ARS | Publication request: EFFECTS OF RSMA ON PHYTOTOXIN PRODUCTION BY PSEUDOMONAS SYRINGAE PATHOVARS

Submitted to: American Society for Microbiology
Publication Type: Abstract
Publication Acceptance Date: June 13, 2007
Publication Date: N/A

Technical Abstract: Posttranscriptional control is known to contribute to the regulation of secondary metabolism and virulence determinants in certain Gram-negative bacteria. A common component in such posttranscriptional control is the Rsm (regulator of secondary metabolites) system, which plays a critical role in gene expression and has a profound effect on bacterial metabolism and behavior in many prokaryotic species. Here we report on the effect of RsmA on secondary product production by several plant pathogenic Pseudomonas syringae pathovars. Pseudomonas syringae pathovars were transformed with pRsmA, a pME6032 derived construct for the overexpression of rsmA and/or with pSK61, a pME6031 derivative for the constitutive expression of rsmA. Control strains were transformed with the respective empty plasmids. Bioassays were used to determine tabtoxin, phaseolotoxin, syringomycin, and tagetitoxin production. The overexpression of rsmA resulted in the total inhibition of tabtoxin production by P. syringae pv. coronafaciens Pc27, phaseolotoxin production by P. syringae pv. phaseolicola NPS3121, syringomycin production by B301D, and tagetitoxin production by P. syringae pv. tagetis EB037. The same effects on toxin production by NPS3121, B301D, and EB037 were obtained when rsmA was constitutively expressed from pSK61. However, some residual tabtoxin was produced by Pc27 and P. syringae BR2R. The results demonstrate that rsmA plays a significant role in the regulation of phytotoxin production in these P. syringae pathovars. The effects of rsmA on other pathogenicity and virulence factors of these pathogens are being examined.