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Genetic diversity analyses in Ralstonia syzygii species

Irda Safni: University of Sumatera Utara

<div>Recently, the taxonomy of the <em>Ralstonia solanacearum</em> species complex has been revised into three genomic species, including <em>Ralstonia solanacearum</em>, <em>Ralstonia pseudosolanacearum</em> and <em>Ralstonia syzgii</em> on the basis of a polyphasic taxonomy approach with an emphasis on DNA-DNA hybridization and whole genome sequences. Based on some differences of phenotypic and chemotaxonomic analyses, the species of <em>R. syzgii</em> is further subdivided into three subspecies, including <em>Ralstonia syzygii </em>subsp.<em> syzygii</em>, <em>R. syzygii</em> subsp. <em>indonesiensis</em>, and <em>R. syzygii</em> subsp. <em>celebesensis</em>. This study utilized genomic fingerprinting Rep-PCR approach (BOX-and ERIC PCR) and Multilocus Sequence Typing (MLST) to analyze the genetic diversity of 27 strains of <em>R.syzygii </em>and 4 representative strains of<em> R. syzygii </em>subsp<em>. celebesensis </em>respectively. Strains of <em>R. syzygii</em> were found highly diverse based on Rep-PCR results. All <em>R. syzygii</em> subsp. <em>celebesensis</em> strains tested with the exception of one strain (UQRS 633), which had distinct band profiles were confirmed as a homogenous species within the <em>R. solanacearum</em> species complex by the consistent similarity of their band patterns in rep-PCR experiments. In contrast, using four housekeeping genes (<em>adk</em>, <em>gapA</em>, <em>gdhA</em> and <em>ppsA</em>) and one megaplasmid gene (<em>hrpB</em>) in MLST analysis, four selected strains of <em>R. syzygii</em> subsp. <em>celebesensis</em> showed homogeneity.</div>