scholarly journals First Report of Bacterial Leaf Streak Caused by Xanthomonas oryzae pv. oryzicola on Rice in Burkina Faso

Plant Disease ◽  
2011 ◽  
Vol 95 (1) ◽  
pp. 72-72 ◽  
Author(s):  
I. Wonni ◽  
L. Ouedraogo ◽  
V. Verdier
Keyword(s):  
Burkina Faso ◽  
Multiplex Pcr ◽  
The Philippines ◽  
Xanthomonas Oryzae ◽  
Distilled Water ◽  
Sterile Water ◽  
Bacterial Leaf Streak ◽  
First Report ◽  
Wild Rice Species ◽  
Strain Collection

Bacterial leaf streak (BLS) caused by Xanthomonas oryzae pv. oryzicola is prevalent in Asia where it can decrease yield by as much as 30%. In Africa, BLS has been reported in Madagascar, Nigeria, Senegal, and recently in Mali (1). The pathogen is seed transmitted and rice seeds can be a source of primary inoculum (3). In October 2009, leaf streak symptoms were observed on 3-month-old field rice grown in three regions of Burkina Faso (Haut-Bassin, Cascades, and East Center). Disease was found on cultivated Oryza sativa (varieties TS2, FKR19, and FKR56N), wild rice species (O. longistaminata and O. barthii), and weeds. Symptoms consisted of water-soaked lesions that developed into translucent, yellow streaks with visible exudates at the leaf surface. Yellow-pigmented Xanthomonas-like colonies were isolated on PSA semiselective medium (peptone 10 g, sucrose 10 g, bacto agar 16 g, distilled water 1,000 ml, actidione 50 mg liter–1, cephalexin 40 mg liter–1, and kasugamycin 20 mg liter–1). A multiplex PCR developed for the identification of Xanthomonas oryzae pathovars (2) was used to check the identity of Xanthomonas-like isolates. X. oryzae pv. oryzicola strains BLS256 from the Philippines and CFBP 7331 from Mali were used as positive controls. Three expected DNA fragments (331, 691, and 945 bp) corresponding to X. oryzae pv. oryzicola were obtained from all isolates using the multiplex PCR. No fragment was observed for negative controls (distilled water as the template). Five X. oryzae pv. oryzicola isolates were further analyzed by sequence analysis using portions of the gyrB housekeeping gene together with reference strains. Two sequence types were identified among Burkinabe isolates differing by only one nucleotide. When compared with the nucleotide database with BLAST, three isolates (BAI6, BAI15, and BAI19) were 100% identical to the type culture strain X. oryzae pv. oryzicola BLS256 (gyrB sequence was obtained from GenBank AAQN01000001.1) while the other two (BAI5 and BAI20) demonstrated 99% sequence similarity. The nucleotide sequence of isolate BAI5 was submitted to GenBank (HQ112342). Pathogenicity tests were performed on greenhouse-grown 3-week-old rice plants cv. Nipponbare. Cultures were grown overnight in PSA medium and adjusted in sterile water to 1 × 108 CFU/ml and inoculated into rice leaves with the blunt end of a 1-ml syringe. Four infiltrations were done per isolate per leaf and two leaves were inoculated per plant. Control plants were inoculated with sterile water. After 15 days of incubation in the greenhouse at 27 ± 1°C with a 12-h photoperiod, inoculated leaves exhibited water-soaked lesions with yellow exudates that were identical to symptoms seen in the field. Control plants remained symptomless. Colonies with morphology typical of Xanthomonas were recovered from the symptomatic leaves and typed using multiplex PCR to fulfill Koch's postulates. Three isolates have been deposited in the Collection Française de Bactéries Phytopathogènes (CFBP) and identified as X. oryzae pv. oryzicola strains CFBP7341–43. To our knowledge, this is the first report of X. oryzae pv. oryzicola in Burkina Faso. Further surveys and strain collection will be necessary to evaluate the geographic distribution and prevalence of BLS in Burkina Faso and neighboring countries. References: (1) C. Gonzalez et al. Mol. Plant-Microbe Interact. 20:534, 2007. (2) J. Lang et al. Plant Dis. 94:311, 2010. (3) G. Xie and T. Mew. Plant Dis. 82:1007, 1998.

scholarly journals First report of Bacterial Leaf Streak disease of rice caused by Xanthomonas oryzae pv. oryzicola in Ivory Coast

Plant Disease ◽  
2021 ◽  
Author(s):  
Amadou Diallo ◽  
Sylvain Zougrana ◽  
Mahamadou Sawadogo ◽  
Daouda KONE ◽  
Drissa Silué ◽  
...  
Keyword(s):  
Burkina Faso ◽  
Multiplex Pcr ◽  
Molecular Characterization ◽  
Ivory Coast ◽  
Reference Strain ◽  
Xanthomonas Oryzae ◽  
Sterile Water ◽  
Bacterial Leaf Streak ◽  
First Report ◽  
Gyrb Sequence

