Phytoplasma Subgroup Research Articles

Molecular characterization of group 16SrI and 16SrIII phytoplasmas associated with loofah witches’ broom disease in Sinaloa, Mexico

Loofah [Luffa acutangula (L.) Roxb.] is grown in some regions of Asia, Africa and the Americas. This vegetable is well known for its high nutritional and medicinal value. Loofah plants showing typical symptoms of phytoplasma infection, such as witches’ broom, fruit deformation, flower proliferation and phyllody were observed in a commercial field in Sinaloa, Mexico, in January 2015. Nineteen symptomatic loofah plants and seven asymptomatic weeds (Helianthus annuus, Sarcostemma sp., Chenopodium sp., Amaranthus palmeri, Rumex sp., Ambrosia sp., and Raphanus sp.) growing nearby were collected and analyzed by phytoplasma-specific nested PCR. Phytoplasmas were detected in 79% of symptomatic loofah plants and in two of the seven weeds. Conventional and virtual restriction fragment length polymorphism (RFLP) analyses of the 16S rRNA-encoding gene sequences indicated the presence of strains of the 16SrIII and 16SrI phytoplasma groups in loofah, which occurred as both single and mixed infections. The phylogenetic analysis confirmed four new phytoplasma strains associated with loofah diseases, two ‘Candidatus Phytoplasma asteris’-related strains (16SrI-AG and 16SrI-AH), and two ‘Candidatus Phytoplasma pruni’-related strains (16SrIII-AA, and 16SrIII-AB). Furthermore, phytoplasmas belonging to groups 16SrI and 16SrIII also were identified in the weeds H. annuus and A. palmeri, respectively; 16SrIII-AC represents a new phytoplasma subgroup described in A. palmeri in Sinaloa. To our knowledge, this is the first report of loofah disease associated with phytoplasmas belonging to the 16SrI and 16SrIII groups in Mexico.

Detection and Identification of Phytoplasmas in the 16SrIV-A, -B, and -D Subgroups in Palms in Tabasco, Mexico.

The 16SrIV-A phytoplasmas are associated with the devastating disease lethal yellowing (LY) of palms. In Tabasco (Mexico), the death of Cocos nucifera, Adonidia merrillii, and Attalea butyracea palms have been suspected to be associated with LY based on symptomatology. Samples from the trunk of both symptomatic and nonsymptomatic palms were collected in three different environments: two species of palms within a rural zone and the other within an urban zone. DNA was extracted to perform a nested PCR with phytoplasma primers P1/P7-LY16SF/R16R2. A 1,345-bp fragment was amplified from the DNA extracted from each of the 29 LY-symptomatic palms sampled. Phytoplasma identification was achieved by amplicon sequencing and virtual restriction fragment length polymorphism analyses. Three 16SrIV phytoplasma subgroups were detected: 16SrIV-A in C. nucifera, 16SrIV-B in A. merrillii, and 16SrIV-D in C. nucifera, A. merrillii, and A. butyracea. Phylogenetic analysis showed also that the three phytoplasma strains found in the palm species clustered with phytoplasmas reported in the literature in the three subgroups identified. This is the first report of phytoplasmas associated with these palm species in Tabasco.

Campsisgrandiflora as a new host species harbouring two novel 16SrI subgroups of phytoplasmas

AbstractIn September 2019, two diseased plants of Campsis grandiflora showing the main symptom of witches' ‐broom (CgWB) were found in a nursery garden in Yangling, Shaanxi province, China. Partial 16S ribosomal RNA (F2nR2 region) and ribosomal protein (rp) genes of phytoplasmas were generated from the symptomatic plants by PCR amplification, and phytoplasma bodies were observed in the sieve tube elements of the CgWB samples under a transmission electron microscope, indicating phytoplasma infection in the two CgWB plants. Restriction fragment length polymorphism analysis of the F2nR2 region and similarity coefficient results suggested that the two associated phytoplasmas belong to two novel subgroups of 16SrI (aster yellows) group, designated as AK and AL. On the reconstructed phylogenetic trees based on F2nR2 regions and rp genes of phytoplasmas, respectively, the CgWB‐associated phytoplasmas clustered together with members of 16SrI subgroups. This was the first record of phytoplasmas infecting C. grandiflora worldwide.

