scholarly journals An Epidemic of Almond Witches'-broom in Lebanon: Classification and Phylogenetic Relationships of the Associated Phytoplasma

Plant Disease ◽  
2002 ◽  
Vol 86 (5) ◽  
pp. 477-484 ◽  
Author(s):  
Yusuf Abou-Jawdah ◽  
Armig Karakashian ◽  
Hana Sobh ◽  
Marta Martini ◽  
Ing-Ming Lee
Keyword(s):  
Rflp Analysis ◽  
Pigeon Pea ◽  
Universal Primers ◽  
Rrna Gene ◽  
Nested Polymerase Chain Reaction ◽  
Main Trunk ◽  
Stunted Growth ◽  
Rdna Sequences ◽  
Pcr Products ◽  
Almond Trees

An epidemic of almond witches'-broom has devastated almond production in Lebanon. Thousands of almond trees have died over the past 10 years due to the rapid spread of the disease. The symptoms, which include early flowering, stunted growth, leaf rosetting, dieback, off-season growth, proliferation of slender shoots, and witches'-brooms arising mainly from the main trunk and roots, resemble those caused by phytoplasmal infections. For the detection of the putative causal agent, nested polymerase chain reaction (PCR) was performed using universal primers (P1/P7, R16mF2/R16mR1, and R16F2n/R16R2) commonly used for the specific diagnosis of plant pathogenic phytoplasmas. Phytoplasmas were readily detected from infected trees with witches'-broom symptoms collected from three major almond growing regions in Lebanon. Restriction fragment length polymorphism (RFLP) analysis of PCR products amplified by the primer pair R16F2n/R16R2 revealed that the phytoplasma associated with infected almonds is similar to, but distinct from, members of the pigeon pea witches'-broom phytoplasma group (16SrIX). A new subgroup, 16SrIX-B, was designated. Sequencing of the amplified products of the phytoplasma 16S rRNA gene indicated that almond witches'-broom (AlmWB) phytoplasma is most closely related to members of the pigeon pea witches'-broom phytoplasma group (with sequence homology ranging from 98.4 to 99.0%). Phylogenetic analysis of 16S rDNA sequences from AlmWB phytoplasma and from representative phytoplasmas from GenBank showed that the AlmWB phytoplasma represents a distinct lineage within the pigeon pea witches'-broom subclade. The same phytoplasma appears also to infect peach and nectarine seedlings.

scholarly journals ‘Candidatus Phytoplasma brasiliense’ (16SrXV-A Subgroup) Associated with Cauliflower Displaying Stunt Symptoms in Brazil

Plant Disease ◽  
2013 ◽  
Vol 97 (3) ◽  
pp. 419-419 ◽  
Author(s):  
M. C. Canale ◽  
I. P. Bedendo
Keyword(s):  
Nested Pcr ◽  
Sequence Similarity ◽  
Rflp Analysis ◽  
The United States ◽  
Rrna Gene ◽  
New Host ◽  
Rdna Sequences ◽  
Pcr Products ◽  
Virtual Rflp ◽  
In The Beginning

