Coordinated regulation of vegetative and reproductive branching in rice
Thursday, 2015/12/17 | 08:06:55
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Lei Wang, Shengyuan Sun, Jiye Jin, Debao Fu, Xuefei Yang, Xiaoyu Weng, Caiguo Xu, Xianghua Li, Jinghua Xiao, and Qifa Zhang SignificanceThe patterns of lateral branching, including tillers and inflorescence branches, determine grain yields of many cereals. In this study, we characterized a regulatory network composed of microRNAs and transcription factor that coordinately regulate vegetative (tiller) and reproductive (panicle) branching in rice. The findings hold tremendous promise for application in rice genetic improvement and may also have general implications for understanding branching regulation of grasses. AbstractGrasses produce tiller and panicle branching at vegetative and reproductive stages; the branching patterns largely define the diversity of grasses and constitute a major determinant for grain yield of many cereals. Here we show that a spatiotemporally coordinated gene network consisting of the MicroRNA 156 (miR156/)miR529/SQUAMOSA PROMOTER BINDING PROTEIN LIKE (SPL) and miR172/APETALA2 (AP2) pathways regulates tiller and panicle branching in rice. SPL genes negatively control tillering, but positively regulate inflorescence meristem and spikelet transition. Underproduction or overproduction of SPLs reduces panicle branching, but by distinct mechanisms: miR156 and miR529 fine-tune the SPL levels for optimal panicle size. miR172 regulates spikelet transition by targeting AP2-like genes, which does not affect tillering, and the AP2-like proteins play the roles by interacting with TOPLESS-related proteins (TPRs). SPLs modulate panicle branching by directly regulating the miR172/AP2 and PANICLE PHYTOMER2 (PAP2)/Rice TFL1/CEN homolog 1 (RCN1) pathways and also by integrating other regulators, most of which are not involved in tillering regulation. These findings may also have significant implications for understanding branching regulation of other grasses and for application in rice genetic improvement.
See: http://www.pnas.org/content/112/50/15504.abstract.html?etoc PNAS December 15 2015; vol. 112 no. 50: 15504–15509
Fig. 1. Tillering and panicle branching regulated by miR156 and miR529. (A and B) The plants (A) and panicles (B) at adult stage of WT, MIM156, miR156OE, and the hybrid between miR156OE and MIM156 plants. (C and D) Main panicles of WT (C) and miR156OE (D) plants with or without tiller removal every other day. Values are means ± SEM (n = 15). (E and F) Plants (E) and panicles (F) of WT and miR529aOE plants at adult stage. (G and H) Scanning electron microscopic images of the panicles at the primary branch initiation stage in WT (G) and miR156OE (H) plants. The red and blue asterisks indicate inflorescence and primary branch meristems, respectively. (Scale bars: 50 μm.) (I–K) In situ hybridization of OSH1 in WT (I and K) and miR156OE (J) plants by using antisense (I and J) and sense (K) probes. [Scale bars: 200 μm (I) and 100 μm (J and K).] |
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