Methylation-sensitive random amplification polymorphism during pre-anthesis stage heat stress response in maize (Zea mays L.)

DNA methylation is one of the important epigenetic processes that regulate gene expression in heat stress conditions. However, very limited information is available regarding in response of heat stress on the DNA methylation pattern of the reproductive tissue of maize. In the present study, ten diverse inbreds of maize were exposed to heat stress at the pre-anthesis stage under field phenotyping facility in two experiment blocks: one with normal environmental conditions (control) and the other subjected to heat stress at the early pre-anthesis stage. The results showed a significant effect of heat stress on plant growth, physiological functions, biochemical processes, and yield attributes. The impact of heat stress varied among the different inbred lines. UASBM35 showed the highest number of pollen grains per anther and the highest seed yield, while UASBM14 produced the lowest number of pollen grains per anther and zero seed set. DNA methylation patterns of leaves and immature anthers under heat stress were studied in UASBM14 and UASBM35 through methylation-sensitive random amplification polymorphism. The results revealed an increase in total DNA methylation levels in both leaves and anthers of the heat-tolerant (UASBM35) and the heat-susceptible (UASBM14) inbred lines under heat stress conditions. Notably, a higher percentage of DNA methylation was observed in the leaves of the heat-susceptible inbred line compared to the heat-tolerant. Overall, these results suggest that DNA methylation regulation might play a key role in adaptation to heat stress tolerance in maize.