Cauliflower stunt, caused by a phytoplasma of the group 16SrIII-J, was reported in the beginning of 2012 and has occurred with high incidences of infected plants (up to 90%) in crops located in the state of São Paulo in the southeast region of Brazil (3). Diseased plants exhibit general stunting, malformation of inflorescence, reddening leaves, and vessel necrosis (3). Further investigations with plants displaying identical symptoms collected in Nova Bassano, state of Rio Grande do Sul, Brazilian south region, have revealed the presence of a phytoplasma distinct from 16SrIII-J subgroup. Four symptomatic plus four asymptomatic samples were assayed from a field, and the presence of phytoplasma was evidenced by nested PCR assays performed with primers P1/Tint followed by R16F2n/16R2 in three affected plants, which amplified genomic fragments of 1.2 kb from the 16S rRNA gene. No amplification occurred in non-affected samples. Nested PCR products analyzed by conventional RFLP (2) using the enzymes AluI, RsaI, KpnI, HpaII, MseI, HhaI, MboI, and BstUI pointed to the presence of a phytoplasma belonging to group 16SrXV-A in all three phytoplasma-positive samples. Virtual RFLP analysis based on restriction patterns, derived from in silico digestion with 17 endonucleases (4), confirmed the previous results obtained from those samples by conventional RFLP. The 16S rDNA sequences of this phytoplasma identified in cauliflower (GenBank Accession No. JN818845) shared 99% sequence similarity with the reference phytoplasma for subgroup 16SrXV-A (Hibiscus witches'-broom phytoplasma, AF147708), designated ‘Candidatus Phytoplasma brasiliense.’ Analysis of putative restriction sites showed excellent identity between the phytoplasma studied here and the reference phytoplasma. In addition, the arrangement of branches of a phylogenetic tree constructed with phytoplasmas representing diverse 16Sr groups and subgroups supported that the phytoplasma found in cauliflower is closed related to the representative of the subgroup 16SrXV-A. Association of distinct phytoplasmas with the same kind of disease is not rare and the present pathosystem constitutes a new example. Members of this subgroup have been described almost exclusively in Brazil and previously reported in Sida sp., periwinkle, and hibiscus (1). In some European countries, as well as in the United States and Canada, phytoplasmas belonging to group 16SrI has been associated with this type of disease, which has been reported for various species of the genus Brassica, as published in previous works (3). However, a representative of the group 16SrVI was described in infected plants in Iran (3). Although the 16SrIII-J phytoplasma is currently the most important agent of cauliflower stunt in Brazil, and members of 16SrI are prevalent in other countries, this study revealed that a 16Sr XV-A phytoplasma may be also associated with this important disease of brassicas. Besides, the findings here reported expand the natural host range, including cauliflower as new host for phytoplasmas affiliated with 16SrXV-A. References: (1) B. Eckstein et al. Plant Dis. 95:363, 2009. (2) I. M. Lee et al. Int. J. Syst. Bacteriol. 48:1153, 1998. (3) M. C. C. Rappussi et al. Eur. J. Plant. Pathol. 133:829, 2012. (4) Wei et al. Int. J. Syst. Evol. Microbiol. 57:1855, 2007.

scholarly journals First Report of an Aster Yellows Subgroup 16SrI-B Phytoplasma Infecting Chayote in Costa Rica

Plant Disease ◽  
2002 ◽  
Vol 86 (3) ◽  
pp. 330-330 ◽  
Author(s):  
W. Villalobos ◽  
L. Moreira ◽  
C. Rivera ◽  
K. D. Bottner ◽  
I.-M. Lee
Keyword(s):  
Costa Rica ◽  
Rflp Analysis ◽  
Restriction Enzymes ◽  
Potential Threat ◽  
Nested Polymerase Chain Reaction ◽  
Aster Yellows ◽  
First Report ◽  
Rdna Sequences ◽  
Pcr Products ◽  
Production Area