Identification of 'Candidatus phytoplasma aurantifolia' associated with leaf yellowing of Narcissus tazetta in Iran

During January to March of 2019, a natural occurrence of Narcissus leaf yellowing (NLY) symptoms was observed on Narcissus (Narcissus tazetta) in korit region (Southern Khorasan province, Iran). Phytoplasmas associated with yellowing of N. tazetta was detected in direct and nested polymerase chain reaction assay. Molecular and phylogenetic analyses of the 16SrRNA gene revealed that the phytoplasma strains associated with NLY symptoms was related to16SrII group. This is the first report of the 16SrII-D Phytoplasma subgroup with Narcissus leaf yellowing from Iran.

Occurrence of ‘Candidatus Phytoplasma omanense’-related strains and other phytoplasmas in Sophora alopecuroides plants showing dwarfing and yellowing

Sophora alopecuroides dwarfing and yellowing symptoms were observed at the edge of several Damaneh and Fereydun Shahr (Isfahan province, Iran) fields. Polymerase chain reaction using primers P1/P7 and nested PCR using the same primers followed by R16mF2/R16mR2 and R16F2n/R16R2 primer pairs amplified the 16S ribosomal RNA-encoding gene in all the symptomatic plants tested, but not in the asymptomatic ones. RFLP analysis of R16F2n/R16R2 amplicons with AluI, HaeIII, HhaI, HpaI, HpaII, RsaI, MseI and TaqI restriction enzymes showed profiles referable to 16SrII, 16SrVI, 16SrIX, 16SrXII and 16SrXXIX phytoplasma ribosomal groups indicating also the presence of mixed infection in several samples. The identity percentage and the phylogeny obtained after direct sequencing of selected 16S rRNA-encoding gene sequences (R16F2n/R2 amplicons) from symptomatic S. alopecuroides confirmed the presence of phytoplasma strains related to ‘Candidatus Phytoplasma omanense’ (group 16SrXXIX), ‘Ca. P. australasia’ (group 16SrII), and ‘Ca. P. trifolii’ (16SrVI). Moreover, in a few samples/amplicons, 16SrXII-A, 16SrIX-H, 16SrVI-F and 16SrXXIX-A phytoplasma subgroups were identified by real and virtual RFLP analyses. The other phytoplasmas detected were classified in subgroups 16SrII-D and 16SrVI-A. This is the first report of the presence of 16SrII and 16SrXXIX phytoplasma groups and of mixed infection of phytoplasma strains belonging to groups 16SrII, 16SrVI, 16SrIX, 16SrXII and 16SrXXIX in S. alopecuroides worldwide.

A timetree for phytoplasmas (Mollicutes) with new insights on patterns of evolution and diversification

The first comprehensive timetree is presented for phytoplasmas, a diverse group of obligate intracellular bacteria restricted to phloem sieve elements of vascular plants and tissues of their hemipteran insect vectors. Maximum likelihood-based phylogenetic analysis of DNA sequence data from the 16S rRNA and methionine aminopeptidase (map) genes yielded well resolved estimates of phylogenetic relationships among major phytoplasma lineages, 16Sr groups and known strains of phytoplasmas. Age estimates for divergences among two major lineages of Mollicutes based on a previous comprehensive bacterial timetree were used to calibrate an initial 16S timetree. A separate timetree was estimated based on the more rapidly-evolving map gene, with an internal calibration based on a recent divergence within two related 16Sr phytoplasma subgroups in group 16SrV thought to have been driven by the introduction of the North American leafhopper vector Scaphoideus titanus Ball into Europe during the early part of the 20th century. Combining the resulting divergence time estimates into a final 16S timetree suggests that evolutionary rates have remained relatively constant overall through the evolution of phytoplasmas and that the origin of this lineage, at ~641 million years ago (Ma), preceded the origin of land plants and hemipteran insects. Nevertheless, the crown group of phytoplasmas is estimated to have begun diversifying ~316 Ma, roughly coinciding with the origin of seed plants and Hemiptera. Some phytoplasma groups apparently associated with particular plant families or insect vector lineages generally arose more recently than their respective hosts and vectors, suggesting that vector-mediated host shifts have been an important mechanism in the evolutionary diversification of phytoplasmas. Further progress in understanding macroevolutionary patterns in phytoplasmas is hindered by large gaps in knowledge of the identity of competent vectors and lack of data on phytoplasma associations with non-economically important plants.

