Survival of Xanthomonas campestris pv. campestris in cultivated plants and weeds
João César Silva: São Paulo State University
<div>Black rot, caused by <em>Xanthomonas campestris</em> pv. <em>campestris</em> (Xcc), is considered the most important brassica disease worldwide. Once survival niches knowledge of this pathogen is extremely important for the disease efficient management, this work aims to evaluate Xcc survival in phylloplane and rhizosphere of cultivated plants as well as weed endophytic survival. Seven differents botanic families among 10 cultivated plants and 11 weed species were used in the experiments. The 3098C strain resistant to rifampicin was inoculated by spraying bacterial suspension (10<sup>7</sup> CFU.mL<sup>-1</sup>) on aerial part of the plants. The cultivated plants soil was infested with 200 mL of the same suspension. After soil and phylloplane samples processing and bacterial weeds isolation, 100 μL of the supernatant were plated in NSARF semi-selective medium and incubated (28°C/72 h). Xcc survived for up to 35 days in tomato, wheat, pumpkin, cultivated radish, black oat and cabbage phylloplanes and 21 days in lettuce rhizosphere. The endophytic survival of Xcc was observed in virginia pepperweed, wild radish and bengal dayflower 28 days after inoculation. Results obtained here support the hypothesis that weeds present in areas with black rot history, as well as cultivated plants used in rotation with brassicas, can be an inoculum source of Xcc.</div>
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