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Xanthomonas euvesicatoria Effector AvrRxo1 Interacts with AIN1 to EnhanceBacterial Growth on Pepper and Tobacco Plants

Zhibo Wang: Virginia Tech

<div>Xanthomonas euvesicatoria Effector AvrRxo1 Interacts with AIN1 to Enhance<br /="/">Bacterial Growth on Pepper and Tobacco Plants<br /="/">Bacterial leaf spot disease caused by Xanthomonas euvesicatoria (Xe) is one of<br /="/">most important pepper diseases. We previously cloned a type III effector (T3E) gene<br /="/">AvrRxo1 from Xanthomonas oryzae pv. oryzicola, which encodes a NAD kinase. The<br /="/">kinase activity is required for the virulence function of AvrRxo1. However, the<br /="/">virulence mechanism of AvrRxo1 is still elusive. AvrRxo1 homologue, Xe-AvrRxo1,<br /="/">was identified from Xe. However, deletion of Xe-AvrRxo1 in Xe strain did not<br /="/">compromise the bacterial virulence on pepper. The virulence function of Xe-AvrRxo1<br /="/">was masked by other Xe effectors. We developed Xe mutants with deletion of<br /="/">multiple virulence effectors in addition of Xe-AvrRxo1, which were used to inoculate<br /="/">pepper and tobacco plants. The Xe mutants carrying Xe-AvrRxo1 but with the<br /="/">deletion of T3E XopQ or a putative glycerol-transporter (GT) would proliferate better<br /="/">on pepper and tobacco than the isogenic strains without Xe-AvrRxo1. Therefore, Xe-<br /="/">AvrRxo1 indeed possesses virulence function that is redundant with XopQ and GT.<br /="/">To identify host proteins required for the virulence function of Xe-AvrRxo1, we<br /="/">performed a yeast two-hybrid (Y2H) screening by using Xe-AvrRxo1 as bait. Plant<br /="/">protein AIN1 was identified as a putative Xe-AvrRox1 interactor. Silencing or<br /="/">knockout Ain1 by Virus Induced Gene Silence (VIGS) or CRISPR/Cas9 approach<br /="/">compromised the virulence function of Xe-AvrRxo1. Therefore, we confirmed that Xe-<br /="/">AvrRxo1 could interact with AIN1 to enhance bacterial growth on pepper and tobacco<br /="/">plants. The interplays between Xe-AvrRxo1, XopQ, GT and plant protein AIN1 will be<br /="/">discussed in the poster.</div>