scholarly journals First Report of Bacterial Foot Rot of Rice Caused by a Dickeya zeae in China

Plant Disease ◽  
2012 ◽  
Vol 96 (12) ◽  
pp. 1818-1818 ◽  
Author(s):  
X. M. Pu ◽  
J. N. Zhou ◽  
B. R. Lin ◽  
H. F. Shen
Keyword(s):  
16S Rdna ◽  
Guangdong Province ◽  
Gyrb Gene ◽  
Bacterial Suspension ◽  
Bacterial Disease ◽  
Sterile Water ◽  
Foot Rot ◽  
Rice Seedlings ◽  
First Report ◽  
Negative Controls

A bacterial disease of rice, bacterial foot rot, was found in Guangdong Province, China in September 2011, with an incidence about 10%. The typical symptom was a dark brown decay of the tillers. In the early stages of the disease, a brown sheath rot seemed to spread from the ligulae regions. The lesions quickly extended down to the nodes, culms, and finally to the crowns. Neighboring tillers of the same crown were invaded systemically, causing foot rot symptoms. A soft rot with an unpleasant odor developed in young tissues of infected tillers. In the advanced stage, many tillers decayed, so that entire diseased plants could easily be pulled from the soil. Six diseased samples were collected and bacteria were isolated from the edge of symptomatic tissues, after samples were sterilized in 0.3% NaOCl for 10 min, rinsed in sterile water three times, and placed on nutrient agar (beef extract 3 g, yeast extract 1 g, peptone 5 g, glucose 10 g, agar 16 g, distilled water 1 L, pH 6.8 to 7.0). For identification, a total of 12 representative isolates were selected. 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) identified isolate EC1 as Pectobacterium chrysanthemi (SIM 0.827), which has since been transferred to genus Dickeya. PCR was used to amplify the 16S rDNA gene with primers 27f and 1492r, the dnaX gene with primers dnaXf and dnaXr (2), and the gyrB gene with primers gyrBf1 (5′-ATGTCGAATTCTTATGACTCCTC-3′) and gyrB-r1 (5′-TCARATATCRATATTCGCYGCTTTC-3′), which were designed based on published gyrB gene sequences of genus Dickeya. A BLASTn search of all three loci [16S rDNA (JQ284040), dnaX (JQ284041), and gyrB (JQ284042)] revealed that EC1 had 100% sequence identify to Dickeya zeae [16S rDNA (AB713560), dnaX (AB713593), gyrB (AB713635)]. Pathogenicity tests were conducted by injecting 10 rice seedlings with 100 μl of the bacterial suspension (1 × 108 CFU/ml) in the stem base, and an additional 10 rice seedlings were injected with 100 μl of sterile water as negative controls. Inoculations were carried out in a greenhouse at 28 to 32°C and 90% relative humidity. Foot rot symptoms identical to those described above were observed after 7 days on inoculated plants, but not on the negative controls. The bacterium was reisolated from the lesions and had 100% sequence identity for all three loci to EC1. Previously, similar symptoms were reported on rice in Guangdong province of China, and the causal agent was identified as Erwinia chrysanthemi (1). To our knowledge, this is the first report of D. zeae causing foot rot disease on rice in China. References: (1) Q. G. Liu et al. J. South China Agric. Univ. 18:128, 1997. (2) M. Sławiak et al. Eur. J. Plant Pathol. 125:245, 2009.

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 Dickeya fangzhongdai Causing Peduncle Soft Rot of Banana in China

Plant Disease ◽  
2021 ◽  
Author(s):  
Di Yang ◽  
Chan Juan Du ◽  
Yunfeng Ye ◽  
Lian Fu Pan ◽  
Jin Zhang ◽  
...  
Keyword(s):  
16S Rdna ◽  
Dna Sequences ◽  
Southern China ◽  
Intergenic Spacer ◽  
Soft Rot ◽  
Bacterial Suspension ◽  
Sterile Water ◽  
Internal Tissue ◽  
Flower Bud ◽  
First Report