Biological and molecular evidence for the transmission of aster yellows phytoplasma to French marigold (Tagetes patula) by the flatid planthopper Metcalfa pruinosa

AbstractAster yellows (AY) phytoplasmas (Candidatus Phytoplasma asteris) are associated with a number of plant diseases throughout the world. Several insect vectors are responsible for spreading AY diseases resulting in wide distribution and low host specificity. Because the role of sucking insects as vectors of phytoplasmas is widely documented, and the citrus flatid planthopper Metcalfa pruinosa is a phloem feeder, it has been incriminated as a possible vector of phytoplasmas. However, its ability to transfer phytoplasma has not been confirmed. The present work shows that M. pruinosa (Hemiptera: Flatidae), a polyphagous planthopper, is able to vector Ca. P. asteris to French marigold (Tagetes patula). Transmission experiments were conducted in 2017 and 2018 in central Hungary by two approaches: (a) AY‐infected M. pruinosa were collected from an area with severe incidence of the disease on T. patula and caged on test plants for an inoculation‐access period of 2 weeks, and (b) presumably phytoplasma‐free insects were collected from apparently healthy grapevines (Vitis vinifera L.) and fed on AY‐infected T. patula plants for 2 weeks prior to being caged on test plants. AY disease symptoms developed on 4 out of 10 and 10 out of 15 test plants, respectively. All phytoplasma‐positive marigold and M. pruinosa samples showed identical RFLP patterns and shared 100% 16S rDNA sequence identity with each other and with the aster yellows phytoplasma strain AJ33 (GenBank accession number MK992774). These results indicated that the phytoplasma belonged to the phytoplasma subgroup 16SrI‐B Ca. P. asteris. Therefore, the work presented here provides experimental evidence that M. pruinosa is a vector of a 16SrI‐B subgroup phytoplasma to T. patula.

Identification of phytoplasma in six fruit crops in India

Symptoms of decline, leaf yellowing and reddening, little leaf and malformation were observed in apricot, guava, lychee, mango, pomegranate and grapevine in fruit orchards belonging to three states of India namely Delhi, Maharashtra and Jammu & Kashmir during 2016–2017. Phytoplasmas belonging to three different groups were detected in all the symptomatic fruit tree samples in polymerase chain reaction with phytoplasma specific primer pairs amplifying 16S rRNA and secA genes. Pair wise sequence comparison and phylogenetic analysis confirmed the presence of phytoplasmas. A ‘Candidatus Phytoplasma asteris’ - related strain was detected in apricot showing decline symptoms in Siot (Jammu & Kashmir). ‘Ca. P. australasia’ - related strain was identified in guava, lychee, mango and pomegranate in Rajbag, Sunjwan (Jammu & Kashmir), Pusa (Delhi) and Baramati (Maharashtra), respectively, exhibiting little leaf, leaf yellows and malformation symptoms. Furthermore, a rice yellow dwarf group (16SrXI-B) - related strain was detected in pomegranate and grapevine that showed leaf yellowing and reddening at Pusa (Delhi) and Baramati (Maharashtra), respectively. Subgroup analysis using virtual RFLP of 16S rDNA sequences allowed enclosing these phytoplasma strains into 16SrI-B, 16SrII-D and 16SrXI-B subgroups. In the study, identification of phytoplasma subgroups, 16SrI-B in apricot, 16SrII-D in guava, lychee, mango and pomegranate (Pusa) and 16SrXI-B in pomegranate (Baramati) and grapevine, are the first records globally.

Geographic Distribution and Host Range of Lethal Bronzing Associated with Phytoplasma Subgroup 16SrIV-D on Palms in Southern Louisiana

Lethal bronzing (LB), also previously known as date palm lethal decline or Texas Phoenix palm decline, associated with phytoplasma subgroup 16SrIV-D, was first identified in Louisiana in December 2013. A survey of palms showed that the disease was not only confined to City Park in New Orleans, where it was first detected, but is present in other parts of Orleans Parish, as well as two adjacent parishes. Canary Island date palms (Phoenix canariensis) tested positive at the highest frequency, and some edible date palms (P. dactylifera) and a small proportion of cabbage palms (Sabal palmetto) tested positive as well. Symptoms do not appear to be a reliable indicator of LB, because a substantial proportion of palms indicated as symptomatic tested negative. Furthermore, not all infected palms showed symptoms. Since the palm survey conducted in 2015 to 2016, LB has positively been identified from silver date palm (P. sylvestris) and Chinese windmill palm (Trachycarpus fortunei) in three additional parishes in Louisiana.

