Trichoderma asperellum efficiently protects Quercus robur leaves against Erysiphe alphitoides

Abstract

The protective effects of Trichoderma asperellum IZR D-11 as a biocontrol agent against the powdery mildew Erysiphe alphitoides infecting leaves of Quercus robur were evaluated for the first time. A strain of Trichoderma had earlier been isolated in Belarus, and was identified in this study as T. asperellum by sequencing of three genomic markers: internal transcribed spacer, translation elongation factor 1 alpha and RNA polymerase II subunit 2, with over 99.2% identity to corresponding genomic sequences in GenBank. When applied once in the first year just after onset of powdery mildew disease, T asperellum IZR D-11 reduced disease progression and continued to reduce powdery mildew levels during the following three years. Photosynthetic activity as represented by chlorophyll fluorescence measured in oak seedlings was increased in treated plants, and greater assimilate production was also found. The use of this antagonistic fungus increased the total water content in oak leaves suggesting that T. asperellum IZR D-11 can serve as a preventive measure to reduce energy losses in the process of water transpiration. GC-MS analysis detected 49 volatile compounds in the headspace of pure cultures of T. asperellum. Sesquiterpenes represented mainly by daucene, dauca-4(11),8-diene and isodaucene were the largest group of compounds emitted. We speculate that these volatiles from T. asperellum IZR D-11 may be involved in induced resistance in the plant, but further research is needed. The above results suggest that T. asperellum strain IZR D-11 has potential as a biocontrol agent of oak powdery mildew in forest nurseries.

Trichoderma and the Plant Heritable Priming Responses

“…Some strains of Trichoderma are effective in the direct control of pathogens in the phyllosphere, although their mechanism of action seems to be linked more to induced resistance and mycoparasitism than to direct competition [ 31 ]. Selected Trichoderma strains may also release VOCs related to plant growth promotion [ 32 ] but may also be involved in reducing energy losses and inducing photosynthesis and resistance to foliar pathogens, such as those producing powdery mildew [ 33 ]. Even endophytic Trichoderma strains can mitigate the negative impact of leaf-cutting ants in both agriculture and silviculture due to the potential to act as bodyguards to their plant hosts affording protection to the whole plant [ 34 ].…”

“…Induced systemic resistance (ISR) is a term that has emerged to define the enhanced defensive capacity of the entire plant against a broad spectrum of pathogens, acquired upon local induction by beneficial microbes [ 20 ]. Interestingly, it has recently been reported that foliar applications of T. asperellum were able to suppress oak powdery mildew disease in the subsequent three years [ 33 ]. It is widely accepted that SA is essential in SAR signal transduction against biotrophic pathogens while ISR was shown to be effective against attackers that are sensitive to JA/ET-dependent defences including necrotrophic pathogens and insect herbivory [ 20 ].…”

Induction of Defense Responses in Pinus sylvestris Seedlings by Methyl Jasmonate and Response to Heterobasidion annosum and Lophodermium seditiosum Inoculation

“…MeJA application increased resistance to both H. annosum and L. seditiosum, and this study also showed that MeJA application had an effect on reducing the impact of insect pests, although this was an unplanned stress factor, and results should be replicated in controlled experiments. Further directions of study include a more detailed investigation of the efficacy of different compounds in stimulating defense responses in Scots pine, including fungal metabolites, or use of fungal species as biocontrol agents [74]. Anatomical parameters, e.g., vessel size and properties, could also have an effect on differential resistance between individuals.…”

Electronic Nose Differentiation between Quercus robur Acorns Infected by Pathogenic Oomycetes Phytophthora plurivora and Pythium intermedium

“…Therefore this type of SPME fibre was used in further research. Analyses were performed according to a previously developed methodology [34][35][36][37], as described below.…”