Bacterial Leaf Streak (BLS) of rice caused by Xanthomonas oryzae pv. oryzicola (Xoc) is considered as the third emerging infectious disease of rice in Africa. First reported in Africa in the 1980s, the disease is now present in at least eight African countries including Burundi, Burkina Faso, Kenya, Madagascar, Mali, Nigeria, Senegal and Uganda. Yield loss caused by BLS is estimated at 20 to 30% (Sileshi and Gebeyehu, 2021). To our knowledge BLS has so far not been reported in Ivory Coast. While BLS has not been described in the adjacent rice-growing countries Ghana and Liberia, Xoc strains isolated from samples collected between 2003 and 2011 in Burkina Faso and Mali have been characterized (Wonni et al., 2014). Xoc is transmitted through rice seeds which favors its spread through rice trading (Sileshi and Gebeyehu, 2021). Given the extensive rice trade between Burkina Faso, Mali and Ivory Coast, we hypothesized that BLS might also be present in this country. Field surveys were carried out across Ivory Coast in October 2018. Typical symptoms of the disease, e.g. translucent lesions in the form of yellow-brown to black streaks with sometimes visible droplets of exudates on the leaf surface, were observed in the area of Korhogo. 5cm-long leaf pieces were successively disinfected, rinsed in sterile water, and then ground using the Qiagen Tissue Lyser System (QIAGEN, Courtaboeuf, France). Leaf powder was resuspended in 1.5 ml of sterile water and incubated at room temperature for 30 minutes. Then, 10 μl of the suspension was streaked on semi-selective PSA medium and incubated at 28 ° C for 3 to 7 days. Colonies characteristic of Xoc, i.e. round, convex, mucous and straw yellow in color were purified from 6 individual samples from 2 distinct sites in Korhogo. To confirm their identity, isolated strains underwent a pathogenicity and molecular characterization test. The multiplex PCR developed for the identification of X. oryzae pathovars (Lang et al., 2010) revealed for all the isolates the characteristic PCR profile of Xoc (two amplicons of 324 and 691 base pairs). Strains of Xoc BLS256 and Xoo PXO99 were used as controls. The pathogenicity test was performed on 5 weeks-old plants of O. sativa cv. Azucena leaves by infiltration with a needleless syringe of a bacterial suspension at an optical density of 0.5. After 7 days of greenhouse incubation (27 ± 1°C with a 12-hour photoperiod), all infiltration points (2 infiltrations x 3 plants per isolate) developed water-soaked lesions identical to the one challenged with BLS256 while water-infiltrated leaves remained asymptomatic. These lesions were collected and subjected to the isolation and multiplex PCR processes described above, thus fulfilling Koch's postulate. Finally, three of the isolates were subjected to sequencing of the housekeeping gene gyrB by PCR amplification using the primers XgyrB1F and XgyrB1R (Young et al., 2008). Analysis of 780bp of the gyrB sequence of strains CI_k1-1, CI_k2-2 and CI_k3-2 revealed 100% identity with the gyrB sequence of Xoc reference strain BLS256 (Acc. No. CP003057) and 10 polymorphic nucleotides compared to the Xoo reference strain PXO99A (Acc. No. CP000967). To our knowledge, this is the first report of BLS in Ivory Coast supported by molecular characterization methods. New surveys in Ivory Coast and neighboring countries where the disease has not been reported will allow to implement collections and assess disease incidence as part of future control strategies.

scholarly journals First Report of Xanthomonas oryzae pv. oryzicola Causing Bacterial Leaf Streak of Rice in Burundi

Plant Disease ◽  
2014 ◽  
Vol 98 (10) ◽  
pp. 1426-1426 ◽  
Author(s):  
O. Afolabi ◽  
B. Milan ◽  
R. Amoussa ◽  
R. Koebnik ◽  
L. Poulin ◽  
...  
Keyword(s):  
Multiplex Pcr ◽  
Xanthomonas Oryzae ◽  
Gyrb Gene ◽  
Universal Primers ◽  
Dna Fragments ◽  
Sterile Water ◽  
Bacterial Leaf Streak ◽  
First Report ◽  
Rice Plants ◽  
Multiplex Pcr Assay

