First Report of a 16SrII-A Subgroup Phytoplasma Associated with Purple Coneflower (Echinacea purpurea) Witches'-Broom Disease in Taiwan

Purple coneflower (Echinacea purpurea), widely grown as an ornamental and medicinal plant, is a perennial flowering plant that is native to eastern North America. In July 2011, symptoms indicative of phytoplasma disease, including floral virescence, phyllody, and witches'-broom (WB), were observed to be affecting plants in coneflower fields in Wufeng, Taichung City, Taiwan. Incidence of infected plants was estimated to be greater than 90% within a single field. Phytoplasmas previously associated with purple coneflower WB disease have all been classified as aster yellows group (16SrI) strains (GenBank Accession Nos. EU333395, AY394856, EU416172, and EF546778) except for pale purple coneflower (Echinacea pallida) WB in Australia, which was identified as a subgroup 16SrII-D member (2). Three diseased plants were uprooted and transplanted in a greenhouse for further study. Transmission electron microscopy revealed clusters of phytoplasma cells ranging from 170 to 490 nm in diameter in phloem sieve elements of virescent and phylloid flowers and stems from diseased plants. Comparable tissues from symptomless plants were devoid of phytoplasma. Total DNA was extracted from plant tissue samples (50 to 100 mg each) including stems, leaves, and flowers by a modified CTAB method (1) from three symptomatic plants as well as from three asymptomatic coneflower plants seedlings. Analyses by a nested PCR using universal primer pairs P1/P7 followed by R16F2n/R16R2 were performed to detect putative phytoplasma (2). Each primer pair amplified a single PCR product of either 1.8 or 1.2 kb, respectively, from diseased plant tissues only. The nested PCR products (1.2 kb) amplified from phylloid flowers of the three diseased plants were cloned separately and sequenced (GenBank Accession Nos. JN885460, JN885461, and JN885462). Blast analysis of the sequences revealed a 99.7 to 99.8% sequence identity with those of Echinacea WB phytoplasma strain EWB5 and EWB6 (GenBank Accession Nos. JF340076 and JF340080), which reportedly belonged to the 16SrII-D subgroup (2). Moreover, iPhyClassifier software (3) was used to perform sequence comparison and generate the virtual restriction fragment length polymorphism (RFLP) profile. The 16S rDNA sequences share a 99.4 to 99.5% similarity with that of the ‘Candidatus Phytoplasma australasiae’ reference strain (Y10097) and the RFLP patterns are identical to that of the 16SrII-A subgroup. Taken together, these results indicated that the phytoplasma infecting purple coneflower in Taiwan is a ‘Ca. Phytoplasma australasiae’-related strain and belongs to the 16SrII-A subgroup. To our knowledge, this is the first report of a 16SrII-A subgroup phytoplasma causing WB disease on purple coneflower in Taiwan. The occurrence of phytoplasma on purple coneflower could have direct implication for the economically important ornamental, medicinal plant, and floral industry in Taiwan, especially to the growers and breeders that eagerly promote the purple coneflower industry. References: (1) T. M. Fulton et al. Plant Mol. Biol. Rep. 13:207, 1995. (2) T. L. Pearce et al. Plant Dis. 95:773, 2011. (3) Y. Zhao et al. Int. J. Syst. Evol. Microbiol. 59:2582, 2009.

Download Full-text

First Report of a 16SrI Group Phytoplasma Associated with Roselle (Hibiscus sabdariffa) Wrinkled Leaves and Phyllody Disorder in Taiwan

Plant Disease ◽

10.1094/pdis-12-13-1256-pdn ◽

2014 ◽

Vol 98 (7) ◽

pp. 991-991 ◽

Cited By ~ 4

Author(s):

Y.-W. Tseng ◽

C.-J. Chang ◽

J.-W. Chen ◽

W.-L. Deng ◽

F.-J. Jan

Keyword(s):

