Evidence That Thaxtomin C Is a Pathogenicity Determinant of Streptomyces ipomoeae, the Causative Agent of Streptomyces Soil Rot Disease of Sweet Potato

摘要: Streptomyces ipomoeae is the causal agent of soil rot sweet potato, a disease marked by highly necrotic destruction adventitious roots, including development lesions on fleshy storage roots. potato scab pathogens produce phytotoxin (thaxtomin A) that appears to facilitate their entrance into host plants. S. produces less-modified thaxtomin derivative C) whose role in pathogenicity has not been examined. Here, we cloned and sequenced gene cluster (txt) ipomoeae, then constructed targeted txt mutants no longer produced C. The were unable penetrate intact roots but still caused necrosis storage-root tissue. These results, taken context with previous histopathological study infection, suggest C plays an essential inter- intracellular penetration ipomoeae. Once inside plant host, pathogen uses one or more yet-to-be-determined factors necrotize root tissue, any it encounters.