Project description:Leaf angle is mainly determined by the lamina joint (LJ), and contributes to ideal crop architecture for high yield. Here, we dissected five successive stages with distinct cytological features of LJs spanning organogenesis to leaf angle formation, and obtained the underlying stage-specific mRNAs and small RNAs, which well explained the cytological dynamics during LJ organogenesis and leaf angle plasticity. Combining the gene coexpression correlation with high-throughput promoter analysis, we identified a set of transcription factors determining the stage- and/or cytological structure-specific profiles. The functional studies of these TFs demonstrated that cytological dynamics determined leaf angle, and the knockout rice of these TFs with erect leaves significantly enhanced yield by maintaining the proper tiller number under dense planting. This work revealed the high-resolution mechanisms how the cytological dynamics of LJ determined the leaf erectness, and served as a valuable resource to remodel rice architecture for high yield via controlling population density.
Project description:Tiller angle is a key factor determining rice plant architecture, planting density, light interception, photosynthetic efficiency, disease resistance, and grain yield. The distribution of auxin and shoot gravitropism play important roles in regulating tiller angles of rice. Several tiller angle-associated genes have been cloned. However, the mechanisms underlying tiller angle control are far from clear. In this study, we isolate bta1-1, a mutant with an enlarged tiller angle throughout its life cycle. A detailed analysis reveals that BTA1 has multiple functions because several major agronomic traits, including tiller and panicle number, biomass production, secondary branch number per panicle, panicle weight, grain size, and grain weight, are increased in bta1-1 plants. Moreover, BTA1 is a positive regulator of shoot gravitropism in rice. Shoot responses to gravistimulation are disrupted in bta1-1 under both light and dark conditions. Gene cloning reveals that bta1-1 is a novel mutant allele of LA1. LA1 is able to rescue the tiller angle and shoot gravitropism defects observed in bta1-1. BTA1/LA1 is required to regulate the expression of auxin transporters and signaling factors that control shoot gravitropism and tiller angle. High-throughput mRNA sequencing is performed to elucidate the molecular and cellular functions of BTA1/LA1. The results show that BTA1/LA1 may have multiple functions in regulating nucleosome and chromatin assembly, and protein and DNA interactions. Our results provide new insight into the mechanisms whereby BTA1/LA1 controls shoot gravitropism and tiller angle in rice.