QTL Mapping of SPAD Values Associated with Leaf Color in Bunching Onion

Area of Science:

• Plant genetics
• Agronomy
• Molecular breeding

Background:

• Dark green leaf color is a valuable trait in bunching onions (Allium fistulosum L.) but its genetic basis is unclear.
• Understanding the genetics of leaf color is crucial for improving market value through breeding.

Purpose of the Study:

• To identify quantitative trait loci (QTLs) associated with leaf color in bunching onions.
• To utilize SPAD values as a phenotypic indicator for leaf color genetic analysis.

Main Methods:

• An F2 population was created from a cross between dark green and light green bunching onion lines.
• A linkage map was constructed using RNA-seq derived SNP markers.
• SPAD values were measured and analyzed for quantitative trait loci (QTLs).

Main Results:

• A linkage map with 765 markers across eight linkage groups was established.
• Significant QTLs for leaf color were detected on chromosomes 4 and 5, explaining substantial phenotypic variance.
• Genes involved in chloroplast protein translation were located within the identified QTL regions.

Conclusions:

• SPAD values are a reliable indicator for genetic studies of bunching onion leaf color.
• Identified QTLs offer valuable targets for molecular breeding programs to enhance dark green leaf color.