OsGEX3 affects anther development and improves osmotic stress tolerance in rice

Area of Science:

• Plant Biology
• Molecular Genetics
• Agricultural Science

Background:

• GEX3 proteins are conserved across plants, with AtGEX3 known for pollen tube guidance.
• The function of the rice homolog, OsGEX3, in pollen development and stress response remained largely uncharacterized.

Purpose of the Study:

• To elucidate the function of OsGEX3 in rice, focusing on its roles in pollen development and response to abiotic stresses.
• To investigate the subcellular localization and expression patterns of OsGEX3 under stress conditions.

Main Methods:

• Subcellular localization assays using transiently transformed Nicotiana benthamiana.
• Gene expression analysis via RT-qPCR in response to polyethylene glycol (PEG), hydrogen peroxide, and abscisic acid (ABA).
• Phenotypic analysis of OsGEX3 overexpression (OsGEX3-OE) lines and Osgex3 mutants, including seed setting rates, pollen fertility, and stress tolerance.

Main Results:

• OsGEX3 localizes to the plasma membrane and nucleus.
• OsGEX3 expression is upregulated by PEG, hydrogen peroxide, and ABA treatments.
• Both OsGEX3 overexpression and loss of function led to reduced seed setting rates and impaired pollen maturation, with delayed development at the late vacuolated stage.
• OsGEX3 overexpression enhanced tolerance to osmotic and oxidative stress by improving reactive oxygen species (ROS) scavenging, while mutants showed reduced osmotic stress tolerance.

Conclusions:

• OsGEX3 is a multifunctional protein involved in rice pollen development and abiotic stress responses.
• OsGEX3 positively regulates osmotic stress response through ROS scavenging.
• Functional characterization of OsGEX3 provides a basis for molecular breeding of drought-resistant and high-yield rice varieties.