Lee Jongchan, Heo Lynn, Han Sang-Wook
Department of Plant Science and Technology, Chung-Ang University, Anseong 17546, Korea.
Plant Pathol J. 2021 Dec;37(6):673-680. doi: 10.5423/PPJ.NT.09.2021.0139. Epub 2021 Dec 1.
Acidovorax citrulli (Ac) is the causative agent of bacterial fruit blotch disease in watermelon. Since resistant cultivars have not yet been developed, the virulence factors/mechanisms of Ac need to be characterized. This study reports the functions of a putative pyridoxal phosphate-dependent aminotransferase (PpdaAc) that transfers amino groups to its substrates and uses pyridoxal phosphate as a coenzyme. It was observed that a ppdaAc knockout mutant had a significantly reduced virulence in watermelon when introduced via germinated-seed inoculation as well as leaf infiltration. Comparative proteomic analysis predicted the cellular mechanisms related to PpdaAc. Apart from causing virulence, the PpdaAc may have significant roles in energy production, cell membrane, motility, chemotaxis, post-translational modifications, and iron-related mechanisms. Therefore, it is postulated that PpdaAc may possess pleiotropic effects. These results provide new insights into the functions of a previously unidentified PpdaAc in Ac.
西瓜嗜酸菌（Acidovorax citrulli，Ac）是西瓜细菌性果斑病的病原菌。由于尚未培育出抗病品种，因此需要对Ac的毒力因子/机制进行表征。本研究报道了一种假定的依赖磷酸吡哆醛的转氨酶（PpdaAc）的功能，该酶将氨基转移到其底物上，并使用磷酸吡哆醛作为辅酶。通过发芽种子接种和叶片浸润引入西瓜后，观察到ppdaAc基因敲除突变体的毒力显著降低。比较蛋白质组学分析预测了与PpdaAc相关的细胞机制。除了引起毒力外，PpdaAc可能在能量产生、细胞膜、运动性、趋化性、翻译后修饰和铁相关机制中发挥重要作用。因此，推测PpdaAc可能具有多效性。这些结果为之前未鉴定的PpdaAc在Ac中的功能提供了新的见解。
