Cytopalynological studies in some Convolvulaceae members from northern Western Ghats, India

ABSTRACT

This paper presents a cyto-palynological study of four species of Convolvulaceae from the northern Western Ghats of India. Ipomoea clarkei and Operculina tansaensis are endemic to the region, whereas I. diversifolia and O. turpethum show wide distribution. A new cytotype with 2n = 28 was reported for I. diversifolia. The chromosome number 2n = 30 in O. turpethum was in conformity with earlier reports. Chromosome numbers for I. clarkei and O. tansaensis (both with 2n = 30) were reported for the first time. Meiosis was found to be normal. At diakinesis 14 bivalents were observed for I. diversifolia while I. clarkei and O. tansaensis showed 15 bivalents. In all the species, chromosomes were small with median region centromeres. The largest chromosome was recorded in I. clarkei (2.15 ± 0.25 µm) and the shortest for I. diversifolia (1.62 ± 0.19 µm). The karyotypes were symmetrical and exhibited Stebbins’s 4a category. Pollens were pantoporate-echinate in both the Ipomoea species and tricolpate-smooth in Operculina.

Abbreviations: THL, total haploid chromosome length; CV_CL, coefficient of variation of chromosome length; M_CA, mean centromeric asymmetry; L, length of the largest chromosome; MCL, mean chromosome length; r, mean arm ratio; R, ratio between the largest and the smallest chromosome of the complement; St, type of asymmetry.

KEYWORDS:

• Chromosomes
• karyotype
• narrow endemics
• pollen
• scanning electron micrographs

Acknowledgements

The authors wish to express sincere thanks to the Head, Department of Botany, Shivaji University, Kolhapur for providing all necessary facilities. One of the authors (SDP) is also grateful to DBT for financial support under ‘Network Programme for Enrichment and Update of Plant Chromosome Database for Spermatophytes and Archegoniate’ vide sanction letter BT/PR7866/NDB/39/272/2013 dated 23 March 2015.

Disclosure statement

No potential conflict of interest was reported by the authors.