Recurrent outbreaks of root mat in cucumber and tomato are associated with a monomorphic, cucumopine, Ri-plasmid harboured by various Alphaproteobacteria

Abstract

Recurrent outbreaks of root mat have occurred in the UK and France in cucumber and tomato. Root mat is caused by bacterial strains harbouring a Ri-plasmid (pRi). Fifteen root mat-associated (RMA) cucumopine pRi were analysed by PCR-restriction fragment length polymorphism (RFLP) and Southern blotting. These pRi were harboured by Agrobacterium biovar 1 strains isolated during a 1970s outbreak of root mat in UK soil grown cucumber, and also by Agrobacterium biovar 1, Ochrobactrum, Rhizobium and Sinorhizobium isolated during outbreaks of root mat in cucumber and tomato grown hydroponically in the UK and France since 1993. PCR-RFLP analysis of the T-DNA and virD2 regions showed sequence homology between all cucumopine pRi, indicating that these pRi are monomorphic, and thus this pRi remained in the UK without inducing symptoms for some 15 years between outbreaks in the 1970s and 1990s. Cucumopine pRi were also shown to possess the virE2 substitute GALLS gene by Southern blotting. Two other pRi, harboured by Agrobacterium isolated from a recent root mat outbreak in one tomato crop, were also shown to possess the GALLS gene but were shown not to be cucumopine pRi by PCR-RFLP.

Agrobacterium rhizogenes: recent developments and promising applications

“…The natural host range of A. rhizogenes appears to be restricted to a limited number of plant species: apple, cucumber, tomato, or melon (Smith and Townsend 1907;Riker et al 1930;Davioud et al 1988;Isogai et al 1990;Weller et al 2000Weller et al , 2004Weller et al , 2006. However, under laboratory conditions, more than 450 different species of plants are found to be susceptible to infection by A. rhizogenes (Tepfer 1984;Porter 1991), including a diverse range of dicotyledonous and monocotyledonous plant families (De Cleene and De Ley 1981;) and some gymnosperms (Diouf et al 1995;Yibrah et al 1996).…”

First report of root mat (hairy root) of tomato (Lycopersicon esculentum) caused by Rhizobium radiobacter harboring cucumopine Ri plasmid in Japan.

“…Bar, 0.02 substitutions per nucleotide position. radiobacter に属する菌株である (Weller et al, 2000a(Weller et al, , 2000b(Weller et al, , 2004(Weller et al, , 2005(Weller et al, , 2006; 塩見ら，1987) ．また，この単系統群には R.…”

“…radiobacter 内に設けられている genomovar と同列のまとまりであるこ とが確認されている (Pulawska et al, 2012;Panday et al, 2011 (Weller et al, 2000a(Weller et al, , 2000b(Weller et al, , 2004(Weller et al, , 2005(Weller et al, , 2006 Davioud et al, 1988;Weller et al, 2000aWeller et al, , 2000bWeller et al, , 2006 …”

“…e) +, positive; −, negative PCR result. f) Primers designed by Weller et al (2006). g) Primers: cusF(5'-TTGTTCATAACACATGGCCTGCAGG-3')/cusR(5'-GGCGGGCCCTAACTGGTGGG-3'), newly designed by the authors based on cus gene sequence (AB039860).…”

“…i) Sequences were determined in this study and deposited in DDBJ. Sawada et al (1992), Sawada (1994), Weller et al (2006), Hodges et al (2004), and Isogai et al (1988). d) Sequences were determined in this study and deposited in DDBJ.…”