Nested Pcr ◽

Hibiscus Sabdariffa ◽

Universal Primer ◽

First Report ◽

Rdna Sequences ◽

Transmission Electron ◽

Pcr Product ◽

Ctab Method ◽

Pcr Products ◽

Single Field

Roselle (Hibiscus sabdariffa L.), an annual plant with acidic taste, has been used for making juice, jelly, and other baking additives in Taiwan. In September 2013, symptoms including phyllody and wrinkled leaves were observed on roselle plants in a field in Tantsu Township, Taichung County, Taiwan. Incidence of the infected plants was estimated to be greater than 80% within a single field. A phytoplasma was recently reported as the causal agent of roselle phyllody and reddening of leaves in India and classified as a group 16SrV-D strain (1). Samples including stems, flowers, and leaves were collected from four symptomatic and one asymptomatic roselle plants from the field. Transmission electron microscopy revealed clusters of phytoplasma cells ranging from 400 to 750 nm in diameter only in phloem sieve elements of petioles and stems of symptomatic plants. These cells were not observed in asymptomatic plants. Total DNA was extracted from plant tissues (100 mg each) including stems, petioles, and mid veins of leaves by a modified CTAB method (2). Analyses by a nested PCR assay using universal primer pairs P1/P7 followed by R16F2n/R16R2 were performed to detect putative phytoplasma (1). Each primer pair amplified a single PCR product 1.8 kb and 1.2 kb long, respectively, only from tissues of the four symptomatic plants. The nested PCR products (1.2 kb) amplified from three independent symptomatic plants were cloned separately and sequenced by automatic DNA sequencing method with ABI3730 DNA Analyzer (Applied Biosystems) at the Biotechnology Center, National Chung Hsing University, Taichung, Taiwan (GenBank Accession Nos. KF923397, KF923398, and KF923399). BLAST analysis of the sequences revealed that they shared 99.8% sequence identity with those of 16SrI group phytoplasma strains, e.g., garlic yellows phytoplasma, torenia yellows phytoplasma, and periwinkle leaf yellowing phytoplasma (AB750363, FJ437568, and GU361754). Moreover, i PhyClassifier software (3) was used to perform sequence comparison and generate a virtual restriction fragment length polymorphism (RFLP) profile for the sequences derived from the symptomatic roselle samples. The 16S rDNA sequences shared 99.6% identity with those of the ‘Candidatus Phytoplasma asteris’ reference strain (M30790) and the RFLP patterns were identical to that of the 16SrI group. However, this strain may represent a new subgroup because the shared similarity coefficient was only 0.94, which is within the values set for a new subgroup (3). Taken together, these results indicate the phytoplasma infecting roselle in Taiwan is a ‘Ca. P. asteris’-related strain belonging to the 16SrI group. To our knowledge, this is the first report of a 16SrI group phytoplasma causing wrinkled leaves and phyllody on roselle in Taiwan. The occurrence of phytoplasma on roselle could have direct implication for the bakery and juice industries in Taiwan. References: (1) C. Biswas et al. Phytoparasitica 41:539, 2013. (2) I. Echevarría-Machado et al. Mol. Biotechnol. 31:129, 2005. (3) W. Wei et al. Int. J. Syst. Evol. Microbiol. 57:1855, 2007.

Download Full-text

First Report on the Association of a 16SrII-A Phytoplasma with Sesame (Sesamum indicum) Exhibiting Abnormal Stem Curling and Phyllody in Taiwan

Plant Disease ◽

10.1094/pdis-12-13-1212-pdn ◽

2014 ◽

Vol 98 (7) ◽

pp. 990-990 ◽

Cited By ~ 9

Author(s):

Y.-W. Tseng ◽

W.-L. Deng ◽

C.-J. Chang ◽

J.-W. Huang ◽

F.-J. Jan

Keyword(s):

