Submitted to: Journal of Helminthology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 31, 2005
Publication Date: January 2, 2006
Citation: Masler, E.P. 2005. Changes in farp-like peptide levels during development of eggs from the plant-parasitic cyst nematode, heterodera glycines. Journal of Helminthology 80(1):53-58. Interpretive Summary: Plant-parasitic nematodes are microscopic worms that attack all crops of agricultural importance, causing over $10 billion in losses annually to U.S. farmers. One problem facing growers is that environmental concerns will eliminate in a few years the most extensively applied chemical used to kill nematodes in the United States. These concerns make the discovery of environmentally and economically sound replacements critical. One approach is to discover natural targets in nematodes that can be used to develop novel control strategies. An important family of molecules called FaRP controls muscular activity in nematodes. This paper demonstrates that FaRP levels increase during a specific time in development of the soybean cyst nematode, the most important pathogen of soybeans in the United States, and that specific FaRPs may be associated with the infective juvenile stage. This discovery is important because it demonstrates that specific FaRPs may be involved in hatching, and will accelerate discovery of novel molecules for controlling nematodes. This information will be used by researchers who are developing safe, selective and cutting-edge methods for nematode control.
Technical Abstract: The plant-parasitic cyst nematode Heterodera glycines requires a host plant to complete its life cycle, which involves hatching of infective juveniles that parasitize through root entry. A laboratory population of H. glycines grown on soybean (Glycine max) undergoes a sharp increase in maturity between 5 and 6 weeks in culture, as measured by the proportion of eggs containing well developed pre-hatch juveniles (late development eggs) versus eggs without visible juveniles (early development eggs). The median percent of eggs classified as late development, representing all samples taken from 4 through 7 weeks in culture, was 61. For all samples taken through 5 weeks, 80% scored below the median. In samples taken after 5 weeks, 15% scored below the median. This shift in population maturity was accompanied by a significant increase (P < .01) in the number of hatched juveniles present in each sample. There was also a significant increase (P < .02) in the amount of FMRFamide-related peptide (FaRP) detected by a specific ELISA. Total FaRP levels increased from 0.18 plus/minus 0.07 fMol FMRFamide equivalent/ng protein in early development eggs to 0.40 plus/minus 0.17 in late development eggs. The level remained high in hatched juveniles. HPLC/ELISA detected as many as 9 potential FaRPs in H. glycines, 2 of which were specifically increased (P < .005) in hatched juveniles. The association of FaRPs with maturing eggs and the possible involvement of these neuropeptides with juvenile hatching and motility are discussed.