An outbreak of a witches' broom disease affected approximately 20% of plants in several chayote (Sechium edule (Jacq.) Schwartz) fields in the commercial production area of the Ujarrás Valley, Cartago Province, Costa Rica during 2000 and 2001. Affected chayote plants exhibited symptoms, including basal proliferation with severe foliage reduction, aborted flowers, and deformed fruits, suggestive of phytoplasmal infection. Two other symptomatic cucurbit species growing near the chayote fields were also identified. These species were tacaco plants (S. tacaco (Pitt.) C. Jeffrey), an edible cucurbit for domestic marketing in Costa Rica, showing severe size reduction of leaves and fruits, and Rytidostylis carthaginensis (Jacq.) Kuntze, a weed in chayote and tacaco fields, exhibiting abnormal tendril proliferation. Plants were analyzed for phytoplasma infection by a nested polymerase chain reaction (PCR) assay, using the universal rRNA primer pair P1/P7 followed by R16F2n/R16R2 (2). Phytoplasmas were detected in all symptomatic samples (18 chayote, 6 tacaco, and 3 weed) tested but were undetectable in all asymptomatic samples (10 chayote, 6 tacaco, and 2 weed). Restriction fragment length polymorphism (RFLP) analysis of PCR products (16S rDNA sequences) by separate digestion with eight restriction enzymes (RsaI, HhaI, KpnI, BfaI, HaeIII, HpaII, AluI, MseI) revealed that a phytoplasma belonging to subgroup 16SrI-B in the aster yellows phytoplasma group (16SrI) was associated with chayote witches' broom (CWB). The same or very similar phytoplasmas were found in both symptomatic tacaco and R. carthaginensis plants. Phylogenetic analysis of 16SrDNA sequences also confirmed the CWB phytoplasma to be most similar to members of subgroup 16SrI-B. Similar diseases in chayote and other cucurbits have been reported in Brazil (3), Taiwan (1), and Mexico (4). The CWB phytoplasma differs from the phytoplasma (16SrIII-J subgroup) associated with chayote in Brazil. The identities of phytoplasmas associated with cucurbits in Taiwan and Mexico are unknown. The occurrence of an aster yellows group phytoplasma in chayote may pose a potential threat to continued production and exportation of this cash crop. To our knowledge, this is the first report of 16SrI-B subgroup phytoplasmas in naturally infected cucurbits in Costa Rica. References: (1) T. G. Chou et al. Plant Dis. Rep. 60:378, 1976. (2) I.-M. Lee et al. Int. J. Syst. Bacteriol. 48:1153, 1998. (3) H. G. Montano et al. Plant Dis. 84:429, 2000. (4) E. Olivas. Rev. Fitopatol. (Lima) 13:14, 1978.

scholarly journals Association of “Candidatus Phytoplasma australiense” with Sudden Decline of Cabbage Tree in New Zealand

Plant Disease ◽  
2001 ◽  
Vol 85 (5) ◽  
pp. 462-469 ◽  
Author(s):  
Mark T. Andersen ◽  
Ross E. Beever ◽  
Paul W. Sutherland ◽  
Richard L. S. Forster
Keyword(s):  
New Zealand ◽  
Rrna Gene ◽  
Mature Trees ◽  
Nested Polymerase Chain Reaction ◽  
Transmission Electron ◽  
Adult Trees ◽  
Leaf Yellowing ◽  
Pcr Products ◽  
One Step ◽  
Cabbage Tree

Sudden decline of the New Zealand cabbage tree (Cordyline australis) results in the rapid death of affected plants within months of first external symptoms becoming apparent. Symptoms, which have been observed in saplings and mature trees, include vascular discoloration and leaf yellowing followed by leaf desiccation and eventual plant collapse. Previous work failed to link the disease with any causal agent. A phytoplasma has now been detected in all symptomatic saplings and some symptomatic trees tested, using one-step and nested polymerase chain reaction (PCR) to amplify portions of the 16S rRNA gene. This phytoplasma was not detected in nonsymptomatic plants. Phytoplasma DNA was found in shoot and rhizome apices, leaves and wood tissue of saplings, and in the rhizome apex and trunk tissues of adult trees. Sequencing of the PCR products from selected samples indicated that the phytoplasma is “Candidatus Phytoplasma australiense.” Phytoplasma cells were detected by transmission electron microscopy in phloem sieve tubes of the rhizomes of affected saplings. One sapling with early symptoms recovered after injection with tetracycline antibiotic, but two saplings with advanced symptoms did not recover. It is concluded that “Candidatus Phytoplasma australiense” is present in symptomatic plants and is the cause of sudden decline.

scholarly journals Fast and reliable PCR/sequencing/RFLP assay for identification of fungi in onychomycoses