Nested Pcr ◽

Early Stage ◽

Sesamum Indicum ◽

Plant Tissues ◽

Oilseed Crop ◽

Universal Primer ◽

Sieve Elements ◽

First Report ◽

Leaf Petiole ◽

Rdna Sequences

Sesame (Sesamum indicum L.), an annual plant, is grown as an oilseed crop and the seeds are used in bakery products in Taiwan. In June 2013, plants exhibiting symptoms including phyllody and abnormal stem curling were observed in sesame fields in Pitou Township, Changhua County, Taiwan. Incidence of infected plants was estimated to be greater than 90% within a single field. Phytoplasmas associated with sesame exhibiting phyllody, witches'-broom, or virescence have been classified as strains of 16SrI-B in Myanmar (GenBank Accession No. AB558132), 16SrII-A in Thailand (JN006075), 16SrII-D in Oman (EU072505) and India (KF429486), 16SrIV-C in Iran (JF508515), and 16SrVI-A (KF156894) and 16SrIX (KC139791) in Turkey (1). Three symptomatic and four asymptomatic plants were uprooted and transplanted in a greenhouse for further study. Transmission electron microscopy (TEM) revealed clusters of phytoplasma cells ranging from 300 to 800 nm in diameter only in phloem sieve elements of stems of three symptomatic and two asymptomatic plants. Comparable tissues from two other symptomless plants were devoid of phytoplasma cells. Total DNA was extracted with a modified CTAB method (2) from plant tissues (100 mg each) including stem, leaf, petiole, and root from the same plants used for TEM work. Analyses by a nested PCR using universal primer pairs P1/P7 (5′-AAGAGTTTGATCCTGGCTCAGGATT/5′-CGTCCTTCATCGGCTCTT) followed by R16F2n/R16R2 (5′-GAAACGACTGCTAAGACTGG/5′-TGACGGGCGGTGTGTACAAACCCCG) were performed to detect putative phytoplasma DNA (3). Each primer pair amplified a single PCR product of either 1.8 or 1.2 kb, respectively, only from the three symptomatic and two asymptomatic plant tissues that had phytoplasma cells in their sieve elements. It is likely that these two asymptomatic plants were in the early stage of infection before symptoms became noticeable. The nested PCR products (1.2 kb) amplified from the symptomatic plants were cloned separately and sequenced (GenBank Accession Nos. KF923391, KF923392, and KF923393). BLAST analysis of the sequences revealed that they shared 99.2% sequence identity with strains reported from India and Thailand (KF429486 and JN006075), which were classified to the 16SrII-D and 16SrII-A subgroups, respectively. Moreover, iPhyClassifier software (4) was used to perform sequence comparison and generate a virtual restriction fragment length polymorphism (RFLP) profile. The 16S rDNA sequences shared 99.4% identity with that of the ‘Candidatus Phytoplasma australasiae’ (Y10097) and the RFLP patterns were identical to that of the 16SrII-A subgroup, indicating the Taiwanese strain is a ‘Ca. P. australasiae’-related strain. To our knowledge, this is the first report of a 16SrII-A subgroup phytoplasma causing phyllody and abnormal stem curling on sesame in Taiwan. The occurrence of phytoplasma on sesame could have direct implications for the cultivation of this economically important oilseed plant and the bakery industry in Taiwan. References: (1) M. Catal et al. Plant Dis. 97:835, 2013. (2) T. M. Fulton et al. Plant Mol. Biol. Rep. 13:207, 1995. (3) D. E. Gundersen and I. M. Lee. Phytopathol. Mediterr. 35:144, 1996. (4) Y. Zhao et al. Int. J. Syst. Evol. Microbiol. 59:2582, 2009.

Download Full-text

First Report of a Group 16SrI Phytoplasma Associated with Amaranthus hypochondriacus Cladodes in China

Plant Disease ◽

10.1094/pdis-03-11-0219 ◽

2011 ◽

Vol 95 (7) ◽

pp. 871-871

Author(s):

J. Y. Long ◽

Y. H. Chen ◽

J. R. Xia

Keyword(s):