First report of 16Sr II‐C subgroup phytoplasma association with Acacia mangium in Tripura, India

AbstractLeaf yellowing symptoms were observed on Acacia mangium in the Sipahijala district of Tripura, India, during June 2017. Symptomatic and asymptomatic leaf samples (three of each) were collected from roadside trees of A. mangium for DNA extraction using the CTAB method. Amplicons of ~1.25 kb and ~480 bp were detected in all the symptomatic samples using the phytoplasma‐specific universal 16S rRNA and secA gene primers. Pair wise sequence analysis of 16S rRNA gene sequences, virtual RFLP and phylogenetic analysis revealed that the phytoplasma strain associated with A. mangium belonged to phytoplasma subgroup 16SrII‐C. This is the first report of an association between the 16SrII‐C subgroup and A. mangium leaf yellowing.

Phytoplasmas associated with declining of hazelnut (Corylus avellana) in Slovenia

Hazelnut (Corylus avellana) is cultivated on 118 ha and ranks eighth in Slovenian fruit growing production, representing 2.8% of the total area of fruit plantations in the country. However, decline of some of the trees appeared in 2012 in two plantations located in eastern Slovenia. Together these orchards cover 5 ha, with around 1600 trees planted 12 to 15 years ago. By October 2018, ~12% of these trees had died, and an additional 12% showed decay symptoms. The dead and dying trees were scattered throughout both orchards, with no apparent pattern. The most affected cultivar was ‘Istrska dolgoplodna leska’. Using molecular diagnostic methods, we showed infection of symptomatic trees with three unrelated phytoplasmas: ‘Candidatus Phytoplasma fragariae’, of the 16SrXII-E phytoplasma subgroup, and phytoplasma of the 16SrV and 16SrIX groups. In 2018, the presence of ‘Ca. P. fragariae’ and/or phytoplasma of 16SrV group were confirmed in decayed hazelnut trees in eastern, north-eastern, central, south-eastern and western Slovenia. ‘Ca. P. fragariae’ has also been detected in a forest in south-western Slovenia, for Acer campestre, Carpinus betulus, Crataegus laevigata, Fraxinus ornus and Quercus petraea. All infected forest trees showed unusual dense proliferation of sprouts from roots and/or trunks. Molecular characterisations of partial 16S rRNA, secY, map and ribosomal protein genetic locus of hazelnut 16SrV phytoplasma isolates show that they are identical to isolates that can cause grapevine flavescence dorée disease. Here, the results of our recent study and the open questions on this burning issue for hazelnut production are presented.

The CpnClassiPhyR Is a Resource for cpn60 Universal Target-Based Classification of Phytoplasmas.

Phytoplasmas are plant-pathogenic bacteria that are associated with yield losses in many crop plants worldwide. Phytoplasma strain differentiation is accomplished using in silico restriction fragment length polymorphism (RFLP) analysis of 16S ribosomal RNA-encoding gene sequences, which has resulted in the definition of ribosomal groups and subgroups of phytoplasmas. Due to limitations associated with this approach, a complementary classification scheme was recently developed based on RFLP analysis of the single-copy, protein-encoding gene chaperonin-60 (cpn60). We present the CpnClassiPhyR, software that facilitates phytoplasma strain classification using both RFLP and automated phylogenetic analysis of cpn60 sequences. This software is available through a web interface at http://cpnclassiphyr.ca.

Detection and identification of 16SrXIII-F and a novel 16SrXIII phytoplasma subgroups associated with strawberry phyllody in Chile

Since the year 2015, strawberry plants with symptoms of phyllody, achenes’ hypertrophy and leaf reddening have been observed in several fields in various regions of Chile. In recent surveys on five individual fields in Biobio and Araucania regions, samples were collected from symptomatic plants and DNA was extracted. Two genomic regions corresponding to the 16S rRNA and tuf genes were amplified by nested PCR using phytoplasma universal primers. Three individual clones of each amplicon from each sample were then sequenced. The RFLP analyses of the 16S rDNA amplicons showed that all of the symptomatic plants were infected by phytoplasmas enclosed in the 16SrXIII group. This result was confirmed by phylogenetic analysis with tuf amplicons. RFLP similarity coefficients indicated the presence of two phytoplasmas, one belonging to the 16SrXIII-F subgroup, while the other resulting not enclosed in any of the described subgroups and therefore it was assigned to the newly proposed 16SrXIII-K subgroup.

