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

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

JOURNAL=Frontiers in Plant Science

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2022.1052017

DOI=10.3389/fpls.2022.1052017

ISSN=1664-462X

ABSTRACT=<p>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 (<italic>Glycine max</italic>) nodulation. RT-qPCR assays showed that <italic>GmTOC1b</italic> is constitutively expressed in soybean. However, <italic>GmTOC1b</italic> was also highly expressed in nodules, and GmTOC1 localized to the cell nucleus, based on transient transformation in <italic>Nicotiana benthamiana</italic> leaves. Homozygous <italic>Gmtoc1b</italic> mutant plants exhibited increased root hair curling and produced more infection threads, resulting in more nodules and greater nodule fresh weight. By contrast, <italic>GmTOC1b</italic> overexpression inhibited nodulation. Furthermore, we also showed that GmTOC1b represses the expression of nodulation-related genes including <italic>GmNIN2a</italic> and <italic>GmENOD40-1</italic> 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 <italic>GmNIN2a</italic>, <italic>GmNIN2b</italic>, and <italic>GmENOD40-1</italic> in soybean.</p>