On May 9, 2013, symptoms reminiscent of bacterial leaf streak (BLS) caused by Xanthomonas oryzae pv. oryzicola were observed on rice plants at the panicle emergence stage at Musenyi, Gihanga, and Rugombo fields in Burundi. Affected leaves showed water-soaked translucent lesions and yellow-brown to black streaks, sometimes with visible exudates on leaf surfaces. Symptomatic leaves were ground in sterile water and the suspensions obtained were subjected to a multiplex PCR assay diagnostic for X. oryzae pathovars (3). Three DNA fragments (331, 691, and 945 bp) corresponding to X. oryzae pv. oryzicola were observed after agarose gel electrophoresis. Single bacterial colonies were then isolated from surface-sterilized, infected leaves after grinding in sterile water and plating of 10-fold dilutions of the cell suspension on semi-selective PSA medium (4). After incubation at 28°C for 5 days, each of four independent cultures yielded single yellow, mucoid Xanthomonas-like colonies (named Bur_1, Bur_2, Bur_6, and Bur_7) that resembled the positive control strain MAI10 (1). These strains originated from Musenyi (Bur_1), Gihanga (Bur_2), and Rugumbo (Bur_6 and Bur_7). Multiplex PCR assays on the four putative X. oryzae pv. oryzicola strains yielded the three diagnostic DNA fragments mentioned above. All strains were further analyzed by sequence analysis of portions of the gyrB gene using the universal primers gyrB1-F and gyrB1-R for PCR amplification (5). The 762-bp DNA fragment was identical to gyrB sequences from the Asian X. oryzae pv. oryzicola strains BLS256 (Philippines), ICMP 12013 (China), LMG 797 and NCPPB 2921 (both Malaysia), and from the African strain MAI3 (Mali) (2). The partial nucleotide sequence of the gyrB gene of Bur_1 was submitted to GenBank (Accession No. KJ801400). Pathogenicity tests were performed on greenhouse-grown 4-week-old rice plants of the cvs. Nipponbare, Azucena, IRBB 1, IRBB 2, IRBB 3, IRBB 7, FKR 14, PNA64F4-56, TCS 10, Gigante, and Adny 11. Bacterial cultures were grown overnight in PSA medium and re-suspended in sterile water (1 × 108 CFU/ml). Plants were inoculated with bacterial suspensions either by spraying or by leaf infiltration (1). For spray inoculation, four plants per accession and strain were used while three leaves per plant and four plants per accession and strain were inoculated by tissue infiltration. After 15 days of incubation in a BSL-3 containment facility (27 ± 1°C with a 12-h photoperiod), the spray-inoculated plants showed water-soaked lesions with yellow exudates identical to those seen in the field. For syringe-infiltrated leaves, the same symptoms were observed at the infiltrated leaf area. Re-isolation of bacteria from symptomatic leaves yielded colonies with the typical Xanthomonas morphology that were confirmed by multiplex PCR to be X. oryzae pv. oryzicola, thus fulfilling Koch's postulates. Bur_1 has been deposited in the Collection Française de Bactéries Phytopathogènes as strain CFBP 8170 ( http://www.angers-nantes.inra.fr/cfbp/ ). To our knowledge, this is the first report of X. oryzae pv. oryzicola causing bacterial leaf streak on rice in Burundi. Further surveys will help to assess its importance in the country. References: (1) C. Gonzalez et al., Mol. Plant Microbe Interact. 20:534, 2007. (2) A. Hajri et al. Mol. Plant Pathol. 13:288, 2012. (3) J. M. Lang et al. Plant Dis. 94:311, 2010. (4) L. Poulin et al. Plant Dis. 98:1423, 2014. (5) J. M. Young et al. Syst. Appl. Microbiol. 31:366, 2008.

scholarly journals First Report of Xanthomonas oryzae pv. oryzicola Causing Bacterial Leaf Streak of Rice in Uganda

Plant Disease ◽  
2014 ◽  
Vol 98 (11) ◽  
pp. 1579-1579 ◽  
Author(s):  
O. Afolabi ◽  
B. Milan ◽  
L. Poulin ◽  
J. Ongom ◽  
B. Szurek ◽  
...  
Keyword(s):  
Sequence Analysis ◽  
Multiplex Pcr ◽  
Dna Sequence ◽  
Disease Incidence ◽  
Xanthomonas Oryzae ◽  
Gyrb Gene ◽  
Sterile Water ◽  
Bacterial Leaf Streak ◽  
Rice Plants ◽  
Multiplex Pcr Assay

In June 2013, symptoms reminiscent of bacterial leaf streak (BLS) caused by Xanthomonas oryzae pv. oryzicola were observed on rice plants at the booting stage in the Doho rice irrigation scheme, Butaleja district, and at the tillering stage in Nambale, Iganga district and Magada, Namutumba district of Uganda. In areas surveyed, disease incidence was about 80, 40, and 30% in Doho, Nambale, and Magada, respectively. Outside the irrigation schemes, it was lower but widespread. Affected leaves showed typical BLS symptoms, such as water-soaked lesions, translucent stripes, and yellow-brown to black streaks, sometimes with visible exudates at the leaf surfaces. To check for the presence of the bacteria, symptomatic leaves were ground in sterile water and the suspension obtained was subjected to a multiplex PCR assay for X. oryzae pathovars, leading to the three diagnostic DNA fragments for X. oryzae pv. oryzicola (3). In parallel, bacterial strains were isolated from surface-sterilized symptomatic leaves. To this end, rice leaves were ground in sterile distilled water and serial dilutions of the cell suspensions were plated on semi-selective PSA medium (4). Each of the three samples yielded yellow, mucoid Xanthomonas-like colonies that resembled the positive control strain MAI10 (1). These isolates were named Ug_1, Ug_10, and Ug_14, which originated from Doho, Magada, and Nambale, respectively. Multiplex PCR on the pure cultures strongly supported that these isolates corresponded to X. oryzae pv. oryzicola. Two isolates, Ug_1 and Ug_14, were further subjected to partial DNA sequence analysis of the gyrB gene upon PCR amplification using the primers XgyrB1F and XgyrB1R (5). The 467-bp DNA sequence was identical to the gyrB sequences from the X. oryzae pv. oryzicola strains BLS256 (Philippines), ICMP 12013 (China), and MAI3 (Mali) (2). The partial nucleotide sequence of the gyrB gene of strain Ug_1 was submitted to GenBank (KJ921786). Pathogenicity tests were performed on greenhouse-grown 4-week-old rice plants of the cultivars Nipponbare, Azucena, IRBB 1, IRBB 2, IRBB 3, FKR 14, PNA64F4-56, TCS 10, Gigante, and Adny 11. For this purpose, bacterial cultures were grown overnight in PSA medium and re-suspended in sterile water at a concentration of 1 × 108 CFU/ml. Bacterial suspensions were sprayed on leaves of rice seedlings. Four seedlings per accession and isolate were inoculated. Fifteen days after incubation in a BSL-3 containment facility (27 ± 1°C with a 12-h photoperiod), inoculated leaves exhibited typical water-soaked lesions with yellow exudates that were similar to the symptoms seen in the fields. Re-isolation of the bacteria from the diseased leaves yielded colonies with the typical morphology of Xanthomonas. Multiplex PCR and sequence analysis of portions of the gyrB gene confirmed that these isolates are X. oryzae pv. oryzicola, thus fulfilling Koch's postulates. One of the three isolates, Ug_1, has been deposited in the Collection Française de Bactéries Phytopathogènes (CFBP) as strain CFBP 8171 ( http://www.angers-nantes.inra.fr/cfbp/ ). Further surveys and strain collections in East and Central Africa will help assess the geographic distribution and importance of BLS. References: (1) C. Gonzalez et al. Mol. Plant Microbe Interact. 20:534, 2007. (2) A. Hajri et al. Mol. Plant Pathol. 13:288, 2012. (3) J. M. Lang et al. Plant Dis. 94:311, 2010. (4) L. Poulin et al. Plant Dis. 98:1423, 2014. (5) J. M. Young et al. Syst. Appl. Microbiol. 31:366, 2008.

