Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: August 20, 2010
Publication Date: August 20, 2010
Citation: Yang, M., Guo, J., Thomashow, L.S., Weller, D.M. 2010. Biological control of take-all of wheat by fluorescent Pseudomonas spp. from China. Phytopathology. 100:S141. Technical Abstract: Take-all disease of wheat caused by the soilborne fungus Gaeumannomyces graminis var. tritici (Ggt) is one of the most important root diseases of wheat worldwide. In order to find biocontrol agents, bacteria were isolated from wheat at different stages of development in Hebei and Jiangsu provinces in China. Samples from rhizosphere soil, roots, stems and leaves were plated onto King’s B agar. All of 105 isolates that inhibited Ggt in vitro were identified as Pseudomonas spp. by ARDRA analysis. Twenty-seven isolates, which represented 24 BOX-PCR groups, were selected for further study. Of these, 14 suppressed take-all in biocontrol assays under greenhouse conditions. The antibiotics phenazine-1-carboxylic acid (PCA) and 2,4-diacetylphloroglucinol (DAPG) are major determinants of biocontrol of soilborne plant pathogens by fluorescent pseudomonads. Using PCR and primers specific for sequences within the biosynthetic operons responsible for production of these antibiotics, 4 of the 14 strains were found to produce PCA but none produced DAPG. High-pressure liquid chromatography (HPLC) analysis of 2-day-old cultures of these four strains confirmed the production of PCA. DNA sequence analysis within the phzF gene indicated that three strains were similar to the well-described PCA producer P. fluorescens 2-79. This is the first report of a 2-79-like strain isolated from outside of Washington State.