The MAP kinase TVK1 regulates conidiation, hydrophobicity and the expression of genes encoding cell wall proteins in the fungus Trichoderma virens.
Mitogen-activated protein (MAP) kinases modulate morphological and genetic processes, which determine cell fate. The tvk1 gene encodes a MAP kinase of Trichoderma virens and its deletion promotes an unusual conidiation phenotype in submerged culture. Here, it is reported that the morphology, physiology and expression of genes encoding cell wall proteins from Trichoderma are significantly affected by Tvk1. Morphological changes were evident in the cell walls of aerial conidia produced by a MAPK null mutant when compared to those produced by the wild-type. Unexpectedly, conidia produced in submerged culture by the Deltatvk1 strain were highly hydrophobic, whereas in aerial conidia hydrophobicity was severely reduced. In addition, the Deltatvk1 strain was unable to break the liquid-air interface when the fungus grew in rich medium; however, when it grew in minimal medium the fungus produced large filaments which were much more efficient at breaking the interface than the wild-type. Through cDNA subtractive hybridization between the wild-type and Deltatvk1 grown in submerged culture, five genes encoding hydrophobin-like proteins and two additional genes encoding cell wall proteins were identified. Four hydrophobin-encoding genes (Tv-hfb1, Tv-srh1, tv-cfth1 and Tv-qid3) and a gene encoding a clock-controlled-like protein (Tv-ccg14/TvSm1) were upregulated in Deltatvk1, whereas genes encoding a cell wall protein (tv-qid74) and an additional hydrophobin (tv-hfb3) were absent in the mutant strain. Clear differences in gene expression were shown during conidiation and emergence from the liquid-air interface, suggesting different functions of the corresponding proteins in these two phenomena. The results support a model in which Tvk1 regulates morphology and genes encoding cell wall proteins during development of Trichoderma.
Mendoza-Mendoza
Artemio
A
Laboratorio Nacional de Genómica para la Biodiversidad, Centro de Investigación y de Estudios Avanzados, Campus Guanajuato, Apartado Postal 629, 36500, Irapuato, Guanajuato, Mexico.
Rosales-Saavedra
Teresa
T
Laboratorio Nacional de Genómica para la Biodiversidad, Centro de Investigación y de Estudios Avanzados, Campus Guanajuato, Apartado Postal 629, 36500, Irapuato, Guanajuato, Mexico.
Cortés
Carlos
C
Laboratorio Nacional de Genómica para la Biodiversidad, Centro de Investigación y de Estudios Avanzados, Campus Guanajuato, Apartado Postal 629, 36500, Irapuato, Guanajuato, Mexico.
Castellanos-Juárez
Verónica
V
Laboratorio Nacional de Genómica para la Biodiversidad, Centro de Investigación y de Estudios Avanzados, Campus Guanajuato, Apartado Postal 629, 36500, Irapuato, Guanajuato, Mexico.
Martínez
Pedro
P
Laboratorio Nacional de Genómica para la Biodiversidad, Centro de Investigación y de Estudios Avanzados, Campus Guanajuato, Apartado Postal 629, 36500, Irapuato, Guanajuato, Mexico.
Herrera-Estrella
Alfredo
A
Laboratorio Nacional de Genómica para la Biodiversidad, Centro de Investigación y de Estudios Avanzados, Campus Guanajuato, Apartado Postal 629, 36500, Irapuato, Guanajuato, Mexico.
D002473:Cell Wall / Q000378:metabolism; D015966:Gene Expression Regulation, Fungal; D057927:Hydrophobic and Hydrophilic Interactions; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism / Q000502:physiology*; D013172:Spores, Fungal; D014242:Trichoderma / Q000235:genetics* / Q000254:growth & development* / Q000378:metabolism
D020928:Mitogen-Activated Protein Kinases; C524435:TVK1 protein, Trichoderma virens