Physiological and gene expression studies of selected Zea mays L. and Pennisetum glaucum (L.) R. Br. genotypes to simulated drought stress condition

Abstract

Drought is a major environmental stress that significantly obstructs productivity of various crops worldwide. Among several remedial methods to conquer this abiotic stress, use of resistant cultivars is most preferred. This study compares the response in selected genotypes of pearl millet and maize under a progressive drought stress conditions at specific intervals. Three genotypes (IP14599, IP14787 and LRNO3) of pearl millet recorded relatively higher water content (RWC) than the three genotypes (DTSYN11, LRN03 and LRIO1) of maize. Leaf water potential (ΨL), leaf osmotic potential (Ψπ), leaf turgor potential (Ψp) and PSII were measured in harvests to attain comparative observations. Furthermore, to correlate these results expression of three genes were measured. It was observed that Ψπ decreased over time and Ψp recorded a decrease with ΨLat a higher rate in maize compared to pearl millet. A more declining trend in maximum fluorescence (∆F/Fm′) and electron transport rate (ETR) in LRIOI, LRNO1 and DTSYN11 was recorded compared to IP14599, IP14787 and LRNO3. The study of gene CBF in leaves and roots revealed it’s responsiveness to drought in genotypes of pearl millet IP14599, LRNO3 and IP14787 while it was absent in maize genotypes LRNO1 and LRIO1, with the exception of DTSYN11. Expression of RubSc gene showed a noteworthy decline in reactive oxygen species in the genotypes IP14599, LRNO3, DTSYN11 and IP14787, while a marked increase was observed in LRNO1 and LRIO1. Likewise gene PIP2;3 were highly responsive to drought in pearl millet but not in maize, where they might support greater water transport. Overall, the results indicate remarkable activation of mRNA expression of these genes under drought stress which provides the resistance against drought.