ERECTA PANICLE 3 (EP3) and ORYZA SATIVA F-BOX KELCH 1 (OsFBK1) proteins share 57% and 54% sequence identity with the Arabidopsis F-box protein HAWAIIAN SKIRT (HWS). Previously we showed that EP3 is a functional orthologue of HWS. Here we demonstrate that OsFBK1 is another functional orthologue of HWS and show the complexity of interaction between EP3 and OsFBK1 genes at different developmental stages of the plant. qRT-PCR expression analyses and studies of EP3-GFP and OsFBK1-RFP promoter reporter lines demonstrate that although EP3 and OsFBK1 expression can be detected in the same tissues some cells exclusively express EP3 or OsFBK1 whilst others co-express both genes. Loss, reduction or gain-of-function lines for EP3 and OsFBK1, show that EP3 and OsFBK1 affect plant architecture, organ size, floral organ number and size, floral morphology, pollen viability, grain size and weight. We have identified the putative orthologue genes of the rice microRNA pathway for ORYZA SATIVA DAWDLE (OsDDL) and ORYZA SATIVA SERRATE (OsSE), and demonstrated that EP3 and OsFBK1 affect their transcript levels as well as those of CROWN ROOT DEFECT 1/ORYZA SATIVA Exportin-5 HASTY (CRD1/OsHST), ORYZA SATIVA DICER-LIKE 1 (OsDCL) and ORYZA SATIVA WEAVY LEAF1 (OsWAF1). We show that EP3 affects OsPri-MIR164, OsNAM1 and OsNAC1 transcript levels. OsNAC1 transcripts are modified by OsFBK1, suggesting two independent regulatory pathways, one via EP3 and OsMIR164 and the other via OsFBK1. Our data propose that EP3 and OsFBK1 conjointly play similar roles in rice to how HWS does in Arabidopsis.

中文翻译：

---

水稻 EP3 和 OsFBK1 E3 连接酶改变植物结构和花发育，并影响 microRNA 通路基因及其靶标的转录本积累

ERECTA PANICLE 3 (EP3) 和 ORYZA SATIVA F-BOX KELCH 1 (OsFBK1) 蛋白与拟南芥 F-box 蛋白 HAWAIIAN SKIRT (HWS) 具有 57% 和 54% 的序列同一性。之前我们表明EP3是HWS的功能直系同源物。在这里，我们证明OsFBK1是HWS的另一个功能直系同源物，并显示了植物不同发育阶段EP3和OsFBK1基因之间相互作用的复杂性。qRT-PCR 表达分析和EP3-GFP和OsFBK1-RFP启动子报告系的研究表明，尽管EP3和OsFBK1可以在相同的组织中检测到表达，一些细胞专门表达EP3或OsFBK1，而另一些细胞则同时表达这两种基因。EP3和OsFBK1的功能丧失、减少或获得系表明EP3和OsFBK1影响植物结构、器官大小、花器官数量和大小、花形态、花粉活力、颗粒大小和重量。我们已经鉴定了水稻 microRNA 通路的假定直系同源基因ORYZA SATIVA DAWDLE (OsDDL ) 和ORYZA SATIVA SERRATE ( OsSE )，并证明EP3和OsFBK1影响它们的转录水平以及冠根缺陷 1 / ORYZA SATIVA Exportin-5 HASTY ( CRD1/OsHST )、ORYZA SATIVA DICER-LIKE 1 ( OsDCL ) 和ORYZA SATIVA WEAVY LEAF1 ( OsWAF1 ) 的转录水平。我们显示EP3影响 OsPri-MIR164、OsNAM1和OsNAC1转录水平。OsNAC1转录本被OsFBK1修饰，表明有两条独立的调节途径，一条通过EP3和OsMIR164，另一条通过OsFBK1。我们的数据表明EP3和OsFBK1在水稻中的作用与HWS在拟南芥中的作用相似。