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

作　　者：Tianyu Mo Tianhao Wang Yinglu Sun Ashmit Kumar Humphrey Mkumbwa Jingjing Fang Jinfeng Zhao Shoujiang Yuan Zichao Li Xueyong Li 

机构地区：[1]State Key Laboratory of Crop Gene Resources and Breeding,National Key Facility for Crop Gene Resources and Genetic Improvement,Institute of Crop Sciences,Chinese Academy of Agricultural Sciences,Beijing 100081,China [2]Beijing Key Laboratory of Crop Genetic Improvement,College of Agronomy and Biotechnology,China Agricultural University,Beijing 100193,China [3]Institute of Wetland Agriculture and Ecology,Shandong Academy of Agricultural Sciences,Jinan 250100,China

出　　处：《Plant Communications》2024年第12期110-126,共17页植物通讯(英文)

基　　金：Biological Breeding-National Science and Technology Major Project of China(2023ZD0406801);Innovation Program of Chinese Academy of Agricultural Sciences(CAAS-CSCB-202402);National Natural Science Foundation of China(32270373,32270653);Agricultural Variety Improvement Project of Shandong Province,China(2021LZGC020).

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

关 键 词：PPR protein rice tillering CHLOROPLAST SUGAR TEOSINTE BRANCHED1 TB1 

分 类 号：S511[农业科学—作物学]