Identification of Genes in Xanthomonas campestris pv. vesicatoria Induced during Its Interaction with Tomato

Abstract

Xanthomonas campestris pv. vesicatoria is the causal agent of bacterial spot disease of tomato and pepper. The disease process is interactive and very intricate and involves a plethora of genes in the pathogen and in the host. In the pathogen, different genes are activated in response to the changing environment to enable it to survive, adapt, evade host defenses, propagate, and damage the host. To understand the disease process, it is imperative to broaden our understanding of the gene machinery that participates in it, and the most reliable way is to identify these genes in vivo. Here, we have adapted a recombinase-based in vivo expression technology (RIVET) to study the genes activated in X. campestris pv. vesicatoria during its interaction with one of its hosts, tomato. This is the first study that demonstrates the feasibility of this approach for identifying in vivo induced genes in a plant pathogen. RIVET revealed 61 unique X. campestris pv. vesicatoria genes or operons that delineate a picture of the different processes involved in the pathogen-host interaction. To further explore the role of some of these genes, we generated knockout mutants for 13 genes and characterized their ability to grow in planta and to cause disease symptoms. This analysis revealed several genes that may be important for the interaction of the pathogen with its host, including a citH homologue gene, encoding a citrate transporter, which was shown to be required for wild-type levels of virulence.

The Periplasmic HrpB1 Protein from Xanthomonas spp. Binds to Peptidoglycan and to Components of the Type III Secretion System

“…For this, we used the suicide vector pLAND-P, which allows the integration of genes by homologous recombination into the hpaFG region next to the hrp gene cluster, which can be used as a neutral site for genomic insertions (28,54,55). Notably, genomic hrpB1 fully restored in planta symptom formation and also partially complemented the deficiency in HrpF secretion (Fig.…”

GLYCOALKALOID METABOLISM1 Is Required for Steroidal Alkaloid Glycosylation and Prevention of Phytotoxicity in Tomato

“…Tomato plants were grown from seeds in a greenhouse (25 to 288C) in 0.6-liter spots containing a mixture of equal parts of sand, vermiculite, and peat. Inoculation of plants for assessment of Xcv growth in planta was performed by vacuum dipping 7-to 8-weekold plants into bacterial suspensions of 5 3 10 5 colony-forming units/mL as described by Tamir-Ariel et al (2007). Seven plants per treatment were inoculated in each experiment.…”

Ketoglutarate Transport Protein KgtP Is Secreted through the Type III Secretion System and Contributes to Virulence in Xanthomonas oryzae pv. oryzae

“…To reach the cell densities required to overcome the host immune system, the pathogen has to adapt to the intercellular environment and utilize available nutrients, especially carbohydrates, from the host plant (51,54). The plant apoplast lacks hexose sugars but is rich in gluconeogenic substrates, including intermediates of the tricarboxylic acid (TCA) cycle (40,54).…”