Contribution of structural and functional modifications to wide distribution of Bermuda grass Cynodon dactylon (L) Pers.

Abstract Fifteen ecologically distinct ecotypes of Bermuda grass Cynodon dactylon (L.) Pers. were evaluated for key factors involved in its widespread distribution in different environmental conditions. Ecotypes collected from saltmarshes showed better vegetative growth, accumulation of inorganic ions (Na+, K+ and Ca2+), compatible solutes (proline and glycine betaine) and higher activities of antioxidative enzymes (superoxide dismutase, catalase and peroxidase) than all other ecotypes. Increased root and stem radii, sclerification intensity, aerenchyma formation, storage parenchyma (pith and cortex), vascular bundle area and metaxylem area were also observed in the same ecotypes. Notable leaf modifications included development of thicker leaves with intensive sclerification around vascular bundles and wide metaxylem vessels. Ecotypes collected from saline dryland featured large leaf area, increased level of glycine betaine, intensive sclerification and wide leaf xylem vessels. Ecotypes from deserts/semi-deserts exhibited higher soluble proteins and carotenoids, thick epidermis of stem and leaf blade, large cortex and broad metaxylem vessels in root, thick leaf sheaths, well-developed bulliform cells and stomata more oriented towards abaxial surface. Ecotypes collected from river or canal bank possessed high chlorophyll content (chl a, chl b and total chl), epidermal and storage parenchyma cell size, endodermal thickness in root, metaxylem area in stem, sclerification in leaf sheath and increased stomatal density on adaxial leaf surface. In conclusion, ecotypes collected from different habitats exhibited explicit variation in structures (internal modifications) and functions (physiology) due to environmental variability that may contribute to the wide distribution of C. dactylon.