title: Salicylic and jasmonic acid pathways are necessary for defence against Dickeya solani as revealed by a novel method for Blackleg disease screening of in vitro grown potato.
abstract: Potato is major crop ensuring food security in Europe, and blackleg disease is increasingly causing losses in yield and during storage. Recently, one blackleg pathogen, Dickeya solani has been shown to be spreading in Northern Europe that causes aggressive disease development. Currently, identification of tolerant commercial potato varieties has been unsuccessful; this is confounded by the complicated etiology of the disease and a strong environmental influence on disease development. There is currently a lack of efficient testing systems. Here, we describe a system for quantification of blackleg symptoms on shoots of sterile in vitro potato plants, which saves time and space compared to greenhouse and existing field assays. We found no evidence for differences in infection between the described in vitro-based screening method and existing greenhouse assays. This system facilitates efficient screening of blackleg disease response of potato plants independent of other microorganisms and variable environmental conditions. We therefore used the in vitro screening method to increase understanding of plant mechanisms involved in blackleg disease development by analysing disease response of hormone- related (salicylic and jasmonic acid) transgenic potato plants. We show that both jasmonic (JA) and salicylic (SA) acid pathways regulate tolerance to blackleg disease in potato, a result unlike previous findings in Arabidopsis defence response to necrotrophic bacteria. We confirm this by showing induction of a SA marker, pathogenesis-related protein 1 (StPR1), and a JA marker, lipoxygenase (StLOX), in Dickeya solani infected in vitro potato plants. We also observed that tubers of transgenic potato plants were more susceptible to soft rot compared to wild type, suggesting a role for SA and JA pathways in general tolerance to Dickeya.
authors.affiliation: Department of Plant Protection Biology, Swedish University of Agricultural Sciences, Alnarp, Sweden.
authors.forename: D D
authors.initials: DD
authors.lastname: Burra
authors.affiliation: Department of Plant Protection Biology, Swedish University of Agricultural Sciences, Alnarp, Sweden.
authors.forename: P
authors.initials: P
authors.lastname: Mühlenbock
authors.affiliation: Department of Plant Protection Biology, Swedish University of Agricultural Sciences, Alnarp, Sweden.
authors.forename: E
authors.initials: E
authors.lastname: Andreasson
mesh_terms: D003517:Cyclopentanes / Q000378:metabolism*; D004198:Disease Susceptibility; D004755:Enterobacteriaceae / Q000502:physiology*; D005819:Genetic Markers / Q000235:genetics; D008084:Lipoxygenase / Q000235:genetics / Q000378:metabolism; D054883:Oxylipins / Q000378:metabolism*; D010935:Plant Diseases / Q000276:immunology* / Q000382:microbiology; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D018520:Plant Shoots / Q000235:genetics / Q000276:immunology / Q000382:microbiology; D035281:Plant Tubers / Q000235:genetics / Q000378:metabolism / Q000382:microbiology; D030821:Plants, Genetically Modified; D020156:Salicylic Acid / Q000378:metabolism*; D011198:Solanum tuberosum / Q000235:genetics / Q000276:immunology* / Q000382:microbiology
chemical_list: D003517:Cyclopentanes; D005819:Genetic Markers; D054883:Oxylipins; D010940:Plant Proteins; C053376:pathogenesis-related proteins, plant; C011006:jasmonic acid; D008084:Lipoxygenase; D020156:Salicylic Acid
keywords: Blackleg disease; Desiree; Dickeya solani; NahG; Pectobacterium atrosepticum; SW93-1015; Sarpo Soft rot; StLOX; StPR1; coi1; in vitro potato; mira