First report of the association of a ‘Candidatus Phytoplasma asteris‘‐ related strain with Plumbago auriculata leaf yellowing in India

Plumbago auriculata (Plumbaginaceae) is a perennial ornamental shrub with many therapeutic values and native to South Africa (Saji & Antony, 5). Several groups of phytoplasma have been reported to infect ornamental and medicinal plants all over the world (Rao et al., 2). However, no phytoplasma has been found so far in P. auriculata. Leaf yellowing symptoms on P. auriculata plants (Fig. 1) were observed in Baramati, Pune, India in March 2016 with a disease incidence of 8-10%. To verify the presence of phytoplasma, three symptom-bearing and three asymptomatic P. auriculata samples were collected and DNA was extracted using the CTAB protocol. PCR was performed in a Mastercycler (Eppendorf, Germany) (Rao et al., 4) and DNA from the sesame phyllody phytoplasma (16SrI group) (GenBank Accession No. KC920747) was used as a positive control. The 16S rRNA gene was amplified from all the symptomatic P. auriculata leaf yellowing (PaLY) samples but not from the asymptomatic samples using P1/P7 (Schneider et al., 6) followed by R16F2n/R2 primer pairs (Gundersen & Lee, 1) in nested PCR. Amplicons of the expected size (c. 1.25 kb) were purified and directly sequenced (MN239503 and MN239504). BLAST analysis showed that these 16Sr RNA gene sequences shared 100% identity with phytoplasmas in the16SrI group (MG252367, MK440284, MK440282, KX15181 & KT957205). A phylogenetic tree was constructed using the neighbour-joining method with MEGA 7.0 (Fig.2). The R16F2n/R2 sequence of the PaLY phytoplasma was subjected to in silico RFLP using the iPhyClassifier online tool (https://plantpathology.ba.ars.usda.gov). The iPhyClassifier analysis indicated that the virtual RFLP patterns derived from the 16S rDNA F2n/R2 fragment of the PaLY phytoplasma strain with restriction enzymes were similar to those of a phytoplasma strain from group 16SrI, ‘Candidatus Phytoplasma asteris’ (M30790), formerly Aster Yellows Group, subgroup B, with a similarity coefficient of 1.0. Based on sequence and RFLP results, the PaLY phytoplasma is classified as a member of the phytoplasma subgroup 16SrI-B. Phytoplasmas have been recorded from plant species in the Plumbaginaceae such as Limonium sinuatum in Canada, Europe and Israel (Rao et al., 2). In India, the ‘Ca. P. asteris’ group is the most widespread group and has been found in 64 plant species (Rao et al., 3). Phytoplasmas in subgroup 16SrI-B have been associated particularly with diseases in pineapple, sesame, sugarcane, squash, rose and fennel. The present study reports P. auriculata as a new host for the 16Sr I-B phytoplasma subgroup worldwide. The authors wish to express sincere thanks to Head, Division of Plant Pathology and Director, Indian Agricultural Research Institute for providing laboratory facilities.

Catharanthus roseus (Apocynaceae) naturally infected with diverse phytoplasmas in Costa Rica

Phytoplasmas (class Mollicutes) are causal agents of plant diseases with an economic impact on crops or threatening local biodiversity. A survey was conducted from 2012 to 2016 on infected Catharanthus roseus plants that exhibited symptoms reminiscent of phytoplasma infection throughout Costa Rica. A total of 73 plants were collected exhibiting symptoms such as virescence, phyllody, axillary proliferation, little leaf, leaf malformation, chlorosis, or yellowing. All samples were tested by nested PCR using phytoplasma universal and specific primer pairs. Phytoplasma infection was detected in 52 (71.2 %) of the plants collected. Phytoplasmas of six subgroups belonging to 16Sr groups I, III, IX, XIII and XV were identified based on sequencing and in silico RFLP analyses. ´Candidatus Phytoplasma asteris´ (16SrI) was the predominant group among the positive samples (n = 30) showing variety of symptoms and wide distribution from sea level to ca. 1 400 masl in six of the seven Costa Rican provinces. Group 16SrIII was the second most abundant (14 samples); and the remaining three groups were seldom found in C. roseus (8 samples). Moreover, group 16SrXIII phytoplasma was detected for the first time in the country. To the best of our knowledge, this is the first report of natural infection of C. roseus with phytoplasma subgroups 16SrI-B, 16SrI-P, 16SrIII-F, 16SrIX-F, 16SrXIII-A, and 16SrXV-B in Costa Rica and Central America.

