OsMADS6-OsMADS32 and REP1 control palea cellular heterogeneity and morphogenesis in rice
Precise regulation of cell proliferation and differentiation is a key factor for diversity in morphology during organogenesis. Rice palea comprises two distinct regions, the marginal region of palea (MRP) and the body of palea (BOP), which exhibit heterogeneity in cellular composition and behavior. This study reveals that REP1 promotes epidermal cell proliferation and differentiation in the BOP, forming hard silicified protrusion cells, by regulating the cyclin-dependent kinase gene, OsCDKB1;1. Conversely, OsMADS6 and OsMADS32 are expressed exclusively in the MRP, where they limit the division rates of epidermal cells by inhibiting OsCDKB2;1 gene expression, promoting endoreduplication and resulting in the formation of elongated epidermal cells. Furthermore, the OsMADS6-OsMADS32 complex and REP1 exhibit reciprocal inhibition to fine-tune the balance between cell division and differentiation during palea morphogenesis. Therefore, our study highlights the importance of controlling cellular heterogeneity in shaping plant morphological diversity. Overall design: Comparative gene expression profiling analysis of RNA-seq data for Osmads6, Osmads32, rep1 and wild type rice paleas