trichoderma species - Weizmann Institute of Science

REVIEWSTable1 | Evidence for, and effectiveness of, induced resistance in plants by Trichoderma speciesSpecies Plant Pathogens Evidence or effects Time after Efficacy Referencesand strainapplicationT. virens G-6, Cotton Rhizoctonia Protection of plants; 4 days 78% reduction in disease; ability to 43G-6-5 and G-11 solani induction of fungitoxic induce phytoalexins required forterpenoid phytoalexinsmaximum biocontrol activityT. harzianum T-39 Bean Colletotrichum Protection of leaves when 10 days 42% reduction in lesion area; 41lindemuthianum; T-39 was present only onnumber of spreading lesionsBotrytis cinerea roots reducedT. harzianum T-39 Tomato, B. cinerea Protection of leaves when 7 days 25–100% reduction in grey-mould 42pepper, T-39 was present only symptomstobacco,on rootslettuce,beanT. asperellum T-203 Cucumber Pseudomonas Protection of leaves when 5 days Up to 80% reduction in disease on leaves; 66syringae pv. T-203 was present only on 100-fold reduction in level of pathogeniclachrymans roots; production of bacterial cells in leavesantifungal compounds inleavesT. harzianum T-22; Bean B. cinerea and Protection of leaves when 7–10 days 69% reduction in grey-mould M. L.,T. atroviride P1 Xanthomonas T-22 or P1 was present (B. cinerea) symptoms with T22; unpublishedcampestris pv. only on roots; production lower level of control with P1. 54% observationsphaseoli of antifungal compounds reduction in bacterial diseasein leavessymptoms.T. harzianum T-1 & Cucumber Green-mottle Protection of leaves when 7 days Disease-induced reduction in growth 99T22; T. virens T3 mosaic virus Trichoderma strains were eliminatedpresent only on rootsT. harzianum T-22 Tomato Alternaria solani Protection of leaves when 3 months Up to 80% reduction in early blight 100T-22 was present only on symptoms from natural fieldrootsinfectionT. harzianum T-22 Maize Colletotrichum Protection of leaves when 14 days 44% reduction of lesion size on 72graminicola Trichoderma strains were wounded leaves; no disease onpresent only on rootsnon-wounded leavesTrichoderma GT3-2 Cucumber C. orbiculare, Protection of leaves when 1 day 59% and 52% protection from disease 40P. syringae Trichoderma strains were caused by C. orbicularepv. lachrymans present only on roots; or P. syringae, respectivelyinduction of lignificationand superoxide generationT. harzianum Pepper Phytophthora Protection of stems when 9 days ~40% reduction in lesion length 101capsici Trichoderma strains werepresent only on roots;enhanced production ofthe phytoalexin capsidiolT. harzianum NF-9 Rice Magnaporthe Protection of leaves when 14 days 34–50% reduction in disease Tong Xu,grisea; NF-9 was present only on unpublishedXanthomonas roots observationsoryzae pv.oryzaeENDOPHYTEA non-pathogenic organismliving within a plant.and characterization of bioactive molecules that arereleased by the action of Trichoderma-secreted cellwall-degradingenzymes on the cell walls of fungalpathogens and plants. These molecules — which areproduced during the multiple interactions that occurin nature between Trichoderma, fungal pathogens andplant roots — function as inducers of the antagonisticgene-expression cascade in Trichoderma, and some alsofunction as elicitors of plant defence mechanisms 57,58 .The nature and structure of these compounds areknown, and will be published shortly.Interactions with plantsTrichoderma strains are well known for their ability tocolonize roots, but Trichoderma conidia have also beenapplied to fruit, flowers and foliage, and plant diseasescan be controlled by their application to any of thesesites 16,59,60 .Crucial components of the associations thatare considered in this review are microorganism–plantinteractions.Plant–Trichoderma associations. Some Trichodermastrains can colonize only local sites on roots 61 ,butrhizosphere-competent strains colonize entire rootsurfaces for several weeks 62 or months 16 .In the few casesthat have been examined thoroughly, Trichodermastrains colonize root surfaces — sometimes withmorphological features reminiscent of those seenduring mycoparasitism (FIG. 3a,b) — and hyphaeinvade the root epidermis (FIG. 3c).Penetration of theroot tissue is usually limited to the first or second layersof cells 61,63,64 (FIG. 3d); however, a strain ofTrichoderma stromaticum that is ENDOPHYTIC in thevascular system in cocoa has been described (REF. 65;48 | JANUARY 2004 | VOLUME 2 www.nature.com/reviews/micro