2006 ◽  
Vol 55 (9) ◽  
pp. 1211-1216 ◽  
Author(s):  
Michel Monod ◽  
Olympia Bontems ◽  
Christophe Zaugg ◽  
Barbara Léchenne ◽  
Marina Fratti ◽  
...  
Keyword(s):  
Rflp Analysis ◽  
Fungal Species ◽  
Universal Primers ◽  
Cure Rate ◽  
Routine Identification ◽  
Identification Of Fungi ◽  
Pcr Products ◽  
Nail Sample ◽  
Fungal Dna ◽  
Rflp Assay

Fusarium spp. and other non-dermatophyte fungi are repeatedly isolated from abnormal nails. To investigate whether these fungi are the aetiological agents of infection or simply transient contaminants, a PCR/sequencing/RFLP assay was developed for direct and routine identification of the infecting fungi in onychomycosis. Fungal DNA was readily extracted using a commercial kit after dissolving nail fragments in a Na2S solution. Amplification of part of the 28S rDNA by PCR was performed with universal primers and the fungal species were identified by sequencing. The PCR/sequencing results were comparable with microbiological identification from the same nail sample. In addition to dermatophytes, Fusarium spp. and other less frequently isolated non-dermatophyte fungi were identified as single fungal agents in onychomycosis. Moreover, mixed infections were clearly demonstrated in 10 % of cases by RFLP analysis of PCR products. Identification of infectious agents could be obtained in 2 days, whilst results from fungal cultures take 1–3 weeks. Rapid and reliable molecular identification of the infectious fungus expedites the choice of appropriate antifungal therapy, thereby improving the cure rate of onychomycosis.

scholarly journals First Report of a Phytoplasma Disease of Almond (Prunus amygdalus) in Lebanon

Plant Disease ◽  
2001 ◽  
Vol 85 (7) ◽  
pp. 802-802 ◽  
Author(s):  
E. Choueiri ◽  
F. Jreijiri ◽  
S. Issa ◽  
E. Verdin ◽  
J. Bové ◽  
...  
Keyword(s):  
Western Europe ◽  
Shoot Proliferation ◽  
Diagnostic Procedures ◽  
Pigeon Pea ◽  
Universal Primers ◽  
Phloem Tissue ◽  
First Report ◽  
Leaf Yellowing ◽  
Almond Trees ◽  
Phytoplasma Infection

During a survey conducted in October 1999 to establish the sanitary status of stone fruits in Lebanon, almond trees with symptoms of leaf yellowing, shoot proliferation, and dieback were observed in the Bekaa region. Because such symptoms are often associated with phytoplasma infections, samples were collected for analysis by PCR using universal primers for amplification of phytoplasma ribosomal RNA genes (2). DNA was extracted from the leaf midveins and/or bark phloem tissue from nine symptomatic trees and one symptomless tree in four different orchards as well as from healthy almond trees collected in France. PCR resulted in amplification of an expected 1.8 kbp rDNA fragment from all symptomatic samples but not from the healthy or symptomless samples. For characterization, the amplified DNA was analyzed by RFLP. Even though the restriction profiles were different from those published for other phytoplasmas and in particular from those infecting almond trees in Western Europe (1), sequence analysis of the amplified DNA revealed that it belongs to the pigeon pea witches' broom cluster (PPWB) (2). This is the first report of a phytoplasma infection in Lebanon and the first report for a PPWB group phytoplasma in almond trees. References: (1) W. Jarausch et al. J. Plant Pathol. 104:17–27, 1998. (2) B. Schneider et al. 1995. Molecular and diagnostic procedures in Mycoplasmology Vol. 1, 369–380, S. Razin and J. G. Tully, eds.

scholarly journals First Report of Two Distinct Phytoplasma Species, ‘Candidatus Phytoplasma cynodontis’ and ‘Candidatus Phytoplasma asteris,’ Simultaneously Associated with Yellow Decline of Wodyetia bifurcata (Foxtail Palm) in Malaysia

Plant Disease ◽  
2013 ◽  
Vol 97 (11) ◽  
pp. 1504-1504 ◽  
Author(s):  
N. Naderali ◽  
N. Nejat ◽  
Y. H. Tan ◽  
G. Vadamalai
Keyword(s):  
16S Rdna ◽  
Nested Pcr ◽  
Rflp Analysis ◽  
Rrna Gene ◽  
Gene Sequences ◽  
First Report ◽  
White Leaf ◽  
General Decline ◽  
Pcr Products ◽  
Plant Pathol

