scholarly journals First Report of Xanthomonas citri pv. citri-A Causing Asiatic Citrus Canker in Mayotte

Plant Disease ◽  
2013 ◽  
Vol 97 (7) ◽  
pp. 989-989
Author(s):  
J. Hoarau ◽  
C. Boyer ◽  
K. Vital ◽  
T. Chesneau ◽  
C. Vernière ◽  
...  
Keyword(s):  
Indian Ocean ◽  
Sweet Orange ◽  
Citrus Canker ◽  
Negative Control ◽  
Sterile Water ◽  
Citrus Species ◽  
Indian Ocean Region ◽  
Southwest Indian Ocean ◽  
Mexican Lime ◽  
Ocean Region

Asiatic citrus canker, caused by Xanthomonas citri pv. citri, is a bacterial disease of major economic importance in tropical and subtropical citrus-producing areas. X. citri pv. citri pathotype A can cause severe infection in a wide range of citrus species and induces erumpent, callus-like lesions with water-soaked margins evolving to corky cankers and leading to premature fruit and leaf drop and twig dieback on susceptible/very susceptible cultivars. A chlorotic halo is typically visible around canker lesions on leaves and young fruit, but not on mature fruit and twigs. This quarantine organism can strongly impact both national and international citrus markets. Long distance dispersal is mainly through infected propagative material. Asiatic citrus canker occurs on most islands in the Southwest Indian Ocean region (Comoros, Mauritius, Reunion, Rodrigues, and Seychelles islands), but was not yet reported in Mayotte (EPPO-PQR available at http://www.eppo.int ). In May 2012, typical canker-like symptoms were observed on sweet orange (Citrus sinensis) groves on Mtsamboro islet and soon after on the main island of Mayotte, mostly on sweet oranges, but also on Tahiti limes (C. latifolia) and mandarins (C. reticulata). Eighty-one Xanthomonas-like strains were isolated using KC semi-selective medium (4) from disease samples collected from both commercial groves and nurseries on different Citrus species located all over the island. Sixteen Xanthomonas-like isolates were tentatively identified as X. citri pv. citri based on a specific PCR assay with 4/7 primers (3). All strains but the negative control, sterile water, produced an amplicon of the expected size similar to X. citri pv. citri strain IAPAR 306 used as positive control. Multilocus sequence analysis targeting six housekeeping genes (atpD, dnaK, efp, gltA, gyrB, and lepA) (1,2) fully identified three strains from Mayotte (LJ225-3, LJ228-1, and LJ229-11) as X. citri pv. citri (and not other xanthomonad pathovars pathogenic to citrus or host range-restricted pathotypes of pathovar citri), and more specifically as sequence type ST2 composed of pathotype A strains of X. citri pv. citri (2) (including all strains from the Southwest Indian Ocean region). Eight strains were inoculated by a detached leaf assay (2) to Mexican lime SRA 140 (C. aurantifolia), Tahiti lime SRA 58, sweet orange cv. Washington Navel, alemow SRA 779 (C. macrophylla), and tangor cv. Ortanique (C. reticulata × C. sinensis) and developed typical erumpent, callus-like tissue at wound sites for all Citrus species, fulfilling Koch's postulates. Xanthomonas-like yellow colonies were reisolated from symptoms produced by the eight strains inoculated on Mexican lime. Boiled bacterial suspensions were assayed by PCR with 4/7 primers (3) and produced the expected 468-bp amplicon in contrast with the negative control (sterile water). No lesions developed on the negative control consisting of inoculations by 10 mM tris buffer (pH 7.2). Citrus canker-free nurseries and grove sanitation should be implemented for decreasing the prevalence of Asiatic canker in this island territory. References: (1) N. F. Almeida et al. Phytopathology 100:208, 2010. (2) L. Bui Thi Ngoc et al. Int. J. Syst. Evol. Microbiol. 60:515, 2010. (3) J. S. Hartung et al. Phytopathology 86:95, 1996. (4) O. Pruvost et al. J. Appl. Microbiol. 99:803, 2005.

scholarly journals First Report of Xanthomonas citri pv. citri Pathotype A Causing Asiatic Citrus Canker in Grande Comore and Anjouan

Plant Disease ◽  
2014 ◽  
Vol 98 (12) ◽  
pp. 1739-1739
Author(s):  
P. Grygiel ◽  
A. Seny-Couty ◽  
F. Abdou Hassani ◽  
C. Boyer ◽  
K. Boyer ◽  
...  
Keyword(s):  
Indian Ocean ◽  
Sweet Orange ◽  
Citrus Canker ◽  
Negative Control ◽  
Citrus Species ◽  
Indian Ocean Region ◽  
Southwest Indian Ocean ◽  
Mexican Lime ◽  
Ocean Region ◽  
Grande Comore

