‘Candidatus Phytoplasma japonicum’, a new phytoplasma taxon associated with Japanese Hydrangea phyllody

Abstract

A phytoplasma was discovered in diseased specimens of f ield-grown hortensia (Hydrangea spp.) exhibiting typical phyllody symptoms. PCR amplification of DNA using phytoplasma specific primers detected phytoplasma DNA in all of the diseased plants examined. No phytoplasma DNA was found in healthy hortensia seedlings. RFLP patterns of amplified 165 rDNA differed from the patterns previously described for other phytoplasmas including six isolates of foreign hortensia phytoplasmas. Based on the RFLP, the Japanese Hydrangea phyllody (JHP) phytoplasma was classified as a representative of a new subgroup in the phytoplasma 165 rRNA group I (aster yellows, onion yellows, all of the previously reported hortensia phytoplasmas, and related phytoplasmas). A phylogenetic analysis of 16s rRNA gene sequences from this and other group I phytoplasmas identified the JHP phytoplasma as a member of a distinct sub-group (sub-group Id) in the phytoplasma clade of the class Mollicutes. The phylogenetic tree constructed from 165 rRNA gene sequences was consistent with the hypothesis that the JHP phytoplasma and its closest known relatives, the Australian grapevine yellows (AUSGY), Phormium yellow leaf (PYL), Stolbur of Capsicum annuum (STOL) and Vergilbungskrankheit of grapevine (VK) share a common ancestor. The unique properties of the DNA from the JHP phytoplasma clearly establish that it represents a new taxon, Candidatus Phytoplasma japonicum '.

'Candidatus Phytoplasma castaneae', a novel phytoplasma taxon associated with chestnut witches' broom disease.

“…A pair of oligonucleotides was designed for specific amplification of CnWB phytoplasma DNA according to the 16S rDNA sequence. PCR conditions were as described by Sawayanagi et al (1999) except that the annealing temperature was 54 mC and 30 cycles were run.…”

“…Sequence analysis of 16S rDNA has also played an important role in the description of novel phytoplasma species (Zreik et al, 1995 ;Davis et al, 1997 ;White et al, 1998 ;Griffiths et al, 1999 ;Sawayanagi et al, 1999 ;Montano et al, 2001). This study used similar approaches to determine the phylogenetic relationships between the CnWB phytoplasma and other phytoplasmas.…”

‘Candidatus Phytoplasma asteris’, a novel phytoplasma taxon associated with aster yellows and related diseases

“…Gundersen et al (1994) proposed that the phytoplasma clade should be recognized as a novel genus within the class Mollicutes and that each subclade (or 16Sr group) represents at least a species. Thus far, eight 'Candidatus Phytoplasma' species have been proposed (Zreik et al, 1995;Davis et al, 1997;White et al, 1998;Griffiths et al, 1999;Sawayanagi et al, 1999;Montano et al, 2001;Jung et al, 2002;Verdin et al, 2003).…”

Exploring the phytoplasmas, plant pathogenic bacteria

“…In 2004, phytoplasmas were proposed to be within a novel genus 'Candidatus Phytoplasma' (IRPCM 2004). Approximately 40 phytoplasmal species have been reported worldwide (Hogenhout et al 2008;Jung et al 2002Jung et al , 2003bSawayanagi et al 1999). In Japan, approximately 70 strains of phytoplasmas (PSJ NIAS 2012) have been reclassified into nine species (Fig.…”

“…In the 1960s, rice yellow dwarf disease occurred in 10-50 % of rice growing areas of Japan and caused serious economic losses in many prefectures (Komori 1966;Sameshima 1967). In other cases, sweet potato witches' broom disease threatened the food supply in the Ryukyu Islands in the 1950s and 1960s (Nakamori and Maezato 1968;Shinkai 1964), and hydrangea phyllody disease remains a destructive disease in hydrangea cultivation (Kanehira et al 1996;Sawayanagi et al 1999;Takinami et al 2013). …”