The foxtail palm (Wodyetia bifurcata), an Australian native species, is an adaptable and fast-growing landscape tree. The foxtail palm is most commonly used in landscaping in Malaysia. Coconut yellow decline (CYD) is the major disease of coconut associated with 16SrXIV phytoplasma group in Malaysia (1). Symptoms consistent with CYD, such as severe chlorosis, stunting, general decline, and death were observed in foxtail palms from the state of Selangor in Malaysia, indicating putative phytoplasma infection. Symptomatic trees loses their green and vivid appearance as a decorative and landscape ornament. To determine the presence of phytoplasma, samples were collected from the fronds of 12 symptomatic and four asymptomatic palms in September 2012, and total DNA was extracted using the CTAB method (3). Phytoplasma DNA was detected in eight symptomatic palms using nested PCR with universal phytoplasma 16S rDNA primer pairs, P1/P7 followed by R16F2n/R16R2 (2). Amplicons (1.2 kb in length) were generated from symptomatic foxtail palms but not from symptomless plants. Phytoplasma 16S rDNAs were cloned using a TOPO TA cloning kit (Invitrogen). Several white colonies from rDNA PCR products amplified from one sample with R16F2n/R16R2 were sequenced. Phytoplasma 16S rDNA gene sequences from single symptomatic foxtail palms showed 99% homology with a phytoplasma that causes Bermuda grass white leaf (AF248961) and coconut yellow decline (EU636906), which are both members of the 16SrXIV ‘Candidatus Phytoplasma cynodontis’ group. The sequences also showed 99% sequence identity with the onion yellows phytoplasma, OY-M strain, (NR074811), from the ‘Candidatus Phytoplasma asteris’ 16SrI-B subgroup. Sequences were deposited in the NCBI GenBank database (Accession Nos. KC751560 and KC751561). Restriction fragment length polymorphism (RFLP) analysis was done on nested PCR products produced with the primer pair R16F2n/R16R2. Amplified products were digested separately with AluI, HhaI, RsaI, and EcoRI restriction enzymes based on manufacturer's specifications. RFLP analysis of 16S rRNA gene sequences from symptomatic plants revealed two distinct profiles belonging to groups 16SrXIV and 16SrI with majority of the 16SrXIV group. RFLP results independently corroborated the findings from DNA sequencing. Additional virtual patterns were obtained by iPhyclassifier software (4). Actual and virtual patterns yielded identical profiles, similar to the reference patterns for the 16SrXIV-A and 16SrI-B subgroups. Both the sequence and RFLP results indicated that symptoms in infected foxtail palms were associated with two distinct phytoplasma species in Malaysia. These phytoplasmas, which are members of two different taxonomic groups, were found in symptomatic palms. Our results revealed that popular evergreen foxtail palms are susceptible to and severely affected by phytoplasma. To our knowledge, this is the first report of a mixed infection of a single host, Wodyetia bifurcata, by two different phytoplasma species, Candidatus Phytoplasma cynodontis and Candidatus Phytoplasma asteris, in Malaysia. References: (1) N. Nejat et al. Plant Pathol. 58:1152, 2009. (2) N. Nejat et al. Plant Pathol. J. 9:101, 2010. (3) Y. P. Zhang et al. J. Virol. Meth. 71:45, 1998. (4) Y. Zhao et al. Int. J. Syst. Evol. Microbiol. 59:2582, 2009.

scholarly journals Genotyping of Trichomonas vaginalis isolates from women in Shahrekord city (Southwestern Iran)

