Corrigendum: Phytoplasmas—The “Crouching Tiger” Threat of Australian Plant Pathology
- 1State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Fujian Agriculture and Forestry University, Fuzhou, China
- 2Institute of Applied Ecology, Fujian Agriculture & Forestry University, Fuzhou, China
- 3Graham Centre for Agricultural Innovation (Charles Sturt University & NSW Department of Primary Industries), Orange, NSW, Australia
- 4NSW Department of Primary Industries, Wagga Wagga Agricultural Institute, Wagga Wagga, NSW, Australia
by Liu, J., Gopurenko, D., Fletcher, M. J., Johnson, A. C., & Gurr, G. M. (2017). Front. Plant Sci. 8:599. doi: 10.3389/fpls.2017.00599
In the original article, information for phytoplasmas in Table 1 did not fully reflect recent changes in taxonomy, or showed changes only as footnotes. Corrections have been made in the sections below and in Table 1.
Table 1. Taxonomic and biological information on phytoplasmas in Australia (empty cells denote the absence of available information).
Phytoplasmas are insect-vectored bacteria that cause disease in a wide range of plant species. The increasing availability of molecular DNA analyses, expertise, and additional methods in recent years has led to a proliferation of discoveries of phytoplasma-plant host associations and in the numbers of taxonomic groupings for phytoplasmas. The widespread use of common names based on the diseases with which they are associated, as well as separate phenetic and taxonomic systems for classifying phytoplasmas based on variation at the 16S rRNA-encoding gene, complicates interpretation of the literature. We explore this issue and related trends through a focus on Australian pathosystems, providing the first comprehensive compilation of information for this continent, covering the phytoplasmas, host plants, vectors, and diseases. Of the 33 16Sr groups reported internationally, only groups II, XI, XII, XXIII, XXV, and XXXIII have been recorded in Australia and this highlights the need for ongoing biosecurity measures to prevent the introduction of additional pathogen groups. Many of the phytoplasmas reported in Australia have not been sufficiently well-studied to assign them to 16Sr groups so it is likely that unrecognized groups and sub-groups are present. Wide host plant ranges are apparent among well studied phytoplasmas, with multiple crop and non-crop species infected by some. Disease management is further complicated by the fact that putative vectors have been identified for few phytoplasmas, especially in Australia. Despite rapid progress in recent years using molecular approaches, phytoplasmas remain the least well-studied group of plant pathogens, making them a “crouching tiger” disease threat.
Issue 2: Complex taxonomic nomenclature, paragraphs 2 and 3
Second, as molecular methods became available, workers were able to group and phenetically classify phytoplasmas using restricted fragment length polymorphism (RFLP) analysis of a PCR amplified portion of the 16S rRNA gene with a defined set of restriction enzymes (Lee et al., 1998). The RFLP profiles generated for different phytoplasmas are generally consistent with sequence-based phylogenetic analyses of the 16S rRNA gene, particularly in the co-identification and grouping of related strains. The 33 16Sr groups currently defined each have a similarity of less than 85% compared with any representative phytoplasma from within an established 16Sr group (Zhao and Davis, 2016). Table 1 summarizes available information on the 16Sr groups reported in Australian studies. Of the 33 16Sr groups reported internationally, only groups II, XI, XII, XXIII, XXV, and XXXIII have been recorded in Australia and this highlights the need for ongoing biosecurity measures to prevent the introduction of additional pathogen groups.
Third, phytoplasmas are classified in the provisional genus “Candidatus Phytoplasma” (IRPCM, 2004). To date, there are 42 formally described species and ten potentially novel phytoplasma species (Davis et al., 2015). This number exceeds the current number of 16s rRNA groups because some of these groups contain several “Candidatus Phytoplasma” species. At least 100 subgroups are known (Dickinson and Hodgetts, 2013). According to Phytoplasma/Spiroplasma Working Team-Phytoplasma Taxonomy Group, a novel “Ca. Phytoplasma” species description should refer to a single, unique 16S rRNA gene sequence (>1,200 bp), and a strain can be recognized as a novel “Ca. Phytoplasma” species if its 16S rRNA gene sequence has <97.5% similarity to that of any previously described “Ca. Phytoplasma” species (Duduk and Bertaccini, 2011). Additional biological characters such as antibody specificity, host range and vector transmission specificity as well as genetic markers can also be used in an integrative taxonomy approach for species differentiation. Of the 42 recognized “Ca. Phytoplasma” species, only Ca. Phytoplasma aurantifolia, Ca. Phytoplasma australasiae and Ca. Phytoplasma australiense are reported in Australia (Table 1) but uncertainty exists because many papers appear without Ca. Phytoplasma names which are used consistently only in the case of the GenBank database.
The authors apologize for this error and state that this does not change the scientific conclusions of the article in any way. The original article has been updated.
Conflict of Interest Statement
The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
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Keywords: “Candidatus Phytoplasma”, 16S rRNA, biosecurity, taxonomy, biodiversity, vector, seed transmission, host range
Citation: Liu J, Gopurenko D, Fletcher MJ, Johnson AC and Gurr GM (2018) Corrigendum: Phytoplasmas—The “Crouching Tiger” Threat of Australian Plant Pathology. Front. Plant Sci. 9:1298. doi: 10.3389/fpls.2018.01298
Received: 21 June 2018; Accepted: 17 August 2018;
Published: 26 October 2018.
Edited and reviewed by: Brigitte Mauch-Mani, University of Neuchâtel, Switzerland
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*Correspondence: Geoff M. Gurr, firstname.lastname@example.org