title: Xylella taiwanensis sp. nov., causing pear leaf scorch disease.
abstract: A Gram-stain-negative, nutritionally fastidious bacterium (PLS229T) causing pear leaf scorch was identified in Taiwan and previously grouped into Xylella fastidiosa. Yet, significant variations between PLS229T and Xylellafastidiosa were noted. In this study, PLS229T was evaluated phenotypically and genotypically against representative strains of Xylellafastidiosa, including strains of the currently known subspecies of Xylellafastidiosa, Xylella fastidiosa subsp. multiplex and 'Xylella fastidiosasubsp.pauca'. Because of the difficulty of in vitro culture characterization, emphases were made to utilize the available whole-genome sequence information. The average nucleotide identity (ANI) values, an alternative for DNA-DNA hybridization relatedness, between PLS229T and Xylellafastidiosa were 83.4-83.9 %, significantly lower than the bacterial species threshold of 95 %. In contrast, sequence similarity of 16S rRNA genes was greater than 98 %, higher than the 97 % threshold to justify if two bacterial strains belong to different species. The uniqueness of PLS229T was also evident by observing only about 87 % similarity in the sequence of the 16S-23S internal transcribed spacer (ITS) between PLS229T and strains of Xylellafastidiosa, discovering significant single nucleotide polymorphisms at 18 randomly selected housekeeping gene loci, observing a distinct fatty acid profile for PLS229T compared with Xylellafastidiosa, and PLS229T having different observable phenotypes, such as different susceptibility to antibiotics. A phylogenetic tree derived from 16S rRNA gene sequences showed a distinct PLS229T phyletic lineage positioning it between Xylellafastidiosa and members of the genus Xanthomonas. On the basis of these data, a novel species, Xylella taiwanensis sp. nov. is proposed. The type strain is PLS229T (=BCRC 80915T=JCM 31187T).
authors.affiliation: Division of Pesticide Application, Taiwan Agricultural Chemicals and Toxic Substances Research Institute, Wufeng, Taichung 41358, Taiwan, ROC.
authors.forename: C-C
authors.initials: CC
authors.lastname: Su
authors.affiliation: Department of Plant Pathology, National Chung Hsing University, Taichung 40227, Taiwan, ROC.
authors.forename: W-L
authors.initials: WL
authors.lastname: Deng
authors.affiliation: Department of Plant Pathology, National Chung Hsing University, Taichung 40227, Taiwan, ROC.
authors.forename: F-J
authors.initials: FJ
authors.lastname: Jan
authors.affiliation: Department of Plant Pathology, National Chung Hsing University, Taichung 40227, Taiwan, ROC.|Department of Plant Pathology, University of Georgia, Griffin, Georgia 30223, USA.
authors.forename: C-J
authors.initials: CJ
authors.lastname: Chang
authors.affiliation: School of Information, University of South Florida, Tampa, FL 33620, USA.
authors.forename: H
authors.initials: H
authors.lastname: Huang
authors.affiliation: Applied Zoology Division, Taiwan Agricultural Research Institute, Council of Agriculture, 189 Chung-Cheng Road, Wufeng, 413 Taichung, Taiwan, ROC.
authors.forename: H-T
authors.initials: HT
authors.lastname: Shih
authors.affiliation: USDA-ARS San Joaquin Valley Agricultural Sciences Center, Parlier, California 93648, USA.
authors.forename: J
authors.initials: J
authors.lastname: Chen
mesh_terms: D015373:Bacterial Typing Techniques; D001482:Base Composition; D004269:DNA, Bacterial / Q000235:genetics; D005227:Fatty Acids / Q000737:chemistry; D009693:Nucleic Acid Hybridization; D010802:Phylogeny; D010935:Plant Diseases / Q000382:microbiology*; D018515:Plant Leaves / Q000382:microbiology; D031989:Pyrus / Q000382:microbiology*; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D013624:Taiwan; D044167:Xylella / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification
chemical_list: D004269:DNA, Bacterial; D005227:Fatty Acids; D012336:RNA, Ribosomal, 16S