1995), changes in biochemical processes (Koul 1990), pollution (Haroun et al. 2004), temperature (Basavaiah and Murthy 1987), chemical mutagens (Bhat et al. 2006) and stress factors as well as genetic control (Malallah and Attia 2003). The observed regularity in the meiotic chromosome behaviour of most of these species indicates a high degree of fertility. This information can help in the prediction of the possible outcome of hybridization with related species and in evaluating the possible gene transfer from one species to another. For example, chromosome pairing or chiasma frequency measures the potential for intra-chromosomal recombination. Furthermore, aberrant chromosome behaviour during meiosis leads to sterility and therefore prevents the recovery of recombinants. The meiotic and mitotic irregularities might have led to structural and numerical variations in the chromosomes of these species as previously reported by Roy (1998). Individuals with the same chromosome number but with differences in karyomorphological details reflect the ongoing evolutionary processes at micro level.

Very little work is available on the variability in the active ingredients of medicinal plants with altitude in the Kashmir Himalaya. Recently, it has been revealed in the different cytotypes of Rumex nepalensis that anthraquinone content increases with increase in the ploidy level and increasing altitude (Farooq, Pandith, et al. 2013). However, a few studies are available that show an increase in the ploidy level along the altitude gradient, along with increasing morphological complexity. Some studies also reveal significant differences in the morphology of diploid and polyploid cytotypes of particular species in relation to geographical distribution. Accordingly, the cytotypes of these species show mild gigantism in vegetative and reproductive characters as compared to their diploid counter parts. Such observations seem to be in complete agreement with the earlier works made in other parts of Western Himalaya (Kumar and Singhal 2011) and worldwide (Luttikhuizen et al. 2007; Zlesak 2009; Omidbaigi et al. 2010).

4. Concluding remarks

Plants of the Kashmir Himalaya have significant level of intraspecific variability not only in chromosome numbers but also in meiotic behaviour, which is reflected in the morphological traits of the species, as well as active principle variability in medicinal plants. Polyploidy seems to have played an important role in the evolution of these species from the Kashmir Himalaya, as is evident from nearly 35% of the species existing at various polyploid levels, predominantly tetraploids but some of the species exhibiting still higher levels as well. Hence, the review clearly indicates the desirability of further cytomorphological surveys of such restricted regions with a view to contributing more to this discipline which makes a backbone to understand relationships among taxa and providing a base for future plant improvement programmes. It is also experienced that, there is need for chemical characterization and DNA profiling of intraspecific cyto/ morphovariants of economically important species particularly medicinal ones, for their proper exploitation and formation of effective conservation strategies. The knowledge of intraspecific variability of these species point out the existence of genetic diversities. The selection and further multiplication of better performing types can boost the economy of the state and country.

Acknowledgements

The authors are grateful to the University Grants Commission, for the award of Dr D. S. Kothari Post-Doctoral Fellowship to Dr Syed Mudassir Jeelani. We are highly thankful to the head of the Division of Floriculture, Medicinal and Aromatic Plants (FMAP), SK University of Agricultural Sciences and Technology Kashmir, Jammu and Kashmir, India, for necessary support. Thanks are also due to the head of the Department of Botany, Punjabi University Patiala, India, for the necessary library facilities.