Rice (Oryza sativa) spikelets are a unique inflorescence structure and their development directly determines grain size and yield. Although many genes related to spikelet development have been reported, the molecular mechanisms underlying this process have not been fully elucidated. In this study, we identified a new recessive rice mutant, lacking rudimentary glume 1 (lrg1). The lrg1 spikelets only formed one rudimentary glume, which, along with the sterile lemmas, was homeotically transformed into lemma-like organs and acquired lemma identity. The transition from the spikelet to the floral meristem was delayed in the lrg1 mutant, resulting in the formation of an ectopic lemma-like organ between the sterile lemma and the terminal floret. In addition, we found that the abnormal lrg1 grain phenotype resulted from the alteration of cell numbers and the hull size. LRG1 encodes a ZOS4-06-C2H2 zinc-finger protein with the typical EAR motifs, and is expressed in all organs and tissues. LRG1 localizes to the nucleus and can interact with the TOPLESS-RELATED PROTEINs (TPRs) to repress the expressions of their downstream target genes. Taken together, our results reveal that LRG1 plays an important role in the regulation of spikelet organ identity and grain size.

水稻 ( Oryza sativa) 的小穗是一种独特的花序结构，它们的发育直接决定了籽粒大小和产量。尽管已经报道了许多与小穗发育相关的基因，但这一过程背后的分子机制尚未完全阐明。在这项研究中，我们发现了一种新的隐性水稻突变体，它缺乏基本颖片 1 ( lrg1 )。lrg1小穗只形成一个不发育的颖片，它与不育的外稃一起被同源转化为外稃样器官并获得外稃身份。从小穗到花分生组织的转变在lrg1中被延迟突变体，导致在不育的外稃和末端小花之间形成异位的外稃样器官。此外，我们发现异常的lrg1谷物表型是由细胞数量和外壳大小的改变引起的。LRG1编码具有典型 EAR 基序的 ZOS4-06-C2H2 锌指蛋白，并在所有器官和组织中表达。LRG1 定位于细胞核，可与 TOPLESS 相关蛋白 (TPR) 相互作用以抑制其下游靶基因的表达。综上所述，我们的结果表明LRG1在调控小穗器官特性和晶粒大小方面起着重要作用。