Banana (Musa spp.) is a popular fruit all over the world, and it’s also an important cash crop with a planting area of 358,924 ha in southern China. In July 2020, a peduncle soft rot disease occurred on dwarf banana (Musa sp. cv. Guangfen) in Guigang city (N22°50'29″, E109° 43'34″), Guangxi province, China. More than 20% plants were infected in the banana plantation. The first external sign of the disease appeared on the incisional wound after the flower bud was cut off from the peduncle. The symptom initially appeared as a black lesion on the wound, then extended into the internal tissue of the whole peduncle. In the later stages, the internal tissue became soft and rot, occasionally formed a necrotic cavity, and eventually led to the black rot of the whole peduncle with a foul smell. To isolate the pathogen, the internal lesion tissues of 5 mm × 5 mm were collected between the border of symptomatic and healthy tissue, treated with 75% ethanol for 10 s, and 0.1% HgCl2 for 3 min, then rinsed with sterile water for three times. Sterilized tissue fragments were cut to pieces with sterilized surgical shears and soaked in 5 mL sterile water, then shaken for 10 min in a vortex oscillator. The suspension was diluted 1000 times with sterilized water，then plated on nutrient-agar medium and incubated at 28℃ in darkness for 24 h. Among the 32 isolates, 23 pure bacterial cultures with similar morphology were predominantly obtained from the samples. These bacteria were gram-negative, and their colonies were initially yellowish white with irregular edges and smooth surfaces, then turned to grayish blue after 72 h incubated at 28℃. The representative isolates GZF2-2 and GZF1-8 were selected for further identification. Genomic DNA was isolated from the bacteria and the 16S rDNA was amplified with primers 27F/1492R (Weisburg et al. 1991) and sequenced. The obtained sequences (GenBank Accession No. MZ768922 and OK668082) showed >99% identities to several records of Dickeya fangzhongdai deposited in NCBI GenBank (1400/1404 bps for GZF2-2 to KT992690, 1409/1417 bps for GZF1-8 to MT613398) based on BLAST analysis. In addition, the recA, fusA, gapA, purA, rplB, dnaX genes and the 16S-23S intergenic spacer (IGS) regions of the two isolates were also amplified and sequenced (GenBank Accession Nos. OK634381-OK634382, OK634369- OK634370, OK634373-OK634374, OK634377-OK634378, OK634385-OK634386, OK634365- OK634366 and OK631722-OK631723) as described by Tian et al. (2016). All the DNA sequences matched that of D. fangzhongdai strains JS5T (percent identities>99.06%), PA1 and ECM-1 in GenBank. Neighbor-joining phylogenetic analysis by software MegaX (Kumar et al. 2018) based on the 16S rDNA sequences revealed that the two isolates were in the same clade with reported D. fangzhongdai strains. Multilocus sequence analysis of the other seven regions also showed the two representative isolates were belong to D. fangzhongdai. Therefore, the isolates were identified as D. fangzhongdai. Pathogenicity of isolate GZF2-2 was investigated to demonstrate Koch’s postulate. The end of the banana peduncles of 6 healthy plants were cut off, and 10 mL bacterial suspension (108 CFU/mL) was inoculated to the fresh wound on the plants using sterile brushes. Six control plants were inoculated with sterilized water. All the inoculated peduncles were covered with plastic bags to maintain high humidity. After 28 days, all the peduncles inoculated with strain GZF2-2 showed soft rot symptoms similar to those observed in the field, while the controls remained symptomless. The same bacteria were re-isolated from the symptomatic peduncles and confirmed by sequencing the 16S rDNA. D. fangzhongdai has been reported to cause soft rot on onion (Ma et al. 2020) and bleeding cankers on pear trees (Chen et al. 2020). To the best of our knowledge, this is the first report of D. fangzhongdai causing peduncle soft rot on banana in China.

scholarly journals First Report of Potato Blackleg Disease Caused by Pectobacterium atrosepticum in Guangdong China

Plant Disease ◽  
2013 ◽  
Vol 97 (12) ◽  
pp. 1652-1652
Author(s):  
X. M. She ◽  
Z. F. He ◽  
Y. F. Tang ◽  
Z. G. Du ◽  
G. B. Lan
Keyword(s):  
16S Rdna ◽  
Vascular Tissue ◽  
Guangdong Province ◽  
Bacterial Suspension ◽  
Post Inoculation ◽  
Blackleg Disease ◽  
Potato Blackleg ◽  
Pectobacterium Atrosepticum ◽  
First Report ◽  
Potato Plants

