Huong Duyen Do Tran, Rajalingam Nagendran, Lee Yong Hoon
Division of Biotechnology, Jeonbuk National University, Iksan 54596, Korea.
Advanced Institute of Environment and Bioscience, Plant Medical Research Center, and Institute of Bio-industry, Jeonbuk National University, Iksan 54596, Korea.
Plant Pathol J. 2021 Oct;37(5):494-501. doi: 10.5423/PPJ.NT.07.2021.0108. Epub 2021 Oct 1.
Pseudomonas cichorii secretes effectors that suppress defense mechanisms in host plants. However, the function of these effectors, including avirulence protein E1 (AvrE1), in the pathogenicity of P. cichorii, remains unexplored. In this study, to investigate the function of avrE1 in P. cichorii JBC1 (PcJBC1), we created an avrE1-deficient mutant (JBC1ΔavrE1) using CRISPR/Cas9. The disease severity caused by JBC1ΔavrE1 in tomato plants significantly decreased by reducing water soaking during early infection stage, as evidenced by the electrolyte leakage in infected leaves. The disease symptoms caused by JBC1ΔavrE1 in the cabbage midrib were light-brown spots compared to the dark-colored ones caused by PcJBC1, which indicates the role of AvrE1 in cell lysis. The avrE1-deficient mutant failed to elicit cell death in non-host tobacco plants. Disease severity and cell death caused by JBC1ΔavrE1 in host and non-host plants were restored through heterologous complementation with avrE1 from Pseudomonas syringae pv. tomato DC3000 (PstDC3000). Overall, our results indicate that avrE1 contributes to cell death during early infection, which consequently increases disease development in host plants. The roles of PcJBC1 AvrE1 in host cells remain to be elucidated.
菊苣假单胞菌分泌抑制宿主植物防御机制的效应蛋白。然而，包括无毒蛋白E1（AvrE1）在内的这些效应蛋白在菊苣假单胞菌致病性中的功能仍未得到探索。在本研究中，为了研究avrE1在菊苣假单胞菌JBC1（PcJBC1）中的功能，我们使用CRISPR/Cas9创建了一个avrE1缺陷突变体（JBC1ΔavrE1）。JBC1ΔavrE1在番茄植株上引起的病害严重程度在感染早期通过减少水渍而显著降低，感染叶片中的电解质渗漏证明了这一点。与PcJBC1引起的深色病斑相比，JBC1ΔavrE1在甘蓝中脉上引起的病害症状是浅褐色斑点，这表明AvrE1在细胞裂解中的作用。avrE1缺陷突变体未能在非寄主烟草植株中引发细胞死亡。通过用来自番茄丁香假单胞菌pv. tomato DC3000（PstDC3000）的avrE1进行异源互补，恢复了JBC1ΔavrE1在寄主和非寄主植物中引起的病害严重程度和细胞死亡。总体而言，我们的结果表明，avrE1在早期感染期间促成细胞死亡，从而增加寄主植物中的病害发展。PcJBC1 AvrE1在宿主细胞中的作用仍有待阐明。
