Trichoderma viridis induces the production of volatile organic compounds in tomato to resist gray mold

Trichoderma viridis induces the production of volatile organic compounds in tomato to resist gray mold

Botrytis cinerea (Botrytis cinerea) is a kind of air-borne plant pathogenic fungi, can infect more than 200 crop hosts, because of its scientific and economic importance in the world's top 10 plant fungal pathogens ranked second. Trichoderma trichoderma is a soil-borne filamentous fungus, some of which can establish beneficial relationships with plants and play an important role in promoting plant growth, protecting plants from abiotic stresses, and improving host resistance to various pathogens. Some trichoderma strains inhibited mycelial growth and conidial germination of pathogenic bacteria by competing for nutrition and colonization space, and inhibited infection and colonization of Botrytis botrytis by producing activities of antifungal metabolites, hydrolase and volatile organic compounds. The secondary metabolites produced by trichoderma trichoderma, such as pyranone, olebutenolactone and antibacterial peptides, also play an important role in inhibiting the proliferation of B. cinerea. However, the defense response and resistance to B. cinerea induced by Trichoderma are not fully understood. In recent years, the role of volatile organic compounds (VOCs) produced and released by plants in response to Botris cinerea infestation in disease prevention and control has been paid more attention. While plant VOCs are known to play an important role in protecting plants from pathogens, their role in trichoderm-induced resistance to various pathogens, including Bovis griseus, remains relatively unclear. To this end, the researchers investigated the metabolic changes of volatile substances in tomato plants treated with T. virens and their relationship with resistance to gray mold disease.

It was found that T. virens TRS 106, a biocontrol agent for gray mold, could significantly reduce the disease index of Perkoz and Remiz varieties of tomato. This study compared the disease symptoms in tomato leaves of botrytis cinerea (Bc) inoculated alone with botrytis cinerea and Trichoderma viridis simultaneously inoculated with Bc + TRS. It was found that within 48 h, Botrytis cinerea began to successfully infect the plants. After 72 hours, the infected area of the leaves of the Remiz plants was larger than that of the Perkoz plants. Compared with Bc plants, the leaf disease symptoms of Bc + TRS treated plants were alleviated and the disease index decreased significantly. Further analysis revealed that plants treated with T. virens TRS 106 significantly increased the release of aromatic and green volatile organic compounds (including salicylate and hexanol derivatives) and had significant defensive effects against B. cinerea. GCxGC TOF-MS method was used to determine the tip of tomato plant, and it was found that tomato leaves could release 100 kinds of volatile organic compounds including annotated and postulated annotations, which were mainly divided into 6 categories. Of particular note are 2-hexenal, (2E,4E)-2, 4-hexadienal, 2-hexene-1-ol, 3,6, 6-trimethyl-2-cyclohexene-1-one, 1-octene-3-ol, 1, 5-octene-3-ol, 2-octenal, octenal, 2-pentene-1-ol, (Z) -6-nonenal, propenol, and acetophenone; 2-hydroxyacetophenone, β-tea tree, β-laurene, 2-carene, delta-olive and caryophyllene; Substances such as β-ionic ketone, 2-methyltetrahydrofuran, 2-ethyl and 2-amylfuran, ethyl, butyl and hexyl acetate, which can be detected only after significantly increased release or induction in trichoderma treated Perkoz, Remiz or both plants, may be related to plant disease resistance.

Volatile organic compounds (VOCs) are released from the leaves, flowers, fruits, and roots of plants and play an important role in the communication between plants and microorganisms. Microbial VOCs belong to a broad chemical class, such as alcohols, carbonyl compounds, hydrocarbons, aromatic compounds, and sulfur- and nitrogen-containing compounds, which have a high degree of structural variability. Because a variety of volatile organic compounds can inhibit the growth and development of plant pathogens, induce the activation of the plant defense system, and promote plant growth and development, they have great benefits for plants and their applications in agriculture.

Figure 1: Trichoderma significantly reduced the disease index of gray mold.

FIG. 2 Differences of volatile organic compounds among different treatments