Journal
APPLIED AND ENVIRONMENTAL MICROBIOLOGY
Volume 83, Issue 3, Pages -Publisher
AMER SOC MICROBIOLOGY
DOI: 10.1128/AEM.02922-16
Keywords
Trichoderma; blue light; oxidative stress; BLR proteins; histone acetylation; histone deacetylases; HDA-2; Hos2p; Trichoderma
Categories
Funding
- SEP-CONACYT [CB-2013-01-220791]
- CONACYT [SEPCB-2013-01-223377, 226637, 333183]
Ask authors/readers for more resources
Fungal blue-light photoreceptors have been proposed as integrators of light and oxidative stress. However, additional elements participating in the integrative pathway remain to be identified. In Trichoderma atroviride, the blue-light regulator (BLR) proteins BLR-1 and -2 are known to regulate gene transcription, mycelial growth, and asexual development upon illumination, and recent global transcriptional analysis revealed that the histone deacetylase-encoding gene hda-2 is induced by light. Here, by assessing responses to stimuli in wild-type and Delta hda-2 backgrounds, we evaluate the role of HDA-2 in the regulation of genes responsive to light and oxidative stress. Delta hda-2 strains present reduced growth, misregulation of the con-1 gene, and absence of conidia in response to light and mechanical injury. We found that the expression of hda-2 is BLR-1 dependent and HDA-2 in turn is essential for the transcription of early and late light-responsive genes that include blr-1, indicating a regulatory feedback loop. When subjected to reactive oxygen species (ROS),Delta hda-2 mutants display high sensitivity whereas Delta blr strains exhibit the opposite phenotype. Consistently, in the presence of ROS, ROS-related genes show high transcription levels in wild-type and Delta blr strains but misregulation in Delta hda-2 mutants. Finally, chromatin immunoprecipitations of histone H3 acetylated at Lys9/Lys14 on cat-3 and gst-1 promoters display low accumulation of H3K9K14ac in Delta blr and Delta hda-2 strains, suggesting indirect regulation of ROS-related genes by HDA-2. Our results point to a mutual dependence between HDA-2 and BLR proteins and reveal the role of these proteins in an intricate gene regulation landscape in response to blue light and ROS. IMPORTANCE Trichoderma atroviride is a free-living fungus commonly found in soil or colonizing plant roots and is widely used as an agent in biocontrol as it parasitizes other fungi, stimulates plant growth, and induces the plant defense system. To survive in various environments, fungi constantly sense and respond to potentially threatening external factors, such as light. In particular, UV light can damage biomolecules by producing free-radical reactions, in most cases involving reactive oxygen species (ROS). In T. atroviride, conidiation is essential for its survival, which is induced by light and mechanical injury. Notably, conidia are typically used as the inoculum in the field during biocontrol. Therefore, understanding the linkages between responses to light and exposure to ROS in T. atroviride is of major basic and practical relevance. Here, the histone deacetylase-encoding gene hda-2 is induced by light and ROS, and its product regulates growth, conidiation, blue light perception, and oxidative stress responses.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available