Potato (Solanum tuberosum L.) is an important crop in China. In 2013, diseased potatoes exhibiting blackleg and soft rot symptoms were found in the winter potato growing areas of Huizhou city, Guangdong Province, China, with an incidence of approximately 20%. Initially, the stem bases of infected plants blackened and this symptom spread upward. Later, foliage of the diseased plants became yellow and the stem rotted with vascular discoloration. Twenty diseased plants with typical black leg symptoms were collected from a 10-ha potato field with approximately 60,000 potato plants per hectare. A bacterium with small, irregular, round, fluidal, white colonies was isolated from the vascular tissue of all diseased plants on nutrient agar at 26°C for 2 days. Ten strains were randomly selected for pathogenicity assays. Potato plants (cv. Favorita) at the five- to six-leaf stage were inoculated by injecting their stems with 1 ml of each strain in a bacterial suspension (3 × 108 CFU/ml). The inoculated potato plants were incubated at 16 to 21°C and 65 to 85% humidity, and exhibited the same symptoms as the diseased potato plants in the field by 3 to 5 days post inoculation (dpi). The bacterium was reisolated from the diseased tissue (stem) of the inoculated potato plants and produced characteristic pits on crystal violet pectate medium (1). The bacterium utilized a-methyl glucoside, glucose, lactose, maltose, cellobiose, raffinose, melibiose, and citrate, but not d-arabitol, sorbitol, or malonate. The bacteria also gave a positive reaction for catalase and production of reducing substances from sucrose, but gave a negative reaction for oxidase, production of phosphatase, and indole. Using the universal bacterial 16S rDNA primer set, 27f/1541R (4), 1,400-bp fragments were amplified from the 10 strains. The sequences of the 10 fragments (GenBank Accessions KC695819 to KC695828) were identical and had 100% sequence identity with 16S rDNA of Pectobacterium atrosepticum CFBP 1526 (JN600332). Further, the 438-bp and 690-bp fragments were respectively amplified from all 10 strains with the P. atrosepticum-specific primers Y45/Y46 (3) and ECA1f/ECA2r (2). To our knowledge, this is the first report of potato blackleg disease caused by P. atrosepticum (formerly named as Erwinia carotovora subsp. atroseptica) in Guangdong Province, China. References: (1) D. Cupples et al. Phytopathology 64:468, 1974. (2) S. H. De Boer et al. Phytopathology 85:854, 1995. (3) D. Frenchon et al. Potato Research 41:63, 1995. (4) M. Horita et al. J. Gen. Plant Pathol. 70:278, 2004.

scholarly journals First Report of Bacterial Blight of Guar Caused by Xanthomonas axonopodis pv. cyamopsidis in China

Plant Disease ◽  
2014 ◽  
Vol 98 (6) ◽  
pp. 840-840 ◽  
Author(s):  
Y. Z. Ren ◽  
Y. L. Yue ◽  
G. X. Jin ◽  
Q. Du
Keyword(s):  
16S Rdna ◽  
Bacterial Blight ◽  
Negative Control ◽  
Bacterial Suspension ◽  
Cyamopsis Tetragonoloba ◽  
Sterile Water ◽  
Bacterial Strains ◽  
Xanthomonas Axonopodis ◽  
First Report ◽  
Pathogenicity Tests

Bacterial blight was observed on field-grown guar (Cyamopsis tetragonoloba L.) for the first time in China. The disease outbreak occurred in the Xinjiang Uyghur Autonomous Region after several weeks of unusually heavy rains during late summer 2013. The disease incidence was generally 40 to 50%, although values as high as 80% were observed in several fields. Initial field symptoms included water-soaked spots on leaves, pods, petioles, and stems. During later stages of infection, the color of the spots became dark. We also observed large, angular, necrotic lesions at leaf tips, black streaks on petioles and stems, split stems, defoliation, wilting or top withering, vascular necrosis, and dieback. Samples of diseased leaves, stems, petioles, pods, and seeds were surface sterilized, ground, and then plated onto King's B medium. Plates were incubated at 28°C for 72 h. Fifteen bacterial strains with yellow-pigmented, opaque, and round colonies were isolated. These strains were aerobic, gram-negative rods with a single, polar flagellum. They were positive for H2S, esculin, oxidase, tobacco hypersensitivity, indole production from tryptophan, nitrate reduction to nitrite, and the utilization of glucose, mannose, trehalose, galactose, and starch. The maximum salt tolerance of the strains was 2 to 3%. Pathogenicity tests using eight strains were conducted in July 2013. A bacterial culture was suspended in sterile water with a final concentration of 108 CFU/ml. Eight 4-week-old guar plants were inoculated by (i) spraying the bacterial suspension on the leaves until runoff, or (ii) puncturing the stems with a needle that had been dipped into the bacterial suspension. Sterile water was used as a negative control. Plants were kept in a mist room with 100% relative humidity for 24 h. Stem and leaf symptoms similar to those of the original plants were observed on the inoculated guar plants within 10 days of inoculation. No symptoms developed on the negative control plants. Yellow bacterial colonies re-isolated from inoculated plant tissues were morphologically identical to the original. 16S rDNA was amplified using universal primers (Pa 5′-AGTTTGATCCTGGCTCAG-3′ and Ph 5′-TACCTTGTTACGACTTCGTCCCA-3′) and sequenced. A BLAST search of the NCBI GenBank database indicated that the 16S rDNA sequences of three strains (accession nos. KF563926, KF563927, and KF563928) had 99.9% identity to Xanthomonas axonopodis strain XV938 (AF123091). Under greenhouse conditions, bacterial strains wilted asparagus bean and pea but rarely infected bean, kidney bean, faba bean, mung bean, soybean, red bean, pea, garbanzo bean, and peanut. Based on morphology, pathogenicity tests, 16S rDNA sequencing, and host plant specificity, the pathogen was confirmed as X. axonopodis pv. cyamopsidis (synonym: X. campestris pv. cyamopsidis [Patel et al., 1953]). To our knowledge, this is the first report of bacterial blight of guar caused by X. axonopodis pv. cyamopsidis in China. Guar has recently been introduced in Xinjiang Province. Our findings indicate that bacterial blight may pose a threat to the economic sustainability of guar production in the region. References: (1) I. A. Milyutina et a1. FEMS Microbiol. Lett. 239:17, 2004. (2) I. M. G. Almeida et al. Summa Phytopathol. 18:255, 1992. (3) J. D. Mihail et al. Plant Dis. 69:811, 1985.