16S Rdna ◽

Nested Pcr ◽

Universal Primer ◽

First Report ◽

Amaranthus Hypochondriacus ◽

Rdna Sequences ◽

16S Rdna Sequences ◽

Ctab Method ◽

Pcr Products ◽

Blastn Analysis

Amaranthus spp. are cultivated worldwide as leafy vegetable, cereal, and ornamentals. In China, stems and leaves of Amaranthus hypochondriacus L. are used as a vegetable (2). In July 2010, sporadic amaranth plants exhibiting symptoms of cladodes and spica proliferation were observed in a vegetable garden near Foshan, Guangdong, China. Stem samples were collected from two symptomatic and two asymptomatic plants. Total DNA was extracted with a modified cetyltrimethylammonium bromide (CTAB) method (1). Nested PCR with a combination of phytoplasma-specific universal primer pairs (P1/P7 and R16F2n/R16R2) amplified 16S rDNA sequences with the expected size of 1.2 kb from all samples of symptomatic amaranth plants, but not from the asymptomatic plants (3). Nested PCR products yielded identical AluI, HhaI, HpaII, HaeIII, KpnI, MseI, RsaI, Sau3AI, and TaqI restriction fragment length polymorphism (RFLP) profiles with chinaberry witches'-broom phytoplasma (16SrI-B subgroup), but different from peanut witches'-broom phytoplasma (16SrII group), jujube witches'-broom phytoplasma (16SrV group), and paulownia witches'-broom phytoplasma (16SrI-D subgroup). Nested PCR products were purified, cloned in pMD18-T Simple Vector (TaKaRa, Dalian, China), and sequenced. The 16S rDNA sequences were identical and deposited in GenBank (Accession No. JF323034). GenBank BLASTn analysis indicated that the amaranth extracts showed as high as 99% sequence identity with the members of 16SrI group phytoplasmas, including those associated with arecanut yellow leaf disease (FJ998269) and aster yellow AY-27 (HM467127). A polygenetic tree was constructed using MEGA 4.0 based on the 16S rDNA sequences of amaranth cladode phytoplasma and other phytoplasmas belonging to 16SrI phytoplasma group. In phylogenetic analysis, the sequences clustered on a single branch with members of 16SrI-B subgroup in the tree. Therefore, the phytoplasma was classified in subgroup 16SrI-B. To our knowledge, this is the first report of a subgroup 16SrI-B phytoplasma associated with diseased A. hypochondriacus in China. References: (1) E. Angelini et al. Vitis 40:79, 2001. (2) M. Costea et al. Econ. Bot. 57:646, 2003. (3) I. M. Lee et al. Int. J. Syst. Bacteriol. 48:1153, 1998.

Download Full-text

First report of Coleus blumei viroid 1 in commercial Coleus blumei in the United States

Plant Disease ◽

10.1094/pdis-05-21-0917-pdn ◽

2021 ◽

Author(s):

Gardenia Orellana ◽

Alexander V Karasev

Keyword(s):

