scholarly journals First Report of Leaf Spot Caused by Cladosporium perangustum on Syagrus oleracea in Brazil

Plant Disease ◽  
2014 ◽  
Vol 98 (2) ◽  
pp. 280-280 ◽  
Author(s):  
R. R. Oliveira ◽  
R. L. Aguiar ◽  
D. J. Tessmann ◽  
W. M. C. Nunes ◽  
A. F. Santos ◽  
...  
Keyword(s):  
Leaf Spot ◽  
Sequence Data ◽  
Elongation Factor ◽  
Leaf Tissue ◽  
Unknown Etiology ◽  
Palm Tree ◽  
First Report ◽  
Potted Plants ◽  
Central Brazil ◽  
Dna Sequence Data

Syagrus oleracea (Mart.) Becc. (bitter coconut), a palm tree species that is native to central Brazil, has been increasingly cultivated in this country for heart-of-palm production. Epidemics of a necrotic leaf spot of unknown etiology have been recorded on bitter coconut plants in transplant nurseries and plantation since 2008. The first symptoms appear as small, yellow, hydrotic flecks on young or mature leaves that evolve to necrotic brown streaks that run parallel to the leaf veins. Usually, yellow halos occur around the lesions and hydrosis is common during lesion expansion. Necrotic lesions can reach up to 40 mm in length and 10 mm in width, and the lesions often coalesce, causing extensive tissue damage. During a survey in a 3-year-old bitter coconut plantation in Maringá County (coordinates: 23°23′51.25″ S, 51°57′02.09″ W; elevation: 507 m) in the state of Parana, a dozen symptomatic leaves were collected with the aim of elucidating the etiology of this disease. Conidia and conidiophores typical of Cladosporium were frequently observed on the diseased leaf tissue under natural field conditions as well on the surfaces of disinfected leaf tissues kept in a humid chamber for 48 h at 25 ± 2°C with a 12-h photoperiod. Five monoconidial cultures growing on potato dextrose agar (PDA) medium were obtained from different leaves showing leaf spot symptoms. The cultures were grown on PDA to induce sporulation. At 7 days after incubation at 25 ± 2°C and a 12-h photoperiod, gray to gray-olive colonies were observed. The conidiophores were macronematous, erect, oblong, branched, 1 to 5 septate, and 75.0 to 120.0 × 1.90 to 3.20 μm. The ramoconidia were cylindrical or oblong, 0 to 2 septate, and 28.0 to 40.0 × 2.8 to 3.6 μm, with a truncate base of 1.9 to 2.2 μm; secondary ramoconidia were cylindrical or oblong, 0 to 2 septate, 8.0 to 31.0 × 2.2 to 3.1 μm, with 3 to 5 distal conidial hila; intercalary 1-septate conidia were 5.5 to 17.0 × 2.1 to 3.4 μm, with 1 to 3 distal conidial hila; terminal 1-septate conidia were catenulate and 2.2 to 4.2 × 1.8 to 3.1 μm. Species identification was performed based on morphology and DNA sequence data (1). Portions of the elongation factor 1α (551 bp; TEF) and actin (213 bp; ACT) genes were amplified by PCR. A BLAST search of the GenBank database revealed that the TEF (KC484658 to KC484662) and ACT (KC484663 to KC484667) sequence fragments from isolates Gua1, Gua2, Gua3, Gua4, and Gua5 had 100% identity with the accessions HM148616 and HM148371 of Cladosporium perangustum (1). Isolates were tested for pathogenicity against bitter coconut. Ten potted plants with 4 to 6 fully expanded leaves were inoculated with each isolate by spraying a suspension of conidia (105 spores per ml) onto leaves until runoff using a handheld spray bottle. Non-inoculated controls (10 plants) were sprayed with distilled water. The plants were kept in a humid plastic chamber at 20 to 26°C. All examined isolates were pathogenic to bitter coconut, causing symptoms identical to those described above 12 days after inoculation. All inoculated tissues were plated onto PDA to confirm the presence of the pathogen. Live cultures are being maintained at the Micoteca/URM/UFPE ( www.ufpe.br/micoteca ), Brazil. To our knowledge, this is the first report of a disease caused by C. perangustum on S. oleracea worldwide, and the study provides valuable plant disease diagnostic information for the palm hearth industry in Latin America. Reference: (1) K. Bensch et al. Stud Mycol. 67:1, 2010.

