The chloroplast pentatricopeptide repeat protein RCN22 regulates tiller number in rice by affecting sugar levels via the TB1–RCN22–RbcL module

• DOI: 10.1016/j.xplc.2024.101073
• Publication Date: 2024-08-28T02:45:27Z
• Authors: Tianyu Mo; Tianhao Wang; Yinglu Sun; Ashmit Kumar; Humphrey Mkumbwa; Jingjing Fang; Jinfeng Zhao; Shoujiang Yuan; Zichao Li; Xueyong Li
• Keywords: Pentatricopeptide repeat; Tiller (botany)

As an important yield component, rice tiller number controls panicle and determines grain yield. Regulation of by chloroplast pentatricopeptide repeat (PPR) proteins has not been reported previously. Here, we report the reduced culm number22 (rcn22) mutant, which produces few tillers owing to suppressed bud elongation. Map-based cloning revealed that RCN22 encodes a chloroplast-localized P-type PPR protein. We found specifically binds 5' UTR RbcL mRNA (encoding large subunit Rubisco) enhances its stability. The abundance in rcn22 leads lower photosynthetic rate decreased sugar levels. Consequently, transcript levels DWARF3 (D3) TEOSINTE BRANCHED1 (TB1) (which encode negative regulators elongation) are increased, whereas protein positive regulator DWARF53 (D53) decreased. Furthermore, high concentrations sucrose can rescue growth defect mutant. On other hand, TB1 directly promoter downregulates expression. tb1/rcn22 double mutant shows tillering phenotype similar rcn22. Our results suggest TB1-RCN22-RbcL module plays vital role elongation affecting