Pectin Methylesterases Enhance Root Cell Wall Phosphorus Remobilization in Rice
Wu Qi,
Tao Ye,
Zhang Xiaolong,
Dong Xiaoying,
Xia Jixing,
Shen Renfang,
Zhu Xiaofang
Affiliations
Wu Qi
State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China; University of Chinese Academy of Sciences, Beijing 100049, China
Tao Ye
State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China; University of Chinese Academy of Sciences, Beijing 100049, China
Zhang Xiaolong
State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China; University of Chinese Academy of Sciences, Beijing 100049, China
Dong Xiaoying
State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China
Xia Jixing
State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Life Science and Technology, Guangxi University, Nanning 530004, China
Shen Renfang
State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China; University of Chinese Academy of Sciences, Beijing 100049, China
Zhu Xiaofang
State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China; University of Chinese Academy of Sciences, Beijing 100049, China; Corresponding author.
Pectin contributes greatly to cell wall phosphorus (P) remobilization. However, it is currently unclear whether the methylesterification degree of the pectin, which is related to the activity of pectin methylesterases (PMEs), is also involved in this process. Here, we demonstrated that elevated PME activity can facilitate the remobilization of P deposited in the cell wall. P-deficient conditions resulted in the reduction of root cell wall P content. This reduction was more pronounced in Nipponbare than in Kasalath, in company with a significant increment of the PME activity, indicating a possible relationship between elevated PME activity and cell wall P remobilization. This hypothesis was supported by in vitro experiments, as pectin with lower methylesterification degree had higher ability to release inorganic P (Pi) from insoluble FePO4. Furthermore, among the 35 OsPME members in rice, only the expression of OsPME14 showed a relationship with PME activity. In addition, transgenic rice lines overexpressing OsPME14 had increased PME activity, released more P from the root cell wall, and more resistant to P deficiency. In conclusion, PMEs enhance P remobilization in P-starved rice by increasing PME activity in Nipponbare, which in turn helps to remobilize P from the cell wall, and thus makes more available P.