scholarly journals First Report of a Chaetomella sp. Causing a Leaf Spot on Sansevieria trifasciata in China

Plant Disease ◽  
2013 ◽  
Vol 97 (7) ◽  
pp. 992-992 ◽  
Author(s):  
Y. L. Li ◽  
Z. Zhou ◽  
W. Lu ◽  
J. R. Ye
Keyword(s):  
Leaf Spot ◽  
Disease Incidence ◽  
Morphological Characteristics ◽  
Leaf Tissue ◽  
Aerial Mycelium ◽  
Control Treatment ◽  
Distilled Water ◽  
First Report ◽  
Potted Plants ◽  
Fungal Isolates

Sansevieria trifasciata originates from tropical West Africa. It is widely planted as a potted ornamental in China for improving indoor air quality (1). In February 2011, leaves of S. trifasciata plants in an ornamental market of Anle, Luoyang City, China, were observed with sunken brown lesions up to 20 mm in diameter, and with black pycnidia present in the lesions. One hundred potted plants were examined, with disease incidence at 20%. The symptomatic leaves affected the ornamental value of the plants. A section of leaf tissue from the periphery of two lesions from a plant was cut into 1 cm2 pieces, soaked in 70% ethanol for 30 s, sterilized with 0.1% HgCl2 for 2 min, then washed five times in sterilized distilled water. The pieces were incubated at 28°C on potato dextrose agar (PDA). Colonies of two isolates were brown with submerged hyphae, and aerial mycelium was rare. Abundant and scattered pycnidia were reniform, dark brown, and 200 to 350 × 100 to 250 μm. There were two types of setae on the pycnidia: 1) dark brown setae with inward curved tops, and 2) straight, brown setae. Conidia were hyaline, unicellular, cylindrical, and 3.75 to 6.25 × 1.25 to 2.50 μm. Morphological characteristics suggested the two fungal isolates were a Chaetomella sp. To confirm pathogenicity, six mature leaves of a potted S. trifasciata plant were wounded with a sterile pin after wiping each leaf surface with 70% ethanol and washing each leaf with sterilized distilled water three times. A 0.5 cm mycelial disk cut from the margin of a 5-day-old colony on a PDA plate was placed on each pin-wounded leaf, ensuring that the mycelium was in contact with the wound. Non-colonized PDA discs were placed on pin-wounded leaves as the control treatment. Each of two fungal isolates was inoculated on two leaves, and the control treatment was done similarly on two leaves. The inoculated plant was placed in a growth chamber at 28°C with 80% relative humidity. After 7 days, inoculated leaves produced brown lesions with black pycnidia, but no symptoms developed on the control leaves. A Chaetomella sp. was reisolated from the lesions of inoculated leaves, but not from the control leaves. An additional two potted plants were inoculated using the same methods as replications of the experiment, with identical results. To confirm the fungal identification, the internal transcribed spacer (ITS) region of rDNA of the two isolates was amplified using primers ITS1 and ITS4 (2) and sequenced. The sequences were identical (GenBank Accession No. KC515097) and exhibited 99% nucleotide identity to the ITS sequence of an isolate of Chaetomella sp. in GenBank (AJ301961). To our knowledge, this is the first report of a leaf spot of S. trifasciata caused by Chaetomella sp. in China as well as anywhere in the world. References: (1) X. Z. Guo et al. Subtropical Crops Commun. Zhejiang 27:9, 2005. (2) T. J. White et al. PCR Protocols: A Guide to Methods and Applications. M. A. Innis et al., eds. Academic Press, San Diego, CA, 1990.

scholarly journals Pseudocercospora and allied genera associated with leaf spots of banana (Musa spp.)

