First Report of Tomato Pith Necrosis Caused by Pseudomonas cichorii in Tanzania

Coreopsis lanceolata L. (Compositae), an ornamental species grown in parks and gardens, is very much appreciated for its long-lasting flowering period. In August of 2008, pot-grown plants with necrotic leaf lesions were observed in a commercial nursery located near Biella (northern Italy). Lesions were present, especially along the margin of basal leaves, and sometimes had a chlorotic halo. On infected leaves, dark brown necrosis developed. Leaf stalks were sometimes affected. In many cases, the leaves, especially those at collar level, were withered. Of 1,500 plants, 15% were infected by the disease. Microscopic examination did not reveal any fungal structures within the lesions. Small fragments of tissue from 30 affected leaves were macerated for 15 min in casein hydrolysate and 0.1-ml aliquots of the resulting suspension were spread onto Luria Bertani agar (LB) and potato dextrose agar (PDA). Plates were maintained at 22 ± 1°C for 48 h. No fungi were isolated from the leaf spots on LB or PDA. Colonies similar to those of Pseudomonas spp. were consistently isolated on LB. Colonies were fluorescent on King's medium B, levan negative, oxidase positive, potato soft rot negative, arginine dihydrolase negative, and tobacco hypersensitivity positive (LOPAT test). The bacterial colonies were identified as Pseudomonas cichorii (2). The internal transcribed spacer (ITS) region of rDNA was amplified using primers 27F and 1492R and sequenced (GenBank Accession No. FJ534557). BLAST analysis (1) of the 998-bp segment showed a 98% homology with the sequence of P. cichorii. The pathogenicity of one isolate was tested twice by growing the bacterium in nutrient broth shake cultures for 48 h at 20 ± 1°C. The suspension was centrifuged, the cell pellet resuspended in sterile water to a concentration of 107 CFU/ml, and 30 4-month-old healthy coreopsis plants were sprayed with the inoculum. The same number of plants was sprayed with sterile nutrient broth as a control. After inoculation, plants were covered with plastic bags for 48 h and placed in a growth chamber at 20 ± 1°C. Five days after inoculation, lesions similar to those seen in the field were observed on all plants inoculated with the bacterium, but not on the controls. Ten days later, 40% of the leaves were withered. Isolations were made from the lesion margins on LB and the resulting bacterial colonies were again identified as P. cichorii. The pathogen caused the same symptoms also on plants of Dendranthema frutescens (cv. Camilla), Chrysanthemum morifolium (cvs. Eleonora and Captiva), and an Osteospermum sp. (cv. Wild side) when artificially inoculated with the pathogen with the same methodology. The same bacterial leaf spot caused by P. cichorii was observed in 2005 in other nurseries in the same area on Phlox paniculata (3). To our knowledge, this is the first report of bacterial leaf spot caused by P. cichorii on C. lanceolata in Italy. References: (1) S. F. Altschul et al. Nucleic Acids Res. 25:3389, 1997. (2) H. Bergey et al. Bergey's Manual on Determinative Bacteriology. Williams and Wilkins, Baltimore, MD, 1994. (3) A. Garibaldi et al. Plant Dis. 89:912, 2005.

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First Report of a Leaf Spot Disease of Tobacco Caused by Pseudomonas cichorii in China

Plant Disease ◽

10.1094/pdis-10-21-2158-pdn ◽

2021 ◽

Author(s):

Dayu Lan ◽

Fangling Shu ◽

Yanhui Lu ◽

Anfa Shou ◽

Wei Lin ◽

...

Keyword(s):

