title: Pectate lyase affects pathogenicity in natural isolates of Colletotrichum coccodes and in pelA gene-disrupted and gene-overexpressing mutant lines.
abstract: Colletotrichum coccodes (Wallr.) S. Hughes, the causal agent of black dot on potato and anthracnose on tomato, reduces yield and crop quality. We explored the role of secreted pectate lyase (PL), a cell wall-degrading enzyme, in the aggressiveness of C. coccodes. In vitro-cultivated highly aggressive isolates secreted immunologically detectable PL levels 6 h after transfer to secondary medium versus 12 h for mildly aggressive isolates, suggesting that secreted PL is a virulence factor. The gene encoding PL, CcpelA, was cloned and used for the genetic manipulation of highly (US-41 and Si-72) and mildly (Si-60) aggressive isolates. CcpelA gene-disrupted mutants showed reduced aggressiveness towards tomato fruits and impaired PL secretion and extracellular activity. Conversely, overexpression of CcpelA in the Si-60 isolate increased its aggressiveness and PL secretion. Comparison of CcpelA cloned from isolates US-41 and Si-60 revealed that both encode identical proteins, but differ in their promoters. Bioinformatics analysis for cis-acting elements suggested that the promoters of the US-41 and Si-60 isolates contain one and no AreA-binding site (GATA box), respectively. AreA has been suggested to be involved in fungal aggressiveness; therefore, CcpelA may be a key virulence factor in C. coccodes pathogenicity, and the differences in isolate aggressiveness might result from promoter activity. Quantitative reverse transcriptase-polymerase chain reaction analyses confirmed the higher level of CcpelA transcript in isolate US-41 versus Si-60.
authors.affiliation: Department of Plant Pathology, Agricultural Research Organization, Gilat Research Center, MP Negev 85280, Israel.
authors.forename: Bat-Hen
authors.initials: BH
authors.lastname: Ben-Daniel
authors.forename: Dudy
authors.initials: D
authors.lastname: Bar-Zvi
authors.forename: Leah
authors.initials: L
authors.lastname: Tsror Lahkim
mesh_terms: D001483:Base Sequence; D003001:Cloning, Molecular; D020231:Colletotrichum / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification / Q000472:pathogenicity*; D005656:Fungal Proteins / Q000235:genetics* / Q000378:metabolism; D017353:Gene Deletion; D015966:Gene Expression Regulation, Fungal; D018390:Gene Targeting; D005800:Genes, Fungal / Q000235:genetics*; D005816:Genetic Complementation Test; D008969:Molecular Sequence Data; D011133:Polysaccharide-Lyases / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D014170:Transformation, Genetic
chemical_list: D005656:Fungal Proteins; D012333:RNA, Messenger; D011133:Polysaccharide-Lyases; C023911:pectate lyase