Genetika ◽  
2017 ◽  
Vol 49 (3) ◽  
pp. 1059-1070 ◽  
Author(s):  
Bahman Khalili ◽  
Payam Ghasemi-Dehkordi ◽  
Gholamreza Pourshahbazi ◽  
Hossein Yousofi-Darani ◽  
Morteza Hashemzadeh-Chaleshtori ◽  
...  
Keyword(s):  
Trichomonas Vaginalis ◽  
Accurate Determination ◽  
Geographical Area ◽  
Rflp Analysis ◽  
Restriction Enzymes ◽  
Nested Polymerase Chain Reaction ◽  
Pcr Products ◽  
Southwestern Iran ◽  
Different Strains ◽  
High Level

Trichomonas vaginalis is a causative agent of vaginitis in female and urethritis in men. It is primarily transmitted by sexually route. It is known that each geographical area has its own set of Trichomonas vaginalis strain. Parasite strains in each region have its specific characterizations and different strains of the parasite are able to cause various diseases with the acuity and severity. The aim of this study was to determine the genotyping of Trichomonas vaginalis strains in the Shahrekord city (Chaharmahal Va Bakhtiari province, southwest Iran). A total of 1725 vaginal samples were taken from clinically suspected women for Trichomonas vaginalis infection and 21 specimens were diagnosed as positive by direct smear wet mount and culture repeated passage of the parasite in the modified TYI-S-33 medium. The genomic DNA was extracted from each sample and the nested polymerase chain reaction was applied using specific oligonucleotide primers for actin gene amplification. Finally, the restriction fragment length polymorphism using RsaI, MseI, and HindII restriction enzymes were done on PCR products for genotyping. PCR-RFLP analysis of 21 positive cases (1.22%) was showing the most frequent genotype was H (8 cases), followed by G (4 cases), E (3 cases), and P (2 cases). N and I genotypes were detected in each 1 case. Also, there was 2 cases mix (E and H) genotype. The findings of the present work were showed 7 different genetic strains in isolated Trichomonas vaginalis from symptomatic and asymptomatic women in Shahrekord city. In this study high level of H genotype in referred women in Shahrekord city was observed and H, G, E, and I genotypes were may be related to burning and itching as well as H, P, and mix genotypes were associated with malodorous discharge with pelvic pain in this region of Iran. For a suggestion, it would be better in further studies the accurate determination of genetic diversity of this parasite done in Chaharmahal Va Bakhtiari province and other parts of the country.

scholarly journals Species-level resolution of 16S rRNA gene amplicons sequenced through the MinIONTM portable nanopore sequencer

2015 ◽  
Author(s):  
Alfonso Benítez-Páez ◽  
Kevin J. Portune ◽  
Yolanda Sanz
Keyword(s):  
16S Rrna ◽  
16S Rrna Gene ◽  
Microbial Diversity ◽  
Amplicon Sequencing ◽  
Species Level ◽  
Taxonomic Resolution ◽  
Universal Primers ◽  
Rrna Gene ◽  
Rdna Sequences ◽  
Dna Sequencer

AbstractBackgroundThe miniaturised and portable DNA sequencer MinIONTM has been released to the scientific community within the framework of an early access programme to evaluate its application for a wide variety of genetic approaches. This technology has demonstrated great potential, especially in genome-wide analyses. In this study, we tested the ability of the MinIONTM system to perform amplicon sequencing in order to design new approaches to study microbial diversity using nearly full-length 16S rDNA sequences.ResultsUsing R7.3 chemistry, we generated more than 3.8 million events (nt) during a single sequencing run. These data were sufficient to reconstruct more than 90% of the 16S rRNA gene sequences for 20 different species present in a mock reference community. After read mapping and 16S rRNA gene assembly, consensus sequences and 2d reads were recovered to assign taxonomic classification down to the species level. Additionally, we were able to measure the relative abundance of all the species present in a mock community and detected a biased species distribution originating from the PCR reaction using ‘universal’ primers.ConclusionsAlthough nanopore-based sequencing produces reads with lower per-base accuracy compared with other platforms, the MinIONTM DNA sequencer is valuable for both high taxonomic resolution and microbial diversity analysis. Improvements in nanopore chemistry, such as minimising base-calling errors and the nucleotide bias reported here for 16S amplicon sequencing, will further deliver more reliable information that is useful for the specific detection of microbial species and strains in complex ecosystems.