United States ◽

Leaf Tissue ◽

The United States ◽

Universal Primers ◽

Rt Pcr ◽

Universal Primer ◽

Tissue Samples ◽

First Report ◽

Specific Pcr ◽

Coleus Blumei

Coleus scutellarioides (syn. Coleus blumei) is a widely grown evergreen ornamental plant valued for its highly decorative variegated leaves. Six viroids, named Coleus blumei viroid 1 to 6 (CbVd-1 to -6) have been identified in coleus plants in many countries of the world (Nie and Singh 2017), including Canada (Smith et al. 2018). However there have been no reports of Coleus blumei viroids occurring in the U.S.A. (Nie and Singh 2017). In April 2021, leaf tissue samples from 27 cultivars of C. blumei, one plant of each, were submitted to the University of Idaho laboratory from a commercial nursery located in Oregon to screen for the presence of viroids. The sampled plants were selected randomly and no symptoms were apparent in any of the samples. Total nucleic acids were extracted from each sample (Dellaporta et al. 1983) and used in reverse-transcription (RT)-PCR tests (Jiang et al. 2011) for the CbVd-1 and CbVd-5 with the universal primer pair CbVds-P1/P2, which amplifies the complete genome of all members in the genus Coleviroid (Jiang et al. 2011), and two additional primer pairs, CbVd1-F1/R1 and CbVd5-F1/R1, specific for CbVd-1 and CbVd-5, respectively (Smith et al. 2018). Five C. blumei plants (cvs Fire Mountain, Lovebird, Smokey Rose, Marrakesh, and Nutmeg) were positive for a coleviroid based on the observation of the single 250-nt band in the RT-PCR test with CbVds-P1/P2 primers. Two of these CbVd-1 positive plants (cvs Lovebird and Nutmeg) were also positive for CbVd-1 based on the presence of a single 150-nt band in the RT-PCR assay with CbVd1-F1/R1 primers. One plant (cv Jigsaw) was positive for CbVd-1, i.e. showing the 150-nt band in RT-PCR with CbVd1-F1/R1 primers, but did not show the ca. 250-bp band in RT-PCR with primers CbVds-P1/P2. None of the tested plants were positive for CbVd-5, either with the specific, or universal primers. All coleviroid- and CbVd-1-specific PCR products were sequenced directly using the Sanger methodology, and revealed whole genomes for five isolates of CbVd-1 from Oregon, U.S.A. The genomes of the five CbVd-1 isolates displayed 96.9-100% identity among each other and 96.0-100% identity to the CbVd-1 sequences available in GenBank. Because the sequences from cvs Lovebird, Marrakesh, and Nutmeg, were found 100% identical, one sequence was deposited in GenBank (MZ326145). Two other sequences, from cvs Fire Mountain and Smokey Rose, were deposited in the GenBank under accession numbers MZ326144 and MZ326146, respectively. To the best of our knowledge, this is the first report of CbVd-1 in the United States.

Download Full-text

First Report of a 16SrII-D Subgroup Phytoplasma Associated with Pale Purple Coneflower Witches'-Broom Disease in Australia

Plant Disease ◽

10.1094/pdis-03-11-0155 ◽

2011 ◽

Vol 95 (6) ◽

pp. 773-773 ◽

Cited By ~ 7

Author(s):

T. L. Pearce ◽

J. B. Scott ◽

S. J. Pethybridge

Keyword(s):

Sequence Homology ◽

Sequence Similarity ◽

Universal Primer ◽

First Report ◽

Purple Coneflower ◽

Echinacea Pallida ◽

Pcr Products ◽

Broom Disease ◽

Plant Pathol ◽

Single Field

Pale purple coneflower, Echinacea pallida (Nutt.) Nutt., is an herbaceous perennial cultivated for its ornamental and medicinal properties. In 2005, phytoplasma-like symptoms, including virescence, phyllody, and chlorotic leaves, were first observed in coneflower fields in northern Tasmania, Australia. During the 2010–2011 growing season, the incidence of affected plants was estimated to be 12% within a single field. Total DNA was extracted from symptomatic plants with a DNeasy Plant Mini Kit (QIAGEN Inc., Valencia, CA) according to the manufacturer's instructions. DNA was also extracted, as described above, from asymptomatic coneflower seedlings obtained by germinating surface-sterilized seed on water agar. DNA was amplified via a nested PCR using universal primer pairs P1/P7 followed by R16F2n/R16R2 to detect putative phytoplasmas (2). Amplifications yielded expected products of 1.8 and 1.2 kb, respectively, only from symptomatic samples. Subsequently, PCR products from six arbitrarily selected samples were used for sequencing (Genome Lab Dye Terminator Cycling Sequence with Quick Start Chemistry) and read in a CEQ8000 sequencer (Beckman Coulter Inc., Brea, CA). Sequence homology indicated 100% similarity between isolates designated EWB1 to EWB4 (GenBank Accession Nos. JF340075 and JF340077 to JF340079) and between EWB5 and EWB6 (JF340076 and JF40080). Sequence homology between the two observed groups was 99.7%, resulting from a 4-bp difference in the R16F2n primer region. Blast search revealed isolates EWB1 to EWB4 were 100% homologous with Catharanthus roseus phytoplasma (EU096500.1), Tomato big bud phytoplasma (EF193359.1), Scaevola witches'-broom phytoplasma (AB257291.1), and Mollicutes sp. (Y10097.1 and Y10096.1). Moreover, isolates EWB5 and EWB6 shared 99% sequence identity with the above isolates. iPhyClassifier (4) was used to perform sequence similarity and generate virtual restriction fragment length polymorphism (RFLP) profiles. The 16S rDNA sequence of isolates EWB1 to EWB4 and EWB5 to EWB6 shared 100 and 99.7% similarity, respectively, to the ‘Candidatus Phytoplasma australasiae’ reference strain (Y10097). RFLP profiles from all isolates suggested that they belonged to the 16SrII-D subgroup. To our knowledge, this is the first report of a 16SrII-D subgroup phytoplasma infecting E. pallida in Australia. Aster yellow phytoplasmas (16SrI-C subgroup) infections of E. purpurea have been recorded in Slovenia (3) and southern Bohemia (1). References: (1) J. Franova et al. Eur. J. Plant Pathol. 123:85, 2009. (2) I. M. Lee et al. Int. J. Syst. Bacteriol. 48:1153, 1998. (3) S. Radišek et al. Plant Pathol. 58:392, 2009. (4) Y. Zhao et al. Int. J. Syst. Evol. Microbiol. 59:2582, 2009.

