Salicylic acid improves arbuscular mycorrhizal symbiosis, and chickpea growth and yield by modulating carbohydrate metabolism under salt stress.

Abstract

Salt stress is a major abiotic stress restricting plant growth and reproductive yield. Salicylic acid (SA) and arbuscular mycorrhizal (AM) symbioses play key roles in eliminating adverse effects of salt stress by modulating ion homeostasis and carbohydrate metabolism in crop plants. Sugars synthesized via carbohydrate metabolism act as osmotic adjustors and signaling molecules in activation of various defense responses against salt stress. The present study investigated the role of SA (0.5mM) seed priming in establishment of AM symbiosis with Rhizoglomus intraradices and the impact on growth, ion-homeostasis, nutrient uptake, and sugar metabolism in Cicer arietinum L. (chickpea) genotypes under salt stress. Salinity had a negative correlation with plant growth and AM symbiosis in both genotypes with more negative effects in relatively salt-sensitive genotype than tolerant. SA enhanced the percent root colonization by significantly increasing the number of arbuscules and vesicles under salt stress. AM symbiosis was more effective in improving root biomass, root to shoot ratio, and nutrient acquisition than SA, while SA was more effective in maintaining ion equilibrium and modulating carbohydrate metabolism and reproductive yield when compared with AM inoculation. SA priming directed the utilization of total soluble sugars (TSS) towards reproductive attributes more efficiently than did AM inoculation by activating TSS metabolic consumption. In AM plants, TSS concentrations were more directed towards sink demand by the fungus itself rather than developing reproductive structures. SA priming further increased sugar export to roots of AM plants, thus favored AM symbiosis. Hence, SA seed priming-induced improvement in AM symbiosis can be a promising strategy in achieving sustainable production of chickpea genotypes under salt stress.