Evidence for sulfate derepression of an arylsulfatase gene of Colletotrichum gloeosporioides f. sp.malvae during infection of round-leaved mallow, Malva pusilla

Abstract

An arylsulfatase gene, cgars, was cloned from Colletotrichum gloeosporioides f. sp.malvae (Cgm), a hemibiotrophic plant pathogenic fungus that causes anthracnose disease of round-leaved mallow (Malva pusilla). The clone of cgars showed high amino acid sequence identity toars-1+ , an arylsulfatase gene of Neurospora crassa. Arylsulfatase genes have been shown to be good reporter genes for detecting available sulfur levels in a variety of microorganisms. Expression of cgars was determined by relative RT-PCR, in which cgars expression levels were compared to those of actA, a constitutively expressed actin gene of Cgm, following coamplification. In culture, expression of cgars was found to be repressed by methionine as has been demonstrated for ars-1+. In host leaf tissue, cgars expression was relatively higher than actA during penetration, similar to actA during biotrophic growth and then progressively lower than actA during necrotrophic growth. These results show that the availability of host sulfur differs depending upon the stage of infection.