Abstract：
Tiller angle is a key agricultural trait that establishes plant architecture, which in turn strongly affects grain yield by influencing planting density in rice. The shoot gravity response plays a crucial role in the regulation of tiller angle in rice, but the underlying molecular mechanism is largely unknown. Here, we report the identification of the BIG TILLER ANGLE2 (BTA2), which regulates tiller angle by controlling the shoot gravity response in rice. Loss-of-function mutation of BTA2 dramatically reduced auxin content and affected auxin distribution in rice shoot base, leading to impaired gravitropism and therefore a big tiller angle. BTA2 interacted with AUXIN RESPONSE FACTOR7 (ARF7) to modulate rice tiller angle through the gravity signaling pathway. The BTA2 protein was highly conserved during evolution. Sequence variation in the BTA2 promoter of indica cultivars harboring a less expressed BTA2 allele caused lower BTA2 expression in shoot base and thus wide tiller angle during rice domestication. Overexpression of BTA2 significantly increased grain yield in the elite rice cultivar Huanghuazhan under appropriate dense planting conditions. Our findings thus uncovered the BTA2-ARF7 module that regulates tiller angle by mediating the shoot gravity response. Our work offers a target for genetic manipulation of plant architecture and valuable information for crop improvement by producing the ideal plant type.
摘要：
蒂勒角是建立植物结构的关键农业性状，这反过来又通过影响水稻的种植密度来强烈影响谷物产量。枝条重力反应在水稻分耕角的调节中起着至关重要的作用,但是潜在的分子机制在很大程度上是未知的。这里,我们报告了BIGTILLERANGLE2（BTA2）的鉴定，它通过控制水稻的射击重力响应来调节耕作角。BTA2的功能丧失突变大大降低了生长素含量，并影响了水稻芽中生长素的分布。导致重力性受损，因此导致较大的分till角。BTA2与AUXIN反应因子7（ARF7）相互作用，通过重力信号通路调节水稻分分池角。BTA2蛋白在进化过程中高度保守。带有表达较少的BTA2等位基因的in稻品种的BTA2启动子中的序列变异会导致芽基部的BTA2表达降低，从而导致水稻驯化过程中的分till角变宽。在适当的密植条件下，BTA2的过表达显着提高了水稻优良品种黄花站的籽粒产量。因此，我们的发现揭示了BTA2-ARF7模块，该模块通过介导射击重力响应来调节耕作角。我们的工作为植物结构的遗传操作提供了目标，并通过生产理想的植物类型为作物改良提供了有价值的信息。
