Interactions between Trichoderma harzianum and defoliating Verticillium dahliae in resistant and susceptible wild olive clones

Abstract

Verticillium wilt (VW) in olive is best managed by an integrated disease management strategy, of which use of host resistance is a key element. The widespread occurrence of a highly virulent defoliating (D) Verticillium dahliae pathotype has jeopardized the use of commercial olive cultivars lacking sufficient resistance to this pathogen. However, the combined use of resistant wild olive rootstocks and Trichoderma spp. effective in the biocontrol of VW can improve the management of VW in olive. In vivo interactions between D V. dahliae and Trichoderma harzianum were studied in olive and wild olive plants displaying different degrees of resistance against this pathogen using confocal microscopy. This multitrophic system included wild olive clones Ac-4 and Ac-15, olive cv. Picual, and the fungal fluorescent transformants T. harzianum GFP22 and V. dahliae V138I-YFP, the latter being obtained in this study. In planta observations indicated that V138I-YFP colonizes the roots and stems of the olive and wild olive genotypes, and that GFP22 grows endophytically within the roots of them all. YFP fluorescence signal quantifications showed that: (i) the degree of root and stem colonization by the pathogen varied depending upon the susceptibility of the tested wild olive genotype, being higher in Ac-15 than in Ac-4 plants; and (ii) treatment with T. harzianum GFP22 reduced the extent of pathogen growth in both clones. Moreover, root colonization by strain GFP22 reduced the percentage of pathogen colonies recovered from stems of olive and wild olive plants.

Assessment of functional and structural changes of soil fungal and oomycete communities in holm oak declined dehesas through metabarcoding analysis

“…from the studied soils to identify the fungus at species level, together with the analysis of root endosphere, which would provide useful information about the endophyte behaviour of the present species, as it has been shown for other Trichoderma spp. 86,87 .…”

Effect of Inorganic N Top Dressing and Trichoderma harzianum Seed-Inoculation on Crop Yield and the Shaping of Root Microbial Communities of Wheat Plants Cultivated Under High Basal N Fertilization

“…Trichoderma species are frequently found as common inhabitants of the soil and the rhizosphere, and even though many of them may become facultative endophytes, the number of truly endophytic Trichoderma spp. is scarce (Bae et al, 2009;Carrero-Carrón et al, 2018). In addition to rhizosphere colonization, nutrient uptake facilitation and plant growth promotion (Hermosa et al, 2012;Samolski et al, 2012), the application of Trichoderma strains may also affect the soil bacterial and fungal communities in a pH-and N supply dependent manner, respectively (Zhang et al, 2018).…”

Defining the root endosphere and rhizosphere microbiomes from the World Olive Germplasm Collection

“…Finally, and regarding beneficial fungi, representatives of the genus Trichoderma were found in the rhizosphere of all cultivars but Chemlal de Kabylie and Llumeta. Species of this genus have been successfully used as BCA against VW of olive 46,47 .…”