The Soil-Plant Interaction Innovation Team of the Institute of Agricultural Resources and Regional Planning (IARRP) of the Chinese Academy of Agricultural Sciences (CAAS) found that the GARP family transcription factor RLI1 modulates plant growth and low-phosphate (Pi) adaptation through a regulatory strategy of alternative splicing. The research results have been published in Plant Cell.

According to Professor Keke Yi, phosphorus (P), a macronutrient, is essential for high crop yields. At present, the total phosphorus content of cultivated soil in China is generally high, while the available phosphorus content that can be absorbed and used by crops is deficient. The problem is often solved by applying a large amount of P-fertilizer in agricultural production, which not only leads to a low utilization rate of P-fertilizer in the field, but also causes environmental risks such as water eutrophication. Therefore, improving the Pi absorption and use efficiency of crops is important for the development of green agriculture. In order to better adapt to different phosphorus status in the soils, plants have evolved various response mechanisms of Pi-uptake, Pi-utilization and growth adaptation. However, how these response mechanisms are coordinated to help crops effectively adapt to different soil phosphorus status remains unclear.

Based on the Pi-availability associated shoot architecture regulator of RLI1, previously reported by Ruan et al. (2018, Plant Cell), the research team further found that there is an alternative splicing phenomenon in the RLI1 gene. Alternative splicing of RLI1 produces two protein isoforms: RLI1a (containing the MYB DNA-binding domain) and RLI1b (containing the MYB and CC domains). The two protein isoforms perform different functions under Pi-sufficient and Pi-deficient conditions. When the soil available Pi supply is sufficient, rice accumulates a large amount of RLI1a isoform protein and activates the biosynthesis and signal transduction of brassinolide, thereby promoting efficient growth under Pi-sufficient. When the soil available Pi supply is deficient, the RLI1b isoform protein level accumulates obviously, and it cooperates with the core phosphate regulator PHR2 to activate the Pi starvation signaling, so as to improve the Pi-uptake and Pi-utilization ability of rice to help rice resist Pi-deficient stress. Further research found that RLI1 integrates Pi-starvation signaling, Pi-homeostasis and growth through alternative splicing are ubiquitous in angiosperms.

The analysis of this conservative mechanism will provide a theoretical basis for cultivating smart crops with high efficiency of phosphorus nutrients and ideal shoot architecture in the future.

Postdoctoral student Guo Meina, master's student Zhang Yuxin and postdoctoral student Jia Xianqing are the co-first authors of the paper, and Professor Keke Yi and associate researcher Ruan Wenyuan are the co-corresponding authors.

The research was supported by the National Key R&D Program, the National Natural Science Foundation of China, the China Postdoctoral Science Foundation, and the "Young Talents" Program of the Innovation Project of the Chinese Academy of Agricultural Sciences.

Paper link:

https://academic.oup.com/plcell/advance-article/doi/10.1093/plcell/koac161/6595036?searchresult=1#supplementary-data