Plant growth and development influenced by transgenic insertion of bacterial chitinolytic enzymes

The role of the chitinolytic enzymes in plants is not necessarilyrestricted to plant defense. Tomato plants transformed with an endochitinaseand a chitobiosidase gene from Streptomyces albidoflavus andgrowth under greenhouse conditions showed a significant reduction in plantheight, and reduced time to flowering compared with the control(non-transformed) plants. The levels of chitobiosidase and endochitinaseactivity in the transgenic tomato plants were positively correlated with earlyflowering, and negatively correlated with plant height. We have not determinedwhether these effects are exclusively due to the expression of the transgenesof endochitinase and chitobiosidase from S. albidoflavus orthe additive effect of these 2 enzymes combined with the endogenouschitinolytic enzymes produced by the plants. However, when control plants were trimmed,early flowering was observed compared with the controls that were not trimmed, whichindicates that wound induced proteins such as chitinolytic enzymes affect thetime of flowering. In addition, the expression of the endochitinase andchitobiosidase genes significantly increased the number of flowers and fruit onthe plants, resulting in an increase in yield of fruit. One of the primarygoals of crop breeding programs is to increase the productivity of plants. These twogenes were directly associated with plant productivity, and should be studied furthe

Chitinolytic enzymes from Streptomyces albidoflavus expressed in tomato plants: effects on Trichoplusia ni

Tomato ( Lycopersicon esculentum ) cultivars were transformed with genes that encode bacterial chitinolytic enzymes (i.e., endochitinase and chitobiosidase) from Streptomyces albidoflavus . Transgenic tomato plants producing these enzymes were found to have enhanced resistance to cabbage looper, Trichoplusia ni (HÜbner) (Lepidoptera: Noctuidae), consistently reducing the growth rates of larvae. Mortality was significantly increased in two of three feeding trials. Ingestion of endochitinase and chitobiosidase not only affected development of larval T. ni from neonate to ultimate instar, but they also caused mortality and decreased insect weight when exposure began during the third instar. The results of this study provide some insight into the mode of action of the chitinolytic enzymes, by supporting the hypothesis that ingested chitinolytic enzymes damage the chitin component of the peritrophic envelope, leading to increased permeability. The size of marker molecules (FITC-dextrans) that permeated the peritrophic envelopes of T. ni feeding on transgenic plants were 50% larger than those permeating the peritrophic envelopes of T. ni feeding on the control plants. Further research is needed to more clearly identify the sites and modes of action of these chitinolytic enzymes, and the potential for synergy between these enzymes and pathogens, allelochemicals, and other environmental factors.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72193/1/j.1570-7458.2001.00817.x.pd

Novel Chitinolytic Enzymes with Biological Activity Against Herbivorous Insects

The soil bacteria, Streptomyces albidoflavus, secretes endochitinases and chitobiosidases that are active over a broad range of pH (4-10). Ingestion of this mixture of chitinolytic enzymes significantly reduced the growth and development of Trichoplusia ni and significantly reduced survival of Myzus persicae, Bemisia argentifolii, and Hypothenemus hampei. Perfusion chromatography was used to separate endochitinases from chitobiosidases. The endochitinases had significantly greater biological activity against Bemisia argentifolii than the chitobiosidases. The utility of chitinolytic enzymes as regulators of populations of herbivorous insects is discusse

Carmenza E Gongora's Quick Files

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