Salt stress is an environmental factor that limits plant growth and crop production. With the rapid expansion of salinized arable land worldwide, investigating the molecular mechanisms underlying the salt stress response in plants is urgently needed. Here, we report that GROWTH REGULATING FACTOR 7 (OsGRF7) promotes salt tolerance by regulating arbutin (hydroquinone-β-D-glucopyranoside) metabolism in rice (Oryza sativa). Overexpression of OsGRF7 increased arbutin content, and exogenous arbutin application rescued the salt-sensitive phenotype of OsGRF7 knockdown and knockout plants. OsGRF7 directly promoted the expression of the arbutin biosynthesis genes URIDINE DIPHOSPHATE GLYCOSYLTRANSFERASE 1 (OsUGT1) and OsUGT5, and knockout of OsUGT1 or OsUGT5 reduced rice arbutin content, salt tolerance, and grain size. Furthermore, OsGRF7 degradation through its interaction with F-BOX AND OTHER DOMAINS CONTAINING PROTEIN 13 (OsFBO13) reduced rice salinity tolerance and grain size. These findings highlight an underexplored role of OsGRF7 in modulating rice arbutin metabolism, salt stress response, and grain size, as well as its broad potential use in rice breeding.

中文翻译：

---

生长调节因子 7 介导的熊果苷代谢增强大米耐盐性

盐胁迫是限制植物生长和作物生产的环境因素。随着全球盐碱化耕地的迅速扩大，迫切需要研究植物盐胁迫反应的分子机制。在此，我们报道生长调节因子 7 (OsGRF7) 通过调节水稻 (Oryza sativa) 中的熊果苷（氢醌-β-D-吡喃葡萄糖苷）代谢来促进耐盐性。 OsGRF7的过表达增加了熊果苷含量，外源熊果苷的应用挽救了OsGRF7敲低和基因敲除植物的盐敏感表型。 OsGRF7直接促进熊果苷生物合成基因尿苷二磷酸糖基转移酶1（OsUGT1）和OsUGT5的表达，敲除OsUGT1或OsUGT5会降低水稻熊果苷含量、耐盐性和籽粒大小。此外，OsGRF7 通过与 F-BOX 和其他含有蛋白 13 的结构域 (OsFBO13) 相互作用而降解，降低了水稻的耐盐性和籽粒尺寸。这些发现凸显了 OsGRF7 在调节水稻熊果苷代谢、盐胁迫反应和籽粒大小方面的作用，以及其在水稻育种中的广泛潜在用途。