Pseudomonas Syringae ◽

Leaf Spot ◽

Leaf Spot Disease ◽

Pathogenicity Test ◽

Pseudomonas Cichorii ◽

Koch’S Postulates ◽

First Report ◽

Initial Symptoms ◽

Wide Range ◽

Koch's Postulates

Tobacco (Nicotiana tabacum L.), one of the chief commercial crops, is wildly cultivated worldwide. In June 2020 and 2021, an unknown bacterial leaf spot on tobacco was found in Hezhou and Hechi City, Guangxi, China. 30% of the tobacco were affected and the rate of diseased leaves reached about 10% in the field under high temperature and rainstorm. The disease mainly damaged the middle and top leaves of tobacco plants at vigorous growing stage. The initial symptoms were water-soaked spots on the frontal half of a leaf, and then expanded into circular to irregular spots with a yellow halo at the edge. The spots mostly appeared dark brown at high air humidity, while yellow brown at low humidity and exhibited a concentric pattern. In severe cases, the lesions coalesced and the whole leaf was densely covered with lesions, resulting in the loss of baking value. A bacterium was consistently isolated from diseased leaf tissues on nutrient agar (NA). Growth on NA was predominantly grayish white circular bacterial colonies with smooth margins, and the bacterium is rod-shaped, gram-negative and fluorescent on King’s B medium. Seven isolates (ND04A-ND04C and ZSXF02-ZSXF05) were selected for molecular identification and pathogenicity tests. Genomic DNA of the bacterium was extracted and the housekeeping gene of cts (encoding citrate synthase) was amplified with the primers cts-Fs/cts-Rs (forward primer cts-Fs: 5’-CCCGTCGAGCTGCCAATWCTGA-3’; reverse primer cts-Rs: 5’-ATCTCGCACGGSGTRTTGAACATC-3’) (Berge et al. 2014; Sarkar et al. 2004). 409-bp cts gene sequences were deposited in the GenBank database for seven isolates (accession no. OK105110-OK105116). Sequence of seven isolates shared 100% identity with several Pseudomonas cichorii strains within the GenBank database (accession no. KY940268 and KY940271), and the phylogenetic tree of cts genes of the seven isolates clustered with the phylogroup 11 of Pseudomonas syringae (accession no. KJ877799 and KJ878111), which was classified as P.cichorii. To satisfy Koch’s postulates, a pathogenicity test was tested by using a needle to dip a suspension of the bacterium (108 CFU/ml) and pricking three holes in the tobacco leaf. The control plants leaves were needled with sterile water. Each tobacco plant was inoculated with three leaves, and the test was repeated three times. All plants were placed in transparent plastic boxes and incubated in a greenhouse at 25 ± 3°C. The water-soaked spots appeared 24h after inoculation and quickly expanded through leaf veins. Three days after inoculation, all the inoculated leaves showed symptoms similar to those observed in the field. Control plants remained healthy. Only P. cichorii was successfully re-isolated from the lesions, confirming Koch’s postulates. Pseudomonas cichorii can infect eggplant, lettuce, tomatoand other crops, and has a wide range of hosts (Timilsina et al. 2017; Ullah et al. 2015). To our knowledge, this is the first report of P. cichorii causing leaf spot on tobacco in China.

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First Report of Bacterial Leaf Spot of Cucumber Caused by Pseudomonas cichorii in China

Plant Disease ◽

10.1094/pdis-02-18-0267-pdn ◽

2019 ◽

Vol 103 (1) ◽

pp. 147

Author(s):

X. Y. Fu ◽

R. Y. Zhang ◽

Z. Q. Tan ◽

T. Liu ◽

Z. Q. Peng

Keyword(s):

Leaf Spot ◽

Bacterial Leaf Spot ◽

Pseudomonas Cichorii ◽

First Report

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First Report of Pseudomonas cichorii Causing Leaf Spot of Vegetable Sponge Gourd in China

Plant Disease ◽

10.1094/pdis-03-13-0312-pdn ◽

2014 ◽

Vol 98 (1) ◽

pp. 153-153 ◽

Cited By ~ 3

Author(s):

B. J. Li ◽

H. L. Li ◽

Y. X. Shi ◽

X. W. Xie

Keyword(s):

