Synergistic activity of endochitinase and exochitinase from Trichoderma atroviride (T. harzianum) against the pathogenic fungus (Venturia inaequalis) in transgenic apple plants

• Published in: Transgenic research Vol. 10; no. 6; pp. 533 - 543
• Main Authors: JYOTHI PRAKASH BOLAR, NORELLI, John L, HARMAN, Gary E, BROWN, Susan K, ALDWINCKLE, Herb S
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer 01.12.2001; Springer Nature B.V
• Subjects: Apples; beta-N-Acetylhexosaminidases - metabolism; Biological and medical sciences; Biological control; Biotechnology; Blotting, Western; Chitinases - metabolism; Control; Drug Synergism; endochitinase; Enzyme-Linked Immunosorbent Assay; Enzymes; exochitinase; Fundamental and applied biological sciences. Psychology; Fungal plant pathogens; Genetic engineering; Genetic technics; Malus; Malus - genetics; Malus - virology; Methods. Procedures. Technologies; Models, Genetic; N-acetyl-^b-D-hexosaminidase; Phytopathology. Animal pests. Plant and forest protection; Plant Viruses - genetics; Plants, Genetically Modified; Plasmids - metabolism; Polymerase Chain Reaction; Transgenic animals and transgenic plants; Transgenic plants; Trichoderma - enzymology; Trichoderma - virology; Trichoderma atroviride; Venturia inaequalis; Chitinase; Plant pathogen; Enzyme; Growth; Rosaceae; β-N-Acetylhexosaminidase; Venturia inaequalis; Malus domestica; Gene expression; Synergism; Fungus resistance; Fungi; Enzymatic activity; Dicotyledones; Glycosidases; Angiospermae; Hydrolases; Ascomycetes; Spermatophyta; Transgenic plant; Fungi Imperfecti; Fruit tree; O-Glycosidases; Thallophyta
• ISSN: 0962-8819; 1573-9368
• DOI: 10.1023/A:1013036732691

Genes from the biocontrol fungus Trichoderma atroviride encoding the antifungal proteins endochitinase or exochitinase (N-acetyl-beta-D-hexosaminidase) were inserted into 'Marshall McIntosh' apple singly and in combination. The genes were driven by a modified CaMV35S promoter. The resulting plants were screened for resistance to Venturia inaequalis, the causal agent of apple scab, and for effects of enzyme expression on growth. Disease resistance was correlated with the level of expression of either enzyme when expressed alone but exochitinase was less effective than endochitinase. The level of expression of endochitinase was negatively correlated with plant growth while exochitinase had no consistent effect on this character. Plants expressing both enzymes simultaneously were more resistant than plants expressing either single enzyme at the same level; analyses indicated that the two enzymes acted synergistically to reduce disease. Selected lines, especially one expressing low levels of endochitinase activity and moderate levels of exochitinase activity, were highly resistant in growth chamber trials and had negligible reduction in vigor relative to control plants. We believe that this is the first report of resistance in plants induced by expression of an N-acetylhexosaminidase and is the first report of in planta synergy between an exochitinase and an endochitinase.