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

Abstract

The process of male reproductive development in plants involves a series of biological events. These events are governed by complex transcriptional regulatory networks, which are composed of numerous transcriptional regulatory components (TRCs). ABERRANT MICROSPORE DEVELOPMENT1 (AMD1) is a recently identified TRC that is essential for rice pollen production. Nevertheless, the molecular roles of AMD1 in regulating rice pollen production are largely unknown. Here, we demonstrate that AMD1 is directly activated by OsMYB103 as a genetic downstream target during rice pollen development. Interestingly, several direct target genes of OsMYB103, including AMD1 itself, exhibit a more drastic expression down-regulation in the double mutant of AMD1 and OsMYB103 than in the single mutants. Our ongoing in vivo and in vitro experiments consistently indicate that AMD1 physically interacts with OsMYB103, thereby facilitating the activation of OsMYB103 on its target genes, possibly through the recruitment of the RNA polymerase II complex component OsTFIIF2-2. Our findings collectively suggest that the transcriptional cascade composed of OsMYB103 and AMD1 precisely regulates rice male fertility through a feed-forward loop mechanism, offering new insights into the role of AMD1 within the transcriptional regulatory network governing rice pollen development.