Genes from mycoparasitic fungi as a source for improving plant resistance to fungal pathogens

Abstract

Disease resistance in transgenic plants has been improved, for the first time, by the insertion of a gene from a biocontrol fungus. The gene encoding a strongly antifungal endochitinase from the mycoparasitic fungus Trichoderma harzianum was transferred to tobacco and potato. High expression levels of the fungal gene were obtained in different plant tissues, which had no visible effect on plant growth and development. Substantial differences in endochitinase activity were detected among transformants. Selected transgenic lines were highly tolerant or completely resistant to the foliar pathogens Alternaria alternata , A. solani , Botrytis cinerea , and the soilborne pathogen Rhizoctonia solani . The high level and the broad spectrum of resistance obtained with a single chitinase gene from Trichoderma overcome the limited efficacy of transgenic expression in plants of chitinase genes from plants and bacteria. These results demonstrate a rich source of genes from biocontrol fungi that can be used to control diseases in plants.

Expression of a fungal endochitinase gene in transgenic tomato and tobacco results in enhanced tolerance to fungal pathogens

“…However, in the present study, none of the transgenic plants of tobacco and tomato, expressing endochitinase showed morphological abnormalities. This result is in agreement with the earlier reports (Lorito et al, 1998;Mora and Earle, 2001;Emani et al, 2003), where endochitinase expression did not adversely affect the plant phenotype.…”

“…The pathogens used in the present study have been widely used in the disease resistance assay (Terakawa et al, 1997;Chakrabarti et al, 2003;Jang et al 2006). Transgenic plants with endochitiase gene from T. harzianum have shown enhanced resistance to B. cinerea and A. alternata (Lorito et al, 1998). Transgenic broccoli plants also showed moderate level of disease resistance (Mora and Earle, 2001), Transgenic apple showed reduced disease severity from 0-99.7 % (number of lesions) or 0-90 % (percentage leaf area infected) (Bolar et al, 2000).…”

“…Trichoderma chitinases are more antifungal in nature than other chitinolytic enzymes purified from other sources (i.e. up to 100 times more active than the corresponding plant enzymes and effective on a much wider range of pathogens) and are nontoxic to plants and higher vertebrates even at high concentrations (Lorito et al, 1998). Although there are reports on development of transgenic plants with fungal chitinase genes in tobacco and potato (Lorito et al, 1998), grape (Kikkert et al, 2000), broccoli (Mora and Earle, 2001), apple (Bolar et al, 2000), petunia (Esposito et al, 2000), cotton (Emani et al, 2003), there are no reports on transfer of chitinase genes from Trichoderma into tomato.…”

Enhanced fungal resistance in transgenic cotton expressing an endochitinase gene from Trichoderma virens

“…In planta expression of endochitinase genes from diverse fungi, such as Trichoderma harzianum ( Lorito et al ., 1998) and Rhizopus oligosporus (Terekawa et al ., 1997), has proven to be more effective both in terms of the level and in the spectrum of fungal pathogen resistance compared to the plant-derived chitinases. In addition to the direct action of chitinases on the cell wall of an invading pathogen, it has been suggested that the fungal cell wall fragments released as a result of extracellular chitinase activity may in turn activate a number of defensive responses in plants (Grison et al ., 1996;Lorito et al ., 1998).…”

An amphibian antimicrobial peptide variant expressed in Nicotiana tabacum confers resistance to phytopathogens

“…Advances in genetic engineering have made possible the development of plants with new predictable phenotypes [1,2]. In particular, to increase resistance against diseases, different genetic strategies have been proposed, which include utilization of antibacterial proteins of both plant [3][4][5] and non-plant origin [6,7].…”