Q-316. Sagebrush Rhizobacterium as Biological Control of Plant Pathogenic Fusarium Species Isolated from Contaminated Pepper Fields of Chihuahua, Mexico

J. Hernandez-Huerta, G. Nevarez-Portillo, L. Robles-Hernández, A. C. Gonzalez-Franco;
Univ. Autonoma de Chihuahua, Chihuahua, MEXICO.

Biological control of soil-borne fungal pathogens is of great importance for a more sustainable agriculture. Streptomyces species are capable of producing an extensive array of antifungal metabolites and Streptomyces sp PRIO-41, an isolate of the rhizosphere of desert big sagebrush (Artemisia tridentata), was studied for their antifungal activities toward pathogenic Fusarium spp isolated from Capsicum annum infested fields in Chihuahua, Mexico. The Fusarium phytopathogens were isolated and identified by colony and cell morphological characteristics. Pathogenicity and virulence of the fungal isolates were determined by in vitro bioassays using the disease severity index. Virulence dynamics in sterile substrate with two pepper varieties were generated. Fusarium strains were more virulent in jalapeno than in Anaheim pepper. Chitinolytic activity of PRIO-41 was detected in colloidal chitin and/or Fusarium cell wall amendment media. In vitro antagonism assays showed that PRIO-41 perform better in the poor medium than in the rich one with the lowest inhibitory growth of pathogenic Fusarium spp over 50% and reaching 100% in some of them. Native polyacrylamide gel revealed electrophoretic profiles of oxidases in jalapeno pepper plants under the effect of Streptomyces PRIO-41 and Fusarium spp treatments. Electrophoretic detection of Fusarium and Streptomyces oxidases were also performed in order to distinguish them from those of plants. These results showed the potential of Streptomyces PRIO-41 as biocontrol agent of phytopathogenic Fusarium spp.