The causal agent of Asiatic citrus canker, Xanthomonas citri pv. citri, is a bacterium of major economic importance in tropical and subtropical citrus-producing areas. X. citri pv. citri pathotype A can cause severe infection in a wide range of citrus species and induces erumpent, callus-like lesions with water-soaked margins evolving to corky cankers and leading to premature fruit, leaf drop, and twig dieback on susceptible cultivars. This quarantine organism can strongly impact citrus markets so it has consequently been subjected to eradication efforts and international quarantine regulations. Asiatic citrus canker occurs on most islands in the Southwest Indian Ocean region including the Mascarene and Seychelles archipelagos. In the Comoros archipelago, the disease was observed for the first time in Mohéli island in 1966 (2), but had not yet been reported in neighboring islands, Grande Comore and Anjouan. In September 2013, leaves of key lime (Citrus aurantifolia) and sweet orange (C. sinensis) showing symptoms of citrus canker were collected from Anjouan, Grande Comore, and Mohéli. Nine Xanthomonas-like strains (three from each of the three islands) were isolated using KC semi-selective medium (5) from diseased samples (LK126-3, LK127-7, LK128-2, LK131-10, LK137-1, LK141-3, LK144-5, LK145-5, LK146-2). Based on a specific PCR assay with 4/7 primers (4), all Xanthomonas-like strains were tentatively identified as X. citri pv. citri. All strains produced a 468-bp amplicon similar to X. citri pv. citri strain IAPAR 306 used as a positive control. Negative control reactions with sterile tris buffer did not produce amplicons. Multilocus sequence analysis (MLSA) targeting six housekeeping genes (atpD, dnaK, efp, gltA, gyrB, and lepA) (1,3) fully identified all strains from the Comoros as X. citri pv. citri. More specifically, eight strains were identified as sequence type ST2 composed of pathotype A strains of X. citri pv. citri (3) (including all strains from the Southwest Indian Ocean region) while one of them (LK141-3 from Mohéli) was identified as a new sequence type based on a non-synonymous single nucleotide polymorphism in gyrB (accession KJ941208). All strains were inoculated by a detached leaf assay (3) onto Mexican lime SRA 140 (C. aurantifolia), Tahiti lime SRA 58 (C. latifolia), sweet orange New Hall Navel SRA 343 (C. sinensis), grapefruit Henderson SRA 336 (C. paradisi), and Ortanique tangor SRA 110 (C. reticulata × C. sinensis). All citrus species inoculated produced typical erumpent, callus-like tissue at wound sites. Xanthomonas-like yellow colonies were re-isolated from lesions produced on Mexican lime. Boiled bacterial suspensions were assayed by PCR with 4/7 primers (4) and produced the expected amplicon, fulfilling Koch's postulates. No lesions developed on the negative control consisting of inoculations with sterile tris buffer. This is the first report of X. citri pv. citri-A causing Asiatic citrus canker in Grande Comore and Anjouan islands confirming the wide distribution of the pathogen in Southwest Indian Ocean islands. Canker-free nurseries and grove sanitation should be implemented to decrease the prevalence of Asiatic canker in the Comoros. References: (1) N. F. Almeida et al. Phytopathology 100:208, 2010. (2) J. Brun. Fruits 26:533, 1971. (3) L. Bui Thi Ngoc et al. Int. J. Syst. Evol. Microbiol. 60:515, 2010. (4) J. S. Hartung et al. Phytopathology 86:95, 1996. (5) O. Pruvost et al. J. Appl. Microbiol. 99:803, 2005.

scholarly journals First Report of Xanthomonas citri pv. citri Causing Asiatic Citrus Canker in Burkina Faso

Plant Disease ◽  
2013 ◽  
Vol 97 (12) ◽  
pp. 1653-1653 ◽  
Author(s):  
C. C. Juhasz ◽  
A. Leduc ◽  
C. Boyer ◽  
F. Guérin ◽  
C. Vernière ◽  
...  
Keyword(s):  
Burkina Faso ◽  
Sweet Orange ◽  
Citrus Canker ◽  
Negative Control ◽  
Citrus Species ◽  
Xanthomonas Citri ◽  
First Report ◽  
Mexican Lime ◽  
Volkamer Lemon ◽  
Wide Range

