Open AccessMulti‐factor regulation of pectate lyase secretion by Colletotrichum gloeosporioides pathogenic on avocado fruits
Author(s) -
MIYARA I.,
SHAFRAN H.,
KRAMER HAIMOVICH H.,
ROLLINS J.,
SHERMAN A.,
PRUSKY D.
Publication year - 2008
Publication title -
molecular plant pathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.945
H-Index - 103
eISSN - 1364-3703
pISSN - 1464-6722
DOI - 10.1111/j.1364-3703.2007.00462.x
Subject(s) - pectate lyase , secretion , mutant , virulence , microbiology and biotechnology , virulence factor , fructose , biology , gene expression , chemistry , gene , biochemistry , enzyme , pectinase
SUMMARY Tissue alkalinization during Colletotrichum gloeosporioides attack enhances the expression of PELB , which encodes pectate lyase (PL), and PL secretion, which is considered essential for full virulence. We studied the regulation of PL secretion by manipulation of C. gloeosporioides PELB . PELB was down‐regulated by knocking out PAC1 , which encodes the PacC transcription factor that regulates gene products with pH‐sensitive activities. We functionally characterized a PACC gene homologue, PAC1 , from C. gloeosporioides wild‐type (WT) Cg‐14 and two independent deletion strains, Δ pac1 372 and Δ pac1 761 . Loss‐of‐function PAC1 mutants showed 85% reduction of PELB transcript expression, delayed PL secretion and dramatically reduced virulence, as detected in infection assays with avocado fruits. In contrast, PELB was up‐regulated in the presence of carbon sources such as glucose. When glucose was used as a carbon source in the medium for the WT strain and the Δ pac1 mutant at pH 6.0, PELB transcript expression and PL secretion were activated. Other sugars, such as sucrose and fructose (but not galactose), also activated PELB expression. These results suggest that the pH‐regulated response is only part of a multi‐factor regulation of PELB , and that sugars are also needed to promote the transition from quiescent to active necrotrophic development by the pathogen.