scholarly journals First Report of a Soft Rot of Phalaenopsis aphrodita Caused by Dickeya dieffenbachiae in China

Plant Disease ◽  
2012 ◽  
Vol 96 (5) ◽  
pp. 760-760 ◽  
Author(s):  
J. N. Zhou ◽  
B. R. Lin ◽  
H. F. Shen ◽  
X. M. Pu ◽  
Z. N. Chen ◽  
...  
Keyword(s):  
16S Rdna ◽  
Large Scale ◽  
Soft Rot ◽  
The Philippines ◽  
Gyrb Gene ◽  
Bacterial Suspension ◽  
Sterile Water ◽  
Gene Sequences ◽  
First Report ◽  
Tropical Asia

Phalaenopsis orchids, originally from tropical Asia, are mainly planted in Thailand, Singapore, Malaysia, the Philippines, and Taiwan and have gained popularity from consumers all over the world. The cultivation area of Phalaenopsis orchids has been rising and large-scale bases have been established in mainland China, especially South China because of suitable environmental conditions. In September 2011, a soft rot of Phalaenopsis aphrodita was found in a Phalaenopsis planting base in Guangzhou with an incidence of ~15%. Infected plants initially showed water-soaked, pale-to-dark brown pinpoint spots on leaves that were sometimes surrounded by a yellow halo. Spots expanded rapidly with rising humidity and temperatures, and in a few days, severely extended over the blade with a light tan color and darker brown border. Lesions decayed with odorous fumes and tissues collapsed with inclusions exuding. The bacterium advanced to the stem and pedicle. Finally, leaves became papery dry and the pedicles lodged. Six diseased samples were collected, and bacteria were isolated from the edge of symptomatic tissues after sterilization in 0.3% NaOCl for 10 min, rinsing in sterile water three times, and placing on nutrient agar for culture. Twelve representative isolates were selected for further characterization. All strains were gram negative, grew at 37°C, were positive for indole production, and utilized malonate, glucose, and sucrose but not glucopyranoside, trehalose, or palatinose. Biolog identification (version 4.20.05, Hayward, CA) was performed and Pectobacterium chrysanthemi (SIM 0.868) was confirmed for the tested isolates (transfer to genus Dickeya). PCR was used to amplify the 16S rDNAgene with primers 27f and 1492r, dnaX gene with primers dnaXf and dnaXr (3), and gyrB gene with primers gyrBf (5′-GAAGGYAAAVTKCATCGTCAGG-3′) and gyrB-r1 (5′-TCARATATCRATATTCGCYGCTTTC-3′) designed on the basis of the published gyrB gene sequences of genus Dickeya. BLASTn was performed online, and phylogeny trees (100% bootstrap values) were created by means of MEGA 5.05 for these gene sequences, respectively. Results commonly showed that the representative tested strain, PA1, was most homologous to Dickeya dieffenbachiae with 98% identity for 16S rDNA(JN940859), 97% for dnaX (JN989971), and 96% for gyrB (JN971031). Thus, we recommend calling this isolate D. dieffenbachiae PA1. Pathogenicity tests were conducted by injecting 10 P. aphrodita seedlings with 100 μl of the bacterial suspension (1 × 108 CFU/ml) and another 10 were injected with 100 μl of sterile water as controls. Plants were inoculated in a greenhouse at 28 to 32°C and 90% relative humidity. Soft rot symptoms were observed after 2 days on the inoculated plants, but not on the control ones. The bacterium was isolated from the lesions and demonstrated identity to the inoculated plant by the 16S rDNA sequence comparison. Previously, similar diseases of P. amabilis were reported in Tangshan, Jiangsu, Zhejiang, and Wuhan and causal agents were identified as Erwinia spp. (2), Pseudomonas grimontii (1), E. chrysanthemi, and E. carotovora subsp. carovora (4). To our knowledge, this is the first report of D. dieffenbachiae causing soft rot disease on P. aphrodita in China. References: (1) X. L. Chu and B. Yang. Acta Phytopathol. Sin. 40:90, 2010. (2) Y. M. Li et al. J. Beijing Agric. Coll. 19:41, 2004. (3) M. Sławiak et al. Eur. J. Plant Pathol. 125:245, 2009. (4) Z. Y. Wu et al. J. Zhejiang For. Coll. 27:635, 2010.

scholarly journals First Report of Septoria Blight of Parsley Caused by Septoria petroselini in the Mediterranean Region of Turkey