2020 ◽  
Author(s):  
P.W. Crous ◽  
J. Carlier ◽  
V. Roussel ◽  
J.Z. Groenewald
Keyword(s):  
Rna Polymerase Ii ◽  
Leaf Spot ◽  
Sequence Data ◽  
Elongation Factor ◽  
Leaf Spot Disease ◽  
Black Sigatoka ◽  
Dna Sequence Data ◽  
Leaf Spots ◽  
Black Leaf Streak ◽  
Close Relatives

The Sigatoka leaf spot complex on Musa spp. includes three major pathogens: Pseudocercospora, namely P. musae (Sigatoka leaf spot or yellow Sigatoka), P. eumusae (eumusae leaf spot disease), and P. fijiensis (black leaf streak disease or black Sigatoka). However, more than 30 species of Mycosphaerellaceae have been associated with Sigatoka leaf spots of banana, and previous reports of P. musae and P. eumusae need to be re-evaluated in light of recently described species. The aim of the present study was thus to investigate a global set of 228 isolates of P. musae, P. eumusae and close relatives on banana using multigene DNA sequence data [internal transcribed spacer regions with intervening 5.8S nrRNA gene (ITS), RNA polymerase II second largest subunit gene (rpb2), translation elongation factor 1-alpha gene (tef1), beta-tubulin gene (tub2), and the actin gene (act)] to confirm if these isolates represent P. musae, or a closely allied species. Based on these data one new species is described, namely P. pseudomusae, which is associated with leaf spot symptoms resembling those of P. musae on Musa in Indonesia. Furthermore, P. eumusae, P. musae and P. fijiensis are shown to be well defined taxa, with some isolates also representing P. longispora. Other genera encountered in the dataset are species of Zasmidium (Taiwan leaf speckle), Metulocladosporiella (Cladosporium leaf speckle) and Scolecobasidium leaf speckle.

scholarly journals First Report of Leaf Spot Caused by Nigrospora aurantiaca in Tobacco in China

Plant Disease ◽  
2020 ◽  
Author(s):  
Yu Huang ◽  
Zhong LI ◽  
Han-cheng Wang ◽  
Qianli Chen ◽  
Wen hong Li
Keyword(s):  
Leaf Spot ◽  
Management Practices ◽  
Large Subunit ◽  
Elongation Factor ◽  
Morphological Characteristics ◽  
Leaf Tissue ◽  
Guizhou Province ◽  
Bootstrap Support ◽  
First Report ◽  
Pcr Products

Tobacco (Nicotiana tabacum L.) is one of the most important cash crops in China. In June 2019, tobacco (cv. Yunyan 87) samples with gray spots surrounded by yellowish ring were collected in Zhengan (107.43° N, 28.55° E), Guizhou province, China. Pieces of leaf tissue (3 mm × 3 mm) that were cut at the junction of diseased and healthy portion were surface sterilized and plated on potato dextrose agar (PDA). After incubation at 25°C in the dark for 7 days, an isolate (T22) was chosen and used for pathogen identification. The colonies had aerial hyphae, initially white and then turned grey, and produced a soluble red pigmen on PDA. The colonies were floccose aerial mycelia, dark grey, with pale brown hyphae, and produced conidia on oatmeal agar. Conidia were ovoid or ampulliform, black, smooth. Based on morphological characteristics, isolate T22 was identified as Nigrospora aurantiaca (Wang et al. 2017). For molecular identification, the large subunit (LSU) and internal transcribed spacer (ITS) of ribosomal RNA, β-tubulin (TUB) and translation elongation factor 1-alpha (TEF1) genes of T22 were amplified by PCR with the primer sets LROR/LR5, ITS1/ITS4, Bt2a/Bt2b and EF1-728F/EF2 (Suwannarach et al.2019), then PCR products were sequenced. Their GenBank accession numbers were MT341787, MT328649, MT348395 and MT348394, respectively. Phylogenetic tree of combined LSU, ITS, TUB, and TEF sequences showed that isolate T22 was assigned to N. aurantiaca strain (CGMCC 3.18130 and LC 7034) with 100% bootstrap support. Based on morphological characteristics and multi-gene molecular analysis, isolate T22 was identified as N. aurantiaca. To fulfill Koch’s postulates, PDA plugs grown with N. aurantiaca were placed on the leaves of four tobacco plants (cv. Yunyan 87) at the 10-leaf stage. Leaves inoculated with PDA only plugs served as the controls. Treated plants were maintained in a greenhouse with temperatures ranging from 18 to 28 °C. Five days after inoculation, typical symptoms were observed on inoculated leaves but not on the controls. N. aurantiaca was re-isolated from the diseased leaves but not from the controls. To our best of knowledge, this is the first report of N. aurantiaca causing leaf spot on tobacco in China. N. aurantiaca has been reported to cause leaf spot on Castanea mollissima in China (Luo et al. 2020). Due to potential serious damage caused by the disease in this region, proper disease management practices should be developed and implemented.

