Phosphate starvation responsive GmSPX5 mediates nodule growth through interaction with GmNF‐YC4 in soybean (Glycine max). (11th October 2021)

• Record Type: Journal Article
• Authors: Zhuang, Qingli; Xue, Yingbin; Yao, Zhufang; Zhu, Shengnan; Liang, Cuiyue; Liao, Hong; Tian, Jiang
• Is Part Of: Plant journal. Volume 108:Number 5(2021)
• Page Start: 1422
• Page End: 1438
• Publication Date: 2021-10-11
• Subjects: phosphate starvation -- SPX protein -- soybean -- nodules -- asparagine synthetase; Plant molecular biology -- Periodicals; Plant cells and tissues -- Periodicals; Botany -- Periodicals; 580
• DOI: 10.1111/tpj.15520
• Languages: English
• ISSNs: 0960-7412

Abstract

SUMMARY: Phosphorus (P) deficiency adversely affects nodule development as reflected by reduced nodule fresh weight in legume plants. Though mechanisms underlying nodule adaptation to P deficiency have been studied extensively, it remains largely unknown which regulator mediates nodule adaptation to P deficiency. In this study, GUS staining and quantitative reverse transcription‐PCR analysis reveal that the SPX member GmSPX5 is preferentially expressed in soybean ( Glycine max ) nodules. Overexpression of GmSPX5 enhanced soybean nodule development particularly under phosphate (Pi) sufficient conditions. However, the Pi concentration was not affected in soybean tissues (i.e., leaves, roots, and nodules) of GmSPX5 overexpression or suppression lines, which distinguished it from other well‐known SPX members functioning in control of Pi homeostasis in plants. Furthermore, GmSPX5 was observed to interact with the transcription factor GmNF‐YC4 in vivo and in vitro . Overexpression of either GmSPX5 or GmNF‐YC4 significantly upregulated the expression levels of five asparagine synthetase‐related genes (i.e., GmASL2 – 6 ) in soybean nodules. Meanwhile, yeast one‐hybrid and luciferase activity assays strongly suggested that interactions of GmSPX5 and GmNF‐YC4 activate GmASL6 expression through enhancing GmNF‐YC4 binding of the GmASL6 promoter. These results not only demonstrate the GmSPX5–GmNF‐YC4–GmASL6 regulatory pathway mediating soybean nodule development, but also considerably improve our understanding of SPX functions in legume crops. Significance Statement: The soybean ( Glycine max ) SPX member GmSPX5 is preferentially expressed in nodules. GmSPX5 overexpression or suppression did not affect the phosphate (Pi) concentration in soybean tissues, which distinguished it from other SPX members functioning in control of Pi homeostasis in plants. Furthermore, GmSPX5 interacted with GmNF‐YC4, and their overexpression led to upregulation of the expression of five asparagine synthetase‐related genes in soybean nodules. These results suggest that the GmSPX5–GmNF‐YC4 regulatory pathway mediates soybean nodule growth.