Thriving in extremes: Adaptability potential of desert cotton Aerva javanica to hyper-arid saline conditions

Aerva javanica is a typical C₄ recretohalophyte predominantly found in the hyper-arid saline regions of the Cholistan Desert (Pakistan) and its adjoining areas. Ten populations were gathered from natural habitats to assess adaptive strategies, aiming to rehabilitate hypersaline environments. Desert populations have thicker epidermal layers, enlarged oil glands, stomata, and trichomes, along with reduced thickness of the leaf midrib and lamina, which are essential for surviving extreme aridity. Their deeper roots and increased biomass indicate resistance to environmental stress. Semi-desert populations feature enlarged vascular bundles and thicker leaves for better water conservation, while agricultural populations have smaller stomata and trichomes and larger leaves with longer shoots. Key features include glandular and non-glandular trichomes, oil gland formation, a bundle sheath cell layer indicative of C₄ physiology, vascular region partitioning by internal parenchyma, and variations in stomatal size and shape, all enhancing species survival in harsh desert conditions. Principal component analysis indicated that trichome area and stomatal area were positively correlated with soil sodium and electrical conductivity, while trichome number and stomatal density correlated with soil pH. Overall, the adaptive traits of A. javanica could provide key insights for breeding salt-tolerant crops, facilitating the successful cultivation of saline lands.