Morphological and molecular features of a Chara vulgaris population from desert springs on the Sinai Peninsula (Springs of Moses, Egypt)

Figures & data

Figure 1. Ayun Musa thermal springs (A, B). Chara vulgaris population Linn. (C). C. vulgaris from the Springs of Moses cultivated in a glass vessel on a layer of fine sand, and showing nodes, internodes, and lateral branchlets (D).

Table 1. Comparison of morphological and ecological characteristics of Chara vulgaris Linn. in this study and in reference literature.

Diagnostic features	Krause (1997)	Caisová and Gąbka (2009)	In this study
			Freshly sampled material	Cultured Material
Stem	Up to 40 cm tall, axis 0.5–1 mm thick	5–70 cm tall, slender, grey to dark green, moderately to heavily encrusted	Green in colour, slender, delicate, 40–50 cm tall	Bright green in colour, slender, more delicate, 20–25 cm tall
Cortex	Diplostichous, partially isostichous, single at the lower cortical cells (aulacanthous)	Diplostichous or isostichous, aulacanthous	Diplostichous, aulacanthous (spines usually present on the primary cortical rows, while secondary rows are larger), corticated. Cortical cells are distinctly spirally coiled (one large siphon cell and 13–17 cortical cells)	The same as freshly collected material
Spine cells	Often as papilla or not visible, but sometimes as long as the shoot diameter	Variable, solitary or geminate, rudimentary, papilous or elongated to the axis diameter	Variable, scattered, solitary, short, papilliform or elongated to the axis diameter, especially on older stems	The same as freshly collected material
Stipulodes	Obtuse in 2 closely placed rows, one-fifth as long as the branchlet diameter	Variable, in 2 rows	Well-developed, short, oblong-ovate in shape in 2 rows	The same as freshly collected material
Internodes	In shallow water, shorter than the branchlets	Firm, corticated, 1–6 times the length of the branchlets	Corticated, clearly variable in length (2.5–8 cm long) comparing to the branchlets (mostly 1–4 times as long as branchlets), 472–602 μm in diameter	Corticated, shorter (8 mm-1.5 cm) mostly 1–3 times the length of the branchlets, 250–325 μm in diameter
Branchlets	5–7 in a whorl, at young shoots bent towards the axis and otherwise spread and often winded, 3–5 corticated segments and ecorticated end parts may also be present and sometimes longer than the corticated parts	6–10 in a whorl, corticated or partly ecorticated and often upper 2–3 segments may be ecorticated	8 in a whorl, 378–448 μm wide, with three corticated segments and ecorticated end parts commonly present and distinctly longer than the corticated parts	8 in a whorl, usually curved inwards for the newly formed ones. Mature ones are spread, 100–110 μm wide, with three corticated segments and ecorticated end parts present and longer than the corticated parts.
Terminal cells of branchlets	Narrow and short, easily breaking off	Variable, tapered, conical, blunt or sharp; rarely forming mucro or reduced	One sharply conical cell, 80–307 μm long x 50–90 μm wide	Just 1 short terminal conical or slightly sharp conical cell, 95–105 μm long x 60–70 μm wide
Bracteoles	4–5, significantly longer than the oogonium	Often well-developed, variable in length	4, well-developed, clearly much longer than the oogonium, about 4–12 times the length of oogonium	4, well-developed, longer than the oogonium, about 2–4 times the length of oogonium
Plant sex	Monoecious, (1-)3–4 pairs per branchlet	Monoecious, conjoined at 1–4 branchlet nodes, without mucus	Monoecious, 3–4 pairs of gametangia per branchlet	The same as freshly collected material
Oogonium	Without corona (crown cells): 500–800 μm long x 350–500 μm wide, 12–15 turns. Crown cells: 200–300 μm long x 100 μm wide, cells blunted, leaning together	Solitary or geminate, 500–1100 μm long x (280) 335–525 (660) μm wide	Solitary, dark green in young state to dark brown-black in mature state, with 5 terminal crown cells, conjoined at the 1–4 lowest branchlets nodes. Without crown cells: 366–590 μm long x 355–437 μm wide, with 10–11 turns. Crown cells: 83–118 μm long x 71–80 μm wide, cells blunted, leaning together	The same description as in freshly collected material. Without crown cells: 650–710 μm long x 355–450 μm wide, with 10–11 turns. Crown cells: 90–100 μm long x 80–95 μm wide
Antheridium	250–450 μm in diameter, bright orange in color	Small and solitary, up to 500 μm in diameter	Solitary, spherical, orange in color, 366–375 μm in diameter, observed very rarely	Solitary, spherical, bright orange in colour, 345–400 μm in diameter. Usually present on the newly formed branchlets at the stem apex. They are usually shed early and are not obviously dominant on the branchlets like oogonia
Mature oospore	Small, brown to dark brown, 11–14 ribs. 420–650 μm long x 250–350 μm wide	Dark brown or black in colour with stripes	Not observed	Brown-dark brown to black, 510–590 μm long x 270–350 μm wide, with a pointed apex and marked stripes (11–13)
Other remarks	Calcified in old age, gametangia present from summer to autumn	Highly polymorphic	Materials were present in heavy mass growth at the sandy bottom of the spring	The vegetative growth of cultured thalli was obviously negatively affected by high summer temperature
Ecology	Mostly in fresh water, occasionally in the discharge of salt springs and brackish water near the sea; preferably in shallow initially ß-mesosaproben water bodies, hardly in lakes; more resistant to eutrophication than other members of Characeae	Common in all types of fresh water, especially in anthropogenic reservoirs, occasionally in brackish waters	Freshwater with anthropogenic effect
Distribution	In all parts of the world. In the Central Sahara, Chara vulgaris growing in wells of the oases. C. Vulgaris occurs most often in landscapes with calcareous substrate and many small water bodies	Commonly worldwide, records from South America, Africa, Asia, Europe rarely on remote oceanic islands	Springs of Moses, Sinai Peninsula (Egypt)

Table 2. Key diagnostic features of Chara vulgaris from the Springs of Moses in freshly collected and cultured materials.

