|
OsRAMOSA2 Shapes Panicle Architecture through Regulating Pedicel Length Abstract：The panicle architecture of rice is an important characteristic that influences reproductive success and yield. It is largely determined by the number and length of the primary and secondary branches. The number of panicle branches is defined by the inflorescence meristem state between determinacy and indeterminacy; for example, the maize ramosa2 (ra2) mutant has more branches in its tassel through loss of spikelet determinacy. Some genes and factors influencing the number of primary and secondary branches have been studied, but little is known about the molecular mechanism underlying pedicel development, which also influences panicle architecture. We report here that rice OsRAMOSA2 (OsRA2) gene modifies panicle architecture through regulating pedicel length. Ectopic expression of OsRA2 resulted in a shortened pedicel while inhibition of OsRA2 through RNA interference produced elongated pedicel. In addition, OsRA2 influenced seed morphology. The OsRA2 protein localized to the nucleus and showed transcriptional activation in yeast; in accordance with its function in pedicel development, OsRA2 mRNA was enriched in the anlagen of axillary meristems, such as primary and secondary branch meristems and the spikelet meristems of young panicles. This indicates a conserved role of OsRA2 for shaping the initial steps of inflorescence architecture. Genetic analysis revealed that OsRA2 may control panicle architecture using the same pathway as that of the axillary meristem gene LAX1 (LAX PANICLE1). Moreover, OsRA2 acted downstream of RCN2 in regulating pedicel and branch lengths, but upstream of RCN2 for control of the number of secondary branches, indicating that branch number and length development in the panicle were respectively regulated using parallel pathway. Functional conservation between OsRA2 and AtLOB, and the conservation and diversification of RA2 in maize and rice are also discussed. 关键结论：水稻OsRA2与LAX1在调控叶腋分生途径处于同一遗传通路，而且OsRA2处于RNC2的下游调控分枝和花梗长度。 FIGURE 2. Phenotypes of OsRA2 transgenic plants. (A–C) Phenotypes of ZH11, dsRNAiOsRA2 and pUbi::OsRA2 plants with respect to panicles, PBs and pedicels, respectively. White rectangles in (B) indicate the position of pedicels in (C). (D) The seed phenotype of ZH11, dsRNAiOsRA2 and pUbi::OsRA2 plants. (E) Morphology of ZH11, dsRNAiOsRA2 and pUbi::OsRA2 plants. (F,G) Statistical analysis of pedicel and panicle length among ZH11, dsRNAiOsRA2 and pUbi::OsRA2 plants. (H–K) Statistical analysis of grain traits among ZH11, dsRNAiOsRA2 and pUbi::OsRA2 plants. Values in (F–K) are means ± SE. n = 30 panicles in (F–K) and 10 replicates in (K). (L–N) Cross sections of the pedicel of ZH11, dsRNAiOsRA2 and pUbi::OsRA2 plants. Student’s t-test at ∗P < 0.05 and ∗∗P < 0.01. FIGURE 3. Expression profile of OsRA2. (A) OsRA2 expression in various plant organs. (A) OsRA2 expression in various plant organs. (B) OsRA2 expression in various stages of panicle development. (C–G) mRNA in situ hybridization of OsRA2. (C) OsRA2 expression in the primordia of the PBs (arrowheads). (D)OsRA2 expression in the primordia of the SBs (arrowheads). (E) OsRA2 expression in the primordia of the spikelet meristem (arrowheads). (F) OsRA2 expression in the developed spikelets (arrowhead). (G) Sense probe of OsRA2 hybridization. (H–K) mRNA in situ hybridization of OSH1. (H) OSH1 expression in the primordia of the PBs (arrowheads). (I) OSH1 expression in the primordia of the SBs (arrowheads). (J)OsRA2 expression in the developed spikelets (arrowheads). (K) Sense probe of OSH1 hybridization. 欢迎点击「PaperRss」↑关注我们！ 2Curr Opin Plant Biol：叶腋分生组织的起始调控分枝的分子机制,文章来源中科院遗传发育所焦雨玲组Axillary meristem initiation-a way to branch out. Curr Opin Plant Biol. 2017 Sep 27;41:61-66 Authors: Wang Y, Jiao Y Abstract Plants differ from most animals in their retained ability to initiate new cycles of growth and development, which relies on the establishment and activity of branch meristems. In seed plants, branching is achieved by axillary meristems, which are established in the axil of each leaf base and develop into lateral branches. Research into axillary meristem initiation has identified transcription factors and phytohormones as key regulators. Based on these findings, a mechanistic framework for understanding axillary meristem initiation has emerged. Taking recent research into account, we discuss mechanisms underlying stem cell fate regulation that enable axillary meristem formation. PMID: 28963901 [PubMed - as supplied by publisher] |
|
|
