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Azospirillum lipoferum FK1 confers improved salt tolerance in chickpea (Cicer arietinum L.) by modulating osmolytes, antioxidant machinery and stress-related genes expression

El-Esawi, Mohamed A., Al-Ghamdi, Abdullah A., Ali, Hayssam M., Alayafi, Aisha A.
Environmental and experimental botany 2019 v.159 pp. 55-65
Azospirillum lipoferum, Cicer arietinum, adverse effects, ascorbate peroxidase, biomass production, carotenoids, chickpeas, chlorophyll, crops, electrolytes, flavonoids, gas exchange, genes, hydrogen peroxide, malondialdehyde, phenols, photosynthesis, rhizosphere bacteria, salinity, salt stress, salt tolerance, sodium chloride, soil, stress tolerance, superoxide dismutase
High salinity restricts crop growth and yield. Plant growth-promoting soil rhizobacteria boost crops growth and ameliorate the adverse effects of salt stress through regulating several physiological, biochemical and molecular processes. This study investigated the effects of Azospirillum lipoferum FK1 strain on chickpea (Cicer arietinum L.) growth and performance under saline conditions (0, 75 and 150 mM NaCl). Salt stress adversely decreased growth, biomass yield, nutrient acquisition, chlorophyll content, gas exchange parameters and total phenolic and flavonoid content of chickpea plants. However, salt stress induced the carotenoid content, osmolytes level, electrolyte leakage, H2O2 content, malondialdehyde level, and levels of enzymatic and non-enzymatic antioxidants in chickpea. Moreover, the expressions of three antioxidants genes (CAT, APX and SOD) and six genes conferring abiotic stress tolerance (PAL, PPO, CHS, CHI, DREB2A and IFS) was induced by high salinity. On the other hand, inoculation of salt-treated chickpea plants with Azospirillum lipoferum FK1 significantly improved nutrient acquisition, growth, biomass, photosynthetic pigment synthesis, osmolytes level, gas exchange attributes, phenols and flavonoids content, and enzymatic and non-enzymatic antioxidant levels in chickpea plants when compared to those exposed to NaCl only. Moreover, inoculated plants revealed lower levels of electrolyte leakage, H2O2 and MDA under saline conditions in relative to plants subjected to salt alone. Inoculated plants exhibited the highest expression level of the antioxidants genes and genes conferring salt tolerance under 150 mM NaCl concentration. Taken together, these findings demonstrated the beneficial role of Azospirillum lipoferum FK1 in alleviating the inhibitory impacts of salinity on chickpea growth via modulating osmolytes, antioxidants machinery and stress-related genes expression.