Grain/seed yield and plant stress tolerance are two major traits that determine the yield potential of many crops. In cereals, grain size is one of the key factors affecting grain yield. Here, we identify and characterize a newly discovered gene Rice Big Grain 1 (RBG1 ) that regulates grain and organ development, as well as abiotic stress tolerance. Ectopic expression of RBG1 leads to significant increases in the size of not only grains but also other major organs such as roots, shoots and panicles. Increased grain size is primarily due to elevated cell numbers rather than cell enlargement. RBG1 is preferentially expressed in meristematic and proliferating tissues. Ectopic expression of RBG1 promotes cell division, and RBG1 co‐localizes with microtubules known to be involved in cell division, which may account for the increase in organ size. Ectopic expression of RBG1 also increases auxin accumulation and sensitivity, which facilitates root development, particularly crown roots. Moreover, overexpression of RBG1 up‐regulated a large number of heat‐shock proteins, leading to enhanced tolerance to heat, osmotic and salt stresses, as well as rapid recovery from water‐deficit stress. Ectopic expression of RBG1 regulated by a specific constitutive promoter, GOS2 , enhanced harvest index and grain yield in rice. Taken together, we have discovered that RBG1 regulates two distinct and important traits in rice, namely grain yield and stress tolerance, via its effects on cell division, auxin and stress protein induction.

中文翻译：

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稻米大米1促进细胞分裂，增强器官发育，抗逆性和谷物产量。

谷物/种子产量和植物抗逆性是决定许多农作物产量潜力的两个主要特征。在谷物中，粒度是影响谷物产量的关键因素之一。在这里，我们鉴定并鉴定了一个新发现的基因水稻大谷粒1（RBG1），该基因调节谷物和器官的发育以及非生物胁迫耐受性。RBG1的异位表达不仅导致谷物的大小显着增加，还导致其他主要器官（例如根，芽和穗）的大小显着增加。晶粒尺寸的增加主要是由于细胞数量增加而不是细胞增大。RBG1优先在分生组织和增生组织中表达。RBG1的异位表达促进细胞分裂，RBG1与已知参与细胞分裂的微管共定位，这可能是器官大小增加的原因。RBG1的异位表达还增加了植物生长素的积累和敏感性，从而促进了根的发育，特别是冠状根。此外，RBG1的过表达上调了许多热休克蛋白，从而增强了对热，渗透压和盐胁迫的耐受性，以及从缺水胁迫中快速恢复的能力。RBG1的异位表达受特定组成型启动子GOS2调控，提高了水稻的收获指数和谷物产量。两者合计，我们发现RBG1 通过对稻米的细胞分裂，生长素和胁迫蛋白的诱导作用，调节稻米的两个重要特征，即谷物产量和胁迫耐受性。