Hydrogen peroxide generated by over-expression of cytosolic superoxide dismutase in transgenic plums enhances bacterial

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ORIGINAL ARTICLE

Hydrogen peroxide generated by over-expression of cytosolic superoxide dismutase in transgenic plums enhances bacterial canker resistance and modulates plant defence responses Mohamed Faize1   · Lydia Faize2 · Nuria Alburquerque2 · Jean Stéphane Venisse3 · Lorenzo Burgos2 Received: 21 May 2020 / Revised: 4 July 2020 / Accepted: 8 July 2020 © Springer Nature B.V. 2020

Abstract H2O2 generated during the oxidative burst, plays important roles in plant defenses responses against pathogens. In this study we examined the role of H ­ 2O2 on bacterial canker resistance in transgenic plums over-expressing cytosolic superoxide dismutase. Three transgenic lines (C64, C66 and F12) with elevated levels of ­H2O2 accumulation showed enhanced resistance against bacterial canker disease caused by Pseudomonas syringae pv. syringae, when compared to the non-transformed control. Analysis of the expression of several genes involved in the plant–pathogen interaction showed that the expression of those involved in SA pathway (pr1 and npr1) and JA (lox3) were activated earlier and transiently in transgenic lines C66 and F12 when compared to the wild type. However, the expression of genes involved in anthocyanin synthesis (chi, chs, f3h, dfr, atcs, myb10) and ethylene (acs) was induced at very low levels whereas it was activated by the pathogen at exaggerated levels in the non-transformed line. These results suggest that resistance observed in transgenic lines over-producing H ­ 2O 2 is correlated with an early and transient induction of defense genes associated with the SA and JA pathways and inhibition of gene expression associated with ethylene and anthocyanin biosynthesis. Keywords  Anthocyanin · Bacterial canker · Cytosolic SOD · Hydrogen peroxide · Pseudomonas syringae pv. syringae

Introduction Bacterial canker caused by Pseudomonas syringae pv. syringae (Pss) and Pseudomonas syringae pv. morspronorum is among the most devastating diseases of plum (Prunus domestica) trees. It occurs worldwide in all major stone fruit producing areas and its incidence could be so high that complete orchards have to be removed [1, 2]. The bacteria Electronic supplementary material  The online version of this article (https​://doi.org/10.1007/s1103​3-020-05660​-8) contains supplementary material, which is available to authorized users. * Mohamed Faize [email protected] 1



Laboratory of Plant Biotechnology, Ecology and Ecosystem Valorisation, Faculty of Sciences, University Chouaib Doukkali, 24000 El Jadida, Morocco

2



Group of Fruit Tree Biotechnology, Department of Plant Breeding, CEBAS-CSIC, PO Box 164, 30100 Murcia, Spain

3

PIAF‑UMR547, University Blaise Pascal, 63177 Aubierre, France



are able to infect all aerial organs, such as leaves, blossoms and fruits. Necrotic cankers that are often associated with gummosis may occur when bacteria infect woody tissues via wounds or leaf scars. The trunks of the affected plum trees are girdled by bacterial canker resulting in sudden death of infected trees. The disease can b