scholarly journals A Phytoplasma Closely Related to the Pigeon Pea Witches'-Broom Phytoplasma (16Sr IX) Is Associated with Citrus Huanglongbing Symptoms in the State of São Paulo, Brazil

2008 ◽  
Vol 98 (9) ◽  
pp. 977-984 ◽  
Author(s):  
D. C. Teixeira ◽  
N. A. Wulff ◽  
E. C. Martins ◽  
E. W. Kitajima ◽  
R. Bassanezi ◽  
...  
Keyword(s):  
16S Rdna ◽  
External Source ◽  
Pigeon Pea ◽  
Sao Paulo ◽  
Rdna Sequence ◽  
Universal Primers ◽  
Insect Vector ◽  
São Paulo ◽  
16S Rdna Sequence ◽  
Pcr Products

In February 2007, sweet orange trees with characteristic symptoms of huanglongbing (HLB) were encountered in a region of São Paulo state (SPs) hitherto free of HLB. These trees tested negative for the three liberibacter species associated with HLB. A polymerase chain reaction (PCR) product from symptomatic fruit columella DNA amplifications with universal primers fD1/rP1 was cloned and sequenced. The corresponding agent was found to have highest 16S rDNA sequence identity (99%) with the pigeon pea witches'-broom phytoplasma of group 16Sr IX. Sequences of PCR products obtained with phytoplasma 16S rDNA primer pairs fU5/rU3, fU5/P7 confirm these results. With two primers D7f2/D7r2 designed based on the 16S rDNA sequence of the cloned DNA fragment, positive amplifications were obtained from more than one hundred samples including symptomatic fruits and blotchy mottle leaves. Samples positive for phytoplasmas were negative for liberibacters, except for four samples, which were positive for both the phytoplasma and ‘Candidatus Liberibacter asiaticus’. The phytoplasma was detected by electron microscopy in the sieve tubes of midribs from symptomatic leaves. These results show that a phytoplasma of group IX is associated with citrus HLB symptoms in northern, central, and southern SPs. This phytoplasma has very probably been transmitted to citrus from an external source of inoculum, but the putative insect vector is not yet known.

scholarly journals ‘Candidatus Phytoplasma asteris’ Strains Associated with Oil Palm Lethal Wilt in Colombia

Plant Disease ◽  
2014 ◽  
Vol 98 (3) ◽  
pp. 311-318 ◽  
Author(s):  
Elizabeth Alvarez ◽  
Juan F. Mejía ◽  
Nicoletta Contaldo ◽  
Samanta Paltrinieri ◽  
Bojan Duduk ◽  
...  
Keyword(s):  
Oil Palm ◽  
Sequence Data ◽  
Severe Disease ◽  
Rflp Analysis ◽  
Nested Polymerase Chain Reaction ◽  
Aster Yellows ◽  
Rdna Sequences ◽  
Polymerase Chain ◽  
Reference Strains

The distribution of lethal wilt, a severe disease of oil palm, is spreading throughout South America. An incidence of about 30% was recorded in four commercial fields in Colombia. In this study, phytoplasmas were detected in symptomatic oil palm by using specific primers, based on 16S ribosomal DNA (rDNA) sequences, in nested polymerase chain reaction assays. The phytoplasmas were then identified as ‘Candidatus Phytoplasma asteris’, ribosomal subgroup 16SrI-B, through the use of restriction fragment length polymorphism (RFLP) analysis and sequencing. Cloning and sequencing of 16S rDNA from selected strains, together with phylogenetic analysis, confirmed the classification. Moreover, collective RFLP characterization of the groEL, amp, and rp genes, together with sequence data, distinguished the aster yellows strain detected in Colombian oil-palm samples from other aster yellows phytoplasmas used as reference strains; in particular, from an aster yellows strain infecting corn in the same country.

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