Fine Mapping of Five Grain Size QTLs Which Affect Grain Yield and Quality in Rice

Area of Science:

• Genetics
• Plant Breeding
• Agronomy

Background:

• Grain size in rice (Oryza sativa) is a complex quantitative trait influenced by multiple genes.
• Understanding the genetic architecture of grain size is crucial for developing high-yielding and quality rice varieties.

Purpose of the Study:

• To identify and fine-map quantitative trait loci (QTLs) controlling rice grain size.
• To investigate the effects of identified QTLs on cell division, expansion, grain yield, and quality.

Main Methods:

• Quantitative trait loci (QTL) analysis using BC1F2 and BC1F2:3 populations derived from two indica rice lines.
• Fine mapping of validated QTLs to narrow genetic regions.
• Scanning electron microscopy (SEM) and gene expression analysis to understand QTL function.

Main Results:

• Twenty-four QTLs for grain size were identified, with five (qGW1, qGW7, qGW12, qGW5, qGL9) validated and fine-mapped.
• qGW7 influences cell expansion, while qGL9 affects cell division; qGW1, qGW5, and qGW12 promote both.
• qGW5 enhances quality without yield reduction, while qGW1 and qGL9 improve both yield and quality.

Conclusions:

• Five key QTLs controlling rice grain size have been identified and fine-mapped.
• Specific QTLs demonstrate distinct roles in cell dynamics and their impact on yield and quality.
• These findings provide valuable genetic resources for marker-assisted breeding of superior rice varieties.