Sheng Yang
Postdoctoral Student
Durham University (UK)
Ames, Iowa USA

Areas of Expertise:
Biochemistry and molecular biology of plant-insect interactions; Expression of recombinant plant and spider fusion proteins in microorganisms; Modification of Bt toxins to target hemipteran pests; Genetic engineering of plants for insect resistance; Plant and Insect biochemistry and molecular biology; Protein engineering

Research Organisms:
aphid, cabbage moth, house fly, mosquito, yeast, E.coli, plant, and so on


Research Focus:

(1) Bt toxin engineering for novel hemipteran gut target sites
Bt toxins have been successfully used in various transgenic crops for almost 20 years to manage lepidopteran and coleopteran pests. However, this strategy has not been used in the management of aphids and other hemipterans due to their low susceptibility to Bt toxins, potentially arising from a lack of binding to the hemipteran gut. To circumvent this limitation in pea aphids, peach-potato aphids and soybean aphids, a phage display library was screened in vivo against the aphid guts to identify candidate gut-binding peptides to add to a Bt toxin. The in vitro binding capacity of candidate gut-binding peptides was characterized. The candidate with the strongest gut binding was used to engineer the Bt toxin by insertion of the peptide sequence at seven sites in the toxin. The Modified toxins are currently being tested against these three kinds of aphids. The results showed modified toxins were extremely more toxic than wild-type toxin against aphids.
(2) Recombinant fusion proteins as new bio-insecticides
My research involves the design and production of recombinant fusion proteins as novel insecticides. These proteins are based on plant lectins as carriers for a variety of neurotoxins from venoms of spiders and are obtained by the methods of yeast fermentation (the yeast Pichia pastoris as an expression host). The novel spider fusion proteins are able to offer the potential prospect in the bio-insecticides market due to their advantages such as low cost, broad-spectrum, no effect on mammals, high oral toxicities against pests and chemical-resistant pests. They also have the ability to enhance the toxicities of Bt, entomopathogens and plants against the pests via transgenosis. Therefore, in the future, spider fusion proteins as new bio-pesticides are probable to become an attractive sustainable alternative to the Bt toxin products and conventional chemical pesticides. Moreover, these proteins have been used as starting points for mutagenesis programmes designed to produce novel proteins, for use as catalysts, and in pharmaceutical applications. The experimental results were published or submitted to different journals. At the same time, I also applied for an International Patent on how to improve the activity of fusion proteins. My PhD research also involves in the production and bioassay of insect-resistant transgenic plants by transferring recombinant fusion protein genes into Arabidopsis, and in evaluating the effects of these plants on non-target organisms, which will come to be seen as an environmentally benign form of pest control, up to now, I have already got positive transgenic Arabidopsis into which the gene of fusion protein was transferred. The expression level of the fusion protein is quite high. The amount of fusion protein is account for 1% of total Arabidopsis. More excitingly, the transgenic plants are effective against cabbage moth.