Mapping of a Quantitative Trait Locus for Stay-Green Trait in Common Wheat

Area of Science:

• Plant Genetics
• Agronomy
• Molecular Biology

Background:

• The stay-green (SG) trait improves photosynthetic activity during late grain filling, crucial for enhancing grain yield under environmental stresses like drought and heat.
• Wheat breeding line CH7034 exhibits the SG trait, making it a valuable resource for genetic studies.

Purpose of the Study:

• To identify the specific genetic loci responsible for the stay-green trait in wheat breeding line CH7034.
• To develop linked molecular markers for the identified SG loci to facilitate marker-assisted selection in breeding programs.

Main Methods:

• A high-density genetic map was constructed using a recombinant inbred line (RIL) population derived from a cross between CH7034 (SG) and SY95-71 (non-SG), genotyped with a Wheat17K SNP array.
• Quantitative trait locus (QTL) mapping was performed by estimating flag leaf chlorophyll content in the RIL population.
• A PCR-based diagnostic marker (7D-16) was developed for the identified QTL.

Main Results:

• A novel QTL for stay-green, designated QSg.sxau-7D, was identified on chromosome 7D, explaining 8.81–11.46% of the phenotypic variance.
• The diagnostic marker 7D-16 confirmed the genetic effect of QSg.sxau-7D on flag leaf chlorophyll content, with the CH7034 allele associated with higher content.
• QSg.sxau-7D is located in a distinct genomic interval on chromosome 7D and shows a positive correlation with thousand-grain weight.

Conclusions:

• A novel SG QTL, QSg.sxau-7D, was discovered and mapped in wheat, with the CH7034 allele conferring a significant stay-green effect.
• The developed diagnostic marker 7D-16 can be utilized in wheat molecular breeding for improving stay-green traits and potentially grain yield.
• The identified QTL and marker provide valuable resources for future research and breeding efforts aimed at enhancing wheat resilience and productivity.