2008 Annual Report
1a.Objectives (from AD-416)
1) Discover nematode proteins and peptides that regulate development, growth and survival, and that provide new targets for controlling nematodes; and.
2)Disrupt the function of steroid- or lipid-based regulatory systems unique to plant-parasitic nematodes and critical for their life processes.
1b.Approach (from AD-416)
1) Identify proteases and peptides that control hatching or molting in soybean cyst nematode and root-knot nematode and evaluate specific molecular inhibitors; and identify regulatory proteins, including membrane receptors, involved in the nematode response to its environment and plant host; and.
2)Isolate and identify lipids and steroids with likely regulatory roles in plant-parasitic nematodes, and elucidate the biochemical pathways involved in the biosynthesis and metabolism of these compounds; and develop rational strategies for nematode management based upon the utilization of knowledge about the endogenous bioregulatory lipids or steroids in phytoparasitic nematodes.
One problem with controlling soybean cyst nematodes is that many nematode eggs remain dormant in the field. We have found that egg populations consist of at least three distinct classes: those from which infective juveniles hatch immediately, hatch gradually over time, or do not hatch even after extended periods. Furthermore, we have developed experimental treatments to change the level of eggs in each class. In addition, we have developed methods to explore these three egg classes for proteins important for the regulation of hatching and thereby providing important targets for control strategies. This research directly addresses Component 2 (Biology, Ecology, Epidemiology, and Spread of Plant Pathogens and Their Relationships with Hosts and Vectors) of National Program 303 (Plant Diseases); specifically, Problem Statement 2A (Pathogen Biology, Virulence Determinants, and Genetics of the Pathogen.)
Small Molecules That Control Nematode Behavior and Hatching are Differentially Metabolized.
One problem with developing safe strategies for nematode control is that the number of nematode molecular targets vulnerable to being exploited by control strategies is very small. Therefore, ARS scientists at Beltsville, Maryland have examined several such targets and have determined that members of a group of naturally occurring small molecules called neuropeptides, which control behaviors in the soybean cyst nematode and root-knot nematodes, are metabolized differently depending upon the type of specific neuropeptide and the species of nematode. Because these peptide molecules regulate the critical processes of movement, hatching and feeding, this discovery is important because it is the first indication that nematodes will not survive when the supply or action of these peptide molecules is altered. Therefore, this information is expected to impact scientists who are developing highly specific inhibitors and new strategies for controlling plant-parasitic nematodes for the eventual benefit of growers. This research directly addresses Component 2 (Biology, Ecology, Epidemiology, and Spread of Plant Pathogens and Their Relationships with Hosts and Vectors) of National Program 303 (Plant Diseases); specifically, Problem Statement 2A (Pathogen Biology, Virulence Determinants, and Genetics of the Pathogen.)
5.Significant Activities that Support Special Target Populations
|Number of Non-Peer Reviewed Presentations and Proceedings||5|
|Number of Other Technology Transfer||2|
Masler, E.P. 2008. Invertebrate Neuropeptides. In: Meyers, R.A., editor. Neurobiology. From Molecular Basis to Disease. Vol. 1. Weinheim: Wiley-VCH Verlag. p. 257-271.
Masler, E.P. 2007. Responses of Heterodera glycines and Meloidogyne incognita to exogenously applied neuromodulators. Journal of Helminthology. 81:421-427.
Masler, E.P. 2007. Characterization of aminopeptidase in the free-living nematode Panagrellus redivivus: subcellular distribution and possible role in neuropeptide metabolism. Journal of Nematology. 39(2):153-160.
Pridannikov, M.V., Petelina, G.G., Palchuk, M.V., Masler, E.P., Dzhavakhiya, V.G. 2007. Influence of components of Globodera rostochiensis cysts on the in vitro hatch of second-stage juveniles. Nematology. 9(6):837-844.
Masler, E.P., Donald, P.A., Sardanelli, S.S. 2008. Stability of Heterodera glycines (Tylenchida: Heteroderidae) juvenile hatching from eggs obtained from different sources of soybean, Glycine max. Nematology. 10(2):271-278.
Masler, E.P., Zasada, I.A., Sardanelli, S. 2008. Hatching behavior in Heterodera glycines in response to low temperature. Comparative Parasitology. 75(1):76-81.