Insertion of cutinase gene into a wound pathogen enables it to infect intact host

Abstract

MANY phytopathogenic fungi must breach the intact plant cuticle to successfully invade and colonize their hosts. It has been suggested that cutinase, an extracellular enzyme secreted by many fungi, is essential for infection in some host–pathogen interactions. Chemical or immunological inhibition of cutinase protects the host from infection^{1, 2}. We have cloned and characterized the cutinase complementary DNA and gene from Fusarium solani f. sp. pisi^{3, 4}, a pea pathogen. A construct containing the cutinase coding region and extensive portions of the 5′ and 3′-flanking regions from theFusarium genome was transferred into another phytopathogenic Ascomycete, Mycosphaerella spp., a parasitic fungus that affects papaya fruits only if the fruit skin is mechanically breached before inoculation⁵. Here we describe the introduction of the Fusarium cutinase gene into Mycosphaerella to yield transformants in which this gene is inducible by cutin hydrolysate. We demonstrate that these transformants of the wound-requiring fungus have the capacity to infect intact papaya fruits, and that this infection can be prevented by antibodies against Fusarium cutinase.