FUSARIUM-ID v.3.0: An updated, downloadable resource for Fusarium species identification

Plant Disease ◽  
2021 ◽  
Author(s):  
Terry Torres-Cruz ◽  
Briana Whitaker ◽  
Robert Proctor ◽  
Kirk Broders ◽  
Imane Laraba ◽  
...  
Keyword(s):  
Sequence Data ◽  
Safety Concern ◽  
Fusarium Species ◽  
Elongation Factor ◽  
Sequence Database ◽  
Accurate Identification ◽  
Dna Sequence Data ◽  
Species Complexes ◽  
Marker Loci ◽  
Feed Safety

Species within Fusarium are of global agricultural, medical, and food/feed safety concern and have been extensively characterized. However, accurate identification of species is challenging and usually requires DNA sequence data. FUSARIUM-ID (http://isolate.fusariumdb.org/) is a publicly available database designed to support the identification of Fusarium species using sequences of multiple phylogenetically informative loci, especially the highly informative ~680 bp 5' portion of the translation elongation factor 1-alpha (TEF1) gene that has been adopted as the primary barcoding locus in the genus. However, FUSARIUM-ID v.1.0 and 2.0 had several limitations, including inconsistent metadata annotation for the archived sequences and poor representation of some species complexes and marker loci. Here, we present FUSARIUM-ID v.3.0, which provides the following improvements: (i) additional and updated annotation of metadata for isolates associated with each sequence, (ii) expanded taxon representation in the TEF1 sequence database, (iii) availability of the sequence database as a downloadable file to enable local BLAST queries, and (iv) a tutorial file for users to perform local BLAST searches using either freely-available software, such as SequenceServer, BLAST+ executable in the command line, and Galaxy, or the proprietary Geneious software. FUSARIUM-ID will be updated on a regular basis by archiving sequences of TEF1 and other loci from newly identified species and greater in-depth sampling of currently recognized species.

scholarly journals Characterization and Pathogenicity of Botryosphaeriaceae Species Collected from Olive and Other Hosts in Spain and California

2010 ◽  
Vol 100 (12) ◽  
pp. 1340-1351 ◽  
Author(s):  
Juan Moral ◽  
Concepción Muñoz-Díez ◽  
Nazaret González ◽  
Antonio Trapero ◽  
Themis J. Michailides
Keyword(s):  
Sequence Data ◽  
Close Association ◽  
Elongation Factor ◽  
Fruit Rot ◽  
Disease Symptoms ◽  
Dna Sequence Data ◽  
Olive Fly ◽  
The Family ◽  
Pathogenicity Tests ◽  
Olive Trees

Species in the family Botryosphaeriaceae are common pathogens causing fruit rot and dieback of many woody plants. In this study, 150 Botryosphaeriaceae isolates were collected from olive and other hosts in Spain and California. Representative isolates of each type were characterized based on morphological features and comparisons of DNA sequence data of three regions: internal transcribed spacer 5.8S, β-tubulin, and elongation factor. Three main species were identified as Neofusicoccum mediterraneum, causing dieback of branches of olive and pistachio; Diplodia seriata, causing decay of ripe fruit and dieback of olive branches; and Botryosphaeria dothidea, causing dalmatian disease on unripe olive fruit in Spain. Moreover, the sexual stage of this last species was also found attacking olive branches in California. In pathogenicity tests using unripe fruit and branches of olive, D. seriata isolates were the least aggressive on the fruit and branches while N. mediterraneum isolates were the most aggressive on both tissues. Isolates of B. dothidea which cause dalmatian disease on fruit were not pathogenic on branches and only weakly aggressive on fruit. These results, together with the close association between the presence of dalmatian disease symptoms and the wound created by the olive fly (Bactrocera oleae), suggest that the fly is essential for the initiation of the disease on fruit. Isolates recovered from dalmatian disease symptoms had an optimum of 26°C for mycelial growth and 30°C for conidial germination, suggesting that the pathogen is well adapted to high summer temperatures. In contrast, the range of water activity in the medium for growth of dalmatian isolates was 0.93 to 1 MPa, which was similar to that for the majority of fungi. This study resolved long-standing questions of identity and pathogenicity of species within the family Botryosphaeriaceae attacking olive trees in Spain and California.

