OsMYB103 targets and interacts with AMD1 to form a feed-forward loop for pollen development in rice

Area of Science:

• Plant reproductive biology
• Molecular genetics
• Transcriptional regulation

Background:

• Plant male reproductive development relies on intricate transcriptional regulatory networks (TRNs).
• ABERRANT MICROSPORE DEVELOPMENT1 (AMD1) is a critical transcriptional regulatory component (TRC) for rice pollen production.
• The precise molecular functions of AMD1 in rice pollen development remain largely unelucidated.

Purpose of the Study:

• To investigate the molecular mechanism of AMD1 in rice pollen development.
• To elucidate the relationship between OsMYB103 and AMD1 in regulating rice male fertility.
• To understand AMD1's role within the broader TRN governing rice pollen development.

Main Methods:

• Genetic analysis using single and double mutants (AMD1 and OsMYB103).
• Gene expression analysis to assess target gene regulation.
• In vivo and in vitro biochemical assays to confirm protein-protein interactions.
• Investigating the recruitment of RNA polymerase II complex components.

Main Results:

• AMD1 is identified as a direct genetic downstream target activated by OsMYB103 during rice pollen development.
• Double mutants of AMD1 and OsMYB103 show more severe down-regulation of target genes than single mutants.
• AMD1 physically interacts with OsMYB103, enhancing OsMYB103's activation of target genes, potentially via OsTFIIF2-2 recruitment.
• A feed-forward loop mechanism involving OsMYB103 and AMD1 is proposed to regulate rice male fertility.

Conclusions:

• The OsMYB103-AMD1 transcriptional cascade precisely controls rice male fertility.
• AMD1 plays a vital role in the TRN governing rice pollen development.
• Findings provide new insights into the regulatory network of plant male gametogenesis.