Quantitative Trait Loci Mapping for Spike Characteristics in Hexaploid Wheat

Area of Science:

• Plant genetics
• Agricultural science
• Wheat breeding

Background:

• Wheat spike characteristics are key determinants of grain yield, but their genetic underpinnings are not fully understood.
• Limited genetic information exists for traits like spike length, spikelet number, and grain number per spikelet in wheat.

Purpose of the Study:

• To investigate the genetic architecture of wheat spike characteristics.
• To identify quantitative trait loci (QTL) and their interactions influencing spike traits.
• To develop a high-density genetic map for hexaploid wheat.

Main Methods:

• Genotyping-by-sequencing (GBS) and iSelect 9K assay were employed on a doubled-haploid (DH) soft red winter wheat population.
• A high-density genetic map was constructed, spanning 2934.1 cM.
• Quantitative trait loci (QTL) analysis was performed, considering additive effects, epistasis (QQ), and QTL × environment (QE), and epistasis × environment (QQE) interactions across five environments.

Main Results:

• A total of 109 QTL, 13 QE, and 20 QQ interactions were detected.
• Spike characteristics are primarily governed by additive effects, modulated by QQ, QE, and QQE interactions.
• Major QTL explained significant phenotypic variation for spike length (up to 30.9%), fertile spikelet number, grain number per spikelet (up to 15.6%), and spike compactness (up to 80.2%).
• QTL clusters for correlated spike traits were identified on chromosomes 1A, 5A, 2B, 3B, 5B, 1D, and 5D.

Conclusions:

• This study significantly enhances the understanding of the genetic basis for spike characteristics in hexaploid wheat.
• Several stable QTL identified hold potential for application in marker-assisted selection strategies.
• The generated genetic map serves as a valuable resource for future research on economically important traits in wheat.