Xie Mengyang, Yang Xiaoli, Chen Wang, Kuang Hudong, Zhu Yanhua, Wang Zhujun, Lin Honghui, Yang Jian
Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Southwest Bio-resources R&D Key Laboratory of Sichuan Province, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu, China.
Plant Biotechnol J. 2025 Aug 28. doi: 10.1111/pbi.70342.
Phosphorus is a crucial nutrient for the normal growth and development of rice. Enhancing the efficiency of phosphorus acquisition in plants is vital for optimising soil phosphorus utilisation. The SUMO E3 ligase OsSIZ1 is an important factor for regulating plant phosphorus acquisition and starvation response in rice. However, how its activity responds to Pi-supplied conditions remains unknown. In this study, we discovered that the mutations in OsCK2β3, which encodes a regulatory subunit of CK2, influenced the Pi starvation response. The global level of SUMOylation was found to decrease in Osck2β3 mutants, mirroring the effects observed under Pi-deficiency treatment. Additionally, we identified that OsCK2 can interact with and phosphorylate OsSIZ1, thereby impacting its stability. Transcriptome analysis with Ossiz1 and Osck2β3 mutants revealed that the 'OsCK2-OsSIZ1' module primarily regulates defence responses by influencing the expression of genes associated with the biosynthesis of diterpenoid phytoalexins and pathogenesis-related genes, in addition to impacting the response to phosphate starvation. Notably, the overexpression of a variant of OsSIZ1, in which the phosphorylation sites targeted by OsCK2 were mutated, enhanced phosphorus acquisition and defence responses while preserving normal growth. Consequently, we not only showed how OsSIZ1 activity responds to Pi starvation but also created a variant of OsSIZ1 that improves phosphorus acquisition efficiency and enhances resistance against multiple pathogens, all without inducing growth defects.
磷是水稻正常生长发育的关键养分。提高植物对磷的吸收效率对于优化土壤磷利用至关重要。SUMO E3连接酶OsSIZ1是调节水稻中植物磷吸收和饥饿反应的重要因子。然而，其活性如何响应磷供应条件仍不清楚。在本研究中，我们发现编码CK2调节亚基的OsCK2β3中的突变影响了磷饥饿反应。在Osck2β3突变体中发现SUMO化的整体水平降低，这与缺磷处理下观察到的效应相似。此外，我们确定OsCK2可以与OsSIZ1相互作用并使其磷酸化，从而影响其稳定性。对Ossiz1和Osck2β3突变体的转录组分析表明，“OsCK2-OsSIZ1”模块除了影响对磷饥饿的反应外，还主要通过影响与二萜类植物抗毒素生物合成相关基因和病程相关基因的表达来调节防御反应。值得注意的是，OsCK2靶向的磷酸化位点发生突变的OsSIZ1变体的过表达提高了磷吸收和防御反应，同时保持正常生长。因此，我们不仅揭示了OsSIZ1活性如何响应磷饥饿，还创造了一种OsSIZ1变体，它提高了磷吸收效率并增强了对多种病原体的抗性，且不会诱导生长缺陷。
