Frontiers in Plant Science (Nov 2022)

GmTOC1b inhibits nodulation by repressing GmNIN2a and GmENOD40-1 in soybean

  • Yuhang Zhang,
  • Qun Cheng,
  • Chunmei Liao,
  • Lanxin Li,
  • Chuanjie Gou,
  • Zheng Chen,
  • Yanan Wang,
  • Baohui Liu,
  • Fanjiang Kong,
  • Liyu Chen

DOI
https://doi.org/10.3389/fpls.2022.1052017
Journal volume & issue
Vol. 13

Abstract

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Symbiotic nitrogen fixation is an important factor affecting the yield and quality of leguminous crops. Nodulation is regulated by a complex network comprising several transcription factors. Here, we functionally characterized the role of a TOC1 family member, GmTOC1b, in soybean (Glycine max) nodulation. RT-qPCR assays showed that GmTOC1b is constitutively expressed in soybean. However, GmTOC1b was also highly expressed in nodules, and GmTOC1 localized to the cell nucleus, based on transient transformation in Nicotiana benthamiana leaves. Homozygous Gmtoc1b mutant plants exhibited increased root hair curling and produced more infection threads, resulting in more nodules and greater nodule fresh weight. By contrast, GmTOC1b overexpression inhibited nodulation. Furthermore, we also showed that GmTOC1b represses the expression of nodulation-related genes including GmNIN2a and GmENOD40-1 by binding to their promoters. We conclude that GmTOC1b functions as a transcriptional repressor to inhibit nodulation by repressing the expression of key nodulation-related genes including GmNIN2a, GmNIN2b, and GmENOD40-1 in soybean.

Keywords