Panicle length (PL) is an important trait for improving panicle architecture and grain yield in rice (Oryza sativa L.). Three populations were used to identify QTLs and candidate genes associated with PL. Four QTLs for PL were detected on chromosomes 4, 6, and 9 through linkage mapping in the recombinant inbred line population derived from a cross between the cultivars Xiushui79 (short panicle) and C-bao (long panicle). Ten SSR markers associated with PL were detected on chromosomes 2, 3, 5, 6, 8, 9, and 10 in the natural population consisting of 540 accessions collected from East and Southeast Asia. A major locus on chromosome 9 with the largest effect was identified via both linkage and association mapping. LONG PANICLE 1 (LP1) locus was delimited to a 90-kb region of the long arm of chromosome 9 through fine mapping using a single segment segregating F2 population. Two single nucleotide polymorphisms (SNPs) leading to amino acid changes were detected in the third and fifth exons of LP1. LP1 encodes a Remorin_C-containing protein of unknown function with homologs in a variety of species. Sequencing analysis of LP1 in two parents and 103 rice accessions indicated that SNP1 is associated with panicle length. The LP1 allele of Xiushui79 leads to reduced panicle length, whereas the allele of C-bao relieves the suppression of panicle length. LP1 and the elite alleles can be used to improve panicle length in rice.
穗長（PL）是改善水稻穗型和提高谷物產(chǎn)量的一個重要性狀。利用3個群體鑒定與穗長相關(guān)的QTL和候選基因。通過對來源于栽培稻秀水79（短穗）和C-bao（長穗）雜交產(chǎn)生的重組自交系進行連鎖圖譜分析，在4、6和9號染色體上檢測到4個穗長相關(guān)的QTLs。在包含從東亞和東南亞收集的540個品種的自然群體中，檢測到位于2、3、5、6、8、9和10號染色體上的10個與穗長相關(guān)的SSR標(biāo)記。通過關(guān)聯(lián)和連鎖圖譜檢測到位于9號染色體的一個主要位點具有最大效應(yīng)。利用單節(jié)段分離F2群體進行精細定位，將LP1位點定位在9號染色體長臂端上90-kb的區(qū)域內(nèi)。LP1的第3個和第5個外顯子中兩個單核苷酸多態(tài)性（SNPs）導(dǎo)致氨基酸變化。LP1編碼一個功能未知的Remorin_包含蛋白，在多個物種中含有同源基因。對兩個親本和103個水稻品種的序列分析表明，SNP1與穗長相關(guān)。秀水79的LP1等位基因?qū)е滤腴L減小，而C-bao的等位基因減弱對穗長的抑制。LP1和它優(yōu)良等位基因能夠用于改善水稻穗長。