Adhesion Pad Formation and the Involvement of Cutinase and Esterases in the Attachment of Uredospores to the Host Cuticle.

Abstract

We have investigated the basis of adhesion of uredospores of the obligately parasitic rust fungus Uromyces viciae-fabae to leaves of its broad bean host. Upon contact with an aqueous environment, spores form a structure that we have termed an adhesion pad. The adhesion pad is formed by both living and autoclaved spores, but only adhesion pads formed by living spores adhered to the cuticle of leaves of the host plant. Treatment of living spores with the serine-esterase inhibitor diisopropyl fluorophosphate prevented the adhesion of the pad to the leaf surface, suggesting a functional role for esterase or cutinase in the process of adhesion. A cutinase and two nonspecific serine-esterases were found to be localized on the surface of spores. These enzymes were released rapidly from the spore surface upon contact with an aqueous environment. The addition of the cutinase and the nonspecific esterases to autoclaved spores restored their ability to adhere to the host cuticle. Thus, whereas pad formation appears to be a passive response to the aqueous environment, the actual adhesion of pads to the host cuticle appears to depend on the cutinase and esterases associated with the spore surface. These results suggest a new role for cutinases and serine-esterases in the fungal infection process.

Diverse Lifestyles and Strategies of Plant Pathogenesis Encoded in the Genomes of Eighteen Dothideomycetes Fungi

“…Although the role of cutinases in fungal pathogenicity stayed controversial for a long time, the relationship with pathogenicity has been proven in several knockout studies [67], [68]. Furthermore, there are several examples of cutinases playing various roles in the establishment of infection by being involved in spore attachment [69], [70], surface signaling [71], and dissolution of the plant cuticle during penetration [72].…”

Secretome Analysis Identifies Potential Pathogenicity/Virulence Factors of Tilletia indica, a Quarantined Fungal Pathogen Inciting Karnal Bunt Disease in Wheat

“…[6] Various commonly secreted fungal proteins, including lipases, proteases, enolases, peroxidases, and xylanases are required for pathogenicity/virulence in several pathogenic fungi. [7][8][9][10][11][12][13] Proteomics is an excellent tool for studying the plant-fungus interaction mediated by such secreted proteins that facilitate the infection (e.g., virulence factors and toxin biosynthetic enzymes) or activation of pathogen defense machinery (avirulence factors). Characterization of secretome of fungal pathogens would elucidate the pathogenic mechanisms used to infect, colonize, and invade their hosts.…”

“…Many phytopathogenic fungi secrete an arsenal of extracellular proteins that perform diverse functions such as infection, colonization, nutrient acquisition, and protection against the host defense responses . Various commonly secreted fungal proteins, including lipases, proteases, enolases, peroxidases, and xylanases are required for pathogenicity/virulence in several pathogenic fungi . Proteomics is an excellent tool for studying the plant–fungus interaction mediated by such secreted proteins that facilitate the infection (e.g., virulence factors and toxin biosynthetic enzymes) or activation of pathogen defense machinery (avirulence factors).…”

Proteome catalog of Zymoseptoria tritici captured during pathogenesis in wheat

“…Two out of the five cutinase genes in the genome of Z. tritici have been identified in this proteome study. Cutinases have been reported to play roles in cuticular penetration (Li et al, 2003), spore attachment (Deising et al, 1992;Pascholati et al, 1993), generation of cutin monomers as signaling molecules (Woloshuk and Kolattukudy, 1986;Podila et al, 1988;Francis et al, 1996) and even in protection of the host plant (Wang et al, 2000). More recently, Cut2, one of the cutinases of Magnaporthe grisea, was reported to be involved in surface sensing, thereby mediating appressorium differentiation and formation of the penetration peg Gurr, 2007, 2008).…”