Contribution of structural and functional adaptations of hyper-accumulator Suaeda vera Forssk. ex JF Gmel. for adaptability across salinity gradients in hot desert

The role of ionic excretions and hyper-accumulation of salts through alterations of structural and functional traits in five populations of Suaeda vera Forssk. ex J.F. Gmel., a halophytic salt-indicator species of saline environments, was explored. Differently adapted populations of S. vera exhibited specific structural and functional responses for the survival in hypersaline conditions. Better growth in population from moderately saline habitat (25-30 dS m(-1)) was linked to high shoot and root K+ and increased ion selectivity (K+/Na+ and Ca2+/Na+). Increased excretion of Na+ and Cl- with increasing salinity level was a critical mechanism in maintaining ionic balance. Drastic differences were observed for anatomical characteristics in populations inhabiting differentially salt-affected lands. The plants from highly saline sites were characterized by narrow metaxylem vessels, low proportion of cortical parenchyma, and reduced phloem area leading to stunted growth. Contrariwise, root area significantly increased due to high proportion of sclerified xylem tissue, which was associated with easier conduction of solutes and protection of roots from collapsing. Root sclerification particularly at the highest salinity regime was a key factor in the survival of this species in salt-affected compact soils. Leaf anatomical characteristics showed reduction with increasing salinity, but the leaf thickness responded otherwise. This contributed to increased leaf succulence because of high proportion of storage parenchyma in populations colonizing hyper-saline habitats. It was concluded that moderate salinity conditions were more suitable for the growth of S. vera, though some populations of this species were able to tolerate much higher salinity levels.

Automated summary

This study explored the role of ionic excretions and salt hyper-accumulation in the survival of Suadea vera in saline environments. Different populations exhibited specific structural and functional adaptations. Moderate salinity conditions were found to be more suitable for growth, but some populations were able to tolerate higher salinity levels. Anatomical differences were observed in plants from different salt-affected lands, with narrow vessels and reduced phloem area in highly saline sites.