磷形态对OsPT4调控水稻根系生长发育的影响及生理基础

Phosphorus is one of the major limiting factors for growth and development of rice, its effects are influenced by phosphorus forms. At present, the researches of phosphorus absorption and utilization of rice are mainly concentrated on their response to H2PO4-, but very little involved in other phosphorus forms. Applicant’s previous studies have confirmed that OsPT4, a key gene for H2PO4- acquisition and translocation in rice, affects the root morphology, whereas, it is unclear yet that how OsPT4 regulates the growth and development of rice roots and whether that mechanism still keeps under different phosphorus forms. In this project, the mutant, RNAi, over-expression and tissue localization plants of OsPT4, will be cultured in liquid solution with K2HPO4, KH2PO4 and sodium phytate, by means of three-dimensional coordinate container method created by the research group. The effects of different phosphorus on the growth and development of rice roots regulated by OsPT4 will be investigated from plants and cellular level, respectively. The physiological mechanism of this regulation under different phosphorus forms will be clarified through plant physiological technologies. The relationship between phosphorus forms, OsPT4 and OsPIN at transcription level will be explored at last. All these results will illuminate the inherent law of phosphorus absorption and utilization of rice roots under different phosphorus forms in this proposal, and which will provide the theoretical foundations and technical references for the application of phosphate fertilizer in rice production.

磷是水稻生长发育的主要限制因子之一，其效应受磷形态影响。目前水稻对磷素吸收与利用的研究主要集中在其对H2PO4-的响应，而甚少涉及其它磷形态。申请人前期研究证实OsPT4是水稻吸收和转运H2PO4-的关键基因，影响水稻根系形态的变化，但OsPT4是怎样调控水稻根系生长发育及其在不同磷形态下的效应是否保持尚不清楚。本项目将以K2HPO4、KH2PO4和植酸钠为磷源，采用研究团队创立的三维容器法培养OsPT4的突变体、RNAi、过表达及组织定位等水稻材料，从植株和细胞水平研究磷形态对OsPT4调控水稻根系生长发育的影响；运用常规生理和分子生理阐明不同磷形态下OsPT4调控水稻根系生长发育的生理机制；并从转录水平上探究磷形态、OsPT4和OsPIN的关系；从而揭示水稻根系对不同形态磷素吸收利用的内在规律，为水稻生产的磷肥施用提供理论基础和技术参考。

磷是水稻生长发育的主要限制因子之一，其效应受磷形态影响。另外随着全球气候变暖，高温引起的颖花不育现象频发，对水稻生产也造成严重威胁。本研究组早期证实OsPT4是水稻吸收和转运H2PO4-的关键基因，影响水稻根系形态的变化；茉莉酸(JA)及其甲酯(MeJA)能诱导水稻开花。在此基础上，本项目对磷形态影响OsPT4调控水稻根系生长发育，和该基因在高产水稻品种磷素吸收利用中的作用，以及激素调控水稻花器官发育等进行了深入研究。主要研究结果包括：(1)利用CRISPR/Cas9基因编辑系，以日本晴为背景创制获得ospt4突变体转基因水稻；OsPT4对水稻磷素吸收利用及根系发育的调控作用在不同磷形态供应下相一致，OsPT4缺失后，显著降低了水稻对各形态磷的吸收和利用，降低了水稻根系生长进程，突变体根系生长发育的各项指标均显著下降。(2)OsPT4在武运粳7号中超表达后能有效促进转基因水稻地上部的磷素积累，增加水稻的单株产量。(3)GA1调控了水稻颖花开放时花丝的伸长；颖花开放时，GA1含量是开花前1d的2.4倍。(4)生长素(IAA)抑制了水稻颖花的开放，而茉莉酸甲酯(MeJA)能有效解除该抑制作用。颖花中IAA在开花前2d大量积累，在开花时浓度快速降至最低。该项目的研究结果为水稻生产的磷肥施用和花时的人工改良提供理论基础和技术参考，具有一定的应用前景。