Non-crop sources of Rapeseed Phyllody phytoplasma (‘Candidatus Phytoplasma asteris’: 16SrI-B and 16SrI-(B/L)L), and closely related strains

In Poland, a phytoplasma belonging to the subgroup 16SrI-B of ‘Ca. Phytoplasma asteris’ species causes disease in winter oilseed rape (Brassica napus), named rapeseed phyllody (RP). Affected plants exhibit malformations of flowers – phyllody, leading to losses in seed production. However, the potential sources of RP phytoplasma (RPp) outside oilseed rape are poorly understood. A screening survey of non-crop wild plants associated with winter oilseed rape was performed in order to identify alternative plant hosts of RPp. Nested polymerase chain reaction (PCR) and sequencing of PCR-amplified 16S rDNA fragments were employed for the detection and identification of phytoplasma strains affecting oilseed rape crops and adjacent wild plants. Phytoplasmas belonging to subgroups 16SrI-B, 16SrI-L, 16SrI-(B/L)L and 16SrI-C, as well as subgroup 16SrXII-H, were detected in non-crop plants. All investigated oilseed rapes manifesting RP disease were positive to ‘Ca. Phytoplasma asteris’ ribosomal subgroup 16SrI-B or heterogenic variant 16SrI-(B/L)L. Wild plants species were predominantly infected with the same phytoplasma subgroups as oilseed rapes. However, comparative sequence analysis revealed single nucleotide polymorphisms that indicate divergence of 16SrI-B and 16SrI-(B/L)L phytoplasma strains in non-crop species. Surprisingly, most of the weeds which tested positive for phytoplasma did not exhibit any characteristic symptoms of infection. In this study we identified for the first time perennial (Elymus repens, Lolium perenne) and annual (Echinochloa crus-galli, Polygonum aviculare, Viola arvensis, Matricaria perforata, Stelaria media) plants as asymptomatic reservoirs of RPp related strains in the winter oilseed rape agroecosystem. We also confirmed RPp related infections in diseased Apera spica-venti, Sisymbrium officinale, Matricaria discoidea, and Papaver rhoeas. These plants potentially play a significant role in RPp evolution and disease aetiology and epidemiology.

A new elm yellows phytoplasma strain associated with leaf yellowing disease of Tamarindus indica in India

Tamarind is an economically important tree species; its fruit pulp is widely used in kitchen in India. A symptomatic tamarind tree with yellow leaf symptoms found in the western part of India was assayed for phytoplasma presence. The 16S rDNA sequence of the detected phytoplasma (TM01) was found clustering with sequences in the elm yellows (16SrV) phytoplasma group. The virtual RFLP analysis of obtained 16S rDNA sequence TM01 revealed that it could be tentatively classified into a novel phytoplasma subgroup, 16SrV-L since its AluI, HaeIII and MseI restriction profiles of R16F2n/R16R2 sequenced amplicons generated were unique as compared to the earlier reported profiles of this phytoplasma subgroup. This is the first phytoplasma report in Tamarindus indica.

A new phytoplasma strain in group 16SrV associated with witches'broom disease of Ziziphus oenoplia in Karnataka, India

Ziziphus oenoplia, also known as jackal jujube or small fruited jujube is a spiny, evergreen small tropical fruit tree. During a survey in October-November 2019, the jujube trees exhibited severe witches’ broom symptoms, therefore, an investigation was carried out, to verify the presence of phytoplasmas in these symptomatic plants. Total DNA was extracted from leaves of jujube plants using a CTAB method and a PCR assay was performed using 16S rRNA gene specific primer pairs P1/P7 and 3Far/3Rev. Amplicons of about 1.3 kb were consistently amplified from all the symptomatic plant samples in nested PCR assays, while, no amplification was observed in non-symptomatic samples. The phylogenetic analysis of 16Sr DNA sequence of the detected phytoplasma strain indicates its clustering with ‘Candidatus Phytoplasma balanitae’ strains and also its close relatedness to 16SrV-F subgroup phytoplasmas. The virtual RFLP analysis of the 16Sr DNA sequence revealed that it could tentatively be classified into a novel phytoplasma subgroup since its AluI restriction profile was unique to earlier reported subgroup strains in 16SrV group.

New phytoplasma subgroups within the 16SrI and 16SrVII groups detected in trees of Bogotá, Colombia

New phytoplasma subgroups within the 16SrI and 16SrVII groups detected in trees of Bogotá, Colombia

Unveiling subgroups of 16SrIII phytoplasmas affecting Trillium sp. and Melothria pendula in Brazil and Canada

Unveiling subgroups of 16SrIII phytoplasmas affecting <i>Trillium</i> sp. and <i>Melothria pendula</i> in Brazil and Canada