Physiological and metabolic adjustments in the xero-halophyte Haloxylon salicornicum conferring drought tolerance

Drought is one of the most catastrophic abiotic stresses that affects global food production severely. The present work investigates the metabolic and physiological adaptation mechanisms in the xero-halophyte Haloxylon salicornicum to counter the effects of drought. This xero-halophyte can withstand a prolonged drought period of 14 days and recovered within 7 days of irrigation with minimal effects of drought on growth and physiological parameters. Photosynthetic parameters such as P-N, g(s), and E decreased significantly, whereas WUE increased under drought condition. Drought induces a significant decline in the Fv/Fm ratio. However, the value of Fv/Fm ratio successfully recovered within 7 days of the recovery period. Differential regulations of various antioxidative enzymes increase the drought tolerance potential of H. salicornicum. The metabolomic analysis of H. salicornicum shoot identified 63 metabolites: 43 significantly increased and 20 significantly decreased under drought conditions. These metabolites mainly include amino acids, organic acids, amines, sugar alcohols, sugars, fatty acids, alkaloids, and phytohormones. The metabolites that have a significant contribution towards drought tolerance include citric acid, malic acid, tartaric acid, d-erythrose, glyceric acid, sucrose, pentanoic acid, d-mannitol, ABA, and palmitic acid. KEGG pathway enrichment analysis showed that the vital drought-responsive metabolic pathways mainly include galactose metabolism, aminoacyl-tRNA biosynthesis, glyoxylate and dicarboxylate metabolism, citrate cycle (TCA cycle), alanine, aspartate, and glutamate metabolism. This study offers comprehensive information on physiological, antioxidative and metabolic adaptations and overall drought tolerance mechanisms in H. salicornicum. The information gained from this study will provide guidance to plant breeders and molecular biologists to develop drought-tolerant crop varieties.

Automated summary

This study investigates the metabolic and physiological adaptation mechanisms in the xero-halophyte Haloxylon salicornicum to counter the effects of drought, revealing the plant's ability to withstand and recover from prolonged drought periods. Metabolomic analysis identified key metabolites contributing to drought tolerance, while KEGG pathway enrichment analysis highlighted crucial metabolic pathways involved in drought response. The findings offer comprehensive information on physiological, antioxidative, and metabolic adaptations in H. salicornicum, providing valuable insights for the development of drought-tolerant crop varieties.