Overexpressing the glutaredoxin (CaGrx) gene enhances the antioxidant defences and improves drought tolerance in chickpea (Cicer arietinum L.)

Rising global temperatures are expected to worsen the impact of drought, which directly impacts the worldwide production of chickpea. Glutaredoxins (Grxs) are ubiquitous, heat-stable, cysteine-rich proteins and glutathione-dependent thiol-disulfide oxidoreductases. The overexpression of the CC-type Grxs gene in plants improves drought and salinity stress tolerance. The present study reports the potential role of chickpea glutaredoxin (CaGrx) gene in response to drought stress. The CaGrx gene from chickpea was overexpressed in Kabuli-type chickpea by the Agrobacterium-mediated gene transformation method. Integration of the CaGrx gene in the Kabuli chickpea genome was confirmed by PCR using gene-specific primers. The qRT-PCR showed an 11- to 14-fold change in the expression of the CaGrx transcript in the T-1 generation of transgenic chickpea. The T-1 generation of the transgenic chickpea exhibit improved tolerance to drought stress due to the enhanced activities of different antioxidant enzymes such as glutaredoxin (GRX), glutathione reductase (GR), glutathione peroxidase (GPX), glutathione-S-transferase (GST), superoxide dismutase (SOD), and catalase (CAT), and reduced levels of stress markers H2O2 and thiobarbituric acid reactive substances (TBARS). Also, the CaGrx overexpression lines of T-1 generation showed improved physiological performance, including net photosynthesis (P-N), transpiration (E), water use efficiency (WUE), stomatal conductance (g(s)), PSII (F-v/F-m), and non-photochemical quenching (NPQ) during drought, which help to maintain the photosynthetic apparatus and protect the plants from oxidative damage. Overall, the study showed that the overexpression of CaGrx improves the ability of chickpea to withstand drought, and the CaGrx gene could be used to develop drought-tolerant crop plants.