Author
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Masler, Edward |
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Submitted to: Journal of Helminthology
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 3/22/2013 Publication Date: 3/31/2013 Citation: Masler, E.P. 2013. Effects of catechin polyphenols and preparations from the plant-parasitic nematode Heterodera glycines on protease activity and behavior in three nematode species. Journal of Helminthology. DOI: 10.1017/S0022149X13000254. 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 Because several chemical pesticides that control nematodes have been withdrawn from use, growers possess a critical need for the discovery of environmentally and economically sound nematode control agents.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 inhibit their reproduction and survival by using naturally derived compounds. We discovered that a series of plant-derived molecules called polyphenols, and heat resistant materials prepared from the soybean cyst nematode, can be used as inhibitors of enzymes essential for nematode reproduction and survival. Further, the cyst nematode inhibitor is most potent against enzymes in both the soybean cyst nematode and the root-knot nematode, two of the most important nematode pathogens of crops worldwide. These results are significant because they show that natural agents can potentially be used to protect host plants when they are most susceptible to nematode attack. 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: Protease activities in preparations from the plant-parasitic nematodes Heterodera glycines and Meloidogyne incognita and the free-living nematode Panagrellus redivivus were inhibited by exposure to a series of 8 catechin polyphenol analogs, (+)-catechin, (-)- epicatechin (EC), (-)-gallocatechin (GC), (-)-epigallocatechin (EGC), (-)-catechin gallate (CG), (-)- gallocatechin gallate (GCG), (-)-epicatechin gallate (ECG), and (-)-epigallocatechin gallate (EGCG) (1mM each), and by a preparation from H. glycines cysts. General protease activity detected with the FRET-peptide substrate QXL520-KSAYMRF-K(5-FAM)a and proteasome chymotrypsin-like (CTL) activity detected with succinyl-LLVY-AMC were each inhibited significantly more (P < 0.05) by the gallated form of the polyphenol than by the corresponding non-gallated form. Species differences in response to inhibition across all analogs were revealed with the CTL substrate, but CG was a consistently potent inhibitor across all 3 species and with each substrate. A heat stable component (CE) from H. glycines cysts inhibited M. incognita CTL activity by 92.07 ± 0.68%, significantly less (P < 0.05) in H. glycines (52.86 ± 2.77%), and by only 17.24 ± 0.55% (P < 0.05) in P. redivivus preparations. CTL activity was, however, inhibited more than 60% in all preparations by MG-132. Hatching of M. incognita infective juveniles exposed to 1mM CG, ECG, GCG, or EGCG was reduced 83.88 ± 4.26%, 69.98 ± 9.14%, 94.93 ± 1.71%, and 87.93 ± 2.89%, respectively, while hatching of H. glycines was reduced less than 25% by each analog. CE had no effect on nematode hatch, but did cause a 60% reduction in mobility of H. glycines infective juveniles exposed overnight to CE in vitro, which was more (P < 0.05) than the reduction of M. incognita infective juveniles mobility (20%). |
