Dissecting a heterotic gene through GradedPool-Seq mapping informs a rice-improvement strategy

Area of Science:

• Plant genetics and breeding
• Agricultural science
• Genomics

Background:

• Hybrid rice breeding leverages hybrid vigor (heterosis) to enhance grain yield, but the underlying genes are not fully understood.
• Current methods for mapping heterosis-related traits are often laborious and time-consuming, hindering genetic dissection.
• Identifying genes controlling rice grain production is crucial for improving crop yields.

Purpose of the Study:

• To develop a rapid quantitative trait locus (QTL) mapping method for identifying heterosis-related genes in rice.
• To dissect and clone a specific heterotic QTL (GW3p6) associated with increased grain yield.
• To evaluate the potential of improving grain production in inbred rice lines.

Main Methods:

• Developed and implemented GradedPool-Seq, a novel method for rapid QTL mapping using whole-genome sequencing of pooled F2 progeny.
• Employed map-based cloning to identify the heterotic QTL GW3p6.
• Generated a near-isogenic line (NIL-FH676::GW3p6) by introgression of the GW3p6 allele into an inbred line.

Main Results:

• The GradedPool-Seq method enabled rapid mapping of QTLs.
• The cloned GW3p6 QTL significantly increased grain yield in the introgressed near-isogenic line (NIL-FH676::GW3p6) compared to the recurrent parent (Fuhui676).
• Demonstrated successful introgression of a yield-enhancing allele into an inbred line.

Conclusions:

• The GradedPool-Seq method offers an efficient approach for dissecting complex traits like heterosis in rice.
• The identified GW3p6 allele has potential for direct application in breeding programs to enhance grain yield in inbred rice.
• This study suggests that high grain production in inbred rice lines is achievable without exclusive reliance on hybrid systems.