08SG2/OsBAK1 regulates grain size and number, and functions differently in Indica and Japonica backgrounds in rice.
08SG2/OsBAK1 regulates grain size and number, and functions differently in Indica and Japonica backgrounds in rice.
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08SG2/OsBAK1 调节水稻籽粒大小和数量，并在籼稻和粳稻背景中发挥不同作用
DOI：
10.1186/s12284-017-0165-2
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发表时间：
2017-12
期刊：
影响因子：
--
通讯作者：
Li S
中科院分区：
文献类型：
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作者：
Yuan H;Fan S;Huang J;Zhan S;Wang S;Gao P;Chen W;Tu B;Ma B;Wang Y;Qin P;Li S
水稻籽粒大小和粒数对产量有显著影响。在过去的十年中，许多与籽粒大小和粒数相关的基因被记录，然而，它们背后的调控机制仍然是模糊的。我们从籼稻品种蜀恢498的EMS突变体库中发现了一个水稻小粒突变体sg 2。使用MutMap基因定位策略，我们确定了两个连锁区域上的第7和第8号染色体，分别与分离比例在F2群体。我们将其定位在第8号染色体上的连锁区域，并将该位点命名为08 sg 2。在连锁区发现的三个SNPs之一位于OsBAK 1的外显子，导致激酶结构域的非同义突变。携带突变型08 sg 2基因座的植物表现出减小的籽粒大小、籽粒数量和株高。细胞学分析表明，08 SG 2通过影响细胞增殖来调控小穗船体的发育。OsBAK 1基因敲除突变体在粳稻背景中的粒大小和数量显著减少，但低于08 sg 2，支持OsBAK 1中的SNP负责08 sg 2表型的观点，但08 sg 2/OsBAK 1在籼稻和粳稻背景中的功能不同。08 sg 2对24-epiBL不敏感，BR相关基因表达明显改变。当08 sg 2和GS 3组合时，粒长成比例地减小，表明08 sg 2和GS 3独立地调节粒长。结果表明，08 SG 2/OsBAK 1基因在籼稻和粳稻背景下均对水稻产量起重要作用，其作用主要是通过调节水稻籽粒大小和粒数来实现的，且08 SG 2/OsBAK 1基因的功能明显受遗传背景的影响。在08 sg 2中取代的氨基酸在不同物种中高度保守，支持其对08 SG 2/OsBAK 1的分子功能重要的想法。这些工作对全面了解08 SG 2/OsBAK 1的功能具有重要意义。本文的在线版本（doi：10.1186/s12284-017-0165-2）包含补充材料，可供授权用户使用。
Both grain size and grain number are significant for rice yield. In the past decade, a number of genes related to grain size and grain number have been documented, however, the regulatory mechanisms underlying them remains ambiguous. We identified a rice small grain (sg2) mutant in an EMS mutant library generated from an indica variety, Shuhui498. Using the MutMap gene mapping strategy, we identified two linkage regions on chromosome 7 and 8, respectively, consistent with the segregation ratios in the F2 population. We focused on the linkage region on chromosome 8, and named this locus as 08sg2. One of three SNPs identified in the linkage region was located in an exon of OsBAK1, leading to a nonsynonymous mutation in the kinase domain. The plant harboring the mutant version 08sg2 locus exhibited a decreased grain size, grain number and plant height. Cytological analysis indicated that 08SG2 regulated spikelet hull development by affecting cell proliferation. The grain size and number of knockout mutants of OsBAK1 in the japonica background were significantly decreased, but less so than in 08sg2, supporting the idea that the SNP in OsBAK1 was responsible for the 08sg2 phenotype, but that 08SG2/OsBAK1 function differently in indica and japonica backgrounds. 08sg2 was insensitive to 24-epiBL, and the expression of BR-related genes was obviously altered in 08sg2. The proportionally decreased grain length when 08sg2 and GS3 were combined indicate that 08SG2 and GS3 regulate grain length independently. Our work shows that 08SG2/OsBAK1 is important for rice yield in both indica and japonica backgrounds, by regulating grain size and grain number, and the function of 08SG2/OsBAK1 is obviously affected by genetic background. The amino acid substituted in 08sg2 is highly conserved among different species, supporting the idea that it is important for the molecular function of 08SG2/OsBAK1. Together, our work is helpful for fully understanding the function of 08SG2/OsBAK1. The online version of this article (doi:10.1186/s12284-017-0165-2) contains supplementary material, which is available to authorized users.