scholarly journals First Report of a Leaf Spot Disease of Bells-of-Ireland (Moluccella laevis) Caused by Cercospora apii in California

Plant Disease ◽  
2003 ◽  
Vol 87 (2) ◽  
pp. 203-203
Author(s):  
S. T. Koike ◽  
S. A. Tjosvold ◽  
J. Z. Groenewald ◽  
P. W. Crous
Keyword(s):  
Leaf Spot ◽  
Sequence Data ◽  
Disease Incidence ◽  
Leaf Spot Disease ◽  
Conidial Suspension ◽  
Internal Transcribed Spacer Region ◽  
First Report ◽  
Spot Disease ◽  
Leaf Spots ◽  
Initial Symptoms

Bells-of-Ireland (Moluccella laevis) (Lamiaceae) is an annual plant that is field planted in coastal California (Santa Cruz County) for commercial cutflower production. In 2001, a new leaf spot disease was found in these commercially grown cutflowers. The disease was most serious in the winter-grown crops in 2001 and 2002, with a few plantings having as much as 100% disease incidence. All other plantings that were surveyed during this time had at least 50% disease. Initial symptoms consisted of gray-green leaf spots. Spots were generally oval in shape, often delimited by the major leaf veins, and later turned tan. Lesions were apparent on both adaxial and abaxial sides of the leaves. A cercosporoid fungus having fasciculate conidiophores, which formed primarily on the abaxial leaf surface, was consistently associated with the spots. Based on morphology and its host, this fungus was initially considered to be Cercospora molucellae Bremer & Petr., which was previously reported on leaves of M. laevis in Turkey (1). However, sequence data obtained from the internal transcribed spacer region (ITS1, ITS2) and the 5.8S gene (STE-U 5110, 5111; GenBank Accession Nos. AY156918 and AY156919) indicated there were no base pair differences between the bells-of-Ireland isolates from California, our own reference isolates of C. apii, as well as GenBank sequences deposited as C. apii. Based on these data, the fungus was subsequently identified as C. apii sensu lato. Pathogenicity was confirmed by spraying a conidial suspension (1.0 × 105 conidia/ml) on leaves of potted bells-of-Ireland plants, incubating the plants in a dew chamber for 24 h, and maintaining them in a greenhouse (23 to 25°C). After 2 weeks, all inoculated plants developed leaf spots that were identical to those observed in the field. C. apii was again associated with all leaf spots. Control plants, which were treated with water, did not develop any symptoms. The test was repeated and the results were similar. To our knowledge this is the first report of C. apii as a pathogen of bells-of-Ireland in California. Reference: (1) C. Chupp. A Monograph of the Fungus Genus Cercospora. Cornell University Press, Ithaca, New York, 1954.

scholarly journals First Report of Corynespora Leaf Spot on Patchouli Caused by Corynespora cassiicola in China

Plant Disease ◽  
2010 ◽  
Vol 94 (12) ◽  
pp. 1508-1508 ◽  
Author(s):  
X. Y. Chen ◽  
C. Sui ◽  
B. C. Gan ◽  
J. H. Wei ◽  
Y. K. Zhou
Keyword(s):  
Leaf Spot ◽  
Control Measures ◽  
Economic Losses ◽  
Leaf Spot Disease ◽  
Commonwealth Mycological Institute ◽  
Corynespora Cassiicola ◽  
Manihot Esculenta Crantz ◽  
First Report ◽  
Spot Disease ◽  
Potted Plants

