TaBT1, affecting starch synthesis and thousand kernel weight, underwent strong selection during wheat improvement

Area of Science:

• Plant Molecular Biology
• Agricultural Science
• Genetics

Background:

• Starch synthesis in cereal grains is vital for yield.
• BRITTLE1 (BT1) facilitates ADP-glucose transport, a key step in starch production.
• Understanding genetic variations in BT1 can improve wheat quality.

Purpose of the Study:

• To investigate the role of TaBT1 homoeologous genes in common wheat.
• To identify genetic variations in TaBT1 associated with grain traits.
• To evaluate the regulatory activity of TaBT1 promoters for breeding applications.

Main Methods:

• Isolation and characterization of three TaBT1 homoeologous genes (on chromosomes 6A, 6B, 6D).
• Gene expression analysis in developing wheat grains.
• Knockdown experiments to assess TaBT1 function.
• Haplotype analysis and association studies for TaBT1-6B.
• GUS staining and enzyme activity assays in transgenic rice.

Main Results:

• TaBT1 expression is concentrated in developing grains.
• Knockdown of TaBT1 reduced grain size, thousand kernel weight (TKW), and starch content.
• High diversity at the TaBT1-6B locus identified three haplotypes (Hap1, Hap2, Hap3).
• Hap1 and Hap2 are associated with significantly higher TKW and exhibit stronger promoter activity.
• Evolutionary analysis indicates strong selection on BT1 during wheat polyploidization.

Conclusions:

• TaBT1 plays a significant role in wheat starch synthesis and TKW.
• Hap1 and Hap2 of TaBT1-6B are preferred haplotypes in modern wheat breeding.
• These haplotypes serve as valuable molecular markers for marker-assisted selection (MAS) in high-yield wheat breeding programs.