Evaluating heat stress tolerance and molecular relationship among inbred lines of maize during early generations

Abstract

Heat stress is one of abiotic stress that has deleterious effects on crops yield. Therefore, this study aims are to evaluate heat-tolerant maize lines and characterizing them by DNA molecular markers. Inbred lines were generated for two generations by selfing pollination. They were evaluated in each generation for the performance of some agro-morphological traits under normal and heat stress conditions. All the traits of the S1 and S2 inbred lines varied significantly among them under both conditions, except plant height was not significant under heat stress for the S1 lines. The L6 inbred line had the highest yield under the stress conditions in both S1 andS2 generations. Moreover, the heat susceptible index showed that the lines, L6 and L40 were the highest tolerant in the both generations. Furthermore, cluster analysis based on morphological traits for the 5 selected S2 inbred lines could be able to isolate the worst S2 inbred line under heat stress conditions in an independent cluster. In addition, they were characterized by ISSR and SRAP molecular markers. The ISSR detected higher polymorphism (79.79%) than SRAP marker (58.46%). The ISSR clustering patterns managed to classify the highest yield line (L6) under the heat stress in a separated cluster, but both the SRAP and combined isolated the worst line (L32) in one cluster. The Mantel’s test showed a positive correlation among all the studied markers. Additionally, the correlation was significant and highly strong (r=0.915) between morphological traits under normal conditions and SRAP marker. However, the identified S2 inbred lines with resistance to heat tolerance could be a beneficial source in the development of heat-tolerant maize hybrids.