Plant Disease ◽  
2003 ◽  
Vol 87 (1) ◽  
pp. 99-99 ◽  
Author(s):  
S. Kurt
Keyword(s):  
Mediterranean Region ◽  
Morphological Characteristics ◽  
Potato Dextrose Agar ◽  
Distilled Water ◽  
Conidial Suspension ◽  
Sterile Water ◽  
First Report ◽  
Foliar Symptoms ◽  
Polyethylene Bags ◽  
The Mediterranean

During December 2001 to March 2002, Septoria blight of parsley was observed in approximately 500 ha of commercial parsley crops in Arsuz County, Hatay, in the Mediterranean Region of Turkey. Incidence of disease ranged from 42 to 80%. Symptoms included irregularly shaped, grayish brown spots (average 3 to 8 mm diameter) with a slightly darker brown margin of necrotic tissue that developed into tan-to-brown lesions surrounded by chlorotic halo on the leaves. Oval-shaped lesions were observed occasionally on petioles. Lesions contained erumpent, dark brown, flask-shaped pycnidia with the ostiole on the upper surface of the foliage. Thirty samples, consisting of diseased leaves and petioles of parsley, were collected from each field. Infected tissues were surface-sterilized in 1% NaOCl for 2 min, rinsed in sterile distilled water, placed on petri dishes containing potato dextrose agar (PDA), and incubated for 10 to 14 days at 25°C. The fungus formed long, multiseptate (0 to 4), hyaline, filiform conidia (14 to 29 μm × 0.5 to 1.9 μm), and short conidiophores within the pycnidia. Based on the morphological characteristics of the fungus, the pathogen was identified as Septoria petroselini Desm. (1). Monoconidial cultures of 18 isolates were prepared. Pathogenicity was confirmed by brush-inoculating slightly wounded foliage of 5- to 7- week-old parsley plants (cv. Kereviz yapragi) with a conidial suspension (106 conidia per ml of sterile water) of each isolate of S. petroselini. Control plants that were brush-inoculated with distilled water and inoculated plants were placed in clear polyethylene bags that were closed and incubated at 20°C for 48 h. The bags were removed, and plants were maintained in a dew chamber for 21 days at 65 to 70% relative humidity. Foliar symptoms developed 15 days after inoculation and appeared similar to lesions observed in the field. Yellowing and necrosis of leaves was also observed on >60% of inoculated plants. No lesions developed on the control plants. The pathogen was readily reisolated on PDA from inoculated plants. To our knowledge, this is the first report of Septoria blight of parsley in the Mediterranean Region of Turkey. Reference: (1) R. F. Cerkauskas and J. Uyenaka. Plant Dis. 74:1037, 1990.

scholarly journals First Report of Anthracnose on Pecan (Carya illinoiensis) Caused by Colletotrichum siamense in Korea

Plant Disease ◽  
2021 ◽  
Author(s):  
Ji Yeon Oh ◽  
Jeong-In Heo ◽  
Dong-Hyeon Lee
Keyword(s):  
Its Region ◽  
Culture Collection ◽  
Likelihood Method ◽  
Malt Extract ◽  
Distilled Water ◽  
Sterile Water ◽  
First Report ◽  
Colletotrichum Siamense ◽  
Plastic Bag ◽  
Water Drops

In 2020, severely infected fruit of pecan, Carya illinoiensis, showing distinct anthracnose symptoms were observed from pecan orchards in Uiseong (36°21'31.5"N 128°27'15.9"E) and Miryang (35°22'54.9"N 128°48'06.5"E) in South Korea. Visible symptoms occurred on fruit of the tree between June and July, which included dark, depressed and covered with irregularly shaped lesions. As the disease progressed, the lesions expanded and merged over time, leading to abscission of the fruit, which resulted in severe yield loss of pecan fruit. Of pecan varieties including Caddo, Giles and Peruque that were cultivated in each pecan orchard, Caddo appeared to be most susceptible to the disease. Estimated losses were approximately 30% and 70% for the Uiseong and Miryang pecan orchard, respectively. For pathogen isolation, ten symptomatic fruits of pecan were randomly collected and brought to the laboratory. The fruits were surface disinfested for 30 s with 70% ethanol and 1% sodium hypochlorite. These were then rinsed with sterile distilled water twice, placed in a humid chamber, and incubated at 25 ± 1°C with a photoperiod of 12 h. Acervuli filled with salmon-colored conidial masses were produced abundantly on the fruit a day after the incubation. Conidia were single celled, hyaline, cylindrical having rounded ends, smooth walls, guttulate, 15.5 to 17.7 µm long, and 3.4 to 4.8 µm wide (n = 20). Monoconidial isolates were made on 2% malt extract agar and incubated at 25°Ϲ for two weeks in the dark condition. Of those that were successfully retained, two representative isolates from each orchard were deposited in the culture collection (CDH) of the National Institute of Forest Science, Korea (Accession No. CDH2020-17–18). To ensure the identity of the pathogen, molecular identification was made based on three gene regions, the internal transcribed spacer (ITS) region of rDNA, beta-tubulin (TUB2) gene and a partial sequence of the actin (ACT), which were amplified with ITS1F/ITS4, T1/Bt2b and ACT-512F/ACT-783R, respectively (Weir et al. 2012). These were then submitted to GenBank with accession numbers of MW380423–24 for ITS, MW387129–30 for TUB2 and MW387127–28 for ACT. A BLAST search in GenBank revealed that the sequences showed high similarity to those of Colletotrichum siamense, which were identical to MT434615 and MT274214 for ITS and ACT, respectively, and 99.7% to MK967337 for TUB2. Phylogenetic analysis based on the maximum likelihood method further showed that the isolates recovered in this study clustered with C. siamense, confirming its identity. Pathogenicity was confirmed by inoculating living pecan trees. Healthy fruits from five trees were surface cleaned with cotton soaked in sterile water and air-dried. To inoculate the pathogen, three to five fruit per tree were wounded with a sterilized needle, and an aliquot of 10 μl of spore suspension (1.0 × 105 conidia/ml) of C. siamense (CDH2020-18) was dropped on each wound. To keep moisture, each treated fruit was enveloped by a plastic bag where the cotton soaked in sterile water had been placed. Controls were treated with sterile distilled water drops. The symptoms with dark, depressed and irregularly shaped lesions developed from all inoculated treatments six weeks after the inoculations, which were identical to those observed in the field. However, no symptom was observed on the control. Colletotrichum siamense was successfully re-isolated, fulfilling Koch’s postulates. Taken together, it was confirmed that C. siamense is the causal agent of anthracnose on pecan. In Korea, C. siamense was reported causing anthracnose on apple, persimmon and plum (Farr and Rossman 2020). However, to our knowledge, this is the first report of anthracnose on pecan caused by C. siamense in Korea. To control the disease effectively, more attention should be paid to other regions of the country where the disease caused by the pathogen might occur.

