Targeted disruption of sti35, a stress-responsive gene in phytopathogenic fungus Fusarium oxysporum

sti35 is one of the heat-shock genes in Fusarium oxysporum, which is a fung al pathogen for wilt disease in plants. We have isolated a genomic clone of sti35 and used it to create disruption mutations. Disruption of the sti35 coding region resulted in the loss of a 32-kDa protein present in heat-shoc ked cells. The disruption had no detectable effect on growth and developmen t at various temperatures, nor on the ability to acquire thermotolerance in nutrient medium. But the sti35 disruptants showed increased thermotoleranc e, relative to the wild-type strain, when incubated in minimal medium after heat treatment.