A tannic acid-inducible and hypoviral-regulated Laccase3 contributes to the virulence of the chestnut blight fungus Cryphonectria parasitica.
A new laccase gene (lac3) from the chestnut blight fungus Cryphonectria parasitica was induced by the presence of tannic acid, which is abundant in the bark of chestnut trees and is assumed to be one of the major barriers against pathogen infection. However, other commonly known laccase inducers, including ferulic acid, 2,5-xylidine, catechol, and pH, did not induce lac3 transcription. Moreover, the hypovirus modulated the induction of lac3 transcription, abolishing the transcriptional induction of the lac3 gene by tannic acid. A functional analysis of lac3 using a lac3-null mutant indicated that fungal growth and other morphological characteristics, including pigmentation and sporulation, were not affected. However, a virulence assay indicated that the loss of function of a tannic acid-inducible and hypoviral-regulated laccase resulted in reduced virulence without detectable changes in the morphological features. The constitutive expression of lac3 resulted in no significant differences in the necrotic lesions from those caused by the wild type, but its expression in the presence of the hypovirus led to larger lesions than those caused by the hypovirulent strain. These results suggest that the lac3 gene product may not be the only determinant of fungal virulence in chestnut trees but is an important factor.
Chung
Hea-Jong
HJ
Division of Natural Sciences and Technology, Wonkwang University, Iksan, Chonbuk 570-749, Korea.
Kwon
Bo-Ra
BR
Kim
Jung-Mi
JM
Park
Seung-Moon
SM
Park
Jong-Kun
JK
Cha
Byeong-Jin
BJ
Yang
Moon-Sik
MS
Kim
Dae-Hyuk
DH
D000595:Amino Acid Sequence; D001203:Ascomycota / Q000187:drug effects / Q000235:genetics* / Q000472:pathogenicity; D003001:Cloning, Molecular; D004271:DNA, Fungal / Q000235:genetics; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal; D005800:Genes, Fungal; D042845:Laccase / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D010641:Phenotype; D012328:RNA Viruses / Q000378:metabolism*; D016415:Sequence Alignment; D020539:Sequence Analysis, Protein; D013634:Tannins / Q000494:pharmacology*; D014158:Transcription, Genetic; D014170:Transformation, Genetic; D014197:Trees / Q000382:microbiology; D014774:Virulence
D004271:DNA, Fungal; D005656:Fungal Proteins; D013634:Tannins; D042845:Laccase