scholarly journals Analysis of DNA Polymorphism and Virulence in Philippine Strains of Xanthomonas oryzae pv. oryzicola

Plant Disease ◽  
1999 ◽  
Vol 83 (5) ◽  
pp. 434-440 ◽  
Author(s):  
A. K. Raymundo ◽  
A. M. Briones ◽  
E. Y. Ardales ◽  
M. T. Perez ◽  
L. C. Fernandez ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Rflp Analysis ◽  
The Philippines ◽  
Xanthomonas Oryzae ◽  
Bacterial Leaf Streak ◽  
Bootstrap Analysis ◽  
Transposase Gene ◽  
Group I ◽  
Dna Types ◽  
Promising Source

Molecular tools were used to analyze the genetic diversity and population structure of Xanthomonas oryzae pv. oryzicola, the bacterial leaf streak pathogen of rice in the Philippines. Representative pathogen strains were selected and used to assess resistance in rice germplasm. A partial genomic library of X. oryzae pv. oryzicola was constructed, and a 459-bp clone containing the repetitive DNA element R41 was selected as a probe for restriction fragment length polymorphism (RFLP) analysis and sequenced. R41 shared 44% sequence homology with the putative transposase gene of IS1112, an insertion element cloned from X. oryzae pv. oryzae. Using R41 as a probe for RFLP analysis, 26 band profiles were discerned in a collection of 123 strains of X. oryzae pv. oryzicola. Analysis of PstI digestion patterns of DNA from the same collection resolved 36 haplotypes. Several clusters of strains were detected after grouping of data based on either pR41 as a probe or Pst1 digestion patterns. However, based on bootstrap analysis, the clusters were not robust. Genetic diversity was high for the entire collection as well as within spatially and temporally defined subsets of strains. Even a set of strains collected from a single site at a single time was highly diverse. Strains representing the different DNA types were inoculated to a set of diverserice cultivars. Consistent rice varietal groupings were obtained from disease reaction data, but there was no correlation between pathogen isolate cluster and host reaction across inoculation trials. Isozyme group I of rice, representing tropical japonica and javanica germplasm, is a promising source of resistance to bacterial leaf streak.

scholarly journals Confirmation of Bacterial Leaf Streak Caused by Xanthomonas oryzae pv. oryzicola on Rice in Madagascar

Plant Disease ◽  
2014 ◽  
Vol 98 (10) ◽  
pp. 1423-1423 ◽  
Author(s):  
L. Poulin ◽  
H. Raveloson ◽  
M. Sester ◽  
L.-M. Raboin ◽  
D. Silué ◽  
...  
Keyword(s):  
West Africa ◽  
Multiplex Pcr ◽  
Pcr Amplification ◽  
Rice Fields ◽  
Xanthomonas Oryzae ◽  
Universal Primers ◽  
Bacterial Leaf Streak ◽  
Gyrb Sequence ◽  
Leaf Tissues ◽  
Symptomatic Leaf