Patchouli (Pogostemon cablin (Blanco) Benth.) is mainly cultivated in Southeast Asia as a medicinal shrub and a source of patchouli oil used in perfumery. In 2008, a leaf spot disease was observed on patchouli plants grown on most farms (some farms had 99% incidence) in Wanning, the predominant cultivation location in the Hainan Province of China. The disease usually began at the tip of leaves, the main veins, or small veinlets. Severely irregular-shaped dark brown leaf spots expanded over 5 to 10 days, eventually causing infected leaves to abscise. The time from initial leaf lesions to abscission usually took 1 month. The disease was usually most severe in April and May, causing significant economic losses along with quality losses to patchouli oil extracted from leaves. To isolate the causal pathogen, diseased leaves were collected in August 2008 from a farm of the Hainan Branch Institute of Medicinal Plant Development in Wanning, surface sterilized in 75% ethanol for 1 min, transferred to potato dextrose agar (PDA), and incubated at 28°C for 14 days. Single-spore cultures of three isolates were obtained and identified as Corynespora cassiicola (Berk. & Curt.) Wei. on the basis of morphological and physiological features (1). Genomic DNA was extracted from all the cultures. The internal transcribed spacer (ITS) region of the rDNA was amplified using primers ITS1 (5′-TCCGATGGTGAACCTGCGG-3′) and ITS4 (5′-TCCTCCGCTTATTGATATGC-3′). Amplicons were 546 bp (GenBank Accession No. HM145960) and had 99% nucleotide identity with the corresponding sequence (GenBank Accession No. GU138988) of C. cassiicola isolated from cassava (Manihot esculenta Crantz). To satisfy Koch's postulates, 50-day-old potted plants in a tent were sprayed until runoff with a spore suspension (1 × 106 spores/ml) prepared from 10-day-old cultures. Using this spray method, one isolate was inoculated separately onto nine leaves of three potted plants. The potted plants were covered with plastic bags to maintain high humidity for 48 h and then placed outside under natural environmental conditions (temperature 20 to 28°C). Another nine leaves of three potted plants, sprayed only with sterile water, served as noninoculated control plants. Leaf spot symptoms similar to those on diseased field plants appeared after 7 days on all inoculated plants. C. cassiicola was reisolated from all inoculated test plants. No symptoms were observed on the control plants. To our knowledge, this is the first report of C. cassiicola causing a leaf spot disease on patchouli in China. Other previous reports of this disease were from Cuba (2). This pathogen has also been reported previously to be economically important on a number of other hosts. On patchouli plants, more attention should be given to prevention and control measures to help manage this disease. References: (1) M. B. Ellis. Dematiaceous Hyphomycetes. Commonwealth Mycological Institute: Kew, Surrey, England, 1971. (2) I. Sandoval et al. Cienc. Tec. Agric., Prot. Plant. 10:21, 1987.

scholarly journals First Report of Leaf Spot Disease on Schisandra chinensis Caused by Phoma glomerata in China

Plant Disease ◽  
2012 ◽  
Vol 96 (2) ◽  
pp. 289-289 ◽  
Author(s):  
X. Wang ◽  
J. Wang ◽  
J. Gao ◽  
L. Yang
Keyword(s):  
Leaf Spot ◽  
Sequence Data ◽  
Leaf Spot Disease ◽  
Infected Leaf ◽  
Its Sequence ◽  
Schisandra Chinensis ◽  
Water Control ◽  
First Report ◽  
Spot Disease ◽  
Leaf Tissues