scholarly journals First report of bacterial shot-hole disease caused by Xanthomonas arboricola pv. pruni on plumcot in South Korea

Plant Disease ◽  
2020 ◽  
Author(s):  
Walftor Dumin ◽  
Mi-Jeong Park ◽  
Jong-Han Park ◽  
Chang Youl Yang ◽  
Chang-Gi Back
Keyword(s):  
16S Rdna ◽  
Causal Agent ◽  
Bacterial Suspension ◽  
Pathogenicity Test ◽  
Total Production ◽  
Sterile Water ◽  
First Report ◽  
Young Leaves ◽  
Leaf Tissues ◽  
Xanthomonas Arboricola

Plumcot is an interspecific hybrid product between Japanese plums (Prunus salicina) and apricots (Prunus armeniaca) obtained by the NIHHS, Korea in 1999 [1]. At the early of 2017, black spots-like symptoms were observed on plumcot fruits and leaves at cultivation areas in Naju (34.965595, 126.665853) province. Further investigation shows that approximately 60% of the plumcot leaves in the affected orchard were infected, which caused 40% total production loss. At the early stage of infection, disease symptoms appear as small, angular and water-soaked spots and develop into circular brown spots at the later stages of infection. As the disease progresses, the leaf tissues around the spots became yellow and the lesions enlarged. When the adjacent lesions merged and the necrotic tissues fall off, shot-hole symptoms appear on the leaves. To identify the causal agent of this disease, infected leaf tissues were excised and surface-sterilized with 1% NaOCl for 30 secs prior to rinsing with sterile water, thrice . Tissue samples were then placed in sterile water (0.5 mL) for 5 min before its aliquots were streaked onto Luria-Bertani (LB) agar. Plates then were incubated at 28°C. To obtain pure colonies, bacteria were re-streak into a new LB agar and colonies showing typical Xanthomonas spp. morphology (i.e. convex, smooth, yellow, and mucoid) were subjected to Gram staining assay. For molecular identification, 16S ribosomal DNA (16S-rDNA) and gyrase B (gyrB) genes were amplified using a 9F/1512r and UP-1/UP-2Sr primers [2,3] respectively from 5 gram-negative isolates. PCR products were sequenced and analysed using BLASTN. Result shows that 16S-rDNA and gyrB genes are 99-100% identical to a similar genomic region of Xanthomonas arboricola pv. pruni (Xap) isolated in almond (MK156163), peach (MG049922) and apricot (KX950802) respectively [4,5,6]. 16S-rDNA and gyrB gene sequences were deposited in the GenBank (LC485472 and LC576824), whereas pathogen isolate was deposited into Korean Agricultural Culture Collection (KACC19949). Pathogenicity test was performed using Xap bacterial suspension (108 cfu/mL) inoculated on the abaxial and adaxial surface of plumcot detached leaves. For inoculation, 10 healthy young leaves were used whereas, 5 young leaves mock-inoculated with sterile LB broth were used as a control. Both leaf samples were kept in a closed container to maintain 100% humidity before being incubated at 25°C. The water-soaked symptoms were observed visually on the inoculated leaves 2 to 3 days post-inoculation. No water-soaked symptoms were observed on the control leaves. Morphology and sequences of molecular markers used showed that the 3 bacterial colonies re-isolated from the inoculated leaves were identical to the original isolate, fulfilling Koch’s postulate. Pathogenicity tests were repeated twice and the results obtained were consistent with the first experiment. As a new variety of stone fruit cultivated in Korea, information about pathogens and registered agrochemicals to control disease outbreak in plumcot are still limited. Therefore, the identification of Xap as a causal agent to the black spot disease is critical for the development of disease management strategies and to identify appropriate agrochemicals to control the occurrence of this disease in the field. To our knowledge, this is the first report of Xap as a causal agent to the shot-hole disease on the plumcot in Korea.

scholarly journals First Report of Dickeya solani Causing Soft Rot in Imported Bulbs of Hyacinthus orientalis in China

Plant Disease ◽  
2015 ◽  
Vol 99 (1) ◽  
pp. 155-155 ◽  
Author(s):  
X. F. Chen ◽  
H. L. Zhang ◽  
J. Chen
Keyword(s):  
16S Rrna ◽  
The Netherlands ◽  
Bacterial Pathogen ◽  
Soft Rot ◽  
Potato Production ◽  
Sterile Water ◽  
First Report ◽  
Hyacinthus Orientalis ◽  
Dickeya Solani ◽  
Negative Controls

