Developmental regulation and cellulase gene expression in Trichoderma reesei

Irina S. Druzhinina, Razieh Karimi-Aghcheh, Lea Atanasova, Christian P. Kubicek

Author address: 

Microbiology Group, Institute of Chemical Engineering, Vienna, Austria


We have recently shown that expression of cellulase and hemicellulase encoding genes in Trichoderma reesei (teleomorph Hypocrea jecorina) is obligatorily dependent on the function of the protein methyltransferase LAE1. Its orthologue in Aspergillus nidulans, LaeA, is a part of the VELVET protein complex consisting of LaeA, VeA and VelB that regulates secondary metabolism and sexual reproduction. Here we have investigated a possible role of VEL1, the T. reesei orthologue of A. nidulans VeA, in expression cellulase genes and the development of the fungus. The T. reesei vel1 gene is not expressed in the darkness and is expressed at a relatively low level under illumination. Deletion of the vel1 locus causes a complete loss of conidiation and essential alteration in sexual development such as loss of formation of perithecia. Overexpression of vel1 under the constitutive expression signals of tef1 did not enhance conidiation in light or darkness. However it led to irregular formation of infertile perithecia in the darkness. Deletion of vel1 did not affect cellulase gene expression, but vel1 overexpression strongly enhanced it. Consistent findings were also obtained for expression of xylanase and b-xylosidase genes. The stimulation of cellulase gene expression by overexpressing vel1 was dependent on a functional lae1 gene. Our data show that VEL1 controls photoinduced sexual development and light-independent conidiation. In addition, while vel1 overexpression stimulates cellulase gene expression, is dispensable for this process and its action is therefore different from that of LAE1

abstract No: 


Full conference title: 

27th Fungal Genetics Conference
    • Fungal Genetics Conference 27th (2013)