Oral Technical Session: Mechanism of Host and Non-Host Resistance

105-O

Host-derived RNA interference targeted to the root-knot nematode parasitism gene 16D10 in tobacco.
K. SCHWERI (1), G. Huang (2), B. Xue (1), M. G. Mitchum (3), T. J. Baum (4), R. S. Hussey (2), R. Lewis (1), E. L. Davis (1)
(1) North Carolina State University, Raleigh, NC, U.S.A.; (2) University of Georgia, Athens, GA, U.S.A.; (3) University of Missouri, Columbia, MO, U.S.A.; (4) Iowa State University, Ames, IA, U.S.A.

The four major species of root-knot nematode (RKN), Meloidogyne incognita, Meloidogyne arenaria, Meloidogyne javanica, and Meloidogyne hapla have many host plant species, including tobacco, and are a global menace in agriculture. RKNs are sedentary endoparasites that transform plant cells into complex feeding sites called giant-cells via effector proteins secreted by the nematode through the stylet. Huang et al demonstrated that one secreted effector called 16D10 interacts with a SCARECROW-like transcription factor and that M. incognita grown on transgenic Arabidopsis engineered to produce 16D10RNAi produced 69-93% less eggs than controls. In this study 2 cultivars of tobacco (TN90 and Hicks) were transformed with Huang’s 16D10RNAi constructs. Infection assays of the transformants with M. arenaria, for which there is no resistance in tobacco, showed reductions in egg counts for 3 out of the 4 lines of TN90 and 2 out of the 4 lines of Hicks tested. One of these lines, TN90 I-8, showed a 56% reduction in egg counts and was tested further with all 4 major species. TN90 I-8 was found to reduce the egg production of 3 of the 4 major species; M. incognita was reduced by 42%, M. javanica by 56%, and M. arenaria by 49%. To correlate the resistance with the siRNA levels, siRNA sequencing of infection assay root tissue is underway. New RNAi constructs created to improve the siRNA production are currently being transformed into both Arabidopsis and tobacco.