Genetic diversity amongst Ralstonia solanacearum isolates of potato in Europe¹

Abstract

Lane, Egham TW20 9TY (United Kingdom) Recent outbreaks of bacterial wilt disease in Europe have alerted the potato industry to the destructive nature and potential threat of this disease. At present, little is known about the diversity of the pathogen and yet this information is vital if accurate disease forecasting and control are to be achieved. In an initial attempt to address this issue, the genetic diversity amongst 43 isolates of Ralstonia solanacearum race 3 biovar 11 of European origin has been determined. Two genomic fingerprinting methods were used to study the population; macro-restriction analysis of genomic DNA resolved by pulsed-field gel electrophoresis and rep-PCR. In addition a smaller subset of isolates has been studied using amplified restriction fragment polymorphism. The relative success and resolution of each method has been assessed and will be discussed. Results relating the findings of this study to previous research on genetic diversity within race 3 biovar I1 populations of worldwide origin are presented (Smith et al., 1995). In conclusion, it is hoped to demonstrate that the results of this study could serve as a valuable reference point from which future research initiatives specifically on the epidemiology and control of bacterial wilt disease in Europe could be derived. Diversite genetique des isolats de Ralstonia solanacearum sur pornrne de terre en EuropeLes ricents foyers de flitrissement bactkrien en Europe ont alert6 l'industrie de la pomme de terre sur la nature destructrice et la menace potentielle de cette maladie. La diversit6 du pathogkne est peu connue mais cette information est vitale pour mettre en place des prkvisions et une lutte adaptbes. Dans une Ctude prkliminaire, la diversit6 gCnCtique de 43 isolats de la race 3, biovar 11 de R. solanacearum d'origine europeenne a Ct C dCterminCe. Deux mCthodes d'empreintes ghomiques ont Ct C utilisees pour Ctudier la population: analyse de 1' ADN gCnomique par macro-restriction suivie d'une Clectrophorkse sur gel champ pulsC et rep-PCR. De plus, un sous-groupe d'isolats plus restreint a Ct C CtudiC par polymorphisme de longueur des fragments de restriction de I'ADN gCnomique. La rkussite de chaque mCthode et sa pricision ont Ctk CvaluCes et sont discutCes. Des risultats mettant en relation cette Ctude avec des Ctudes antkrieures sur la diversit6 gCnCtique dans des populations de la race 3 biovar I1 de diverses origines (Smith, J.J. et al. 1995) sont prCsentCs. En conclusion, on espkre dbmontrer que les risultats de cette Ctude peuvent servir de point de dipart a de futurs projets de recherche sur I'CpidCmiologie et la lutte contre le flhtrissement bacdrien en Europe. renernulrecKoe pa3noo6pa3ue cpedu u3on~rnoe Ralstonia solanacearum u3 Kaprnocpem 6 Eepone HenaBHue oqarn 6 a~~e p u a n b~o r o Y B J T A~W I B b p o n e npenynpenunu KapTo4enbHoe npow3~oncr-BO o AecrpymnBHoM xapamepe u noTeHqnanbHoi4 yrpose moro 3a60ne~mm. B Hamonmee Bpem oqem MUIO U~B~C T H O o pa3~006pa3nu naToresa, HO TeM He MeHee ma nH OPMWWI m e w xu3-HeHH...

ERECTA, an LRR receptor‐like kinase protein controlling development pleiotropically affects resistance to bacterial wilt

“…Although all the European isolates tested were virulent to some extent in A. thaliana, they were generally less aggressive than the GMI1000 tropical strain (Table 2; Deslandes et al, 1998). We chose to study strain 14.25 further, as it was strongly aggressive in tomato, from which it was isolated, eggplant (Trigalet et al, 1998) and A. thaliana (11 susceptible accessions out of 27 tested, unpublished data), and induced clear differential responses in Col-0 and Ler accessions, for which a recombinant inbred mapping population was available (Lister and Dean, 1993). A non-pathogenic derivative of strain 14.25, 14.25hrpB À , was constructed and used as a control (see Experimental procedures).…”

“…This soil‐borne vascular pathogen, found mostly in tropical and subtropical areas, affects hundreds of different species, including many crops of agronomical importance (Hayward, 1991) as well as the model plant A. thaliana (Deslandes et al ., 1998; Yang and Ho, 1998). This pathogen was recently detected in Europe, where it caused brown rot disease in potato (Smith et al ., 1998) and sporadically infected other solanaceous plants (Elphinstone et al ., 1998; Grousset et al ., 1998). The emergence of these novel R. solanacearum strains adapted to temperate climates and potentially to new wild‐plant species ( Solanum dulcamara and S. nigrum ) raises intriguing questions about pathogen evolution, host range definition and plant resistance strategies.…”

Phylogeny and Population Structure of Brown Rot- and Moko Disease-Causing Strains of Ralstonia solanacearum Phylotype II

“…Also, since the ancestral Ralstonia prototype is assumed to be a plant pathogen (15,19), study of the extent of the diversity of this genus, along with the evolutionary pathways involved, is of major importance for a broad understanding of pathogen evolution. We hypothesized that there was much more biodiversity to discover from genomic analysis of phylotype II strains of R. solanacearum, namely, cold-tolerant potato brown rot strains (IIB-1), previously recognized to be clonal after various neutral marker approaches (5,27,34), tropical Moko disease-causing strains (IIB-4), and emerging strains (IIB-4NPB). We thus focus on phylogenetically closely related phylotype II groups of strains with well-characterized and diverging ecological and phenotypical traits, in an attempt to reconstruct their epidemiological pathways along with the acquisition of their lifestyles.…”