|NADERALI, NEDA - Universiti Putra Malaysia|
|NEJAT, NAGHMEH - Universiti Putra Malaysia|
|VADAMALAI, GANESAN - Universiti Putra Malaysia|
|HARRISON, NIGEL - University Of Florida|
|KONG, LIHLING - Universiti Putra Malaysia|
|KADIR, JUGAH - Universiti Putra Malaysia|
|TAN, YEE-HOW - Universiti Putra Malaysia|
Submitted to: International Journal of Systematic and Evolutionary Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/29/2017
Publication Date: 10/1/2017
Citation: Naderali, N., Nejat, N., Vadamalai, G., Davis, R.E., Wei, W., Harrison, N., Kong, L., Kadir, J., Tan, Y., Zhao, Y. 2017. ‘Candidatus Phytoplasma wodyetiae’, a new taxon associated with yellow decline disease of foxtail palm (Wodyetia bifurcata) in Malaysia. International Journal of Systematic and Evolutionary Microbiology. 67:3765-3772.
Interpretive Summary: Palm trees have high economic and aesthetic values. In the vast tropical and subtropical areas around the globe, palms provide unparalleled elegance and architectural stature in landscapes. The fruits, seeds, leaves, and the stem of palm trees are rich sources of food, biofuels, cosmetic products, and timber. However, palm trees are vulnerable to destructive diseases caused by infection by a group of small bacteria known as phytoplasmas. Palm trees infected by phytoplasmas often develop symptoms including premature fruit drop, discoloration of leaves and floral clusters, and necrosis of emerging shoot tips. In many cases, mortality of affected palms occurs within a few months. Prior to the present study, seven mutually distinct phytoplasma species had been linked to various palm diseases around the world. During 2012, foxtail palm trees growing in Bangi, Malaysia developed symptoms indicative of phytoplasma infections. In collaboration with researchers in Malaysia and University of Florida, ARS scientists found that a previously unknown phytoplasma was involved in the foxtail palm disease. Results from DNA fingerprinting and gene ancestry analyses confirmed that the phytoplasma possesses distinct genetic features and represents a new species. The research team named this species ‘Candidatus Phytoplasma wodyetii’. The team also identified molecular markers that can be used to detect this and other phytoplasmas belonging to this species. This report will be of interest to research scientists, diagnostics laboratories, and extension personnel who are concerned with genetic diversity of bacterial pathogens and plant disease management. This information is also important to regulatory agencies for implementing new quarantine measures to prevent spread of the new pathogen.
Technical Abstract: Landscape grown foxtail palm (Wodyetia bifurcata A.K. Irvine) trees displaying symptoms of severe foliar chlorosis, stunting, general decline and mortality reminiscent of coconut yellow decline disease were observed in Bangi, Malaysia during 2012. DNA samples from foliage tissues of 15 symptomatic palms were analyzed employing a nested polymerase chain reaction (PCR) assay primed by phytoplasma universal rrn primer pairs, P1/P7 followed by R16f2n/R2. The assay yielded singular amplicons of 1.25 kb on samples from 11 affected palms. Results from cloning and sequence analysis of the PCR-amplified 16S rDNA segments revealed that, in three affected palms, three mutually distinct phytoplasmas comprised of ‘Candidatus Phytoplasma asteris’- and ‘Ca. Phytoplasma cynodontis’-related strains, as well as a novel phytoplasma, were present as triple infections. The 16S rDNA sequence derived from the novel phytoplasma shared less than 96% nucleotide sequence identity with that of each previously described ‘Ca. Phytoplasma’ species, justifying its recognition as reference strain of a new taxon, ‘Candidatus Phytoplasma wodyetii’. Virtual restriction fragment length polymorphism (RFLP) profiles of the F2n/R2 portion (1251 bp) of the 16S rRNA gene and pattern similarity coefficient value (0.74) supported the delineation of ‘Ca. Phytoplasma wodyetii’ as the sole representative subgroup A member of a new phytoplasma ribosomal group 16SrXXXVI.