Diagnostic features			Freshly collected materials	Cultured materials	P-value
Stem length (cm)			45.51 ± 3.22	22.9 ± 1.65	0.005*
Internodes	Length (mm)		56.8 ± 17.5	12.12 ± 2.52	0.001*
	Diameter (μm)		563.57 ± 36.51	292.42 ± 25.5	0.001*
Width of branchlets (μm)			410.64 ± 19.22	105.74 ± 3.65	0.001*
Terminal cells	Length (μm)		173.88 ± 66.27	100.26 ± 4.05	0.042*
	Width (μm)		64.7 ± 9.87	64 ± 3.78	0.18
Length of bracteoles (mm)			4.71 ± 1.16	1.42 ± 0.54	0.021*
Oogonia	Length (μm) (without crown cells)		440.32 ± 75.38	667.7 ± 21.48	0.035*
	Width (μm)		375.64 ± 28.62	400.4 ± 21.94	0.072
	Crown cells	Length (μm)	96.26 ± 11.22	96 ± 4.04	0.093
		Width (μm)	75.24 ± 3.7	86 ± 5.62	0.081
Diameter of antheridia (μm)			368.86 ± 3.12	361.1 ± 18.91	0.31

Data are expressed as mean (n = 50) ± S.D.

^* Difference is significant at p ≤ 0.05.

Figure (2–5). Some diagnostic characteristics of freshly sampled material of Chara vulgaris Linn. in this study. Scale bar = 1 cm (Fig. 2); scale bar = 100 μm (Fig. 3); scale bar = 1 mm (Fig. 4); scale bar = 200 μm (Fig. 5). (2) Macroscopic habitus of thallus showing long internodes. (3) Terminal branchlet cell. (4) Overview of branchlet node showing four well-developed bracteoles clearly much longer than oogonium. (5) Branchlet node with solitary dark-brown mature oogonium and absence of antheridium.

Figure (6–31). Diagnostic features of cultured material of Chara vulgaris Linn. in this study. Scale bar = 1 cm (Figs. 6–11); scale bar = 100 μm (Figs. 12–18, 20–21, 23, 30–31); scale bar = 200 μm (Figs. 19, 24–29); Scale bar = 0.5 mm (Fig. 22). (6, 7) Macroscopic habitus of Chara vulgaris thallus. (8) Part of thallus stem showing antheridia usually present at the newly formed branchlets at the stem apex (arrowhead), while oogonia are only still present on old branchlets (double arrowheads). (9–11) Whorls of branchlets usually curved inwards for the newly formed ones (arrowheads). (12–14) Nodes showing obtuse stipulodes in two closely placed rows (arrowheads). (15–18) Diplostichous, aulacanthous spine cells (arrowheads indicat spines present on the primary cortical rows, while double arrows depict larger secondary rows). (19) Elongated spine to the axis diameter in older stem. (20, 21) Terminal branchlet conical cells. (22) Fertile branchlet showing mature oogonia only and shedding antheridia. (23, 24) Fertile branchlet node with immature dark-green oogonium and solitary, spherical orange antheridium. (25, 26) Dark-black mature oogonia at branchlet node. (27, 28) Brown mature oospores with marked stripes. (29) Black mature oospore with pointed apex. (30–31) Internode cross-sections showing central siphon cells and cortical cells.

Figure 32. Maximum likelihood tree determined on the basis of partial matK gene sequences of 22 Chara samples. Outgroup = Nitellopsis obtusa (AY170447). The specimen from this study is marked in bold. Bootstrap values above 50 are included. The scale bar indicates 5% sequence divergence.

Map 1. Location of the sampling site in the Sinai Peninsula in Egypt.

Table 3. List of Chara individuals used for the phylogenetic analysis. All samples were taken from herbarium collections. In addition, two sequences from GenBank were included in the phylogenetic analyses (see Fig. 32).

Identification	Authority	Field ID	Coll. year	Country
Chara aspera	Willd. 1809	MB 14	2000	Germany
		MB 73	2001	France
Chara contraria		T51	2009	Norway
		MB 22	2005	Greece
		S54	2006	Canada
		MB 82	2000	Germany
Chara galioides	De Candolle 1813	MB 81	2001	France
Chara globularis	Thuill. 1799	MB 29	2005	Sweden
		17	2009	Macedonia
Chara intermedia	A. Br. in Br., Rab. and Stiz. 1859	MB 86	2001	Germany
		MB 85	2003	Sweden
		35	2012	Poland
Chara tomentosa		T40	2010	Norway
		MB7	2004	Germany
Chara virgata	Kütz. 1834	50	2012	Germany
		39	2012	Finland
Chara vulgaris	L. 1753	MB 16	2005	Greece
		MB 59	2001	France
		S 14	2009	Poland
		S 58	2013	Egypt

Krause, W. 1997. “Charales (Charophyceae).” In Süsswasserflora von Mittleuropa. 18 vols, edited by H. Ettl, G. Gärtner, H. Heynig, and D. Mollenhauer, 202. Jena: Gustav Fischer Verlag.

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Caisová, L., and M. Gąbka. 2009. “Charophytes (Characeae, Charophyta) in the Czech Republic: Taxonomy, Autecology and Distribution.” Fottea 9 (1): 1–43.10.5507/fot.2009.001

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