Leaf Spot ◽

Pathogenic Bacteria ◽

Identification System ◽

Pathogenicity Test ◽

Distilled Water ◽

Pseudomonas Cichorii ◽

First Report ◽

Microbial Identification ◽

Pectolytic Activity ◽

Sponge Gourd

A suspect bacterial leaf spot on vegetable sponge gourd (Luffa cylindrical (L.) Roem.) was found in a commercial greenhouse in Pi County, Chengdu City, Sichuan Province, China, in February 2011. Approximately 20 to 30% of plants were affected, causing serious economic loss. Symptoms occurred only on seedlings and consisted of water-soaked, irregularly shaped, black lesions on the surface and margins of cotyledons. A bacterium was consistently isolated on nutrient agar from diseased leaf tissues that had been surface disinfected in 70% ethyl alcohol for 30 s. The bacterium produced small gray colonies with smooth margins, was gram negative, fluoresced on King's B medium, and showed pectolytic activity when inoculated on potato slices. The partial sequences of 16SrRNA gene (1,377 bp) of the bacterium (GenBank Accession No. KC762217), amplified by using universal PCR primers 16SF (5′-AGAGTTTGATCCTGGCTCAG-3′) and 16SR (5′-GGTTACCTTGTTACGACTT-3′), shared 100% similarity with that of Pseudomonas cichorii (GenBank Accession No. HM190228). The vegetable sponge gourd isolate was also identified by using the Biolog Microbial Identification System (version 4.2, Biolog Inc., Hayward, CA) as P. cichorii with the following characteristics (1): negative for arginine dihydrolase, gelatin liquefaction, and N2 production. Positive reactions were obtained in tests for catalase, oxidase, potato rot, utilization of melibiose, and mannitol. Tests were negative for utilization of sucrose, trehalose, D-arabinose, raffinose, cellobiose, and rhamnose. A pathogenicity test was conducted on 4-week-old vegetable sponge gourd plants by spray-inoculation with 108 CFU/ml sterile distilled water on the leaves of 15 vegetable sponge gourd plants and by needle puncture on the stems of 15 other plants with P. cichorii, respectively. Control plants were misted with sterile distilled water or punctured on the stem with a clean needle. Plants were placed in a greenhouse maintained at 28 ± 2°C with relative humidity of 80 to 85%. Symptoms, the same as seen on the original diseased plants, developed after 7 to 10 days on inoculated plants. Control plants remained healthy. The bacterium was readily re-isolated from inoculated plants and identified as P. cichorii using P. cichorii-specific primer hrpla/hrp2a (1). To our knowledge, this is the first report of P. cichorii causing disease on commercially grown vegetable sponge gourd in China. This new finding will provide the basis for developing resources for diagnostics and management, including screening varieties for resistance. References: (1) S. Mazurier et al. J. FEMS Microbiol. Ecol. 49:455, 2004. (2) N. W. Schaad et al., eds. Laboratory Guide for Identification of Plant Pathogenic Bacteria, 3rd ed. APS Press, St. Paul, MN, 2001.

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First Report of Tomato Pith Necrosis Caused by Pseudomonas mediterranea in Georgia, USA

Plant Disease ◽

10.1094/pdis-06-15-0715-pdn ◽

2016 ◽

Vol 100 (2) ◽

pp. 518-518 ◽

Cited By ~ 1

Author(s):

J. V. K. Searcy ◽

S. Smith ◽

R. D. Gitaitis ◽

B. Dutta

Keyword(s):

First Report ◽

Pith Necrosis

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First report of Fusarium proliferatum causing crown and stem rot, and pith necrosis, in cannabis (Cannabis sativa L., marijuana) plants

Canadian Journal of Plant Pathology ◽

10.1080/07060661.2020.1793222 ◽

2020 ◽

pp. 1-20

Author(s):

Zamir K. Punja

Keyword(s):

Cannabis Sativa ◽

Fusarium Proliferatum ◽

Stem Rot ◽

First Report ◽

Pith Necrosis

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First Report of Bacterial Leaf Spot Caused by Pseudomonas cichorii on Thai Basil in Hawaii

Plant Disease ◽

10.1094/pdis-06-18-0995-pdn ◽

2018 ◽

Vol 102 (12) ◽

pp. 2637-2637

Author(s):

B. C. Luiz ◽

W. P. Heller ◽

E. Brill ◽

B. C. Bushe ◽

L. M. Keith

Keyword(s):

Leaf Spot ◽

Bacterial Leaf Spot ◽

Pseudomonas Cichorii ◽

First Report

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First Report of Bacterial Leaf Spot of Witloof, Caused by Pseudomonas cichorii in Korea

Plant Disease ◽

10.1094/pdis-04-13-0436-pdn ◽

2013 ◽

Vol 97 (10) ◽

pp. 1376-1376 ◽

Cited By ~ 1

Author(s):

I.-S. Myung ◽

J.-K. Choi ◽

J. Y. Lee ◽

M.-J. Yoon ◽

E. Y. Hwang ◽

...