Citrus canker, caused by Xanthomonas citri pv. citri, is a bacterial disease of economic importance in tropical and sub-tropical citrus-producing areas (EPPO-PQR online database). X. citri pv. citri causes severe infection in a wide range of citrus species, and induces erumpent, callus-like lesions with water-soaked margins leading to premature fruit drop and twig dieback. It has consequently been subjected to eradication efforts and international regulations. It was first described on the African continent in South Africa at the beginning of the 20th century, from which it was eventually eradicated. Since 2006, several outbreaks caused by phylogenetically diverse strains of X. citri pv. citri have been reported from several African countries (Ethiopia, Mali, Senegal, and Somalia). In July 2011, citrus canker in Burkina Faso was suspected in the area adjacent to the Sikassso Province of Mali where X. citri pv. citri has been confirmed. In November and December 2012, leaves of clementine (Citrus clementina), lemon (C. limon), Volkamer lemon (C. volkameriana), sweet orange (C. sinensis), tangelo (C. paradisi× C. reticulata), and mandarin (C. reticulata) were collected from orchards with trees showing symptoms of citrus canker in the Comoé, Houet, and Kénédougou provinces of Burkina Faso. Isolations performed using KC semi-selective medium (4) recovered 45 Xanthomonas-like strains. All Xanthomonas-like strains were tentatively identified as X. citri pv. citri by PCR (4/7 primers) using IAPAR 306 and sterile distilled water as the positive and negative controls, respectively (3). Among these, two strains (LK4-4 and LK4-5) produced a ‘fuscans’-like brown diffusible pigment, a phenotype never reported previously for X. citri pv. citri. MultiLocus Sequence Analysis targeting six housekeeping genes (atpD, dnaK, efp, gltA, gyrB, and lepA) (1,2) fully identified seven strains from Burkina Faso (LJ301-1, LJ303-1, LK1-1, LK2-6, LK4-3, LK4-4, and LK4-5) as X. citri pv. citri (and not to any other Xanthomonas pathovars pathogenic to citrus or host range-restricted pathotypes of pathovar citri), and more specifically as sequence type ST2 which is composed mostly of pathotype A strains of X. citri pv. citri (2). The same seven strains were inoculated to at least four leaves of each of grapefruit cv. Henderson, Mexican lime SRA 140 (C. aurantifolia), Tahiti lime SRA 58 (C. latifolia), and sweet orange cv. Washington Navel, using a detached leaf assay (2). All strains developed typical erumpent, callus-like tissue at wound sites on all citrus species inoculated. No lesions developed on the negative control (sterile 10 mM tris buffer). Koch's postulate was fulfilled after reisolation of Xanthomonas-like yellow colonies from symptoms on Mexican lime produced by the seven strains. Boiled bacterial suspensions were assayed by PCR with 4/7 primers (3) and produced the expected 468-bp amplicon in contrast with the PCR negative control. To our knowledge, this is the first report of X. citri pv. citri in Burkina Faso. Citrus canker-free nurseries and grove sanitation should be implemented for reducing the prevalence of Asiatic canker in Burkina Faso and a thorough survey of citrus nurseries and groves in the region should be conducted. References: (1) N. F. Almeida et al. Phytopathology 100:208, 2010. (2) L. Bui Thi Ngoc et al. Int. J. Syst. Evol. Microbiol. 60:515, 2010. (3) J. S. Hartung et al. Phytopathology 86:95, 1996. (4) O. Pruvost et al. J. Appl. Microbiol. 99:803, 2005.

scholarly journals Genetic and Pathological Diversity Among Xanthomonas Strains Responsible for Bacterial Spot on Tomato and Pepper in the Southwest Indian Ocean Region

Plant Disease ◽  
2010 ◽  
Vol 94 (8) ◽  
pp. 993-999 ◽  
Author(s):  
A. A. Hamza ◽  
I. Robène-Soustrade ◽  
E. Jouen ◽  
L. Gagnevin ◽  
P. Lefeuvre ◽  
...  
Keyword(s):  
Indian Ocean ◽  
Development Program ◽  
Housekeeping Genes ◽  
Agricultural Pests ◽  
Bacterial Spot ◽  
Indian Ocean Region ◽  
Southwest Indian Ocean ◽  
Synonymous Mutations ◽  
Strain Collection ◽  
Ocean Region

Bacterial spot of tomato and pepper, a major problem in tropical climates, can be caused by several Xanthomonas genospecies. We examined the genetic and pathological diversity of a collection of 72 strains from the southwest Indian Ocean region as part of a regional research and development program to update inventories of agricultural pests and pathogens. Xanthomonas euvesicatoria, X. perforans, X. gardneri, and X. vesicatoria were identified in our strain collection. The identification of strains at the species level was consistently achieved by amplified fragment length polymorphism (AFLP) and multilocus sequence analysis (MLSA). Overall, X. euvesicatoria was the species recovered prevalently. MLSA data based on four housekeeping genes identified two to three sequence types per genospecies. It suggested that sequence variations primarily consisted of synonymous mutations, although a recombination event spanning several hundred nucleotides was detected for some strains of X. euvesicatoria on the atpD gene coding for the F1-F0-ATPase β subunit. The pathogenicity of strains was consistent with data found in the literature. Some pathological variations were primarily observed among strains identified as X. euvesicatoria. This study provides the first ever comprehensive description of the status of Xanthomonas species that cause bacterial spot of tomato and pepper in the southwest Indian Ocean region.

