Nosaki, S. | bioRxiv Science

bioRxiv2025

An NLP-inherited motif confers broad DNA-binding specificity to NIN in root nodule symbiosis

Nitrogen-fixing root nodule symbiosis (RNS) occurs in some eudicots, including legumes, and is regulated by the transcription factor NODULE INCEPTION (NIN), derived from the NIN-LIKE PROTEIN (NLP) family. However, how the NIN protein acquired RNS-specific functions remains unclear. We identify a previously undescribed motif in Lotus japonicus NIN, located downstream of the RWP-RK domain, which we term the FR. This motif broadens the DNA-binding specificity of NIN by stabilizing the RWP-RK dimer interface. nin mutants lacking the FR motif show defective nodulation and impaired nitrogen fixation. Arabidopsis NLP2 carries a NIN-type FR and shares key features with NIN. Furthermore, the NIN-type FR likely originated as early as gymnosperms, suggesting that the molecular feature of NIN for RNS regulation was inherited from ancestral NLPs before RNS emerged.

plant biology↗

bioRxiv2021

VISUAL network analysis reveals the role of BEH3 as a stabilizer in the secondary vascular development in Arabidopsis

During secondary growth in plants, vascular stem cells located in the cambium continuously undergo self-renewal and differentiation throughout the lifetime. Recent cell-sorting technique enables to uncover transcriptional regulatory framework for cambial cells. However, the mechanisms underlying the robust control of vascular stem cells have not been understood yet. By coexpression network analysis using multiple transcriptome datasets of an ectopic vascular cell transdifferentiation system using Arabidopsis cotyledons, VISUAL, we newly identified a cambium-specific gene module from an alternative approach. The cambium gene list included a transcription factor BES1/BZR1 homolog 3 (BEH3), whose homolog BES1 is known to control vascular stem cell maintenance negatively. Interestingly, the vascular size of the beh3 mutants showed a large variation, implying the role of BEH3 as a stabilizer. BEH3 almost lost the transcriptional repressor activity and functioned antagonistically with other BES/BZR members via competitive binding to the same motif BRRE. Indeed, mathematical modeling suggests that the competitive relationship among BES/BZRs leads to the robust regulation of vascular stem cells.

developmental biology↗