A bacterial pathogen, Dickeya solani, emerged as a major threat to potato (Solanum tuberosum) production in Europe in 2004 and has spread to many potato-growing regions via international trade. In December 2013, soft rot symptoms were observed in hyacinth (Hyacinthus orientalis) bulbs imported from the Netherlands into China at Ningbo Port. Diseased bulbs gave off an offensive odor. The base and internal parts of diseased bulbs rotted, and the margins of diseased tissues showed brown discoloration. Isolation on nutrient agar glucose (NAG) medium resulted in dominating colonies of characteristic “fried egg” morphology (1). One colony was chosen for further investigation and tentatively named “isolate 6165-3.” Under microscopic visualization after gram stain, the cells of isolate 6165-3 were gram-negative, motile, and rod shaped. The isolate was then identified as a member of genus Dickeya using the Biolog GN microplate. The 16S rRNA, recA, and dnaX sequences of isolate 6165-3 were subsequently determined and deposited in GenBank with accession numbers KM405240, KM405241, and KM405242, sharing 99% (16S rRNA), 100% (recA), and 100% (dnaX) nucleotide identity with those of known D. solani isolates, respectively. By this means, the isolate 6165-3 was identified as D. solani (1,2). To confirm the pathogenicity of the isolate, four plants each of 30-day-old hyacinth, 14-day-old potato, and 60-day-old moth orchid (Phalaenopsis amabilis) were inoculated with suspensions of the isolate with a concentration of 108 CFU/ml in sterile water by stabbing. Plants were incubated in a climate chamber at 28°C during the day and 24°C during the night with a relative humidity of 93% and a photoperiod of 12/12 h. Plants inoculated with sterile water were included as negative controls. After 2 or 3 days, typical symptoms such as water-soaked lesions and soft rot developed around the inoculation point, while the negative controls remained symptomless. Koch's postulates were fulfilled by re-isolating bacteria from lesions, which had identical sequence and morphology characters with the inoculated isolate. This is the first report of intercepted D. solani on hyacinth bulbs imported from the Netherlands into China, indicating that D. solani can spread via hyacinth. Further spread of the pathogen into potato production might lead to immeasurable economic consequences for China. References: (1) P. F. Sarris et al. New Dis. Rep. 24:21, 2011. (2) J. M. van der Wolf et al. Int. J. Syst. Evol. Microbiol. 64:768, 2014.

scholarly journals First Report of a Soft Rot of Philodendron ‘Con-go’ in China Caused by Dickeya dieffenbachiae

Plant Disease ◽  
2012 ◽  
Vol 96 (3) ◽  
pp. 452-452 ◽  
Author(s):  
B. R. Lin ◽  
H. F. Shen ◽  
J. N. Zhou ◽  
X. M. Pu ◽  
Z. N. Chen ◽  
...  
Keyword(s):  
16S Rdna ◽  
Phylogenetic Trees ◽  
Soft Rot ◽  
Gyrb Gene ◽  
Control Treatment ◽  
Gene Sequences ◽  
16S Rdna Gene ◽  
First Report ◽  
Rdna Gene ◽  
Plastic Bags