Bacterial leaf streak (BLS) caused by Xanthomonas oryzae pv. oryzicola is an important disease of rice. BLS is prevalent in Asia and West Africa, where it was first reported in Nigeria and Senegal in the early 1980s (4). Recently, molecular analysis of strains from Mali (2) and Burkina Faso (5) further confirmed the presence of BLS in West Africa. In Madagascar, BLS symptoms were first reported in the 1980s by Buddenhagen but the causal agent was not unequivocally determined (1). To confirm Buddenhagen's observations using modern molecular typing tools, we surveyed several rice fields in the Antananarivo and Antsirabe districts in March 2013. BLS symptoms were observed on cultivated Oryza sativa grown under both upland and lowland conditions, with a proportion of diseased individuals varying from 30% up to 80%. Symptomatic leaves presenting water-soaked lesions that developed into translucent, yellow streaks with visible exudates at the surface were sampled. One to four centimeter long pieces of diseased leaves were ground using the Qiagen TissueLyser system at 30 rps for 30 s (Qiagen, Courtaboeuf, France). The ground tissue was then macerated in 1 ml of sterile water for 1 h at 4°C. Non-diluted and 10-fold diluted tissue macerates were plated on semi-selective PSA medium (peptone 10 g/liter, sucrose 10 g/liter, glutamic acid 1 g/liter, bacto agar 16 g/liter, actidione 50 mg/liter, cephalexin 40 mg/liter, and kasugamycin 20 mg/liter) and incubated for 3 to 7 days at 28°C. Single, yellow, Xanthomonas-like colonies were isolated on non-selective PSA medium. Diagnostic multiplex PCR was performed on single colonies for pathovar identification (3). Five strains that produced three diagnostic bands corresponding to the X. oryzae pv. oryzicola pattern were further analyzed for pathogenicity on 3-week-old O. sativa cv. Nipponbare plants. Bacteria grown on PSA plates and adjusted to 1 × 108 CFU/ml were infiltrated into rice leaves with a needleless 1-ml syringe (2 × 3 infiltrations per plant and strain). Seven days after incubation in the greenhouse (27 ± 1°C with a 12-h photoperiod), inoculated leaves showed water-soaked lesions that produced yellow exudates corresponding to those initially observed in rice fields and observed for leaves challenged with the X. oryzae pv. oryzicola reference strain BLS256. Symptomatic leaf tissues were ground and plated on non-selective PSA medium, resulting in colonies with typical Xanthomonas morphology that were confirmed as X. oryzae pv. oryzicola by multiplex PCR typing (3), thus fulfilling Koch's postulates. Finally, the five strains were subjected to gyrB sequencing upon PCR amplification using the universal primers XgyrB1F (5′-ACGAGTACAACCCGGACAA-3′) and XgyrB1R (5′-CCCATCARGGTGCTGAAGAT-3′). The 743-bp partial gyrB sequences were 100% identical to the gyrB sequence of strain BLS256. As expected, the gyrB sequence of strains KACC10331, MAFF311018, and PXO99A of the X. oryzae pv. oryzae pathovar respectively showed nine, 16, and 10 mismatches in comparison to the Malagasy strains, thus further supporting that they belong to the pathovar oryzicola. References: (1) I. W. Buddenhagen. Int. Rice Comm. Newsl. 34:74, 1985. (2) C. Gonzalez et al. Mol. Plant Microbe Interact. 20:534, 2007. (3) J. M. Lang et al. Plant Dis. 94:311, 2010. (4) D. O. Niño-Liu et al. Mol. Plant Pathol. 7:303, 2006. (5) I. Wonni et al. Plant Dis. 95:72, 2011.

scholarly journals First Report of New Bacterial Leaf streak of Rice Caused by Pantoea ananatis in China

Plant Disease ◽  
2022 ◽  
Author(s):  
Xinhua Ding ◽  
Chongchong Lu ◽  
Mingxia Hao ◽  
Lingguang Kong ◽  
Lulu Wang ◽  
...  
Keyword(s):  
16S Rdna ◽  
Shandong Province ◽  
Bacterial Suspension ◽  
Distilled Water ◽  
Bacterial Leaf Streak ◽  
Accession Number ◽  
Pantoea Ananatis ◽  
First Report ◽  
Rice Leaves ◽  
Dark Green

Rice (Oryza sativa L.) is the largest grain crop, accounting for about 40 % of the total grain production in China. In mid-July 2021, bacterial leaf streak-like disease emerged in rice varieties Chunyou584 and Yongyou2604 in Linyi city, Shandong Province, China. Disease incidences of the disease ranged from 80% to 90% in the surveyed fields. Infected rice leaves displayed dark green to yellowish-brown water-soaked thin streaks, and a large amount of beaded yellow oozes were observed on the lesions. After drying, there were gelatinous granules that were not easy to fall off and spread between leaf veins (Fig.S1A). According to the field symptoms of this disease, it was preliminarily suspected to be rice bacterial leaf streak caused by Xanthomonas oryzae pv. oryzicola (Xoc), which is a guaranteed disease in China. To isolate the causal agent, leaf discs (~1 cm2) of diseased leaves were collected from the margins of the lesions, surface sterilized and ground into pieces in sterile double distilled water. The 10-3, 10-4 and 10-5 dilutions were spread onto peptone sugar agar (PSA) and incubated at 28°C for 36 hours. Yellow mucous bacterial colonies were consistently obtained on PSA medium. To identify the pathogen, fragments of the 16S rDNA, leuS and rpoB were amplified and sequenced using the primers previously reported (Yu et al. 2021). Three strains (LY01, LY02 and LY03) showed identical colony morphology and LY01 was used for further analyses. Sequence analyses showed that the fragments of 16S rDNA (955 bp, GenBank accession number: OK261898), leuS (755 bp, GenBank accession number: OK298387) and rpoB (926 bp, GenBank accession number: OK298388) of strain LY01 shared 99.16%, 99.46% and 100% similarities with those of Pantoea ananatis TZ39 (GenBank accession numbers: CP081342.1 for 16S rDNA, MW981338.1 for leuS and MW981344.1 for rpoB), respectively, which suggest the pathogenic bacterial strain LY01 isolated is P. ananatis. In addition, the single colony of P. ananatis LY01 was shown as Fig. S2B. Furthermore, pathogenicity tests were also performed according to the following steps. Bacterial suspension at OD600=0.1 was inoculated into eight rice leaves of four healthy rice plants (Chunyou 584) at 25-33°C and 60%-80% relative humidity in the field using a clipping method (Yang et al. 2020) or spraying methods, and sterile distilled water was as negative control. The clipped leaves (Fig. S1B) and spray-inoculated leaves (Fig. S1C) showed dark green water-soaked streaks at 14 days after inoculation, respectively, which showed similar symptoms with those samples collected from the fields (Fig. S1A). On contrary, the control rice leaves remained healthy and symptomless (Fig. S2A). The bacterium was re-isolated in the inoculated rice leaves and the re-isolated bacterial isolates, which was confirmed by sequencing 16S rDNA, leuS and rpoB, incited the same symptoms as in fields, which fulfills Koch’s postulates. In the past decade, P. ananatis was reported to result in grain discoloration and leaf blight in China (Yan et al. 2010; Xue et al. 2020, Yu et al. 2021), which could result in 40% - 60% yield losses. To our best knowledge, this is the first report of the bacterial leaf streak-likely disease occurred in Shandong Province caused by P. ananatis, so we named it as Pantoea leaf streak of rice. Although P. ananatis was also reported in Zhejiang province and Jiangxi province, which caused leaf streak lesions on rice, the disease symptoms are completely different from those of Pantoea leaf streak of rice. To the best of our knowledge, this is the first report of Pantoea leaf streak of rice caused by P. ananatis. This study provides sloid evidence that Pantoea leaf streak of rice in Eastern China can be caused by the new pathogen, P. ananatis, rather than Xoc as traditionally assumed. Disease development and quarantine of the new Pantoea leaf streak of rice disease caused by P. ananatis on rice need more attention in the near future.

