**Acknowledgements**

ture of the soybean genome (Doyle et al. 1999; Schmutz et al. 2010), RNAi studies of soy‐ bean genes may be met with complications and may require methodologies that can

Another procedure to modulate gene expression in soybean to engineer resistance involves the engineering of soybean genes as overexpression constructs (Matsye et al. 2012). To do the studies, genes that are highly expressed during a resistant reaction, identified in acces‐ sions of little agronomic value can be expressed to high levels in a soybean genotype that is normally susceptible, but of great economic value. The hypothesis is that if the gene is im‐ portant in the defense response, the overexpression of that gene in a genotype that is nor‐ mally susceptible would result in suppressed nematode infection. Such a result was obtained by Matsye et al. (2012) with the overexpression of a naturally occurring truncated allele of an α-SNAP gene. When the α-SNAP gene that was identified in the *G. max*[Peking/PI 548402] accession was overexpressed in the normally susceptible *G. max*[Williams 82/PI 518671] geno‐ type, nematode infection was suppressed (Figure 4). The experiments demonstrated the effi‐ cacy of the approach, opening up the possibility for large scale reverse genetic screens since the plasmid vectors used to engineer the genes into soybean through the hairy root proce‐ dure (Tepfer et al. 1984) was designed with an enhanced green fluorescent reporter (eGFP) (Collins et al. 2005; Klink et al. 2008) was designed using the Gateway® technology for both

**Figure 4.** An overexpressed gene affects nematode development. A, a nematode, stained with acid fuchsin for visuali‐ zation, developing in an experimental control plant. The boundary of the nematode feeding site is encircled in blue. B, a nematode failing to develop in a plant overexpressing a gene identified in the gene expression studies of the syncy‐

The soybean-SCN pathosystem has been under study for over 60 years. Through a massive amount of basic studies involving agricultural production practices, genomics and genetic engineering, solutions to the chronic and global SCN problem are emerging. The difficulty of studying the system has been met with many improvements in technology that are allow‐ ing for basic features of the pathosystem to be exploited so that agricultural practices and economic returns are improved. The basic knowledge gained in this system can now be ap‐

knock down entire gene families (Alvarez et al. 2006).

158 Soybean - Pest Resistance

RNAi and overexpression studies (Klink et al. 2009a; Matsye et al. 2012).

tium. The boundary of the nematode feeding site is encircled in blue.

**2. Conclusion**

VPK is thankful for start-up support provided by Mississippi State University and the De‐ partment of Biological Sciences; funds in the forms of a competitive Research Improvement Grant; support from the Mississippi Soybean Promotion Board. GWL is thankful to the de‐ partment of Department of Biochemistry, Molecular Biology, Entomology and Plant Pathol‐ ogy, Mississippi State University, KSL is thankful to the Department of Entomology and Plant Pathology, Auburn University.