Schisandra chinensis (Turcz.) Baill is a perennial liana belonging to the Schisandra genus of the family Magnoliaceae, which is cultivated in China as an important medicinal plant. In the summer of 2008, we observed a previously unknown foliar disease on the schisandras in Jingyu and Antu counties and the cities of Ji'an and Hunchun in Jilin Province. Symptoms appeared on the apex, margin, and center of leaves. The infection initially manifested as pale brown, small, necrotic spots on the leaves. Subsequently, these lesions became grayish brown in the center and dark brown with slight protuberances at the margins. Finally, these lesions developed concentric rings with a clear boundary separating them from the healthy tissue, were round to elliptical or irregular in shape, and had a diameter of 3 to 5 mm. In severely infected leaves, these spots eventually covered the entire leaf. Black spots (pycnidia) were produced on the infected leaf tissues in a humid environment. Fungus from infected leaf tissues was isolated on potato dextrose agar. The cultures were initially pale brown and turned dark green with age. Embedded pycnidia were generally formed after 5 days. The pycnidia were agglutinating, globose to subglobose, and measured 60.0 to 212.0 × 33.6 to 268.0 μm. Abundant conidia (4.06 to 7.2 × 1.65 to 3.53 μm) exhibiting zero to three oil droplets were produced by an 8-day-old colony; these conidia were ovoid or ellipsoidal, colorless, and aseptate; they were similar to conidia of Phoma glomerata. The internal transcribed spacer (ITS) sequence of rDNA of the isolated pathogenic strain (PG11; GenBank Accession No. GU724511) had 100% identity to P. glomerata (GenBank Accession No. HM769279). Therefore, the pathogen was identified as P. glomerata (Corda) Wollenw. & Hochapfel on the basis of morphology and ITS sequence data. To validate Koch's postulates, schisandra leaves were spray inoculated with a 2.5 × 105 conidia/ml suspension of the isolated pathogen. An equal number of healthy plants were inoculated with sterile water (control). After inoculation, 10 plants were covered with plastic bags for 3 days and maintained in a growth chamber at 25°C. After 8 days, all inoculated plants showed symptoms identical to those observed on the schisandra leaves infected in the field, whereas the controls did not show any symptoms. Reisolation of the fungi from lesions of inoculated leaves confirmed that the causal agent was P. glomerata. Diseases caused by P. glomerata have been reported on some plants (1,2). However, to our knowledge, this is the first report of leaf spot disease caused by P. glomerata on S. chinensis in China as well as in the world. References: (1) J. S. Chohan et al. Trans. Br. Mycol. Soc. 75:509, 1980. (2) T. Thomidis et al. Eur. J. Plant Pathol. 131:171,2011.

scholarly journals First report of Curvularia plantarum causing leaf spot on sweet potato (Ipomoea batatas) in China

Plant Disease ◽  
2021 ◽  
Author(s):  
Jiahao Lai ◽  
Tongke Liu ◽  
Bing Liu ◽  
Weigang Kuang ◽  
Shuilin Song
Keyword(s):  
Sweet Potato ◽  
Molecular Identification ◽  
Leaf Spot ◽  
Ipomoea Batatas ◽  
Morphological Characteristics ◽  
Distilled Water ◽  
Gene Sequences ◽  
First Report ◽  
Potted Plants ◽  
Fungal Isolates

Sweet potato [Ipomoea batatas (L.) Lam], is an extremely versatile vegetable that possesses high nutritional values. It is also a valuable medicinal plant having anti-cancer, antidiabetic, and anti-inflammatory activities. In July 2020, leaf spot was observed on leaves of sweet potato in Nanchang, China (28°45'51"N, 115°50'52"E), which affected the growth and development of the crop and caused tuberous roots yield losses of 25%. The disease incidence (total number of diseased plants / total number of surveyed plants × 100%) was 57% from a sampled population of 100 plants in the field. Symptomatic plants initially exhibited small, light brown, irregular-shaped spots on the leaves, subsequently coalescing to form large irregular brown lesions and some lesions finally fell off. Fifteen small pieces (each 5 mm2) of symptomatic leaves were excised from the junction of diseased and healthy tissue, surface sterilized in 75% ethanol solution for 30 sec and 0.1% mercuric chloride solution for 2 min, rinsed three times with sterile distilled water and incubated on potato dextrose agar (PDA) plates at 28°C in darkness. A total of seven fungal isolates with similar morphological characteristics were obtained as pure cultures by single-spore isolation. After 5 days of cultivation at 28°C, dark brown or blackish green colonies were observed, which developed brown, thick-walled, simple, or branched, and septate conidiophores. Conidia were 18.28 to 24.91 × 7.46 to 11.69 µm (average 21.27 × 9.48 µm, n = 100) in size, straight or slightly curved, middle cell unequally enlarged, brown to dark brown, apical, and basal cells slightly paler than the middle cells, with three septa. Based on morphological characteristics, the fungal isolates were suspected to be Curvularia plantarum (Raza et al. 2019). To further confirm the identification, three isolates (LGZ1, LGZ4 and LGZ5) were selected for molecular identification. The internal transcribed spacer region (ITS), glyceraldehyde-3-phosphate-dehydrogenase (GAPDH), and translation elongation factor 1-alpha (EF1-α) genes were amplified and sequenced using primers ITS1/ITS4 (Peever et al. 2004), gpd1/gpd2 (Berbee et al. 1999), EF-983F/EF-2218R (Rehner and Buckley 2005), respectively. The sequences of ITS region of the three isolates (accession nos. MW581905, MZ209268, and MZ227555) shared 100% identity with those of C. plantarum (accession nos. MT410571-72, MN044754-55). Their GAPDH gene sequences were identical (accession nos. MZ224017-19) and shared 100% identity with C. plantarum (accession nos. MN264120, MT432926, and MN053037-38). Similarly, EF1-α gene sequences were identical (accession nos. MZ224020-22) and had 100% identity with C. plantarum (accession nos. MT628901, MN263982-83). A maximum likelihood phylogenetic tree was built based on concatenated data from the sequences of ITS, GAPDH, and EF-1α by using MEGA 5. The three isolates LGZ1, LGZ4, and LGZ5 clustered with C. plantarum. The fungus was identified as C. plantarum by combining morphological and molecular characteristics. Pathogenicity tests were conducted by inoculating a conidial suspension (106 conidia/ml) on three healthy potted I. batatas plants (five leaves wounded with sterile needle of each potted plant were inoculated). In addition, fifteen wounded leaves of three potted plants were sprayed with sterile distilled water as a control. All plants were maintained in a climate box (12 h light/dark) at 25°C with 80% relative humidity. All the inoculated leaves started showing light brown flecks after 7 days, whereas the control leaves showed no symptoms. The pathogenicity test was conducted three times. The fungus was reisolated from all infected leaves of potted plants and confirmed as C. plantarum by morphological and molecular identification, fulfilling Koch’s postulates. To our knowledge, this is the first report of C. plantarum causing leaf spot on sweet potato in China. The discovery of this new disease and the identification of the pathogen will contribute to the disease management, provide useful information for reducing economic losses caused by C. plantarum, and lay a foundation for the further research of resistance breeding.

