Submitted to: Society of Nematology Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: January 23, 2006
Publication Date: October 1, 2006
Citation: Skantar, A.M., Chitwood, D.J. 2006. Molecular characterization of 17-hydroxysteroid dehydrogenase genes from heterodera glycines. Society of Nematology Abstracts. vol. 8(3), 321-333.
Nematodes are nutritionally dependent upon their hosts for sterols, making steroid metabolism an attractive area of investigation for the development of new methods for managing plant-parasitic nematodes. We recently identified two genes in Heterodera glycines (Hg-hsd-1 and Hg-hsd-2) with similarity to 17 beta-hydroxysteroid dehydrogenases involved in the synthesis of steroid hormones in mammals. Sequence comparisons revealed similar gene sequences in other plant parasites, including Meloidogyne spp., Pratylenchus penetrans, and Globodera pallida. Quantitative real-time PCR of Hg-hsd-1 and Hg-hsd-2 showed the highest expression in developing females, with relatively low levels in second-stage juveniles, eggs, or males. Decreases in expression of both genes in aging females corresponded to increased cuticle pigmentation of the cyst. Transcription was localized to the cyst contents and absent from developing embryos, suggesting that Hg-hsd-1 and Hg-hsd-2 are most likely involved in gonad development or oogenesis. These 17 beta-hydroxysteroid dehydrogenases genes may play a role in the conversion of ingested sterols into steroid hormones in nematodes. Additionally, experiments by one of us (D.J.C.) using the free-living nematode Caenorhabditis elegans have demonstrated the inhibitory effects of azacoprostane and other inhibitors on sterol metabolism and revealed the impact of such perturbations on nematode development and responses to UV and temperature stress. Together, these studies provide new insights into the role of sterols and how they are processed in nematodes.