Through exploitation of RNA interference technology we have successfully developed transgenic soybean events which are simultaneously resistant to three major soybean virus diseases, soybean mosaic virus (SMV), alfalfa mosaic virus (AMV) and bean pod mottle virus (BPMV). Over the course of the past year, we challenged field plots planted with a subset of the transgenic events, along with appropriate control plots, with inoculum mixtures of the three viruses. The data gathered from this study revealed that the resistance phenotype is stable across multiple generations.

A second set of field trials were conducted to gain insight on protection of yield relying upon natural infections. The information gleaned from these latter trials is suggestive of a yield protection benefit, albeit additional studies are required to confirm these preliminary observations.

The second component of this program targets RNA interference technology as a means to combat aphid predation. Here we have assembled vector constructs carrying genetic elements designed to synthesize either small interfering RNAs (siRNAs) or micro RNAs (miRNAs) in soybean, which when presented to the insect during feeding theoretically should impede expression of critical genes for aphid survival. Transgenic soybean events have been established that harbor the genetic elements designed for the accumulation of both siRNAs and miRNAs. Preliminary data gathered from aphid challenged transgenic soybeans producing siRNAs were promising. Deeper genetic and phenotypic characterizations of these transgenic soybean events are necessary to support the initial observations and monitor durability and stability of a resistance phenotype through these RNA interference strategies.