1a.Objectives (from AD-416):
The objective of this cooperative research project is to identify genes important in resistance of soybean to the soybean cyst nematode and to develop soybean plants with broad resistance to soybean cyst nematode.
1b.Approach (from AD-416):
Soybean genes expressed during nematode invasion will be identified that may be used to broaden resistance to SCN through soybean transformation or targeted mutations. Virtually nothing is known about the resistance or susceptible response of soybean to SCN. These genes can be over- or under-expressed in soybean roots and challenged with SCN. Genes will be identified that are up regulated during the resistance response using microarrays or genes localized to known SCN resistance quantitative trait loci (QTLs). These up-regulated genes will be over-expressed using strong constitutive promoters or under-expressed using RNA interference. Transgenic roots with altered expression profiles for candidate resistance-associated genes will be challenged with different races of SCN and the resistance profile examined.
Four DNA sequences that control expression of genes (promoters) were cloned from a portion of the soybean genome known to confer resistance to the cyst nematode. The promoters were cloned into a plant transformation vector to determine the strength and timing of the promoter using a visual marker. The promoter constructs were transformed into Arabidopsis plants and the expression of the promoters was documented by the production of GUS, a reporter enzyme, and concomitantly a blue color. Roots were examined in the presence and absence of nematodes to determine if the promoter controlled expression at the nematode feeding site. One promoter may express more at the feeding site and is undergoing further testing. These promoters may be useful for controlling the expression of gene constructs proven to confer resistance to nematodes.