scholarly journals Draft Genome Sequences of 284 Xanthomonas citri pv. citri Strains Causing Asiatic Citrus Canker

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Damien Richard ◽  
Adrien Rieux ◽  
Pierre Lefeuvre ◽  
Azali Hamza ◽  
Kanta Kumar Lobin ◽  
...  
Keyword(s):  
Draft Genome ◽  
Citrus Canker ◽  
Transcription Activator ◽  
Indian Ocean Region ◽  
Xanthomonas Citri ◽  
Genome Sequences ◽  
Southwest Indian Ocean ◽  
Content Type ◽  
Ocean Region ◽  
Atypical Feature

ABSTRACT High-quality Illumina assemblies were produced from 284 Xanthomonas citri pv. citri pathotype A strains mostly originating from the Southwest Indian Ocean region, a subset of which was also sequenced using MinION technology. Some strains hosted chromosomally encoded transcription activator-like effector (TALE) genes, an atypical feature for this bacterium.

A Contest of Status and Legitimacy in the Indian Ocean

2018 ◽  
Author(s):  
David Brewster
Keyword(s):  
Indian Ocean ◽  
International System ◽  
Special Role ◽  
Indian Ocean Region ◽  
Major Powers ◽  
Threat Perceptions ◽  
Ocean Region ◽  
The Status ◽  
The Indian Ocean ◽  
The Asymmetry

This chapter examines Indian and Chinese perspectives of each other as major powers and their respective roles in the Indian Ocean. It focuses on the following elements: (a) China’s strategic imperatives in the Indian Ocean Region, (b) India’s views on its special role in the Indian Ocean and the legitimacy of the presence of other powers, (c) China’s strategic vulnerabilities in the Indian Ocean and India’s wish to leverage those vulnerabilities, (d) the asymmetry in Indian and Chinese threat perceptions, and (d) Chinese perspectives of the status of India in the international system and India’s claims to a special role in the Indian Ocean. The chapter concludes that even if China were to take a more transparent approach to its activities, significant differences in perceptions of threat and over status and legitimacy will produce a highly competitive dynamic between them in the maritime domain.

Heat and freshwater changes in the Indian Ocean region

2021 ◽  
Author(s):  
Caroline C. Ummenhofer ◽  
Sujata A. Murty ◽  
Janet Sprintall ◽  
Tong Lee ◽  
Nerilie J. Abram
Keyword(s):  
Indian Ocean ◽  
Indian Ocean Region ◽  
Ocean Region ◽  
The Indian Ocean

scholarly journals Spatiotemporal Evolution and Determinant Factors of the Intra-Regional Trade Community Structures of the Indian Ocean Region

2021 ◽  
Vol 10 (4) ◽  
pp. 214
Author(s):  
Lihua Yuan ◽  
Xiaoqiang Chen ◽  
Changqing Song ◽  
Danping Cao ◽  
Hong Yi
Keyword(s):  
Indian Ocean ◽  
Explanatory Power ◽  
Community Structures ◽  
Indian Ocean Region ◽  
Spatiotemporal Evolution ◽  
Regional Trade ◽  
Determinant Factors ◽  
Ocean Region ◽  
The Indian Ocean ◽  
The Impact

The Indian Ocean Region (IOR) has become one of the main economic forces globally, and countries within the IOR have attempted to promote their intra-regional trade. This study investigates the spatiotemporal evolution of the community structures of the intra-regional trade and the impact of determinant factors on the formation of trade community structures of the IOR from 1996 to 2017 using the methods of social network analysis. Trade communities are groups of countries with measurably denser intra-trade ties but with extra-trade ties that are measurably sparser among different communities. The results show that the extent of trade integration and the trade community structures of the IOR changed from strengthening between 1996 and 2014 to weakening between 2015 and 2017. The largest explanatory power of the formation of the IOR trade community structures was the IOR countries’ economic size, indicating that market remained the strongest driver. The second-largest explanatory power was geographical proximity, suggesting that countries within the IOR engaged in intra-regional trade still tended to select geographically proximate trading partners. The third- and the fourth-largest were common civilization and regional organizational memberships, respectively. This indicates that sharing a common civilization and constructing intra-regional institutional arrangements (especially open trade policies) helped the countries within the IOR strengthen their trade communities.

Sign in / Sign up

Export Citation Format

Share Document