Genome-Edited Triple-Recessive Mutation Alters Seed Dormancy in Wheat

Area of Science:

• Agricultural Science
• Genetics
• Molecular Biology

Background:

• Hexaploid wheat possesses three sub-genomes, complicating the observation of mutations, especially for recessive genes.
• Seed dormancy is a crucial trait for preventing pre-harvest sprouting, but its genetic control in wheat is complex.

Purpose of the Study:

• To develop a method for creating loss-of-function mutations in wheat homeoalleles using CRISPR/Cas9.
• To investigate the role of Qsd1, a barley gene controlling seed dormancy, in common wheat.
• To generate and characterize a transgene-free recessive mutant for improved trait analysis.

Main Methods:

• Agrobacterium-mediated CRISPR/Cas9 was used to target Qsd1 homeoalleles in hexaploid wheat.
• Mutagenized plants were crossed with wild-type to obtain transgene-free segregants.
• Mendelian segregation analysis, PCR, Southern blotting, and whole-genome shotgun sequencing were employed for characterization.

Main Results:

• Three independent wheat events with mutations in Qsd1 homeoalleles were obtained.
• A transgene-free triple-recessive mutant exhibiting significantly longer seed dormancy was generated.
• Genomic analysis confirmed the absence of transgenes in the mutant line.

Conclusions:

• CRISPR/Cas9-mediated gene editing is an effective tool for studying recessive traits in polyploid wheat.
• The Qsd1 gene plays a role in regulating seed dormancy in wheat, offering potential for pre-harvest sprouting reduction.
• This approach provides a model for trait improvement in wheat using locus information from related diploid species.