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Title: 4r2Host status of different potato (Solanum tuberosum) varieties and hatching in root diffusate of Globodera ellingtonae

Author
item Zasada, Inga
item Peetz, Amy
item Wade, N - Oregon State University
item Navarre, Duroy - Roy
item Ingham, R - Oregon State University

Submitted to: Journal of Nematology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/10/2013
Publication Date: 9/1/2013
Citation: Zasada, I.A., Peetz, A.B., Wade, N., Navarre, D.A., Ingham, R.E. 2013. Host status of different potato (Solanum tuberosum) varieties and hatching in root diffusate of Globodera ellingtonae. Journal of Nematology. 45:195-201.

Interpretive Summary: The potato cyst nematodes (Globodera rostochiensis and Globodera pallida) are of regulatory concern to the United States because of their potential impact on potato production and on the ability of U.S. growers to export potatoes to other countries. Because of these concerns, surveys have been conducted to determine the occurrence and distribution of these nematodes in the United States. During one such survey in Oregon, an atypical Globodera was found that could not be identified as G. rostochiensis or G. pallida based upon morphological and molecular data. Because of the inability to place this nematode into a species, the host range of this nematode and its ability to parasitize potato are unknown. This research was conducted to identify root diffusates (chemical compounds released by roots) that stimulate/inhibit egg hatch in this atypical Globodera; exposure of potato cyst nematodes to potato diffusates is known to be important for the nematodes to complete their life cycles. Twenty-one root diffusates were tested against the Oregon nematode in laboratory experiments. This nematode hatched readily only in the presence of diffusates from potato and tomato. Root diffusates from arugula, sudangrass, and common vetch inhibited egg hatch compared to the other tested root diffusates. These results are significant because the first evidence regarding the host range of this atypical Globodera is presented. This research will be used by scientists and regulatory agencies involved in the management and possible regulation of this nematode in the United States.

Technical Abstract: An atypical Globodera population was detected in Oregon in 2008. As the first step towards understanding the biology of this nematode, cysts were exposed to a range of root diffusates. The Globodera population hatched readily in the presence of diffusates from potato (Solanum tuberosum; PRD) and tomato (Solanum lycopersicum; TRD). Egg hatch occurred in an average of 87 and 90% of exposed cysts, with an average of 144 and 164 juveniles emerging per cyst, from PRD- and TRD-treated cysts, respectively. This nematode hatched rapidly in the presence of PRD and TRD, with at least 66% of total hatch occurring by day 3 of exposure. There was no dose-response of egg hatch to concentrations of PRD or TRD ranging from 1:5 to 1:100 diffusate to water. When the Globodera population was exposed to 21 diverse root diffusates representing five plant families, hatch occurred in 0 to 70% of exposed cysts, with an average of 0 to 27 juveniles emerging per cyst. When root diffusate-exposed cysts were subsequently transferred to PRD to test viability, root diffusates from arugula (Eruca sativa), sudangrass (Sorghum bicolor subsp. drummondii), and common vetch (Vicia sativa) continued to inhibit egg hatch compared to the other root diffusates and water in which hatch occurred readily (60 to 182 juveniles emerging per cyst). Egg hatch was also evaluated in cysts exposed to sodium metavanadate, sodium orthovanadate, and sodium thiocyanate, commercially-available stimulants of hatching in G. rostochiensis and G. pallida. After a 24-day exposure, all hatching chemicals at 0.01 and 1.0 mg/ml stimulated some egg hatch, and this level of hatch was different from the water control. All hatching chemicals at 1.0 and 10.0 mg/ml inhibited egg hatch from cysts during direct exposure and after cysts were transferred to PRD to test viability. Although the atypical population of Globodera from Oregon hatched readily in PRD and TRD, the pathogenicity of this nematode on these plants needs to be specifically determined.