RESUMEN
The development of floral organs is coordinated by an elaborate network of homeotic genes, and gibberellin (GA) signaling is involved in floral organ development; however, the underlying molecular mechanisms remain elusive. In the present study, we found that MOS4-ASSOCIATED COMPLEX 5A (MAC5A), which is a protein containing an RNA-binding motif, was involved in the development of sepals, petals, and stamens; either the loss or gain of MAC5A function resulted in stamen malformation and a reduced seed set. The exogenous application of GA considerably exacerbated the defects in mac5a null mutants, including fewer stamens and male sterility. MAC5A was predominantly expressed in pollen grains and stamens, and overexpression of MAC5A affected the expression of homeotic genes such as APETALA1 (AP1), AP2, and AGAMOUS (AG). MAC5A may interact with RABBIT EARS (RBE), a repressor of AG expression in Arabidopsis flowers. The petal defect in rbe null mutants was at least partly rescued in mac5a rbe double mutants. These findings suggest that MAC5A is a novel factor that is required for the normal development of stamens and depends on the GA signaling pathway.
Asunto(s)
Flores/efectos de los fármacos , Giberelinas/farmacología , Proteínas de Unión al ARN/genética , Proteínas de Unión al ARN/metabolismo , Flores/genética , Flores/metabolismo , Regulación de la Expresión Génica de las Plantas/efectos de los fármacos , Genes Homeobox/efectos de los fármacos , Genes Homeobox/genética , Genes de Plantas/efectos de los fármacos , Genes de Plantas/genética , Morfogénesis/efectos de los fármacos , Morfogénesis/genética , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Polen/efectos de los fármacos , Polen/genética , Factores de Transcripción/genética , Factores de Transcripción/metabolismoRESUMEN
MAC5 is a component of the conserved MOS4-associated complex. It plays critical roles in development and immunity. Here we report that MAC5 is required for microRNA (miRNA) biogenesis. MAC5 interacts with Serrate (SE), which is a core component of the microprocessor that processes primary miRNA transcripts (pri-miRNAs) into miRNAs and binds the stem-loop region of pri-miRNAs. MAC5 is essential for both the efficient processing and the stability of pri-miRNAs. Interestingly, the reduction of pri-miRNA levels in mac5 is partially caused by XRN2/XRN3, the nuclear-localized 5'-to-3' exoribonucleases, and depends on SE. These results reveal that MAC5 plays a dual role in promoting pri-miRNA processing and stability through its interaction with SE and/or pri-miRNAs. This study also uncovers that pri-miRNAs need to be protected from nuclear RNA decay machinery, which is connected to the microprocessor.