Panicle architecture is one of the most important agronomical traits that directly contribute to grain yield in rice (Oryza sativa L.). We report herein an in-depth characterization of two allelic larger panicle (lp) mutants that show significantly increased panicle size as well as improved plant architecture. Morphological analyses reveal that panicles of two mutants produced more inflorescence branches, especially the primary branches, and contained more grains. Moreover, mutant plants also display more lodging resistance than the wild type. The grain yield per plant in mutants is also increased, suggesting that mutant plants have useful potential for high grain yield in rice breeding. Map-based cloning reveals that LARGER PANICLE (LP) encodes a Kelch repeat-containing F-box protein. RNA in situ hybridization studies display that LP expression was enriched in the branch primordial region. Subcellular localization analyses demonstrate that LP is an endoplasmic reticulum (ER) localized protein, suggesting that LP might be involved in ER-associated protein degradation (ERAD). Using yeast two-hybrid assay and bimolecular fluorescence complementation analysis, we confirm that LP is an F-box protein and could interact with rice SKP1-like protein in an F-box domain-dependent manner. Quantitative real-time PCR results show that OsCKX2, which encodes cytokinin oxidase/dehydrogenase, is down-regulated evidently in mutants, implying that LP might be involved in modulating cytokinin level in plant tissues. These results suggest that LP plays an important role in regulating plant architecture, particularly in regulating panicle architecture, thereby representing promising targets for genetic improvement of grain production plants.
穗型是提高水稻籽粒產(chǎn)量的最重要農(nóng)藝性狀之一，本文深度報道了2個大穗且穗型改良的等位突變體lp。表型分析表明2個突變體的花枝梗更多，尤其是一級枝梗數(shù)目，籽粒數(shù)增加，突變體較野生型更抗倒伏，每株籽粒產(chǎn)量也相應增加。表明該突變體對提高水稻育種的產(chǎn)量有潛在利用價值，圖位克隆表明，LP 編碼一個富含Kelch的F-box蛋白，原位雜交表明該LP 集中在枝梗原基區(qū)域表達，亞細胞定位表明Lp定位在內(nèi)質網(wǎng)上，表明LP可能參與了ER相關蛋白的降解（ERAD），酵母雙雜和BIFC試驗均說明該基因編碼的F-box蛋白能與水稻SKP1-like蛋白互作，定量PCR表明突變體中細胞分裂素氧化酶/脫氫酶OsCKX2的水平出現(xiàn)下調(diào)，表明LP可能參與植物組織的細胞分裂素水平的調(diào)節(jié)，以上表明LP是調(diào)節(jié)水稻株型的重要農(nóng)藝性狀，尤其是改善穗型方面，因此在提高水稻籽粒產(chǎn)量方面提供了一個有前途的前景目標。