Role of Biotic Elicitors as Potent Inducer of Defence Mechanism against Salt-Stress in Wheat (Triticum aestivum L.)

Abstract

Wheat (Triticum aestivum L.) known as bread wheat (hexaploid), is an important cereal for millions around the world. Excessive salts in soil affect growth, development and productivity of crop plants and have been major constraints to agriculture. Plants, being sessile in nature, have developed mechanisms to cope with high salt concentrations in soil. To understand salt-tolerance in crop plant and its improvement, Total Phenolic Content (TPC), Lipid Peroxidation (LP), total Antioxidant activity (AO) and high affinity potassium transporters (HKTs) in shoot and root regions of contrasting wheat genotype WH 542 (salt-susceptible) and KRL 210 (salt-tolerant) were studied on seed priming with two different biotic elicitors-Salicylic Acid (SA) and Methyl Jasmonate (MJ). Primed seeds were sown in pots under controlled conditions in phytotron and were exposed to 150 mM NaCl stress after 14 days of germination. Expression pattern of HKT genes in the root and shoot of the primed and unprimed as well as stressed and unstressed seedlings were also studied using semi-quantitative and quantitative analysis. Higher levels of TPC, LP and AO activity were observed in the contrasting wheat genotypes under salt stressed condition. Both HKT1 and HKT3 genes were involved in regulating ion homeostasis. Up and down regulation of expression of HKT genes in shoot and root, respectively, provide resistance against salt uptake. Biotic elicitors (SA and MJ) were found to mitigate the effect of salt-stress by affecting expression of HKT genes as well their biochemical-processes. MJ showed better response than that of SA, and can be utilized to improve defense responses of crop plant against salt stress. The regulation of gene expressions and signaling cascades that regulate Na+ transporters remain to be elucidated and these studies will help in understanding the mechanism of ion homeostasis during salt stress to improve crop yield.