scholarly journals First Report of Anthracnose on Peach Fruit Caused by Colletotrichum truncatum in South Carolina

Plant Disease ◽  
2014 ◽  
Vol 98 (8) ◽  
pp. 1154-1154 ◽  
Author(s):  
A. Grabke ◽  
M. Williamson ◽  
G. W. Henderson ◽  
G. Schnabel
Keyword(s):  
South Carolina ◽  
Causal Agent ◽  
Distilled Water ◽  
Conidial Suspension ◽  
Sterile Water ◽  
Colletotrichum Truncatum ◽  
Peach Fruit ◽  
First Report ◽  
Anthracnose Disease ◽  
Control Fruit

In July 2013, two diseased peach fruit (Prunus persica (L.) Stokes) of the cv. Sweet Dream were collected from a commercial orchard in Ridge Springs, South Carolina. Affected peaches were at or near maturity and symptoms resembled anthracnose disease caused by Colletotrichum spp. with circular sunken tan to brown lesions that were firm in touch, and had wrinkled concentric rings. The center of the lesion was covered with black acervuli containing setae. To isolate the causal agent, the two symptomatic fruit were surface-sterilized in 10% bleach for 2 min and rinsed with sterile distilled water. Lesions were cut in half, and necrotic tissue from the inside of the fruit was placed on acidified potato dextrose agar (APDA). Flat colonies covered with olive-gray to iron-gray acervuli developed on APDA incubated at 22°C with a 12-h cycle of fluorescent light and darkness. Morphology of acervuli, setae (avg. 90 to 160 μm), conidiophores (up to 90 um long), and conidia (avg. 22 × 3.8 μm) of single spore isolates were consistent with descriptions of Colletotrichum truncatum (Schwein.) Andrus & W.D. Moore (3), a causal agent of anthracnose disease. Genomic DNA was extracted from isolate Ct_RR13_1 using the MasterPure Yeast DNA Purification Kit (Epicentre, Madison, WI). The ribosomal ITS1-5.8S-ITS2 region and a partial sequence of the actin gene were amplified with primer pair ITS1 and ITS4 (4), and primer pair ACT-512F and ACT-783A (2), respectively. A multilocus sequence identification in Q-bank Fungi revealed a 100% similarity with C. truncatum (1). The C. truncatum sequences from the peach isolate were submitted to GenBank (accessions KF906258 and KF906259). Pathogenicity of isolate Ct_RR13_1 was confirmed by inoculating five mature but still firm peach fruits with a conidial suspension of C. truncatum. Peaches were washed with soap and water, surface-disinfected for 2 min with 10% bleach, rinsed with sterile distilled water, and air dried. Dried fruit were stabbed at three equidistant points, each about 2 cm apart, to a depth of 9.5 mm using a sterile 26G3/8 beveled needle (Becton Dickinson & Co., Rutherford, NJ). For inoculation, a 30-μl droplet of conidia suspension prepared in distilled, sterile water (1 to 2 × 104 spores/ml) was placed on each wound; control fruit received sterile water without conidia. Fruit were incubated at 22°C for 2 days at 100% humidity and another 12 days at 70% humidity. Inoculated fruit developed anthracnose symptoms with sporulating areas as described above and the fungus was re-isolated. All control fruit remained healthy. C. truncatum has a wide host range, including legumes and solanaceous plants of the tropics, and is especially common in the Fabaceae family. Its occurrence in a commercial peach orchard is worrisome because control measures may need to be developed that are different from those developed for endemic species, i.e. C. acutatum and C. gloeoporioides, due to differences in disease cycle or fungicide sensitivity. To our knowledge, this is the first report of C. truncatum causing anthracnose on a member of the genus Prunus. References: (1) P. Bonants et al. EPPO Bull. 43:211, 2013. (2) I. Carbone et al. Mycologia 91:553, 1999. (3) U. Damm et al. Fungal Divers. 39:45, 2009. (4) T. J. White et al. Pages 315-322 in: PCR Protocols: A Guide to Methods and Application. Academic Press, NY, 1993.

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