Determining of genetic affinity and divergence of some local cultivars of zea mays grown under water stress conditions

Abstract

Abstract

Three varieties of corn seeds (local, Sudanese, and Spanish) were studies for their pattern of ahb2 expression under three periods of water stress conditions. Our findings indicated that the ahb2 gene in corn exhibits a pronounced response to water stress, but in a manner contingent upon genotype. In both the local and Spanish cultivars, ahb2 expression exhibited a non-linear trajectory, characterized by an initial upregulation at one week, suppression at ten days, and a pronounced induction by two weeks. This dynamic profile indicates that ahb2 may be involved in early signaling, mid-phase metabolic adaptation, and late-stage stress resilience processes. The substantial late induction, however, seems to contradict functional investigations that showed CRISPR knockout lines of ahb2 were more drought-resistant and lost less water than the wild type. This suggests that prolonged or delayed overexpression of ahb2 may be detrimental to drought survival, presumably by delaying stomatal closure. The Sudanese type, on the other hand, showed a steady decrease in ahb2 levels as the drought progressed. This pattern is more in line with better drought adaptability. Such inhibition may augment ABA buildup, facilitate stomatal closure, and initiate stress-adaptive signaling pathways, mirroring the phenotype of knockout plants. These data demonstrate that several maize genotypes control ahb2 in varied manners, indicative of unique drought response strategies. The non-linear expression seen in certain kinds may indicate stress intensity limits or circadian/physiological regulation, whereas gradual suppression corresponds more closely with adaptive drought tolerance mechanisms. In general, our work shows that ahb2 is an important regulator whose expression pattern during drought may affect the balance between sensitivity and tolerance in maize.