Philodendron is a popular foliage plant cultivated in interiorscapes of homes, offices, and malls throughout China. A severe outbreak of a soft rot of Philodendron ‘Con-go’ occurred in Guangzhou, China from 2010 to 2011. The disease was characterized by leaf infections starting as pinpoint spots that are water soaked and yellow to pale brown. The lesions are sometimes surrounded by a diffuse yellow halo. When the humidity is high and temperatures are warm to hot, the spots expand rapidly, becoming slimy, irregular, and sunken with light tan centers, darker brown borders, and diffused yellow margins and may involve the entire leaf in a few days. An invasion of the midrib and larger veins by the causal bacterium often results in advancement into the petiole and stem. A survey of three areas of production of Philodendron ‘Con-go’ (5 ha) in Guangzhou revealed that 91% of the fields were affected at an incidence ranging from 15 to 30%. Of 41 bacterial isolates obtained from lesions, three were selected randomly for further characterization. All strains were gram negative, negative for oxidase and positive for catalase and tryptophanase (indole production), and utilized citrate, tartrate, malonate, glucose, sucrose, fructose, and maltose but not glucopyranoside, trehalose, or palatinose. Biolog analysis (version 4.20.05, Hayward, CA) identified the isolates as Pectobacterium chrysanthemi (SIM 0.804 to 0.914). According to Samson et al. (1), it was renamed as a Dickeya sp. PCR was performed on the 16S rDNA gene with primers 27f and 1495r (3) and 1,423 bp of the 16S rDNA gene (GenBank No. JN709491) showed 99% identity to P. chrysanthemi (GenBank No. AF373202), and 98% to Dickeya dieffenbachiae (GenBank No. JF311644). Additionally, the gyrB gene was amplified with primers gyrB-f1 (5′-atgtcgaattcttatgactcctc-3′) and gyrB-r1 (5′-tcaratatcratattcgcygctttc-3′) designed based on all the submitted gyrB gene sequences of Dickeya spp. The dnaX gene was amplified with primers dnaXf and dnaXr (2). The products were sequenced and phylogeny analyses were performed by means of MEGA 5.05. Results showed that the gyrB and the dnaX genes of the strains were 98% homologous to those of D. dieffenbachiae (GenBank Nos. JF311652 and GQ904757). Therefore, on the basis of phylogenetic trees of the 16S rDNA, gyrB, and dnaX gene sequences, the bacterial isolate named PC1 is related to D. dieffenbachiae (100% bootstrap values). Pathogenicity of each of the three strains on Philodendron ‘Con-go’ was confirmed by injecting 60 50-day-old seedlings each with 0.1 ml of the isolate suspension (108 CFU/ml) into the leaves. Another 60 were injected with sterile water to serve as the control treatment. Plants were enclosed in plastic bags and returned to the greenhouse under 50% shade at 32°C day and 28°C night temperatures with high humidity. After 72 h, all the injected plants started to show symptoms similar to those observed on field plants, but no symptoms appeared on the control plants. The reisolates were identical to the inoculated strains in biochemical characteristics. Bacteria characteristic of the inoculated strains were not reisolated from the control plants. To our knowledge, this is the first report of D. dieffenbachiae causing soft rot of Philodendron ‘Con-go' in China. References: (1) R. Samson et al. Evol. Microbiol. 55:1415, 2005. (2) M. Sławiak et al. Eur. J. Plant Pathol. 125:245, 2009. (3) W. G. Weisbury et al. J. Bacteriol. 173:697, 1991.

scholarly journals First Report of Bacterial Wilt Caused by Ralstonia solanacearum on Plectranthus amboinicus in Martinique

Plant Disease ◽  
2021 ◽  
Author(s):  
Peninna Deberdt ◽  
Gilles Cellier ◽  
Régine Coranson-Beaudu ◽  
Mathis Delmonteil--Girerd ◽  
Joanye Canguio ◽  
...  
Keyword(s):  
Bacterial Wilt ◽  
Ralstonia Solanacearum ◽  
Disease Incidence ◽  
Bacterial Suspension ◽  
Diagnostic Pcr ◽  
Tomato Plants ◽  
First Report ◽  
Initial Symptoms ◽  
Plectranthus Amboinicus ◽  
Negative Controls

Plectranthus amboinicus, commonly known as Gwo ten in the French West Indies (Martinique), is a semi-succulent perennial plant of the Lamiaceae family. This aromatic plant wich is widespread naturally throughout the tropics is of economic importance because of the therapeutic and nutritional properties attributed to its natural phytochemical compounds wich are highly valued in the pharmaceutical industry. In March 2019, wilted P. amboinicus plants intercropped with tomato plants (cv. Heatmaster) in order to reduce the insect-pest damages on tomato, were observed in a field located at the CIRAD experimental station in Lamentin, Martinique (14.663194 N, -60.999167 W). Average disease incidence of 65.74% was recorded on P. amboinicus, in 3 plots with an area of 22.04 m2. The initial symptoms observed were irregular, black, necrotic lesions on leaves. After 10 days, plants wilted and black stripes were observed on stems. Within 4 weeks, more than 50% of plants were fully wilted. Longitudinal stem sections of the wilted plants showed brown vascular discoloration. The cut stems of the wilted plants released a whitish bacterial ooze in water. In all, 108 stem sections were collected, surface disinfected with 70% ethanol and each was crushed in 2 mL of Tris-buffer, then processed for bacterial isolation by plating on modified Semi-Selective Medium from South Africa SMSA (Engelbrecht 1994). Typical Ralstonia solanacearum colonies grew on SMSA medium for 100 of the 108 samples after incubation for 48h at 28°C and were identified as Ralstonia solanacearum using diagnostic PCR with 759/760 primers (Opina et al. 1997). A phylotype-specific multiplex PCR (Fegan and Prior 2005) classified all the strains in R. solanacearum Phylotype IIA. A subset of 11 strains was selected for sequevar identification. All the strains were identified as sequevar I-39 (100% nucleotide identity with strain ANT92 - Genbank accession EF371828), by partial egl sequencing (Fegan and Prior 2005) (GenBank Accession Nos. MT314067 to MT314077). This sequevar has been reported to be widespread in the Caribbean and tropical America on vegetable crops (particularly on tomato), but not on P. amboinicus (Deberdt et al. 2014; Ramsubhag et al. 2012; Wicker et al. 2007). To fulfil Koch’s postulates, a reference strain, isolated from diseased P. amboinicus (CFBP 8733, Phylotype IIA/sequevar 39), was inoculated on 30 healthy P. amboinicus plants. A common tomato cultivar grown in Martinique (cv. Heatmaster) was also inoculated on 30 plants with the same bacterial suspension. Three-weeks-old plants of both crops grown in sterilized field soil were inoculated by soil drenching with 20 ml of a calibrated suspension (108 CFU/mL). P. amboinicus and tomato plants drenched with sterile water served as a negative controls. Plants were grown in a fully controlled environment at day/night temperatures of 30–26°C ± 2°C under high relative humidity (80%). The P. amboinicus plants started wilting 9 days after inoculation, and within four weeks 60% of the P. amboinicus plants had wilted. The tomato plants started wilting 5 days after inoculation with 62% of wilted plants within four weeks. R. solanacearum was recovered from all symptomatic plants on modified SMSA medium. No symptoms were observed and no R. solanacearum strains were isolated from negative controls plants. To our knowledge, this is the first report of R. solanacearum causing bacterial wilt on Gwo ten (P. amboinicus) in Martinique. The importance of this discovery lies in the reporting of an additional host for R. solanacearum, which can be associated with other crops as tomato crop in order to reduce the abundance of insect-pests. Further studies need to be conducted to assess the precise distribution of bacterial wilt disease on P. amboinicus in Martinique and to develop a plan of action avoiding its association with R. solanacearum host crops as tomato for reducing epidemic risk.

