Why Sequence the Soybean Cyst Nematode?

Soybean is a major oil, feed, and export crop, with $17 billion annually in unprocessed crop value in the U.S. alone. Soy biodiesel is a leading contender for a renewable, alternative vehicle fuel with a high energy density. Soybean has the environmental and energy advantage of not requiring the use of nitrogen fertilizer. Soybean is also an essential rotation crop with maize, the dominant source of bioethanol (the other chief contender for a vehicle biofuel). Maximizing soybean yield is thus critical to the energy independence of the US.

Micrograph of H. glycines (soybean cyst nematode) second stage juvenile.
Photo courtesy Kris Lambert.

Heterodera glycines, the soybean cyst nematode (SCN), is the most devastating pathogen of soybean in the USA, causing hundreds of millions of dollars in damage annually to this valuable biological-energy crop. In order to devise strategies to control SCN, basic information about the nematode’s genome is required. A genome sequence for SCN should provide the necessary DNA sequence infrastructure to obtain a detailed understanding of SCN parasitism and virulence. Specifically, this genome sequencing project will be the backbone for a functional genomics platform for SCN that will allow the assessment of gene structure, gene regulation, genetic diversity, and the nature of SCN metabolism. In particular, this project will allow for the discovery of novel genes and metabolic pathways that are unique to plant parasitic nematodes and not present in other nematode species.

Plant parasitic nematodes establish a complex feeding relationship with their host plant. To do this, the nematode has apparently acquired significant numbers of genes via horizontal gene transfer from microorganisms or plants. Such unique genes often alter the host plant's metabolism or development and thus are good target genes for engineering nematode resistance in soybean. In addition, an SCN genome sequence would allow for the efficient map-based cloning of SCN virulence genes (genes that allow SCN to grow on resistant soybean plants). Identification of SCN virulence genes is important since such knowledge could be used to monitor and prevent the buildup of virulent biotypes that would otherwise decrease the useful life of SCN-resistant soybean germplasm, the only current method of SCN control.

Principal Investigators: Kris Lambert and Matthew E. Hudson (Univ. of Illinois at Urbana-Champaign)