Maize defective kernel mutant generated by insertion of a Ds element in a gene encoding a highly conserved TTI2...

Area of Science:

• Plant genetics
• Molecular biology
• Maize genetics

Background:

• The defective kernel (dek) phenotype in maize can result from mutations in essential genes.
• Transposable elements are valuable tools for gene tagging and functional analysis.

Purpose of the Study:

• To identify the gene responsible for the dek38 mutation using a novel transposable element, Dsg.
• To characterize the function of the maize dek38 gene and its protein product, TTI2.

Main Methods:

• Gene tagging with the engineered transposable element Dsg.
• Analysis of the dek38-Dsg mutant phenotype, including seed development and pollen transmission.
• Yeast two-hybrid assays to study protein interactions between maize TTI2, TTI1, and TEL2 homologs.

Main Results:

• Dsg insertion in dek38 caused embryonic lethality, defective basal endosperm transfer layer, and underdeveloped seeds.
• The maize dek38 gene encodes a TTI2 molecular cochaperone, a component of the triple T complex.
• Maize TTI2 interacts with TTI1 and TEL2, regulating phosphatidylinositol 3-kinase-related kinases (PIKKs).
• dek38-Dsg mutants showed reduced pollen transmission, highlighting TTI2's role in male reproductive development.

Conclusions:

• The dek38 gene is crucial for maize kernel development and encodes a TTI2 cochaperone involved in DNA damage response.
• The TTI2-TTI1-TEL2 complex plays a conserved role in regulating PIKKs and is essential for male gametogenesis in maize.