Submitted to: Journal of Helminthology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 4, 2011
Publication Date: March 1, 2012
Citation: Masler, E.P. 2012. In vitro proteolysis of nematode FLPs by preparations from the free-living nematode Panagrellus redivivus and two plant-parasitic nematodes (Heterodera glycines and Meloidogyne incognita). Journal of Helminthology. 86(1):77-84. Interpretive Summary: Plant-parasitic nematodes attack all crops of agricultural importance, causing over $10 billion in losses annually to U.S. farmers. Because several chemical pesticides used to control nematodes have been withdrawn from use, growers possess a critical need for the discovery of environmentally and economically sound nematode control agents. One approach to discovering new ways to control nematodes is to identify ways to disrupt their normal biochemical processes by using chemicals that occur naturally inside the nematode. We have previously reported the discovery in plant-parasitic nematodes of small protein molecules called FLPs which are produced naturally by nematodes and are essential for their survival. In this paper we describe the discovery of the species-specific degradation of a key FLP in the root-knot nematode and the discovery of unique root-knot nematode FLP-degrading enzymes. These are highly significant discoveries for the design of precisely targeted control agents. Consequently, this information will be used by researchers in the agrochemical and agricultural biotechnology industries who are developing safe, selective methods for nematode control.
Technical Abstract: Proteolytic activities in extracts from three nematodes, the plant parasites Heterodera glycines and Meloidogyne incognita, and the free-living Panagrellus redivivus, were surveyed for substrate preferences using a battery of seven FRET-modified peptide substrates, all derived from members of the large FMRF-amide like peptide (FLP) family in nematodes. Overall protease activity in P. redivivus was 4-5-fold greater (P < 0.05) than in either of the parasites, a result that might reflect developmental differences. However, digestion of the M. incognita FLP KHEFVRFa (substrate Abz-KHEFVRF-Y(3-NO2)a) by M. incognita extract was 7-fold greater than with H. glycines extract and 2-fold greater than P. redivivus, suggesting species-specific preferences. Comparison of extract activities using two different substrates (Abz-KHEFVRF-Y(3-NO2)a and Abz-KPSFVRF-Y(3-NO2)a), which was digested equally by all three species, in combination with 12 different protease inhibitors revealed additional species differences. It is suggested that M. incognita differs significantly from P. redivivus and H. glycines in its complement of cysteine proteases, particularly cathepsin-L type protease.