'Roly-poly toy' motion during pollen exudation promotes rapid pollen adhesion in rice

Area of Science:

• Plant reproductive biology
• Angiosperm pollination mechanisms
• Plant cell physiology

Background:

• Pollen adhesion and hydration are critical for angiosperm fertilization.
• The cellular dynamics and chemical composition of pollen exudates in self-pollinating grasses like rice are not well understood.

Purpose of the Study:

• To investigate the cellular dynamics and chemical composition of pollen exudates in rice.
• To elucidate the role of pollen exudates in pollen adhesion and subsequent self-pollination.

Main Methods:

• Observation of pollen grain behavior on exudates.
• Single-cell metabolomics analysis of exudates, mature pollen, and stigma cells.

Main Results:

• Rice pollen grains displayed a 'Roly-poly toy'-like rocking motion on exudates, facilitating adhesion.
• Exudates contained high sugar content, fatty acids, and redox-related metabolites, distinct from pollen and stigma.
• These exudate components may influence osmotic and molecular signaling, increasing fluid viscosity.

Conclusions:

• The unique rocking motion of rice pollen grains is crucial for optimal self-positioning and adhesion.
• Pollen exudates play a vital role in facilitating rapid self-pollination in rice through osmotic and molecular signaling.