A nopA Deletion Mutant of Sinorhizobium fredii USDA257, a Soybean Symbiont, is Impaired in Nodulation
A nopA Deletion Mutant of Sinorhizobium fredii USDA257, a Soybean Symbiont, is Impaired in Nodulation
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DOI：
10.1007/s00284-013-0469-4
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发表时间：
2014-02-01
影响因子：
2.6
通讯作者：
Krishnan, Hari B.
中科院分区：
文献类型：
--
作者：
Kim, Won-Seok;Krishnan, Hari B.
fredii Sinorhizobium USDA257通过III型分泌系统（T3SS）将效应蛋白通过菌毛输送到宿主细胞中。nopA蛋白是USDA257菌毛的主要成分。USDA257 nopA的启动子区具有保守性较好的tts盒。序列缺失分析表明，tts框对nopA的类黄酮诱导是绝对必需的。nopA的缺失显著降低了USDA257在北京豇豆和大豆品种上形成的根瘤数量。与亲本菌株相比，USDA257 nopA突变体在麦考尔和威廉姆斯82号大豆品种上很少形成根瘤。光镜和透射电镜检查显示，在感染细胞和未感染细胞中均有大量淀粉粒。
Sinorhizobium fredii USDA257 employs type III secretion system (T3SS) to deliver effector proteins into the host cells through pili. The nopA protein is the major component of USDA257 pili. The promoter region of USDA257 nopA possesses a well conserved tts box. Serial deletion analysis revealed that the tts box is absolutely essential for flavonoid induction of nopA. Deletion of nopA drastically lowered the number of nodules formed by USDA257 on cowpea and soybean cultivar Peking. In contrast to the parental strain, the USDA257 nopA mutant was able to form few nodules on soybean cultivars McCall and Williams 82. Light and transmission electron microscopy examination of these nodules revealed numerous starch grains both in the infected and uninfected cells.