scholarly journals First Report of Pectobacterium aroidearum Causing Soft Rot in Olecranon Honey Peach (Prunus persica L.) in China

Plant Disease ◽  
2021 ◽  
Author(s):  
Zhibin Liang ◽  
Huidi Liu ◽  
Zeling Xu ◽  
Lian-hui Zhang
Keyword(s):  
16S Rdna ◽  
Dna Sequences ◽  
Prunus Persica ◽  
Bacterial Species ◽  
Guangdong Province ◽  
Housekeeping Genes ◽  
Soft Rot ◽  
Accession Number ◽  
First Report ◽  
Conserved Region

Olecranon honey peach (Prunus persica L.) is a popular fruit tree cultivated in Guangdong Province of China. Due to its excellent economic values and popularity, it has recently been widely adopted and planted in several other southern Provinces and Autonomous Region in China, including Yunnan, Hunan, Jiangxi, Guizhou, and Guangxi. In Lianping County of Guangdong Province alone, the annual peach fruit production was about 78,800 tonnes (Xie et al. 2017). In July 2021, peach fruits showing soft rot symptoms were collected from an olecranon honey peach plantation in Lechang, Guangdong, China. Symptoms included tissue disintegration with bacterial oozes and rotting smells. To isolate the causal agent of soft rot in the peach fruits, the bacterial oozes from various rotted fruits were streaked on the modified YEB agar plate (Huang et al. 2021), and 21 bacterial colonies were selected for PCR amplification using the primers targeting the conserved region of 16S rDNA gene (Wei et al. 2020). A blastN analysis of the DNA sequences of the obtained PCR fragments in NCBI website indicated that 17 isolates named as ZL strains were potential bacterial species of Pectobacterium with about 99% similarity (Genbank accession number of ZL1: OK189602) to Pectobacterium aroidearum SCRI 109T (Genbank accession number: NR_159926). Three of them (ZL1, ZL2 and ZL3) were selected for assay of pathogenicity. The bacterial suspensions (10 μl, 1×106 CFU/ml) of strains ZL1, ZL2 and ZL3 were injected into olecranon honey peach fruits by using a syringe. A portion of peach fruits were similarly injected with sterile distilled water as the negative control. After 18 h incubation at 25 °C, the typical symptom of soft rot, i.e., tissue decay, became visible on the peach fruits inoculated with the bacterial suspensions. After inoculation for 42 h, bacterial oozes were exuded from rotting tissues. Peach fruits without injuries were also sprayed with the bacterial suspensions under the same conditions, but decay symptoms were not observed, suggesting that the bacterial infection needs the wounding or injuries. To fulfill the Koch’s postulates, bacterial colonies were re-isolated from bacterial oozes, and their conserved region of 16S rDNA fragments were amplified and sequenced. Bioinformatics analysis of the DNA sequence data confirmed that all the isolated colonies were Pectobacterium strains. Using the Biolog Gen III system, the representative strain ZL1 was identified as Pectobacterium (SIM 0.56). Transmission electron microscopy analysis showed that the bacterial cells of strain ZL1 were rod-shaped with peripheral flagella. To further determine the species of ZL strains, eight housekeeping genes (acnA, gapA, icd, mdh, mtlD, pgi, proA and rpoS) were analyzed by the methods described previously (Nabhan et al. 2013). The amplified DNA sequences analyzed by the blastN program in NCBI showed that the sequences of eight housekeeping genes from strains ZL1, ZL2 and ZL3 were identical to each other (Genbank accession number: OK274248 to OK274255), and most of the gene sequences shared over 99% similarity to their counterparts in P. aroidearum L6 (Genbank accession number: NZ_CP065044) (Xu et al. 2021), except that the acnA and proA genes showed about 98% and 96% similarity respectively to the corresponding genes of P. aroidearum L6. In addition, the multi-locus sequence analysis (MLSA) using DNA sequences of above eight housekeeping genes showed that ZL strains were grouped with other P. aroidearum strains. Taken together, the results of molecular and biochemical assays confirmed that ZL strains isolated from olecranon honey peach fruits were P. aroidearum. To our knowledge, this is the first report of P. aroidearum causing soft rot disease in olecranon honey peach in China. P. aroidearum is a relatively newly described soft rot pathogen (Nabhan et al. 2013). More recently, the pathogen was found causing soft rot infections in lettuce, Chinese cabbage, pepper (Capsicum annuum) fruits, konjac, carrot and Syngonium podophyllum (Barroso et al. 2019; Moraes et al. 2020; Sun et al. 2019; Tang et al. 2020; Xu et al. 2021). The results of this study add a new plant species to the host range of P. aroidearum.