Download Full-text

First Report of Pear Decline Phytoplasmas on Pear in Serbia

Plant Disease ◽

10.1094/pd-89-0774c ◽

2005 ◽

Vol 89 (7) ◽

pp. 774-774 ◽

Cited By ~ 3

Author(s):

B. Duduk ◽

M. Ivanović ◽

A. Obradović ◽

S. Paltrinieri ◽

A. Bertaccini

Keyword(s):

Nested Pcr ◽

Restriction Enzymes ◽

Diagnostic Procedures ◽

Nested Polymerase Chain Reaction ◽

Universal Primer ◽

First Report ◽

Taxonomy Group ◽

Pyrus Communis L ◽

Polymerase Chain ◽

Symptomatic Plant

During August of 2004, pear (Pyrus communis L.) plants with typical symptoms of pear decline (PD) were observed in orchards in central Serbia. The affected plants showed premature reddening and upward rolling of leaves that often showed down-turned petioles. In some cases, premature defoliation was observed. Although a similar decline of pear was observed earlier, until now, the causal agent had not been identified. DNA was extracted with a chloroform/phenol procedure from fresh leaf midribs and branch phloem scrapes of four symptomatic and one asymptomatic pear plants separately. A nested polymerase chain reaction assay (PCR) was used for phytoplasma detection (first PCR round with P1/P7 (4) phytoplasma universal primer pair, followed by nested PCR with group 16SrX specific primers f01/r01) (3). With these primers, the expected products from phloem scrapes and midrib extracts of symptomatic plant samples were obtained. Restriction fragment length polymorphism (RFLP) analyses of the f01/r01 amplicon, with RsaI and SspI restriction enzymes, discriminating among 16SrX subgroup phytoplasmas, showed profiles corresponding to those of the apple proliferation phytoplasma group, 16SrX-C subgroup, “Candidatus Phytoplasma pyri” (2). A 1,155-bp sequence of 16S rDNA gene for one of the PA2f/r (1) amplicons obtained in nested PCR on P1/P7 products from one of the leaf midrib samples was deposited in GenBank (Accession No. AY949984); both strands of the fragment were sequenced with the Big Dye Terminator reaction kit (Applied Biosystems, Foster City, CA). The sequences were analyzed with the Chromas 1.55 DNA sequencing software (Technelysium, Queensland, Australia) and aligned with BLAST software ( http://www.ncbi.nlm.nih.gov ). The blast search showed 100% homology of this sequence with that of PD strain Y16392, confirming the identity with PD of the phytoplasma detected. To our knowledge, this is the first report of pear decline phytoplasmas in Serbia. References: (1) M. Heinrich et al. Plant Mol. Biol. Rep. 19:169, 2001. (2) IRPCM Phytoplasma/Spiroplasma Working Team-Phytoplasma Taxonomy Group. Int. J. Syst. Evol. Microbiol. 54:1243, 2004. (3) K.-H. Lorenz et al. Phytopathology 85:771, 1995. (4) Schneider et al. Pages 369–380 in: Molecular and Diagnostic Procedures in Mycoplasmology. Vol I. S. Razin and J. G. Tully, eds. The American Phytopathological Society, 1995.

