Potato purple top wilt (PPT) is a devastating disease that occurs in various regions of North America and Mexico. At least three distinct phytoplasma strains belonging to three different phytoplasma groups (16SrI, 16SrII and 16SrVI) have been associated with this disease. A new disease with symptoms similar to PPT was recently observed in Texas and Nebraska, USA. Two distinct phytoplasma strain clusters were identified. One belongs to the 16SrI phytoplasma group, subgroup A, and the other is a novel phytoplasma that is most closely related to, and shares 96.6 % 16S rRNA gene sequence similarity with, a member of group 16SrXII. Phylogenetic analysis of 16S rRNA gene sequences of the novel PPT-associated phytoplasma strains, previously described ‘Candidatus Phytoplasma’ organisms and other distinct unnamed phytoplasmas indicated that the novel phytoplasma, termed American potato purple top wilt (APPTW) phytoplasma, represents a distinct lineage and shares a common ancestor with stolbur phytoplasma, ‘Candidatus Phytoplasma australiense’, ‘Candidatus Phytoplasma japonicum’, ‘Candidatus Phytoplasma fragariae’, bindweed yellows phytoplasma (IBS), ‘Candidatus Phytoplasma caricae’ and ‘Candidatus Phytoplasma graminis’. On the basis of unique 16S rRNA gene sequences and biological properties, it is proposed that the APPTW phytoplasma represents ‘Candidatus Phytoplasma americanum’, with APPTW12-NE as the reference strain.
ArochaY.,
LópezM.,
PiñolB.,
FernándezM.,
PicornellB.,
AlmeidaR.,
PalenzuelaI.,
WilsonM. R.,
JonesP.2005; ‘ Candidatus Phytoplasma graminis' and ‘ Candidatus Phytoplasma caricae’, two novel phytoplasmas associated with diseases of sugarcane, weeds and papaya in Cuba. Int J Syst Evol Microbiol 55:2451–2463[CrossRef]
GreenM. J.,
ThompsonD. A.,
MacKenzieD. J.1999; Easy and efficient DNA extraction from woody plants for the detection of phytoplasmas by polymerase chain reaction. Plant Dis 83:482–485[CrossRef]
IRPCM Phytoplasma/Spiroplasma Working Team - Phytoplasma Taxonomy Group; 2004; ‘ Candidatus Phytoplasma’, a taxon for the wall-less, non-helical prokaryotes that colonize plant phloem and insects. Int J Syst Evol Microbiol 54:1243–1255[CrossRef]
KhadhairA. H.,
HirukiC.,
HwangS. F.,
WangK.1997; Molecular identification and relatedness of potato witches'-broom phytoplasma isolates from four potato cultivars. Microbiol Res 152:281–286[CrossRef]
LeeI.-M.,
Gundersen-RindalD. E.,
DavisR. E.,
BartoszykI. M.1998; Revised classification scheme of phytoplasmas based on RFLP analyses of 16S rRNA and ribosomal protein gene sequences. Int J Syst Bacteriol 48:1153–1169[CrossRef]
LeeI.-M.,
BottnerK. D.,
MunyanezaJ. E.,
SecorG. A.,
GudmestadN. C.2004a; Clover proliferation group (16SrVI) subgroup A (16SrVI-A) phytoplasma is a probable causal agent of potato purple top disease in Washington and Oregon. Plant Dis 88: 429
LeeI.-M.,
MartiniM.,
MarconeC.,
ZhuS. F.2004b; Classification of phytoplasma strains in the elm yellows group (16SrV) and proposal of ‘ Candidatus Phytoplasma ulmi’ for the phytoplasma associated with elm yellows. Int J Syst Evol Microbiol 54:337–347[CrossRef]
Leyva-LópezN. E.,
Ochoa-SánchezJ. C.,
Leal-KlevezasD. S.,
Martinez-SorianoJ. P.2002; Multiple phytoplasmas associated with potato diseases in Mexico. Can J Microbiol 48:1062–1068[CrossRef]
McCoyR. E.,
CaudwellA.,
ChangC. J.15 other authors1989; Plant diseases associated with mycoplasma-like organisms. In The Mycoplasmas vol 5 pp 545–560 Edited by
WhitcombR. F.,
TullyJ. G.
New York: Academic Press;
SchneiderB.,
SeemüllerE.,
SmartC. D.,
KirkpatrickB. C.1995; Phylogenetic classification of plant pathogenic mycoplasma-like organisms or phytoplasmas. In Molecular and Diagnostic Procedures in Mycoplasmology vol 2 pp 369–380 Edited by
RazinS.,
TullyJ. G.
San Diego, CA: Academic Press;
SecorG. A.,
LeeI.-M.,
BottnerK. D.,
Rivera-VarasV.,
GudmestadN. C.2006; First report of a defect of processing potatoes in Texas and Nebraska associated with a new phytoplasma. Plant Dis 90:377