scholarly journals First Report of Aster Yellows Phytoplasma in Alfalfa

Plant Disease ◽  
1999 ◽  
Vol 83 (5) ◽  
pp. 488-488 ◽  
Author(s):  
R. D. Peters ◽  
M. E. Lee ◽  
C. R. Grau ◽  
S. J. Driscoll ◽  
R. M. Winberg ◽  
...  
Keyword(s):  
16S Rdna ◽  
Nested Pcr ◽  
Sequence Data ◽  
Sequence Similarity ◽  
Similarity Function ◽  
Sterile Water ◽  
Aster Yellows ◽  
First Report ◽  
Pcr Product ◽  
Aster Yellows Phytoplasma

Samples of alfalfa (Medicago sativa L.) leaves and stems showing symptoms of inter-veinal chlorosis and purpling, commonly associated with insect feeding, were collected from 8 sites in central and southern Wisconsin in autumn of 1998. Samples were frozen within 24 h of collection. Approximately 0.3 g of plant tissue from each sample was used for total DNA extraction according to the protocol of Zhang et al. (4), with minor modifications in grinding procedures and reagent volumes to optimize results. Nested polymerase chain reaction (PCR) was carried out by amplification of 16S rDNA with the universal primer pairs R16mF2/R16mR1 followed by R16F2n/R16R2 as described by Gunder-sen and Lee (1). Undiluted total sample DNA was used for the first amplification; PCR products were diluted (1:30) in sterile water prior to final amplification. Alfalfa DNA and sterile water were used as negative controls; DNA from phytoplasma causing X-disease in peach (CX) served as a positive control. Fragments of 16S rDNA from putative phytoplasmas amplified by PCR with the primer pair R16F2n/R16R2 were characterized by restriction endonuclease digestion (3). The resulting restriction fragment length polymorphism (RFLP) patterns were compared with patterns for known phytoplasmas described by Lee et al. (3). Products of nested PCR were also purified and sequenced with primers R16F2n/R16R2 and an automated DNA sequencer (ABI 377XL; C. Nicolet, Biotechnology Center, University of Wisconsin-Madison). Of 51 samples of alfalfa assessed, one sample from Evansville, WI, yielded a nested PCR product of the appropriate size (1.2 kb), indicating the presence of phytoplasma. Digestion of this product with various restriction enzymes produced RFLP patterns that were identical to those for phytoplasmas in the aster yellows phytoplasma subgroup 16SrI-A (3). Alignment of the DNA sequence of the nested PCR product from the positive sample with sequences found in the GenBank sequence data base (National Center for Biotechnology Information, Bethesda, MD) with the BLAST sequence similarity function confirmed this result. Although other phytoplasma strains (particularly those causing witches'-broom) have been reported to infect alfalfa (2), this is the first report of the presence of the aster yellows phytoplasma in the alfalfa crop. Vectors involved in transmission and the potential agronomic impacts of aster yellows phytoplasma in alfalfa are topics of current investigation. References: (1) D. E. Gundersen and I.-M. Lee. Phytopathol. Mediterr. 35:144, 1996. (2) A.-H. Khadhair et al. Microbiol. Res. 152:269, 1997. (3) I.-M. Lee et al. Int. J. Syst. Bacteriol. 48:1153, 1998. (4) Y.-P. Zhang et al. J. Virol. Methods 71:45, 1998.

Sign in / Sign up

Export Citation Format

Share Document