Does a terminal drought tolerance QTL contribute to differences in ROS scavenging enzymes and photosynthetic pigments in pearl millet exposed to drought?
Abstract
We studied how ascorbate peroxidase (APX), superoxide dismutase (SOD), catalase (CAT) isozyme activities and photosynthetic pigments content responded to drought and whether they related to presence of a terminal drought tolerance QTL in pearl millet. Under drought there was no significant change in the total APX activity; only the proportional APX5 activity increased, with higher band intensity in tolerant genotypes.
There were no significant changes in total activities of CAT and SOD, with similar band intensities in all genotypes, and a new CAT isozyme was induced in all genotypes. The pigment content decreased under drought, but not differently in any genotype.
The activities of most APX, CAT and SOD isozymes were closely related to the total chlorophyll/carotenoids ratio. The absence of discrimination for the ROS scavenging enzymes and for the pigment content under stress suggests that these traits may not play a key role in terminal drought tolerance in pearl millet.