2026-07-30 ニューヨーク大学（NYU）
＜関連情報＞
- https://www.nyu.edu/about/news-publications/news/2026/july/plant-nitrogen-satiety.html
- https://academic.oup.com/plcell/article/38/7/koag201/8747291
HHO5は、シロイヌナズナにおける有機窒素と無機窒素のシグナル伝達の用量依存的なフィードバック制御を調整する HHO5 orchestrates dose-dependent feedback regulation of organic versus inorganic nitrogen signaling in Arabidopsis
Will E Hinckley,Joseph Swift,Francisco Romei,Jorge P Muschietti,Samantha Frangos,Shao-shan Carol Huang,Gloria M Coruzzi,Mariana Obertello
The Plant Cell Published:30 July 2026
DOI:https://doi.org/10.1093/plcell/koag201
Abstract
A major goal in agriculture is to engineer crops to maintain yield with less nitrogen (N) fertilizer. Important regulators of plant N-responses include HRS1 HOMOLOG (HHO) transcription factors (TFs); yet, their redundant repressive mode of action hinders functional analyses. Here, we highlight HHO5 as a unique HHO TF based on its phylogenetic position, phloem specific expression, and dual role in regulating responses to inorganic and organic N-dose signals. Our results support a model whereby HHO5 mediates feedback repression of inorganic nitrate uptake under organic N satiety: (i) Meta-analyses revealed HHO5 expression is repressed by inorganic N, but induced by organic N treatments. (ii) HHO5 directly binds and represses nitrate response genes, but indirectly induces organic N-response genes. (iii) HHO5 indirect target gene induction occurs via WRKY partner TFs, validated using a cell-based DoubleTARGET TF co-perturbation assay. (iv) HHO5 initiates a validated gene regulatory network path which encompasses ∼12% of the N-dose response genes in planta. (v) Phenotypically, single hho5 T-DNA mutants show reduced N-dose dependent growth, and decreased seed N content. (vi) HHO5 represses nitrate uptake but induces root growth responses to Glu in planta. Overall, our findings support a model wherein HHO5 orchestrates dose dependent feedback regulation of organic versus inorganic N-signaling in Arabidopsis.
