Changes in taxonomy of plant pathogenic bacteria

Issue Date

10-2000

Abstract

Considerable changes in the classification and nomenclature of plant pathogenic bacteria have occurred arising from the development of sophisticated techniques applied in delineating genera, species and pathovars. Combined analyses of phenotypic, chemotaxonomic and genetic data have led to a more stable taxonomy. Genetic analyses like percent G+C content, DNA-DNA hybridization, DNA-rRNA hybridization and ribosomal RNA sequence analysis have provided data for establishing relationships based on the ancestry of the organism. Phylogenetic relationships have provided stability in the classification and nomenclature of bacteria.

From the original five major genera, namely Agrobacterium, Corynebacterium, Erwinia, Pseudomonas and Xanthomonas, there are now 29 genera of phytopathogenic bacteria. Species under the genus Corynebacterium have been transferred to five genera (Arthrobacter, Clavibacter, Curtobacterium, Rathayibacter and Rhodococcus). The genus Erwinia has been subdivided into Erwinia, Enterobacter, Brenneria, Pectobacterium and Pantoea.

Before 1980, the genus Xanthomonas had more than 140 species. After 1980, the number was reduced to five species, with the majority lumped under the species Xanthomonas campestris and downgraded as pathovars of that species. As more and more studies were conducted on this species, some pathovars were restored to the There are now 22 valid species of species level and new species were created. Xanthomonas. Three genera have branched out from the phytopathogenic pseudomonads, namely Acidovorax, Burkholderia and Ralstonia. Those included as pathovars of Pseudomonas syringae have been moved to Pseudomonas savastanoi.

Minor changes have been observed in the genus Agrobacterium, like the addition of a new species, A. vitis. Other species considered as marine bacteria later have been transferred to new genera. The other genera of phytopathogenic bacteria that have one to three species are Streptomyces, Nocardia, Streptomyces, Bacillus, Clostridium, Spiroplasma, Rhizobacter, Rhizomonas (Sphingomonas), Acetobacter, Gluconobacter, Serratia, Xylella and Xylophilus.

Source or Periodical Title

Philippine Agricultural Scientist, The (Formerly: The Philippine Agriculturist)

ISSN

0031-7454

Volume

83

Issue

4

Page

365-378

Document Type

Article

College

College of Agriculture and Food Science (CAFS)

Frequency

quarterly

Physical Description

tables, references

Language

English

Subject

taxonomy, phytobacteriology, bacterial diseases of plants

En – AGROVOC descriptors

PLANT PATHOLOGY; PATHOGENIC BACTERIA; TAXONOMY; CLASSIFICATION SYSTEMS; NOMENCLATURE; BACTERIOLOGY; GENUS

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