INTERACTIONS BETWEEN PSEUDOMONAS SPECIES AND SCLEROTIUM ROLFSII, CAUSAL AGENT OF STEM ROT DISEASE OF GROUNDNUT Nhu Cuong Le Laboratory of Phytopathology, Wageningen University 1, Droevendaalsesteeg, 6708 PB, Wageningen, Netherlands Hue University of Agriculture and Forestry 102, Phung Hung, Hue, Thua Thien Hue, Vietnam Jos M. Raaijmakers Laboratory of Phytopathology, Wageningen University 1, Droevendaalsesteeg, 6708 PB, Wageningen, Netherlands Aims and Background Groundnut (Arachis hypogaea L.) is an important oil crop worldw ide, but its production and yield are adversely affected by various diseases and insect pests. Stem rot disease caused by the fungus Sclerotium rolfsii is one of the most devastating soil-borne diseases of groundnut with disease incidences of up to 25% in central Vietnam. To date, methods to control this disease mostly rely on fungicides but many of these fungicides are not effective or too expensive for local farmers. Methods In this study, we explored the efficacy of biological control of S. rolfsii by testing various Pseudomonas species and strains that exhibit different mechanisms of pathogen control. Interactions betw een Pseudomonas and S. rolfsii were tested in vitro, in plant bioassays and in field trials in central Vietnam. Results In vitro assays show ed that many Pseudomonas strains producing phenazines, 2,4- diacetylphloroglucinol or cyclic lipopeptides (CLPs) were effective in inhibition of mycelial grow th of S. rolfsii. In plant bioassays, however, only phenazine-producing Pseudomonas strain Phz24 and the CLP- producing Pseudomonas strain SH- C52 suppressed stem rot disease of groundnut . Their biosynthetic mutants defective in the production of these bioactive compounds were not effective in disease control. In field trials in central Vietnam, only CLP-producing strain SH- C52 w as effective in controlling S. rolfsii, w hereas CLP-producing P. fluorescens strain SS101 was effective in promoting plant grow th and yield. Conclusions Plant bioassays and field tr ials with diverse Pseudomonas strains that exhibit different mechanisms of pathogen control resulted in the identification of at least two promising strains for grow th promotion and biological control of stem rot disease of groundnut. The results further show ed that Pseudomonas strains producing structurally different cyclic lipopeptides differ in their efficacy to control stem rot disease of groundnut.
|Publication status||Published - 2011|
|Event||Rhizosphere 3 - Perth, Australia|
Duration: 25 Sep 2011 → 30 Sep 2011
|Period||25/09/11 → 30/09/11|