Trichoderma harzianum

About: Trichoderma harzianum is a research topic. Over the lifetime, 4731 publications have been published within this topic receiving 96796 citations.

Hyphal interactions between Trichoderma harzianum and Rhizoctonia solani : ultrastructure and gold cytochemistry of the mycoparasitic process

Abstract: The interaction between Trichoderma harzianum and the soilborne plant pathogen Rhizoctonia solani was studied by both scanning (SEM) and transmission (TEM) electron microscopy Macroscopic observations of fungal growth in dual cultures revealed that pathogen growth inhibition occurred soon after contact with the antagonist SEM investigations demonstrated that coiling of the antagonist (T harzianum) around its host (R solani) was an early event preceding hyphal damage Ultrastructural observations of hyphal interactions showed that contact between the two fungi was mediated by a fine, extracellular matrix originating from cells of R solani The use of gold-complexed Ricinus communis agglutinin provided evidence that this matrix was rich in galactose residues []

Cell wall synthesis is a major target of mycoparasitic antagonism by Trichoderma harzianum.

Abstract: We have investigated the molecular basis for the reported synergism between peptaibols and cell wall hydrolytic enzymes in the antagonism of phytopathogenic fungi by Trichoderma harzianum. beta-Glucan synthase activity on isolated plasma membranes of Botrytis cinerea was inhibited in vitro by the peptaibols trichorzianin TA and TB, and this inhibition was reversed by the addition of phosphatidylcholine. beta-Glucan synthesis in vivo, assayed by the incorporation of [2-(3)H]glucose into cell wall material, was inhibited by the presence of peptaibols, and this inhibition was synergistic with exogenously added T. harzianum beta-1,3-glucanase. This synergism is therefore explained by an inhibition of the membrane-bound beta-1,3-glucan synthase of the host by the peptaibols, which inhibit the resynthesis of cell wall beta-glucans, sustain the disruptive action of beta-glucanases, and all together enhance the fungicidal activity. Therefore, we have identified cell wall turnover as a major target of mycoparasitic antagonism.

Biological control of the root-knot nematode Meloidogyne javanica by Trichoderma harzianum

Abstract: The filamentous fungi Trichoderma spp. is currently developed as biocontrol agents against many plant pathogens. Recent studies have shown that these fungi are able to infect nematode eggs and juveniles. In this research, biological control of root-knot nematode (Meloidogyne javanica) by Trichoderma harzianum BI was investigated in greenhouse and laboratory experiments. Results showed that different concentrations (102–108 spores/ml) of T. harzianum BI decreased nematode infection and other parameters significantly, compared to control. T. harzianum BI was able to penetrate nematode egg mass matrix and significantly decreased nematode egg hatching level. Specific activities of resistance-related enzymes, namely peroxidase (POX), polyphenol oxidase (PPO) and phenylalanine ammonia lyase (PAL) increased significantly in T. harzianum BI inoculated plants. Maximum activities of POX, PPO and PAL were observed at the 5, 5 and 6 days after inoculation, respectively. Chitinase activity was also increased in culture filtrates of T. harzianum BI grown on wheat bran moistened with salt solution supplemented with colloidal chitin or nematode eggs. Maximum activity of chitinase was recorded at the 4 days after inoculation, in media supplemented with colloidal chitin (1.15 U/min per ml) and nematode eggs (0.85 U/min per ml). Results suggested that direct parasitism of eggs through the increase in extracellular chitinase activity, which would be indicator of eggs infection capability, and inducing plant defense mechanisms leading to systemic resistance are two main suppression mechanisms used by T. harzianum BI against nematode.

Improved biocontrol activity of Trichoderma harzianum by over-expression of the proteinase-encoding gene prb1

Abstract: Transformation systems developed for Trichoderma spp. were utilized to improve the biocontrol efficiency of the mycoparasitic fungus Trichoderma harzianum by increasing the copy number of the basic proteinase gene prb1. The transformants were stable and carried from two to ten copies of prb1. High levels of expression of prb1 during fungus-fungus interaction were detected when T. harzianum and Rhizoctonia solani were confronted in vitro. In liquid cultures the proteinase was induced by cell walls of R. solani. Under greenhouse conditions, incorporation of T. harzianum transformants into pathogen-infested soil significantly reduced the disease caused by R. solani in cotton plants.

Short title: Trichoderma harzianum systematics Systematics of the Trichoderma harzianum species complex and the re-identification of commercial biocontrol strains

Abstract: Trichoderma harzianum is known as a cosmopolitan, ubiquitous species associated with a wide variety of substrates. It is possibly the most commonly used name in agricultural applications involving Trichoderma, including biological control of plant diseases. While various studies have suggested that T. harzianum is a species complex, only a few cryptic species are named. In the present study the taxonomy of the T. harzianum species complex is revised to include at least 14 species. Previously named species included in the complex are T. guizhouense, T. harzianum, and T. inhamatum. Two new combinations are proposed, T. lentiforme and T. lixii. Nine species are described as new, T. afarasin, T. afroharzianum, T. atrobrunneum, T. camerunense, T. endophyticum, T. neotropicale, T. pyramidale, T. rifaii and T. simmonsii. We isolated Trichoderma cultures from four commercial biocontrol products reported to contain T. harzianum. None of the biocontrol strains were identified as T. harzianum s. str. In addition, the widely applied culture ‘T. harzianum T22’ was determined to be T. afroharzianum. Some species in the T. harzianum complex appear to be exclusively endophytic, while others were only isolated from soil. Sexual states are rare. Descriptions and illustrations are provided. A secondary barcode, nuc translation elongation factor 1(TEF1) is needed to identify species in this complex.