Genetic diversity of Ralstonia solanacearum strains from China

Abstract

A survey of bacterial wilt in China collected 286 strains of Ralstonia solanacearum from 17 plant species in 13 Chinese provinces to investigate genetic diversity using the biovar (bv.) and phylotype classification schemes. A phylotype-specific multiplex-PCR showed that 198 isolates belonged to phylotype I (bv. 3, 4 and 5) and 68 to phylotype II (bv. 2 and bv. 1). A phylogenetic analysis examined the partial sequence of the egl and hrpB gene of all strains and the genetic diversity of 95 representatives was reported, demonstrating that Chinese strains are partitioned into phylotype I (Asia) and II (Americas). Phylotype I strains (historically typed bv. 3, 4 and 5), had considerable phylogenetic diversity, including 10 different sequevars: seven previously described sequevars 12 to 18 and three new sequevars: 34, 44 and 48. Chinese strains Z1, Z2, Z3, Z7, Pe74 and Tm82 were not genetically distinguishable from the edible ginger reference strain ACH92 (r4-bv. 4) for sequevar 16. This is believed to be the first report of this ginger group in China. All Chinese bv. 2 strains falling into the genetically and phenotypically diverse phylotype II were placed into phylotype IIB sequevar 1 (historically the Andean race3-bv. 2 potato brown rot agent). In both the egl and hrpB sequence-based trees, strains isolated from mulberry were present in two distinct branches found in sequevars 12 and 48 (reference strains R292 and M2, respectively).

The sequevar distribution of Ralstonia solanacearum in tobacco-growing zones of China is structured by elevation

“…The phylotype identity of each strain was determined by multiplex PCR as described by Fegan and Prior (2005). Pmx-PCR was carried out in 25 μl of reaction mixture containing 1× Taq MasterMix (PCR buffer, 1.5 mM MgCl 2 , 250 μM of each dNTP, 50 mM KCl, 10 mM Tris-HCl and 1.25 U of Taq DNA polymerase) (Tiangen Biotech), 6 pmoles of primers Nmult:21:1F, Nmult:21:2F, Nmult:22:InF, 18 pmoles of the primer Nmult:23:AF and 4 pmoles of primers 759 and 760 (all primers are listed in Supplemental Table 2) (Opina et al 1997;Xu et al 2009). This P m x -P C R a m p l i f i e s a 2 8 1 -b p Bu n i v e r s a lR .…”

“…solanacearum specific reference band in addition to the following phylotype-specific PCR products: a 144-bp band from phylotype I strains; a 372-bp band from phylotype II strains; a 91-bp amplicon from phylotype III strains; and a 213-bp band from phylotype IV strains. The PCR program was carried out in a thermocycler as previously described (Xu et al 2009). Then, 5 μl of PCR product was subjected to electrophoresis on 1.5 % agarose gel, stained with ethidium bromide and visualized on a UV-transilluminator.…”

“…1, 2, 3, 4 and 5) have been identified (He et al 1983;Lu 1998). Xu et al (2009) analyzed the genetic diversity of Chinese R. solanacearum strains, suggesting that Chinese R. solanacearum strains belonged to phylotype I and II and that phylotype I was predominant and included 10 different sequevars. According to Xue et al (2011), the majority of tested Chinese strains belonged to Asian phylotype I, which had a high diversity from the BOX-PCR fingerprints generated from the genomic DNA.…”

Genetic mapping of a major dominant gene for resistance to Ralstonia solanacearum in eggplant

“…Moreover, genes or QTLs associated with BW-resistance were reported against non-characterized R. solanacearum strains, whereas strain-and phylotype-specific QTLs were reported for tomato. Among solanaceous-infecting R. solanacearum populations, phylotype I strains are the most prevalent clade found in most Asian eggplant production areas (Horita and Tsuchiya 2001;Ivey et al 2007;Jaunet and Wang 1999;Xu et al 2009) as well as in Africa (Mahbou Somo Toukam et al 2009), America (Ji et al 2007;Norman et al 2009;Sanchez Perez et al 2008), and the Caribbean ). In a previous study, we showed that phylotype I strains display different virulence patterns, called pathoprofiles, on a core collection of tomato, pepper and eggplant representative of the genetic diversity for resistance in these species (Lebeau et al 2011).…”

Occurrence and diversity of Ralstonia solanacearum populations in Brazil

“…Classification into phylotypes is done by PCR Multiplex with the Nmult series primers (based on ITS region) and the classification into sequevar by partially sequencing gene egl (encoding the enzyme endoglucanase). Presently, four phylotypes and 51 sequevares of R. solanacearum are described (XU et al, 2009;FONSECA et al, 2014). Analysis of genetic diversity can be conducted based on repetitive sequences (rep-PCR), comprised by the elements BOX, ERIC, and REP, by randomly amplified DNA (RAPD), by amplification of restriction fragments (AFLP), repeated simple sequences (SSR) and by polymorphisms based on restriction fragment size (RFLP) (JAUNET;WANG, 1999;VANDEWALLE;LUISETTI, 1999;COENYE;VANDAMME, 2003;YU et al, 2003;KUMAR;SARMA;ANANDARAJ, 2004;SILVEIRA et al, 2005;LOPES, 2007;IVEY et al, 2007).…”