Trihelix Transcription Factor ZmThx20 Is Required for Kernel Development in Maize

Area of Science:

• Plant Biology
• Genetics
• Biochemistry

Background:

• Maize kernel development is crucial for yield and quality, with the endosperm serving as a major storage organ.
• Understanding genetic factors influencing endosperm development is key to improving cereal grain production.

Purpose of the Study:

• To identify and characterize a natural mutation affecting maize kernel development.
• To elucidate the genetic basis of the shrunken kernel phenotype and its impact on seed composition.

Main Methods:

• Identification and phenotypic analysis of the shrunken 2008 (sh2008) mutant.
• Map-based cloning to identify the causative gene.
• CRISPR/Cas9 to generate additional alleles.
• Transcriptome analysis to understand molecular changes.

Main Results:

• The sh2008 mutation results in loose starch grains and reduced storage proteins, particularly zeins.
• Map-based cloning identified ZmThx20, a GT-2 trihelix transcription factor, as the gene responsible for the sh2008 phenotype.
• CRISPR/Cas9 confirmed ZmThx20's role, and overexpression rescued the shrunken phenotype.
• Transcriptome analysis revealed enrichment of down-regulated genes related to translation and nutrient reserves in sh2008 kernels.

Conclusions:

• ZmThx20 plays a critical role in maize endosperm development and storage reserve accumulation.
• Mutations in ZmThx20 lead to defects in seed filling and reduced kernel yield.
• This study provides insights into the genetic regulation of maize seed quality and potential targets for crop improvement.