Keyword(s):

16S Rrna ◽

Economic Impact ◽

Leaf Spot ◽

Reference Strain ◽

Bacterial Leaf Spot ◽

Pseudomonas Cichorii ◽

First Report ◽

Field Isolates ◽

Original Field ◽

Index Value

In August 2011, bacterial leaf spot was observed on witloof (Cichorium intybus L. var. foliosum) grown in a commercial field with 15% incidence in Injae, Korea. Symptoms on leaves included irregular brown to reddish brown spots in the center. Bacterial streaming from the lesions was observed microscopically. Bacterial isolates (BC3286, BC3287, and BC3308-BC3310) were recovered on Trypticase soy agar from lesions surface-sterilized in 70% ethyl alcohol for 30 s. The isolates were gram negative, urease negative, fluorescent on King's B agar, and had aerobic rods with 2 to 6 polar flagella. Pathogenicity tests were separately performed in different greenhouses located in Suwon (National Academy of Agricultural Science) and Chuncheon (Gangwondo Agricultural Research and Extension Services) in Korea. Pathogenicity was confirmed by spray inoculation of healthy, 10-day-old leaves of witloof plants (two plants/isolate) with a suspension of original field isolate (106 CFU/ml). Sterile distilled water was used as negative control. The inoculated plants were incubated in a growth chamber (25°C and 95% relative humidity [RH]) overnight, then transferred to a greenhouse at 23 to 27°C and 60 to 70% RH. Characteristic leaf spot symptoms were observed on inoculated witloof plants 8 days after inoculation. No symptoms were observed on control plants. The bacterium reisolated from the inoculated leaves was confirmed by analyzing sequence of the gyrB gene with direct sequencing method of PCR products using primers gyr-F and gyr-R (2). The sequence of reisolated bacteria shared 100% similarity with inoculated ones. In LOPAT (1) tests, all isolates and the reference strain of Pseudomonas cichorii CFBP2101T (=BC2595) were levan negative, oxidase positive, potato rot negative, arginine dihydrolase negative, and tobacco hypersensitivity positive, indicative of group III (–, +, –, –, +) of fluorescent pseudomonads. The 16S rRNA (1,408 bp), and gyrB (676 bp) regions were sequenced to aid in identification of the original field isolates as well as P. cichorii CFBP 2101T (=BC2595) using reported sets of PCR primers, fD1/rP2 and gyr-F/gyr-R, respectively (2,4). Phylogenetic analyses based on partial sequences of the gyrB and the 16S rRNA of Psudomonas spp. available in GenBank, the reference strain of P. cichorii CFBP2101T (=BC2595), and the witloof field isolates were conducted using the neighbor-joining method with Juke-Cantor model of distance calculation in MEGA version 5.1 (3). The isolates and the reference strain of P. cichorii CFBP2101T (=BC2595) was clustered in one group with P. cichorii strains in both phylogenetic trees based on the two sequences. Sequences of the 16S rRNA region had a distance index value ranging from 0.000 to 0.001 between the reference strain of P. cichori CFBP2101T (GenBank JX913784) and the field isolates (JX913785 to JX913789), and ranged from 0.000 to 0.001 within the field isolates. Sequences of the gyrB region had a distance index value ranging 0.029 to 0.033 between the reference strain (JX913790) and the field isolates (JX913791 to JX913795), and ranged from 0.000 to 0.041 within the field isolates. To our knowledge, this is the first report of bacterial leaf spot of witloof caused by P. cihorii in Korea. P. cichorii has a wide host range, and an important economic impact on vegetables. The disease is expected to result in a significant economic impact on root production of witloof in Korea. References: (1) R. A. Lelliott et al. J. Appl. Bacteriol. 29:470, 1966. (2) H. Sawada et al. J. Mol. Evol. 49:627, 1999. (3) K. Tamura et al. Mol. Biol. Evol. 28:2731, 2011. (4) W. G. Weinsburg et al. J. Bacteriol. 173, 697, 1991.

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