Download Full-text

First Report of Botrytis Blight Caused by Botrytis cinerea on Purple Coneflower (Echinacea purpurea) in Italy

Plant Disease ◽

10.1094/pdis-09-17-1400-pdn ◽

2018 ◽

Vol 102 (4) ◽

pp. 821-821

Author(s):

A. Garibaldi ◽

G. Gilardi ◽

S. Franco Ortega ◽

M. L. Gullino

Keyword(s):

Botrytis Cinerea ◽

Echinacea Purpurea ◽

First Report ◽

Purple Coneflower

Download Full-text

First Report of Group 16SrXII Phytoplasma Causing Stolbur Disease in Potato Plants in the Eastern and Southern Anatolia Regions of Turkey

Plant Disease ◽

10.1094/pdis-06-10-0439 ◽

2010 ◽

Vol 94 (11) ◽

pp. 1374-1374 ◽

Cited By ~ 6

Author(s):

S. Eroglu ◽

H. Ozbek ◽

F. Sahin

Keyword(s):

16S Rdna ◽

Rdna Sequence ◽

Universal Primers ◽

Effective Control ◽

Diseased Plant ◽

Eastern Anatolia ◽

Universal Primer ◽

16S Rdna Sequence ◽

First Report ◽

Potato Plants

In recent years, a stolbur-like disease has had devastating effects on the yield and marketable quality of potato production in Erzurum (Eastern Anatolia) and Akcakale-Sanliurfa (Southern Anatolia) regions of Turkey. Potato plants exhibited several different symptoms including stunting, upward rolling of the top leaves along with reddish or purplish coloration, chlorosis, shortened internodes, swollen nodes, proliferated axillary buds, aerial tubers, and early plant decline. An extensive survey from 2003 to 2010 was performed and diseased plant samples were collected. Total genomic DNAs were isolated from the leaf mid-veins of the six different symptomatic and two symptomless plants selected. Nested-PCRs, carried out by using phytoplasma-universal primer pair P1/P7 followed by R16F2n/R16R2 (2), amplified 16S rDNA fragments (F2nR2) from only templates derived from symptomatic plants. F2nR2 PCR products from two independent symptomatic plants were cloned and sequenced from both directions with M13 universal primers. The obtained 16S rDNA sequence (GenBank Accession No HM485579) was subjected to virtual restriction fragment length polymorphism (RFLP) analysis using iphyclassifier software (3). Results indicated that the phytoplasma, here identified in association with potato plants, shared best sequence identity (99%) with members of subgroup 16SrXII-A (e.g., GenBank Accession No. EU010006). Moreover, collective RFLP pattern of potato-associated phytoplasma differed from digestion profiles of previously described 16SrXII subgroups, sharing best similarity coefficient (0.94) with the reference phytoplasma strain of subgroup 16SrXII-A (GenBank Accession No. AJ964960). Thus, it was confirmed that potato-associated phytoplasma represents a new 16SrXII subgroup (16SrXII-N). Furthermore, a new primer set (PatsecF/PatsecR) was designed for priming specific PCR-amplification of potato-associated phytoplasma 16S rDNA sequence. PCR reaction was successfully used for specifically detecting stolbur phytoplasma in infected potato plants. The use of this method may help to determine possible alternative hosts and vectors of potato phytoplasma, which is important for development of an integrated management strategy for effective control of this disease in the future. Presence of potato stolbur diseases in the Eastern Anatolia Region of Turkey has previously been reported (1). To our knowledge, this is the first report of occurrence of a 16SrXII group phytoplasma causing potato stolbur diseases caused in the Eastern and Southern Anatolia regions of Turkey. References: (1) A. Citir. J. Turk. Phytopathol. 14:53, 1985. (2) D. E. Gundersen and I. M. Lee. Phytopathol. Mediterr. 35:144, 1996. (3)Y. Zhao et al. Int. J. Syst. Evol. Microbiol. 59:2582, 2009.

