TaKMT-7A Gene Positively Regulates Spike Number in Wheat.

Area of Science:

• Plant Genetics
• Agricultural Science
• Molecular Biology

Background:

• Wheat (Triticum aestivum L.) is a vital global food crop, essential for food security.
• Spike number per unit area (SN) is a critical determinant of wheat grain yield.
• Understanding the genetic regulation of SN is crucial for improving crop productivity.

Purpose of the Study:

• To identify and characterize genes controlling spike number per unit area in wheat.
• To elucidate the function of the candidate gene TraesCS7A02G-364700 (TaKMT-7A) in wheat development.
• To investigate the molecular mechanisms underlying TaKMT-7A's role in regulating SN.

Main Methods:

• Quantitative trait locus (QTL) mapping using a recombinant inbred line (RIL) population across 27 environments.
• CRISPR/Cas9 gene editing to generate knockout (KO) mutant lines of TaKMT-7A.
• Generation of overexpression (OE) lines for TaKMT-7A.
• RNA-sequencing (RNA-Seq) analysis to identify differentially expressed genes (DEGs) in mutant lines.

Main Results:

• A novel QTL for SN, QSn-7A-9048, was mapped, containing the candidate gene TaKMT-7A.
• TaKMT-7A KO mutants exhibited significantly reduced SN compared to wild type, without affecting grain number per spike or thousand-grain weight.
• OE lines showed significantly increased SN compared to the negative control.
• RNA-Seq identified 2315 DEGs, including genes related to nutrient transport, hormone signaling (auxin, strigolactone), and gibberellin response, suggesting downstream regulatory pathways.

Conclusions:

• TaKMT-7A functions as a positive regulator of spike number per unit area in wheat.
• The study provides insights into the molecular basis of SN regulation, involving hormone signaling and nutrient transport pathways.
• TaKMT-7A represents a potential target for genetic improvement of wheat yield through breeding strategies.