Open AccessCation-Stress-Responsive Transcription Factors SltA and CrzA Regulate Morphogenetic Processes and Pathogenicity of Colletotrichum gloeosporioides
Author(s) -
Amit Dubey,
Shiri Barad,
Neta Luria,
Dilip Kumar,
Eduardo A. Espeso,
Dov Prusky
Publication year - 2016
Publication title -
plos one
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.99
H-Index - 332
ISSN - 1932-6203
DOI - 10.1371/journal.pone.0168561
Subject(s) - aspergillus nidulans , biology , mutant , appressorium , transcription factor , zinc finger , fungal protein , microbiology and biotechnology , biochemistry , genetics , gene
Growth of Colletotrichum gloeosporioides in the presence of cation salts NaCl and KCl inhibited fungal growth and anthracnose symptom of colonization. Previous reports indicate that adaptation of Aspergillus nidulans to salt- and osmotic-stress conditions revealed the role of zinc-finger transcription factors SltA and CrzA in cation homeostasis. Homologs of A . nidulans SltA and CrzA were identified in C . gloeosporioides . The C . gloeosporioides CrzA homolog is a 682-amino acid protein, which contains a C 2 H 2 zinc finger DNA-binding domain that is highly conserved among CrzA proteins from yeast and filamentous fungi. The C . gloeosporioides SltA homolog encodes a 775-amino acid protein with strong similarity to A . nidulans SltA and Trichoderma reesei ACE1, and highest conservation in the three zinc-finger regions with almost no changes compared to ACE1 sequences. Knockout of C . gloeosporioides crzA (Δ crzA ) resulted in a phenotype with inhibited growth, sporulation, germination and appressorium formation, indicating the importance of this calciu006D-activated transcription factor in regulating these morphogenetic processes. In contrast, knockout of C . gloeosporioides sltA (Δ sltA ) mainly inhibited appressorium formation. Both mutants had reduced pathogenicity on mango and avocado fruit. Inhibition of the different morphogenetic stages in the Δ crzA mutant was accompanied by drastic inhibition of chitin synthase A and B and glucan synthase, which was partially restored with Ca 2+ supplementation. Inhibition of appressorium formation in Δ sltA mutants was accompanied by downregulation of the MAP kinase pmk1 and carnitine acetyl transferase ( cat1 ), genes involved in appressorium formation and colonization, which was restored by Ca 2+ supplementation. Furthermore, exposure of C . gloeosporioides Δ crzA or Δ sltA mutants to cations such as Na + , K + and Li + at concentrations that the wild type C . gloeosporioides is not affected had further adverse morphogenetic effects on C . gloeosporioides which were partially or fully restored by Ca 2+ . Overall results suggest that both genes modulating alkali cation homeostasis have significant morphogenetic effects that reduce C . gloeosporioides colonization.