Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China.
Jiangsu Key Laboratory of Crop Genomics and Molecular Breeding/Zhongshan Biological Breeding Laboratory/Key Laboratory of Plant Functional Genomics of the Ministry of Education, Agricultural College of Yangzhou University, Yangzhou 225009, China.
Proc Natl Acad Sci U S A. 2024 Aug 20;121(34):e2404199121. doi: 10.1073/pnas.2404199121. Epub 2024 Aug 13.
Low phosphate (Pi) availability decreases photosynthesis, with phosphate limitation of photosynthesis occurring particularly during grain filling of cereal crops; however, effective genetic solutions remain to be established. We previously discovered that rice phosphate transporter OsPHO1;2 controls seed (sink) development through Pi reallocation during grain filling. Here, we find that OsPHO1;2 regulates Pi homeostasis and thus photosynthesis in leaves (source). Loss-of-function of OsPHO1;2 decreased Pi levels in leaves, leading to decreased photosynthetic electron transport activity, CO assimilation rate, and early occurrence of phosphate-limited photosynthesis. Interestingly, ectopic expression of greatly increased Pi availability, and thereby, increased photosynthetic rate in leaves during grain filling, contributing to increased yield. This was supported by the effect of foliar Pi application. Moreover, analysis of core rice germplasm resources revealed that higher expression was associated with enhanced photosynthesis and yield potential compared to those with lower expression. These findings reveal that phosphate-limitation of photosynthesis can be relieved via a genetic approach, and the gene can be employed to reinforce crop breeding strategies for achieving higher photosynthetic efficiency.
低磷酸盐（Pi）供应会降低光合作用，特别是在谷类作物灌浆期间，磷酸盐会限制光合作用；然而，目前仍需要建立有效的遗传解决方案。我们之前发现，水稻磷酸盐转运蛋白 OsPHO1;2 通过在灌浆过程中重新分配 Pi 来控制种子（汇）发育。在这里，我们发现 OsPHO1;2 调节 Pi 动态平衡，从而调节叶片中的光合作用（源）。OsPHO1;2 的功能丧失会降低叶片中的 Pi 水平，导致光合作用电子传递活性、CO 同化率降低，并较早出现磷酸盐限制的光合作用。有趣的是，异位表达 会大大增加 Pi 的可用性，从而在灌浆期间增加叶片的光合速率，有助于提高产量。这一结果得到了叶面 Pi 应用的支持。此外，对核心水稻种质资源的分析表明，与表达较低的品种相比，较高的 表达与增强的光合作用和产量潜力相关。这些发现表明，通过遗传方法可以缓解光合作用的磷酸盐限制，并且可以利用 基因来加强作物育种策略，以实现更高的光合作用效率。
