Rice GA3ox1 modulates pollen starch granule accumulation and pollen wall development

Area of Science:

• Plant Molecular Biology
• Reproductive Biology
• Genetics

Background:

• The gibberellin (GA) biosynthetic gene OsGA3ox1 in rice is suggested to regulate gametophytic pollen development.
• However, detailed cellular characterization of its mutant pollen has been limited.

Purpose of the Study:

• To functionally characterize the OsGA3ox1 gene's role in rice pollen development using CRISPR/Cas9 gene editing.
• To investigate the cellular and molecular mechanisms underlying pollen defects in osga3ox1 mutants.

Main Methods:

• CRISPR/Cas9 gene editing was employed to generate biallelic variants of the OsGA3ox1 gene.
• Homozygous mutants were analyzed for effects on vegetative and floral organ development, seed-setting rate, and pollen viability.
• Anatomical and molecular characterizations were performed on mutated pollen.

Main Results:

• Homozygous osga3ox1 mutants exhibited reduced seed-setting rates and pollen viability without affecting most vegetative and floral organs.
• Mutant pollen showed defects in starch granule accumulation and pollen wall development.
• Abnormal pollen development was linked to the regulation of transcription factors OsGAMYB, OsTDR, and OsbHLH142.

Conclusions:

• The rice GA3ox1 gene plays a critical role in modulating pollen starch granule accumulation and pollen wall development during the gametophytic phase.
• OsGA3ox1 is crucial for male gametophyte development and fertility in rice.