pseudomonas helianthi pseudomonas helianthi "pseudomonas helianthi" is a gram-negative plant pathogenic bacterium that infects a variety of plants. it was once considered a pathovar of pseudomonas syringae, but following dna-relatedness studies, it was recognized as a separate species and p. syringae pv. tagetis was incorporated into it, as well. since no official name has yet been given, it is referred to by the epithet 'pseudomonas helianthi' . pseudomonas helianthi scientific classification domain: bacteria phylum: pseudomonadota class: gammaproteobacteria order: pseudomonadales family: pseudomonadaceae genus: pseudomonas species: p. helianthi binomial name pseudomonas helianthielasri et al. 2001 type strain cfpb 1694 pathovars "p. h." pv. helianthi "p. h." pv. tagetis pathovars "pseudomonas helianthi" pv. helianthi attacks sunflowers (helianthus annuus). "pseudomonas helianthi" pv. tagetis attacks marigolds (tagetes erecta).