Unravelling Actinidia molecular mechanisms against Pseudomonas syringae pv. actinidiae and P. syringae pv. actinidifoliorum - first steps
Kiwifruit bacterial canker (KBC), caused by Pseudomonas syringae pv. actinidiae (Psa), is currently the most destructive disease of kiwifruit worldwide. In contrast, the closely related pathovar P. syringae pv. actinidifoliorum (Psaf) only causes necrotic spots, not being associated with plant mortality. Moreover, there is some evidence for greater susceptibility of Actinidia deliciosa cultivars to KBC, compared with Actinidia arguta, but the reasons behind this observation are still largely unknown. In this work, micropropagated female plants of A. deliciosa Hayward and A. arguta Kens Red were inoculated with Psa or with Psaf (107 CFU mL-1). Disease development was monitored at 1, 2 and 5 days post-inoculation (dpi) through CFU determination and gene expression analysis of plant defence-related genes (APX, CAT, SOD, LOX1, SAM and TLP1). At 5 dpi, Psa and Psaf CFU were 17.4- and 2.8-fold higher, respectively, in Hayward compared with Kens Red. Expression of antioxidant enzyme-related genes was very distinct between the two species: SOD expression was drastically increased in Hayward (up to 1.1-fold), whereas, in Kens Red, CAT was the most upregulated gene (up to 0.7-fold). LOX1, involved in jasmonic acid biosynthesis, was upregulated in both species, but at different time-points: up to 1.2-fold in Hayward at 2 dpi and 0.9-fold in Kens Red at 1 dpi. These results demonstrate that Kens Red seems to be much more tolerant of Psa than Hayward and that the resistance mechanisms between the two species involve specific defence pathways being triggered at distinct moments after plant infection. While Acta Horticulturae publishes the proceedings of symposia or congresses, i.e. papers presented at those meetings, select articles such as the current one may be suggested by the ISHS Science Editor for consideration by one of the ISHS peer reviewed journals eJHS or Fruits. After having successfully passed the regular peer review procedures in place with the journal eJHS this paper has been accepted for publication and is available here: eJHS is in print - DOI for this paper in eJHS will be made available upon publication.
Nunes da Silva, M., Machado, J., Balestra, G.M., Mazzaglia, A., Vasconcelos, M.V. and Carvalho, S.M.P. (2018). Unravelling Actinidia molecular mechanisms against Pseudomonas syringae pv. actinidiae and P. syringae pv. actinidifoliorum - first steps. Acta Hortic. 1218, 307-314
antioxidant enzymes, bacterial canker, jasmonic acid, kiwifruit, tolerance