The rhizobial type III secretion system secretes effector proteins into host plant cells, which may either promote or inhibit symbiosis with legumes. We herein demonstrated that the type III secretion system of Bradyrhizobium sp. SUTN9-2 obstructed symbiosis with Lotus japonicus Miyakojima, L. japonicus Gifu, and Lotus burttii. A mutant of SUTN9-2 that is unable to secrete effector proteins showed better nodulation and plant growth promotion than wild-type SUTN9-2 when paired with these Lotus spp. We propose that SUTN9-2 is a useful strain for understanding the mechanisms by which effector proteins obstruct symbiosis between Bradyrhizobium and Lotus spp.

中文翻译：

---

Bradyrhizobium sp. III 型分泌系统 SUTN9-2 阻碍与莲花的共生。

根瘤菌III型分泌系统将效应蛋白分泌到宿主植物细胞中，这可能促进或抑制与豆类的共生。我们在此证明了 Bradyrhizobium sp. 的 III 型分泌系统。SUTN9-2 阻碍了与 Lotus japonicus Miyakojima、L. japonicus Gifu 和 Lotus burttii 的共生。无法分泌效应蛋白的 SUTN9-2 突变体与野生型 SUTN9-2 配对时显示出更好的结瘤和植物生长促进作用。我们认为 SUTN9-2 是一种有用的菌株，可用于了解效应蛋白阻碍慢生根瘤菌和莲花属之间共生的机制。