New Report of Three Unrecorded Species in Trichoderma harzianum Species Complex in Korea

Trichoderma carraovejensis: a new species from vineyard ecosystem with biocontrol abilities against grapevine trunk disease pathogens and ecological adaptation

Trichoderma strains used in vineyards for the control of grapevine trunk diseases (GTDs) present a promising alternative to chemical products. Therefore, the isolation and characterization of new indigenous Trichoderma strains for these purposes is a valuable strategy to favor the adaptation of these strains to the environment, thus improving their efficacy in the field. In this research, a new Trichoderma species, Trichoderma carraovejensis, isolated from vineyards in Ribera de Duero (Spain) area, has been identified and phylogenetically analyzed using 20 housekeeping genes isolated from the genome of 24 Trichoderma species. A morphological description and comparison of the new species has also been carried out. In order to corroborate the potential of T. carraovejensis as a biological control agent (BCA), confrontation tests against pathogenic fungi, causing various GTDs, have been performed in the laboratory. The compatibility of T. carraovejensis with different pesticides and biostimulants has also been assessed. This new Trichoderma species demonstrates the ability to control pathogens such as Diplodia seriata, as well as high compatibility with powdered sulfur-based pesticides. In conclusion, the autochthonous species T. carraovejensis can be an effective alternative to complement the currently used strategies for the control of wood diseases in its region of origin.

Three new species of Trichoderma (Hypocreales, Hypocreaceae) from soils in China

Trichoderma spp. are diverse fungi with wide distribution. In this study, we report on three new species of Trichoderma, namely T.nigricans, T.densissimum and T.paradensissimum, collected from soils in China. Their phylogenetic position of these novel species was determined by analyzing the concatenated sequences of the second largest nuclear RNA polymerase subunit encoding gene (rpb2) and the translation elongation factor 1- alpha encoding gene (tef1). The results of the phylogenetic analysis showed that each new species formed a distinct clade: T.nigricans is a new member of the Atroviride Clade, and T.densissimum and T.paradensissimum belong to the Harzianum Clade. A detailed description of the morphology and cultural characteristics of the newly discovered Trichoderma species is provided, and these characteristics were compared with those of closely related species to better understand the taxonomic relationships within the Trichoderma.

Enzymatic Pretreatment Improved the In Vitro Ruminal Degradability of Oil Palm Fronds

This study aims to increase the in vitro ruminal degradability of oil palm fronds (OPFs) through enzymatic pretreatment. The isolated fungi were selected based on their lignocellulosic degrading enzyme activities. Eleven fungi were successfully isolated, and their enzyme activities were evaluated. Three fungi, F1, F2 and F4 were selected, and they were identified as Trichoderma harzianum MK027305, Trichoderma harzianum MK027306 and Fusarium solani MK027309, respectively. The highest total gas and methane production was produced when OPFs were pretreated with an enzyme extract from 15 and 30 days of solid-state fermentation of T. harzianum MK027305 and T. harzianum MK027306, respectively. Meanwhile, OPFs pretreated with an enzyme extract from F. solani MK027309 after 45 days of solid-state fermentation produced the highest amount of volatile fatty acids. The pretreatment using the enzymes extracted from 45 days of solid-state fermentation of F. solani MK027309 increases the apparent rumen degradable carbohydrate (ARDC) by 35.29% compared to unpretreated OPF. This study showed that pretreatment of the OPFs using selected fungi’s enzymes increases the volatile fatty acid production and in vitro ruminal degradability of OPF, hence improving livestock production via increased utilization of agricultural by-products with minimal impact on the production cost.

Biofumigation activities of volatile compounds from two Trichoderma afroharzianum strains against Fusarium infections in fresh chilies

BACKGROUND

Two Fusarium fungi, F. oxysporum and F. proliferatum, have been recognized as major pathogenic fungi that cause postharvest decay of chili fruits. Ozone and some toxic chemicals are used to control pathogenic infections, leading to longer storage lives of agricultural commodities. However, these chemicals may pose some risks to the applicators and the environment. Therefore, alternative, easy-to-use fumigants for effective control of Fusarium infections in harvested fresh chilies are needed.

RESULTS

Two endophytic fungi, Trichoderma afroharzianum strain MFLUCC19-0090 and T. afroharzianum strain MFLUCC19-0091, were isolated from Schefflera leucantha leaves. Their volatile compounds were investigated for antifungal activities against F. oxysporum and F. proliferatum. In vitro results showed that the volatile compounds produced by each strain inhibited pathogen growth. Additionally, the Trichoderma-derived volatile compounds significantly reduced Fusarium-related disease severity and incidence percentages in the inoculated fresh chilies. Antifungal properties of the volatile compounds were found to be specific to the species of the tested pathogens (MFLUCC19-0090 greatly suppressed F. oxysporum and MFLUCC19-0091 greatly suppressed F. proliferatum). Seventy-three volatile compounds were detected from both strains. Among the major volatile compounds detected, phenyl ethyl alcohol was found to possess the strongest antifungal activity against both pathogens.

CONCLUSION

These Trichoderma-derived volatile compounds may be used as alternative fumigants for controlling Fusarium rot in harvested fresh chilies. The successful use of volatile compounds as biofumigants can prevent significant market losses and, more importantly, may reduce the health hazards caused by Fusarium-associated mycotoxin exposures among consumers. © 2021 Society of Chemical Industry.

Endophytic Trichoderma Species Isolated from Persea americana and Cinnamomum verum Roots Reduce Symptoms Caused by Phytophthora cinnamomi in Avocado

Avocado root rot caused by the oomycete Phytophthora cinnamomi is a severe disease that affects avocado production in Mexico and worldwide. The use of biological control agents such as Trichoderma species isolated from places where the disease is always present, represents an efficient alternative to reduce losses. Thus, the objective of this research was to evaluate the biocontrol ability of 10 endophytic Trichoderma spp. strains against P. cinnamomi tested both in vitro and in the greenhouse. The endophytic Trichoderma spp. were recovered from Persea americana and Cinnamomum verum roots, isolated and purified on potato-dextrose-agar medium. Ten strains were identified by phylogenetic reconstruction of the internal transcribed spacer region of rDNA sequences as T. asperellum (T-AS1, T-AS2, T-AS6, and T-AS7), T. harzianum (T-H3, T-H4, and T-H5), T. hamatum (T-A12), T. koningiopsis (T-K8 and T-K11), and P. cinnamomi (CPO-PCU). In vitro dual-culture assay, the percentage of inhibition of radial growth (PIRG) between Trichoderma spp. and P. cinnamomi strains was measured according to the Bell's scale. PIRG results indicated that T-AS2 reached the highest value of 78.32%, and T-H5 reached the lowest value of 38.66%. In the greenhouse, the infection was evaluated according to the percentage of disease incidence. Plants with the lowest incidence of dead by avocado root rot were those whose seedlings were inoculated with T-AS2 and T-AS7, resulting in only 5% death by root rot caused by P. cinnamomi. The disease incidence of seedlings with wilt symptoms and death decreased more than 50% in the presence of Trichoderma spp. Relying on the results, we conclude that T. asperellum and T. harzianum contribute to the biocontrol of soil-borne pathogenic oomycete P. cinnamomi.