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Faculty Sponsor

Vamsi Nalam




The soybean aphid continues to be an important pest in the major soybean growing regions around the country. The current consensus management recommendations that have been developed over more than a decade of research include cultural, genetic, economic and chemical controls. Although these strategies reduce the threat posed by soybean aphids, they do not completely eliminate it as a pest. As a complement to current management practices, we propose utilizing a biotechnological approach to enhance plant immunity. The genetic manipulation of components of the plant’s own defense signaling pathways offers an attractive strategy for boosting plant defenses. Regulatory genes that control the expression of multiple defenses are excellent targets for developing a broad spectrum of pathogens. This approach has several important advantages, including a minimal impact on crop yield for an economically important plant, reduced impact on the environment and the natural enemies of the aphid due to reduced insecticide application. A defense regulatory gene PHYTOALEXIN DEFICINT4 (PAD4) is an excellent candidate for over-expression soybean plants due to its important role in plant defenses against a broad-spectrum of pathogens. Previously, we have developed transgenic soybean plants that over-express the native PAD4 gene under the control of a constitutive promoter. Evaluation of the T0 and T1 plants from five transgenic events indicates that the PAD4 gene is indeed present and expressed in the transgenic plants. Soybean infestation assays indicate that the transgenic plants display enhanced resistance to soybean aphids. Data from the screening of second-generation transgenic plants for response to the soybean aphid indicate that the transgenic plants continue to show enhanced resistance to soybean aphids. Our research demonstrates a central role for PAD4 in plant defense against soybean aphids and that the genetic manipulation of regulatory genes in crop plants can produce a broad spectrum of resistance with a lack of detrimental effects on crop yield and plant traits. Key words: PAD4, Soybean, Soybean aphid, Host defense, transgenic plant



Evaluation of Second Generation Transgenic Soybean Plants for Resistance Against Soybean Aphids

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