Chen Chen, Begcy Kevin, Liu Kan, Folsom Jing J, Wang Zhen, Zhang Chi, Walia Harkamal
Department of Agronomy and Horticulture (C.C., K.B., J.J.F., Z.W., H.W.) and School of Biological Sciences (K.L., C.Z.), University of Nebraska, Lincoln, Nebraska 68583; andKey Laboratory of Crop Genetics and Physiology of Jiangsu Province and Key Laboratory of Plant Functional Genomics of the Ministry of Education, College of Agriculture, Yangzhou University, Yangzhou 225009, China (C.C.).
Department of Agronomy and Horticulture (C.C., K.B., J.J.F., Z.W., H.W.) and School of Biological Sciences (K.L., C.Z.), University of Nebraska, Lincoln, Nebraska 68583; andKey Laboratory of Crop Genetics and Physiology of Jiangsu Province and Key Laboratory of Plant Functional Genomics of the Ministry of Education, College of Agriculture, Yangzhou University, Yangzhou 225009, China (C.C.)
Plant Physiol. 2016 May;171(1):606-22. doi: 10.1104/pp.15.01992. Epub 2016 Mar 2.
Early seed development events are highly sensitive to increased temperature. This high sensitivity to a short-duration temperature spike reduces seed viability and seed size at maturity. The molecular basis of heat stress sensitivity during early seed development is not known. We selected rice (Oryza sativa), a highly heat-sensitive species, to explore this phenomenon. Here, we elucidate the molecular pathways that contribute to the heat sensitivity of a critical developmental window during which the endosperm transitions from syncytium to the cellularization stage in young seeds. A transcriptomic comparison of seeds exposed to moderate (35°C) and severe (39°C) heat stress with control (28°C) seeds identified a set of putative imprinted genes, which were down-regulated under severe heat stress. Several type I MADS box genes specifically expressed during the syncytial stage were differentially regulated under moderate and severe heat stress. The suppression and overaccumulation of these genes are associated with precocious and delayed cellularization under moderate and severe stress, respectively. We show that modulating the expression of OsMADS87, one of the heat-sensitive, imprinted genes associated with syncytial stage endosperm, regulates rice seed size. Transgenic seeds deficient in OsMADS87 exhibit accelerated endosperm cellularization. These seeds also have lower sensitivity to a moderate heat stress in terms of seed size reduction compared with seeds from wild-type plants and plants overexpressing OsMADS87 Our findings suggest that OsMADS87 and several other genes identified in this study could be potential targets for improving the thermal resilience of rice during reproductive development.
早期种子发育事件对温度升高高度敏感。这种对短期温度峰值的高敏感性会降低成熟种子的活力和大小。早期种子发育过程中热应激敏感性的分子基础尚不清楚。我们选择了高度热敏的水稻（Oryza sativa）来探究这一现象。在此，我们阐明了导致关键发育窗口热敏感性的分子途径，在此期间，年轻种子中的胚乳从合胞体转变为细胞化阶段。对暴露于中度（35°C）和重度（39°C）热应激的种子与对照（28°C）种子进行转录组比较，鉴定出一组假定的印记基因，这些基因在重度热应激下被下调。在合胞体阶段特异性表达的几个I型MADS盒基因在中度和重度热应激下受到差异调节。这些基因的抑制和过度积累分别与中度和重度应激下的早熟和延迟细胞化相关。我们表明，调节与合胞体阶段胚乳相关的热敏印记基因之一OsMADS87的表达，可调控水稻种子大小。缺乏OsMADS87的转基因种子表现出加速的胚乳细胞化。与野生型植物和过表达OsMADS87的植物的种子相比，这些种子在种子大小减少方面对中度热应激的敏感性也较低。我们的研究结果表明，OsMADS87和本研究中鉴定的其他几个基因可能是提高水稻生殖发育期间热耐受性的潜在靶点。