scholarly journals Phylogeny, Distribution, and Pathogenicity of Lasiodiplodia Species Associated With Cankers and Dieback Symptoms of Persian Lime in Mexico

Plant Disease ◽  
2019 ◽  
Vol 103 (6) ◽  
pp. 1156-1165 ◽  
Author(s):  
M. A. Bautista-Cruz ◽  
G. Almaguer-Vargas ◽  
S. G. Leyva-Mir ◽  
M. T. Colinas-León ◽  
K. C. Correia ◽  
...  
Keyword(s):  
Sequence Data ◽  
Elongation Factor ◽  
Internal Transcribed Spacer Region ◽  
Translation Elongation ◽  
Dna Sequence Data ◽  
Tubulin Genes ◽  
Fungal Identification ◽  
Mycelial Plug ◽  
Inference Methods ◽  
Stem Cankers

Persian lime (Citrus latifolia Tan.) is an important and widely cultivated fruit crop in several regions of Mexico. In recent years, severe symptoms of gummosis, stem cankers, and dieback were detected in the Persian lime-producing region in the states of Veracruz and Puebla, Mexico. The aims of this study were to identify the species of Lasiodiplodia associated with these symptoms, determine the distribution of these species, and test their pathogenicity and virulence on Persian lime plants. In 2015, symptomatic samples were collected from 12 commercial Persian lime orchards, and 60 Lasiodiplodia isolates were obtained. Fungal identification of 32 representative isolates was performed using a phylogenetic analysis based on DNA sequence data of the internal transcribed spacer region and part of the translation elongation factor 1-α and β-tubulin genes. Sequence analyses were carried out using the Maximum Likelihood and Bayesian Inference methods. Six Lasiodiplodia species were identified as Lasiodiplodia pseudotheobromae, Lasiodiplodia theobromae, Lasiodiplodia brasiliense, Lasiodiplodia subglobosa, Lasiodiplodia citricola, and Lasiodiplodia iraniensis. All Lasiodiplodia species of this study are reported for the first time in association with Persian lime in Mexico and worldwide. L. pseudotheobromae (46.9% of isolates) was the most frequently isolated species followed by L. theobromae (28.1%) and L. brasiliense (12.5%). Pathogenicity on Persian lime young plants using a mycelial plug inoculation method showed that all identified Lasiodiplodia species were able to cause necrotic lesions and gummosis, but L. subglobosa, L. iraniensis, and L. pseudotheobromae were the most virulent.

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