Carbon and Nitrogen Sources Influence Parasitic Responsiveness in Trichoderma atroviride NI-1

Parasitic species of <i>Trichoderma</i> use hydrolytic enzymes to destroy the host cell wall. Preferent carbon and nitrogen sources suppress the expression of genes related to parasitism. Here, different nutrients were evaluated in the parasitic isolated NI-1, which was identified as <i>Trichoderma atroviride</i>. The genes <i>cbh1</i> and <i>chb2</i> (cellobiohydrolases), <i>bgl3.1</i> (endoglucanase), and <i>pra1</i> and <i>prb1</i> (proteinases) were poorly expressed during the interaction between NI-1 and <i>Phytophthora capsici</i> on PDA. However, gene expression improved on minimal medium with preferent and alternative carbon sources. Dextrin and glucose stimulated higher transcript levels than cellulose, sucrose, and glycerol. Also, ammonium stimulated a stronger parasitic responsiveness than the alternative nitrogen sources. During interaction against different phytopathogens, NI-1 detects their host differentially from a distance due to the <i>cbh1</i> and <i>cbh2</i> genes being only induced by <i>P. capsici</i>. The <i>pra1</i> and <i>ech42</i> genes were induced before contact with <i>Botrytis cinerea</i> and <i>Rhizoctonia solani</i>, while when confronted with <i>P. capsici</i> they were stimulated until contact and overgrowth. The <i>prb1</i> and <i>bgl3.1</i> genes were induced before contact against the three-host assayed. Overall, <i>T. atroviride</i> prefers to parasitize and has the capacity to distinguish between an oomycete and a fungus, but nutrient quality regulates its parasitic responsiveness.