Download Full-text

First Report of Leaf Blight and Root and Foot Rot of a Strelitzia Caused by Phytophthora nicotianae in Italy

Plant Disease ◽

10.1094/pdis-94-1-0134a ◽

2010 ◽

Vol 94 (1) ◽

pp. 134-134 ◽

Cited By ~ 1

Author(s):

L. Luongo ◽

M. Galli ◽

L. Riccioni ◽

A. Belisario

Keyword(s):

Leaf Blight ◽

Phytophthora Nicotianae ◽

Flowering Plant ◽

Foot Rot ◽

In Planta ◽

Phytophthora Blight ◽

Tissue Samples ◽

First Report ◽

Leaf Spots

Bird of paradise, also known as crane flower (Strelitzia reginae Aiton), is a monocotyledonous flowering plant indigenous to South Africa. It is commonly grown and commercialized as an ornamental plant and it is appreciated for its beautiful flowers. In October of 2008, dark leaf spots and leaf blight associated with a severe root and foot rot were observed on several plants of S. reginae grown in a private garden located in Fiumicino, Italy. Small fragments of tissues (approximately 3 mm) collected from the base of leaves and roots and the margins of brown lesions, previously surface disinfected with 0.5% NaOCl, were plated onto potato dextrose agar (PDA) and incubated at 22°C in the dark. White, web-like, slow-growing colonies with coenocytic mycelium and hyphal swellings consistently developed from all plated tissue samples. Sporangia were ovoid or ellipsoid with prominent papillae (including some bipapillate) and frequently caducous with a short stalk. The dimensions of sporangia were 27 to 64 × 23 to 45 μm (average 43 × 35 μm). Chlamydospores were terminal or intercalary and approximately 30 μm in diameter. Isolates were considered heterothallic because they did not produce gametangia in vitro or in planta. On the basis of morphological features, isolates were identified as Phytophthora nicotianae (Breda de Haan). The identity was confirmed by internal transcribed spacer (ITS) sequence comparison in NCBI database with 99% identity with sequences available in GenBank (e.g., EU331089) and with cytochrome c oxidase subunit I (Cox I) with 99% identity with AY564196 by Kroon et al. (2). The sequences of one isolate, AB177, were deposited in GenBank (Accession Nos. FN430681 and FN552051 for ITS and Cox I, respectively). Pathogenicity tests were conducted in the greenhouse on leaves of a 1-year-old potted S. reginae plant by placing 5-mm-diameter mycelial plugs, cut from the margins of 10-day-old actively growing cultures, with mycelium in contact with plant tissues gently wounded with a needle. Controls were treated as described above, except that PDA sterile plugs were used. Plants were misted with water and placed in sealed plastic bags for 48 h. After 10 days, artificially wounded strelitzia leaves showed lesions (approximately 1 cm long). Controls remained symptomless. All inoculated leaves showed the same leaf symptoms as observed on naturally diseased plants. The pathogen was consistently reisolated from lesions. P. nicotianae has been reported as the causal agent of leaf blight and stem, collar, and root rot on several plants (1). It has been reported as an agent of Phytophthora blight on strelitzia in Japan (3). To our knowledge, this is the first report of P. nicotianae on strelitzia in Italy. References: (1) D. C. Erwin and O. K. Ribeiro. Phytophthora Diseases Worldwide. The American Phytopathological Society, St. Paul, MN, 1996. (2) L. P. N. M. Kroon et al. Fungal Genet. Biol. 41:766, 2004. (3) S. Uematsu et al. Ann. Phytopathol. Soc. Jpn. 60:746, 1994.

Download Full-text