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Tomato Susceptibility to Root-Knot Nematodes Requires an Intact Jasmonic Acid Signaling Pathway

September 2008 , Volume 21 , Number  9
Pages  1,205 - 1,214

Kishor K. Bhattarai,1 Qi-Guang Xie,1 Sophie Mantelin,1 Usha Bishnoi,1 Thomas Girke,2 Duroy A. Navarre,3 and Isgouhi Kaloshian1

1Department of Nematology and 2Department of Botany and Plant Sciences, Center for Plant Cell Biology, University of California, Riverside 92521, U.S.A.; 3United States Department of Agriculture--Agricultural Research Service, Washington State University, Prosser 99350, U.S.A.

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Accepted 29 April 2008.

Responses of resistant (Mi-1/Mi-1) and susceptible (mi-1/ mi-1) tomato (Solanum lycopersicum) to root-knot nematodes (RKNs; Meloidogyne spp.) infection were monitored using cDNA microarrays, and the roles of salicylic acid (SA) and jasmonic acid (JA) defense signaling were evaluated in these interactions. Array analysis was used to compare transcript profiles in incompatible and compatible interactions of tomato roots 24 h after RKN infestation. The jai1 and def1 tomato mutant, altered in JA signaling, and tomato transgenic line NahG, altered in SA signaling, in the presence or absence of the RKN resistance gene Mi-1, were evaluated. The array analysis identified 1,497 and 750 genes differentially regulated in the incompatible and compatible interactions, respectively. Of the differentially regulated genes, 37% were specific to the incompatible interactions. NahG affected neither Mi-1 resistance nor basal defenses to RKNs. However, jai1 reduced tomato susceptibility to RKNs while not affecting Mi-1 resistance. In contrast, the def1 mutant did not affect RKN susceptibility. These results indicate that JA-dependent signaling does not play a role in Mi-1-mediated defense; however, an intact JA signaling pathway is required for tomato susceptibility to RKNs. In addition, low levels of SA might be sufficient for basal and Mi-1 resistance to RKNs.

Additional keywords:Coi-1, plant defense, proteinase inhibitors.

© 2008 The American Phytopathological Society