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

Abstract

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.

Antifungal activity of Trichoderma harzianum and T. koningiopsis against Fusarium solani in seed germination and vigor of Miahuateco chili seedlings

“…Its use and success in agriculture is due to action mechanisms such as competition for space, mycoparasitism, antibiosis (Nawrocka et al, 2018) and the production of volatile compounds (Hernández-Melchor et al, 2019). In previous investigations, T. harzianum T-H4 presented a higher percentage of inhibition (78.3%) against Phytophthora cinnamomi than T. koningiopsis T-K11 in vitro (Andrade-Hoyos et al, 2020). Likewise, the strain T-H4 presented 63.6% of PICR and class III of the Bell scale against Fusarium sp.…”

“…El éxito y uso en la práctica agrícola, se debe a sus mecanismos de acción como la competencia por espacio, micoparasitismo, antibiosis (Nawrocka et al, 2018) y la producción de compuestos volátiles (Hernández-Melchor et al, 2019). En trabajos previos, T. harzianum T-H4 presentó el mayor porcentaje de inhibición (78.3%) contra Phytophthora cinnamomi que T. koningiopsis T-K11 in vitro (Andrade-Hoyos et al, 2020). Así mismo la cepa T-H4 presentó 63.6% de PICR y clase III de la escala de Bell contra Fusarium sp.…”

“…Esto indica que probablemente, T. harzianum puede tener una tasa de incorporación de nutrientes y un metabolismo superior a F. solani, así como distintos mecanismos de secreción de enzimas hidrolíticas; entre ellas celulasas, quitinasas, glucanasas, xylasas y proteasas, las cuales pueden estar implicadas en los mecanismos de biocontrol, permitiéndole aprovechar mejor los nutrientes del medio y privar al patógeno de utilizar los recursos (Michel-Aceves et al, 2005). Además T. harzianum es capaz de inhibir del crecimiento de fitopatógenos porque produce numerosos antibióticos como tricodermina, suzukacilina, alameticina, dermadina, penicilina, tricotecenos, tricorzianinas, entre otros (Andrade-Hoyos et al, 2020).…”

“…Esto resalta la eminente capacidad micoparasítica de (Michel-Aceves et al, 2005). T. harzianum is also capable of inhibiting the growth of phytopathogens, since it produces numerous antibiotics, such as trichodermine, suzukacillin, alameticin, dermadin, penicillin, trichothecenes, trichorzianines and others (Andrade-Hoyos et al, 2020).…”

“…The genus Trichoderma can parasite pathogenic fungi and produce antibiotics. It also presents positive effects in plant growth, yield, absorption of nutrients, fertilizer use efficiency and the systemic resistance of plants to diseases (Hyder et al, 2017;Andrade-Hoyos et al, 2020). In a study carried out by Cole and Zvenyika (1988), they noticed that the infection caused by F. solani in tobacco plants could be controlled when applying T. harzianum in disease management procedures.…”