Map-based cloning and WGCNA uncover the key genes controlling cold tolerance in maize introgression lines seedlings

Abstract

Summary Low-temperature chilling injury in early spring or late spring severely restricts maize production. Therefore, improving its temperature tolerance is one of the important goals of maize breeding. The wild maize relatives such as Z. perennis and T. dactyloides have strong cold tolerance and thus can be used to improve the cold tolerance of cultivated maize. In the previous study, the allohexaploid MTP ( Zea . Z. perennis and T. dactyloides ) was created as a genetic bridge material and the introgressed cross of the backbone maize inbred line to obtain the MTP-maize introgression line with strong cold tolerance. In this study, F 2:3 populations was developed of the cold-tolerant maize introgression line IB030 and the cold-sensitive maize introgression line IB021. A high-density genetic linkage map was constructed using SSR genetic markers and performed QTL mapping for related traits at 2°C, RNA-seq was performed using cold-tolerant introgression line IB030 and recurrent parent B73 (cold-sensitive) after low temperature stress at seedling stage. The key genes controlling REC, SDW and SFW of maize introgression line seedlings were located by forward genetics combined with WGCNA analysis strategy. Key genes function verification results showed that, Zm00001d037590 REC and Zm00001d012321 REC have the highest expression levels in introgression line IB030, followed by the wild type B73, and finally the EMS mutant after low temperature stress, these results initially concluded that key genes positively regulate the cold tolerance of maize, and also laid a theoretical and practical foundation for improvement of cultivated maize against low-temperature stress.