Secretome of Trichoderma Interacting With Maize Roots: Role in Induced Systemic Resistance*

Abstract

Trichoderma virens is a biocontrol agent used in agriculture to antagonize pathogens of crop plants. In addition to direct mycoparasitism of soil-borne fungal pathogens, T. virens interacts with roots. This interaction induces systemic resistance (ISR), which reduces disease in aboveground parts of the plant. In the molecular dialog between fungus and plant leading to ISR, proteins secreted by T. virens provide signals. Only a few such proteins have been characterized previously. To study the secretome, proteins were characterized from hydroponic culture systems with T. virens alone or with maize seedlings, and combined with a bioassay for ISR in maize leaves infected by the pathogen Cochliobolus heterostrophus. The secreted protein fraction from coculture of maize roots and T. virens (Tv؉M) was found to have a higher ISR activity than from T. virens grown alone (Tv). A total of 280 fungal proteins were identified, 66 showing significant differences in abundance between the two conditions: 32 were higher in Tv؉M and 34 were higher in Tv. Among the 34 found in higher abundance in Tv and negatively regulated by roots were 13 SSCPs (small, secreted, cysteine rich proteins), known to be important in the molecular dialog between plants and fungi. The role of four SSCPs in ISR was studied by gene knockout. All four knockout lines showed better ISR activity than WT without affecting colonization of maize roots. Furthermore, the secreted protein fraction from each of the mutant lines showed improved ISR activity compared with WT. These SSCPs, apparently, act as negative effectors reducing the defense levels in the plant and may be important for the fine tuning of ISR by Trichoderma. The down-regulation of SSCPs in interaction with plant roots implies a revision of the current model for the Trichoderma-plant symbiosis and its induction of resistance to pathogens. Molecular & Cellular Proteomics

Emergência e análise ultraestrutural de plântulas de soja inoculadas com Sclerotinia sclerotiorum sob efeito da aplicação de Trichoderma harzianum

“…Lamdan et al (17) verificaram que existem diversas proteínas secretadas por Trichoderma virens presentes quando em raízes de milho e ausente em sua ausência. Foi demonstrado que no secretoma estudado havia proteínas específicas importantes no diálogo molecular entre planta e fungo, as quais participam da ativação do sistema de defesa sistêmico vegetal.…”

Cellulase from Trichoderma harzianum interacts with roots and triggers induced systemic resistance to foliar disease in maize

“…This experiment aimed to study the effects of treatments with the Trichoderma WT strain (Th22) and ΔThph1 strain on maize root proteins using label-free quantitative proteomics analysis59. The Trichoderma conidia suspensions (concentration of 1 × 10 6 CFU/mL) were coated on the corn seeds and germinated in sterile wet filter paper for 72 h at 25 °C.…”

Transcriptional reprogramming underpins enhanced plant growth promotion by the biocontrol fungus Trichoderma hamatum GD12 during antagonistic interactions with Sclerotinia sclerotiorum in soil

“…Some SSCRPs are likely to function as potential effector molecules that collaborate in biocontrol and PGP. Consistent with this, in other Trichoderma species, SSCRPs have been shown to be up‐regulated during PGP (Moran‐Diez et al ., ), during induction of systemic resistance (Lamdan et al ., ) and during biocontrol (Atanasova et al ., ). Thus, the expanded repertoire of SSCRPs unique to GD12 may contribute to its dual biocontrol and PGP properties.…”

“…The biological control and plant growth promotion (PGP) properties of Trichoderma species have been well documented (Hermosa et al ., ; Matarese et al ., ; Omann et al ., ; Ryder et al ., ). Diseases are controlled through direct hyperparasitism of rhizosphere pathogens (Benítez et al ., ), through competition (Ryder et al ., ), through the production of antimicrobial compounds (Steindorff et al ., ; Vos et al ., ), through the secretion of compounds that induce systemic resistance in plants (Lamdan et al ., ) and, in many cases, most likely through a combination thereof (Howell, ). In addition, certain Trichoderma strains are able to improve the productivity of monocot and dicot plants by accelerating seed germination and root and shoot development (Chang et al ., ; Yedidia et al ., ), and by increasing resilience to abiotic stresses, such as drought (Bae et al ., ; Donoso et al ., ) and salinity (Brotman et al ., ; Mastouri et al ., ).…”