Susceptibility to the sugar beet cyst nematode is modulated by ethylene signal transduction in Arabidopsis thaliana

• Published in: Molecular plant-microbe interactions Vol. 14; no. 10; pp. 1206 - 1212
• Main Authors: WUBBEN, Martin J. E. II, HONG SU, RODERMEL, Steven R, BAUM, Thomas J
• Format: Journal Article
• Language: English
• Published: St Paul, MN APS Press 01.10.2001; The American Phytopathological Society
• Subjects: Agronomy. Soil science and plant productions; Amino Acids, Cyclic - pharmacology; Animals; Arabidopsis - genetics; Arabidopsis - metabolism; Arabidopsis - parasitology; Beta vulgaris - parasitology; Biological and medical sciences; Ethylenes - antagonists & inhibitors; Ethylenes - metabolism; Female; Fundamental and applied biological sciences. Psychology; Genetics and breeding of economic plants; Glycine - analogs & derivatives; Glycine - pharmacology; Lyases - antagonists & inhibitors; Lyases - metabolism; Mutation; Nematoda - growth & development; Nematoda - pathogenicity; Pest animals; Pest resistance; Phytopathology. Animal pests. Plant and forest protection; Plant Proteins - antagonists & inhibitors; Plant Proteins - metabolism; Plant Roots - growth & development; Plant Roots - parasitology; Protozoa. Invertebrates; Receptors, Cell Surface - antagonists & inhibitors; Receptors, Cell Surface - metabolism; Records, symptoms, damages, economic importance, population surveys; Signal Transduction - drug effects; Silver Nitrate - pharmacology; Varietal selection. Specialized plant breeding, plant breeding aims; Heteroderidae; Exudate; Ethylene; Arabidopsis thaliana; Morphogenesis; Signal transduction; Regulation(control); Pest; Cruciferae; Dicotyledones; Angiospermae; Plant growth substance; Intraspecific comparison; Nematoda; Attraction; Root; Sensitivity resistance; Animal plant relation; Helmintha; Pest resistance; Nemathelminthia; Spermatophyta; Phytohormone; Invertebrata; Experimental plant; Heterodera schachtii
• ISSN: 0894-0282; 1943-7706
• DOI: 10.1094/mpmi.2001.14.10.1206

Previously, we identified Arabidopsis thaliana mutant rhd1-4 as hypersusceptible to the sugar beet cyst nematode Heterodera schachtii. We assessed rhd1-4 as well as two other rhd1 alleles and found that each exhibited, in addition to H. schachtii hypersusceptibility, decreased root length, increased root hair length and density, and deformation of the root epidermal cells compared with wild-type A. thaliana ecotype Columbia (Col-0). Treatment of rhd1-4 and Col-0 with the ethylene inhibitors 2-aminoethoxyvinylglycine and silver nitrate and the ethylene precursor 1-aminocyclopropane-1-carboxylic acid suggests that the rhd1-4 hypersusceptibility and root morphology phenotypes are the result of an increased ethylene response. Assessment of known ethylene mutants further support the finding that ethylene plays a role in mediating A. thaliana susceptibility to H. schachtii because mutants that overproduce ethylene (eto1-1, eto2, and eto3) are hypersusceptible to H. schachtii and mutants that are ethylene-insensitive (etr1-1, ein2-1, ein3-1, eir1-1, and axr2) are less susceptible to H. schachtii. Because the ethylene mutants tested show altered susceptibility and altered root hair density and length, a discrimination between the effects of altered ethylene signal transduction and root hair density on susceptibility was accomplished by analyzing the ttg and gl2 mutants, which produce ectopic root hairs that result in greatly increased root hair densities while maintaining normal ethylene signal transduction. The observed normal susceptibilities to H. schachtii of ttg and g12 indicate that increased root hair density, per se, does not cause hypersusceptibility. Furthermore, the results of nematode attraction assays suggest that the hypersusceptibility of rhd1-4 and the ethylene-overproducing mutant eto3 may be the result of increased attraction of H. schachtii-infective juveniles to root exudates of these plants. Our findings indicate that rhd1 is altered in its ethylene response and that ethylene signal transduction positively influences plant susceptibility to cyst nematodes.