Graduate School of Agriculture and Life Sciences, The University of Tokyo, Yayoi, Bunkyo, Tokyo 113-8657, Japan.
Proc Natl Acad Sci U S A. 2013 Jan 8;110(2):767-72. doi: 10.1073/pnas.1216151110. Epub 2012 Dec 24.
Inflorescence structures result from the activities of meristems, which coordinate both the renewal of stem cells in the center and organ formation at the periphery. The fate of a meristem is specified at its initiation and changes as the plant develops. During rice inflorescence development, newly formed meristems acquire a branch meristem (BM) identity, and can generate further meristems or terminate as spikelets. Thus, the form of rice inflorescence is determined by a reiterative pattern of decisions made at the meristems. In the dominant gain-of-function mutant tawawa1-D, the activity of the inflorescence meristem (IM) is extended and spikelet specification is delayed, resulting in prolonged branch formation and increased numbers of spikelets. In contrast, reductions in TAWAWA1 (TAW1) activity cause precocious IM abortion and spikelet formation, resulting in the generation of small inflorescences. TAW1 encodes a nuclear protein of unknown function and shows high levels of expression in the shoot apical meristem, the IM, and the BMs. TAW1 expression disappears from incipient spikelet meristems (SMs). We also demonstrate that members of the SHORT VEGETATIVE PHASE subfamily of MADS-box genes function downstream of TAW1. We thus propose that TAW1 is a unique regulator of meristem activity in rice and regulates inflorescence development through the promotion of IM activity and suppression of the phase change to SM identity.
花序结构是由分生组织的活动产生的,分生组织协调中心干细胞的更新和外围器官的形成。分生组织的命运在其起始时被指定,并随着植物的发育而改变。在水稻花序发育过程中,新形成的分生组织获得了一个分支分生组织(BM)的身份,可以进一步产生分生组织或终止为小穗。因此,水稻花序的形式由分生组织做出的重复决策决定。在显性获得功能突变体 tawawa1-D 中,花序分生组织(IM)的活性被延长,小穗的特化被延迟,导致分支形成延长和小穗数量增加。相比之下,TAWAWA1(TAW1)活性的减少导致过早的 IM 流产和小穗形成,导致小的花序产生。TAW1 编码一种未知功能的核蛋白,在茎尖分生组织、IM 和 BM 中表达水平较高。TAW1 表达从小穗分生组织(SMs)中消失。我们还证明,SHORT VEGETATIVE PHASE 亚家族的 MADS 盒基因成员在 TAW1 下游发挥作用。因此,我们提出 TAW1 是水稻分生组织活性的独特调节因子,通过促进 IM 活性和抑制向 SM 身份的相变来调节花序发育。