Identification of Candidate Heat-Tolerance Genes in Maize by Integrating Linkage and Transcriptomic Analyses

Area of Science:

• Plant genetics and breeding
• Abiotic stress response in crops
• Genomics and transcriptomics

Background:

• High-temperature stress is a major threat to maize (Zea mays L.) yield and quality due to global warming.
• Heat stress induces sunscald in maize, impairing photosynthesis and leading to yield losses.

Purpose of the Study:

• To identify quantitative trait loci (QTLs) associated with heat tolerance in maize.
• To pinpoint candidate genes involved in maize's response to heat stress.

Main Methods:

• Developed F2 and F2:3 populations from heat-tolerant (Zheng58) and heat-sensitive (HSBN) maize inbred lines.
• Performed phenotyping for sunscald across three environments and genotyped the F2 population using a 10K SNP array.
• Constructed a genetic map and performed transcriptome analysis to identify differentially expressed genes (DEGs) co-localized with QTLs.

Main Results:

• Identified eight QTLs for heat tolerance on chromosomes 1, 4, 5, and 8, explaining significant phenotypic variation.
• Discovered a stable QTL (qHT1-2) and a major QTL (qHT1-3) on chromosome 1, with qHT1-3 explaining 33.70% of the variation.
• Found 9262 DEGs, with 21 co-localized within QTL intervals, and identified four highly differentially expressed candidate genes (Zm00001eb013260, Zm00001eb012720, Zm00001eb013600, Zm00001eb013100).

Conclusions:

• This study provides valuable genetic resources for breeding heat-tolerant maize varieties.
• The identified QTLs and candidate genes are crucial for understanding and improving maize resilience to heat stress.