Differential expression of maize chitinases in the presence or absence of <it>Trichoderma harzianum </it>strain T22 and indications of a novel exo- endo-heterodimeric chitinase activity

• Main Authors: Harman Gary E, Shoresh Michal
• Format: Article
• Language: English
• Published: BMC 2010-07-01
• Series: BMC Plant Biology
• Online Access: http://www.biomedcentral.com/1471-2229/10/136

<p>Abstract</p> <p>Background</p> <p>The interaction of plants with endophytic symbiotic fungi in the genus <it>Trichoderma </it>alters the plant proteome and transcriptome and results in enhanced plant growth and resistance to diseases. In a previous study, we identified the numerous chitinolytic enzyme families and individual enzymes in maize which are implicated in plant disease resistance and other plant responses.</p> <p>Results</p> <p>We examined the differential expression of the entire suite of chitinolytic enzymes in maize plants in the presence and absence of <it>T. harzianum</it>. Expression of these enzymes revealed a band of chitinolytic enzyme activity that had greater mass than any known chitinase. This study reports the characterization of this large protein. It was found to be a heretofore undiscovered heterodimer between an exo- and an endo-enzyme, and the endo portion differed between plants colonized with <it>T. harzianum </it>and those grown in its absence and between shoots and roots. The heterodimeric enzymes from shoots in the presence and absence of <it>T. harzianum </it>were purified and characterized. The dimeric enzyme from <it>Trichoderma</it>-inoculated plants had higher specific activity and greater ability to inhibit fungal growth than those from control plants. The activity of specific chitinolytic enzymes was higher in plants grown from <it>Trichoderma </it>treated seeds than in control plants.</p> <p>Conclusions</p> <p>This is the first report of a dimer between endo- and exochitinase. The endochitinase component of the dimer changed post <it>Trichoderma </it>inoculation. The dimer originating from <it>Trichoderma </it>inoculated plants had a higher antifungal activity than the comparable enzyme from control plants.</p>