Control of tobacco mosaic virus by Pseudomonas fluorescens CZ powder in greenhouses and the field

Abstract

Pseudomonas fluorescens strain CZ has been reported to inhibit tobacco mosaic virus (TMV) by producing an antibiotic protein. In this study the effects of CZ powder on TMV infection were investigated on tobacco grown in greenhouses and in the field. CZ stocks were cultured in a mixture medium (5 g wheat bran, 1 g soybean flour, 1 g corn flour, 1 g peanut flour), and then mixed with silica white at a ratio of 6 ml:1 g to make CZ powder. The effective cell concentration in a 100-fold dilution of CZ powder was 49.8 × 1010 cfu ml−1. In greenhouse experiments where Nicotiana tabacum cv. Samsun NN plants were challenged by mechanical inoculation with a mixture of the 100-fold diluted CZ powder and TMV, the in vitro suppression of the TMV infection was 88.3% compared to the controls in which a mixture of water and TMV was used as inoculum. Similarly when N. tabacum cv. NC89 plants were inoculated by cutting the leaves with virus-contaminated scissors, dipping the scissors in a 100-fold dilution of CZ powder before cutting showed a disinfection effect of 96.3% compared with water dipping controls. Drenching and spraying a 100-fold dilution of CZ promoted growth and inhibited virus infection by 59.2% on N. tabacum cv. NC89 plants in the greenhouse. In field trials, 100-fold dilution of CZ suppressed TMV infection by 58.2% and 47.6% in 2010 and 2011, respectively, which was similar to the effect of Ningnanmycin (antibiotic purified from Streptomyces noursei var. xichangensis), a registered antiviral agent in tobacco. All these results indicated that CZ has a potential to be used as a hand tool disinfector and an antiviral agent against TMV.