Regulation of Toxin Synthesis and Phenotypic Variation in Pseudomonas Tolaasii, Cause of Brown Blotch Disease of Mushrooms

Abstract

Brown blotch disease of mushrooms is caused by the Gram-negative bacterium Pseudomonas tolaasii [1-3]. The disease symptoms are characteristic brown sunken lesions on the mushroom cap and stipe, which make affected mushrooms unmarketable. These lesions arise due to collapse of fungal hyphae and the consequent release of tyrosinase activity [4]. The mushroom crop is a very lucrative protected horticultural commodity with an estimated world-wide value of over \pounds{}1 billion per annum. Up to 20% of this crop is lost or downgraded as a result of P. tolaasii infection. P. tolaasii is thus an important biotic factor responsible for mushroom crop loss and is endemic in many mushroom farms [3]. Development of new methods of disease control, through an understanding of the disease process, is therefore an important aim.