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Faculty Sponsor

Dr. Punya Nachappa


Department of Biology

University Affiliation

Indiana University – Purdue University Fort Wayne


Soybean is the major source of both protein in animal diets and vegetable oil for human consumption. Currently, U.S. is the leading producer of soybean in the world. Indiana ranks fourth in the U.S accounting for approximately 10% of the nation’s production. Over the last decade, soybean production in the U.S. has been threatened by an exotic insect pest, the soybean aphid (Aphis glycines Matsumura). The insect pest not only causes damage through feeding but also transmits several plant viral diseases such as Soybean mosaic virus (SMV). Since, soybean aphids were only detected in the U.S. a decade ago, soybean plant defenses against aphids has not been well-characterized. Identification of plant genes that contribute to host resistance or susceptibility to insects and pathogens may be used to develop resistant cultivars by either over-expressing or silencing target genes. Hence, the objective of this study was to determine the timing and nature of plant defense responses against soybean aphid and SMV infection. Plant defense responses against insects and pathogens are carried out by plant hormones or phytohormones. For instance, insect feeding predominantly activates a defense pathway mediated by the phytohormone, Jasmonic acid (JA), whereas, pathogens such as viruses primarily activate defenses regulated by the phytohormone, Salicylic acid (SA).To determine plant defense responses against soybean aphid and SMV, we exposed cohorts of plants to three treatments: 1) uninfected-aphids, 2) SMV-infected aphids, and 3) healthy plants (control). Following the experiment, we analyzed JA and SA defense gene expression in leaf tissues from each of the treatments using Reverse-transcriptase-PCR. Preliminary results indicate that exposure to soybean aphids and SMV predominately activated the SA pathway in soybean plants. Results of this study will shed light on the ecological and molecular interactions between soybean plant, aphid and SMV, which may be applied to biotechnology-based pest management programs.


Biology | Life Sciences

Activation of soybean plant defense signaling pathways in response to soybean aphid (Aphis glycines Matsumura) and Soybean mosaic virus

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