Variability in drought stress-induced physiological, biochemical responses and expression of DREB2A, NAC4 and HSP70 genes in groundnut (Arachis hypogaea L.)

Abstract

Drought stress is one of the most important factors of physiological stress and the major constraint on crop productivity which limits plant growth and metabolism. The goal of this work was to study the differential response of groundnut genotypes to drought stress at the physiological, biochemical, and molecular levels during summer in the field. Thirty days old seedlings of six genotypes of groundnut viz. Kadiri 9, Narayani, Dharani, JL24, TPT-3, and Kadiri 6 were subjected to drought stress by withdrawing irrigation for 15 days. The results suggested a significant influence of drought stress on the physiological and biochemical levels in all the groundnut genotypes. A substantial decrease for physiological parameters viz. membrane stability index, chlorophyll stability index, and relative water content was observed under moderate and severe stress conditions compared to control across all genotypes. The high proline accumulating genotypes also exhibited lower lipid peroxidation under all stress periods. In Kadiri 9, Narayani, and Dharani genotypes, the antioxidant enzyme activity of superoxide dismutase, catalase, peroxidase, and glutathione reductase was significantly higher than JL24, TPT-3, and Kadiri 6 genotypes under all stress regimes. Among the genotypes tested, Kadiri 9, Narayani, and Dharani retained higher growth, yield, and seed quality characteristics showing tolerance for drought stress. qPCR analysis revealed stress-responsive existence of the selected genes, heat shock protein 70 (HSP70), dehydration-responsive element binding-2A (DREB2A), and no apical meristem, ATAF1/2, cup-shaped cotyledon 2 (NAC4) with 30 fold increase in the level of expression in Kadiri 9 compared to Kadiri 6.