Suchergebnisse

USE OF CLOMAZONE IN PLANTAIN (MUSA ACUMINATA) ; USE OF CLOMAZONE IN PLANTAIN (MUSA ACUMINATA)

For decades, Xanthomonas vasicola pv. musacearum (Xvm) has been an economically important bacterial pathogen on enset in Ethiopia. Since 2001, Xvm has also been responsible for significant losses to banana crops in several East and Central African countries, with devastating consequences for smallholder farmers. Understanding the genetic diversity within Xvm populations is essential for the smart design of transnationally reasoned, durable, and effective management practices. Previous studies have revealed limited genetic diversity in Xvm, with East African isolates from banana each falling into one of two closely related clades previously designated as sublineages SL 1 and SL 2, the former of which had also been detected on banana and enset in Ethiopia. Given the presumed origin of Xvm in Ethiopia, we hypothesized that both clades might be found in that country, along with additional genotypes not seen in Central and East African bananas. Genotyping of 97 isolates and whole-genome sequencing of 15 isolates revealed not only the presence of SL 2 in Ethiopia, but additional diversity beyond SL 1 and SL 2 in four new clades. Moreover, SL 2 was detected in the Democratic Republic of Congo, where previously SL 1 was the only clade reported. These results demonstrate a greater range of genetic diversity among Xvm isolates than previously reported, especially in Ethiopia, and further support the hypothesis that the East/Central Africa xanthomonas wilt epidemic has been caused by a restricted set of genotypes drawn from a highly diverse pathogen pool in Ethiopia. ; Wellcome Trust Multi-User Equipment Award; Wellcome Trust Institutional Strategic Support Fund; BBSRC Impact Accelerator Award grant and BBSRC LOLA award. ; https://onlinelibrary.wiley.com/journal/13653059 ; am2021 ; Forestry and Agricultural Biotechnology Institute (FABI) ; Microbiology and Plant Pathology

This is the final version. Available on open access from Elsevier via the DOI in this record ; We performed shotgun genome sequencing on a total of 19 different Musa genotypes including representatives of wild banana species Musa acuminata and M. balibisiana, allopolyploid bananas and plantains, Fe'i banana, pink banana (also known as hairy banana) and abacá (also known as hemp banana). We aligned sequence reads against a previously sequenced reference genome and assessed ploidy and, in the case of allopolyploids, the contributions of the A and B genomes; this provides important quality-assurance data about the taxonomic identities of the sequenced plant material. These data will be useful for phylogenetics, crop improvement, studies of the complex story of intergenomic recombination in AAB and ABB allotriploid bananas and plantains and can be integrated into resources such as the Banana Genome Hub. ; European Union Horizon 2020 ; Gatsby Charitable Foundation

For decades, Xanthomonas vasicola pv. musacearum (Xvm) has been an economically important bacterial pathogen on enset in Ethiopia. Since 2001, Xvm has also been responsible for significant losses to banana crops in several East and Central African countries, with devastating consequences for smallholder farmers. Understanding the genetic diversity within Xvm populations is essential for the smart design of transnationally reasoned, durable, and effective management practices. Previous studies have revealed limited genetic diversity in Xvm, with East African isolates from banana each falling into one of two closely related clades previously designated as sublineages SL 1 and SL 2, the former of which had also been detected on banana and enset in Ethiopia. Given the presumed origin of Xvm in Ethiopia, we hypothesized that both clades might be found in that country, along with additional genotypes not seen in Central and East African bananas. Genotyping of 97 isolates and whole-genome sequencing of 15 isolates revealed not only the presence of SL 2 in Ethiopia, but additional diversity beyond SL 1 and SL 2 in four new clades. Moreover, SL 2 was detected in the Democratic Republic of Congo, where previously SL 1 was the only clade reported. These results demonstrate a greater range of genetic diversity among Xvm isolates than previously reported, especially in Ethiopia, and further support the hypothesis that the East/Central Africa xanthomonas wilt epidemic has been caused by a restricted set of genotypes drawn from a highly diverse pathogen pool in Ethiopia.

BACKGROUND and OBJECTIVES Viruses are major constraints to the production and exchange of banana and plantain (Musa spp.) germplasm in the world. Several viruses are recognized to affect Musa spp: Banana bunchy top virus (BBTV), Banana streak GF virus (BSGFV), Banana streak OL virus (BSOLV), Banana streak IM virus (BSIMV), Banana streak MY virus (BSMYV), Cucumber mosaic virus (CMV), Banana bract mosaic virus, (BBrMV). To date, in Democratic Republic of Congo (DRC), except BBTV, others banana viruses are not yet reported. The main aim of this work was to elucidate the epidemiological situation, genetic variability and origin of Musa spp. viruses in DRC. MATERIALS and METHODS Epidemiological surveys were conducted from 2011-2013, in DRC, to search main viruses of Musa spp. Up to 666 samples collected from 122 locations; Samples were analysed using PCR based method. Detected viruses were sequenced and phylogenetic studies were performed. RESULTS BBTV is the most widespread virus (frequency=44,8%) in DRC. Molecular analyses support infrequent BBTV dispersal events between continents. This study reveals a low genetic variability of DRC BBTV isolates. They are close, gather in the South Pacific group and are linked with isolates of other sub-Saharan Africa (SSA) countries, but no with Egyptian isolates. Since the earliest BBTV report in SSA was in DRC in 1950, it is likely that BBTV spread from DRC to other SSA countries rather than from Egypt and that at least two BBTV introductions occurred in Africa. Haplotypes analysis based on the coding region m-Rep protein showed 38 haplotypes (haplotype diversity value of 0.944±0.013). In Bas Congo, symptoms of Banana streak disease were associated to the presence of BSV species (frequency=19,9%); the most widespread were BSGFV (frequency=67,2%) and (BSOLV) (frequency=24,2%). The sequenced BSOLV isolate from Musa acuminata, gather in the clade I recognized to gathering the BSV species with endogenous counterpart. CMV was also detected (frequency=9,3%). Genetic diversity analysis reveals the high similarity between DRC CMV isolates with a South African isolate). BBrMV was not detected in collected samples. CONCLUSION DRC is a place of high prevalence of banana viruses, indicating the need for an improved quality of planting material. DRC seems to be the primary center of BBTV spread in Africa. BSV species data revealed the activation of endogenous BSV and the transmission of BSV species from plantain (B genome) to banana (A genome), in natural conditions. While for CMV, data suggest the hypothesis of a unique introduction through infected planting material and the distribution of a single strain of CMV. The BBrMV still absent in DRC. (Texte intégral)

Introducción: En la medicina militar, los agentes cicatrizantes naturales frente a heridas por incisión son relevantes en el tratamiento de los militares. Objetivo: Evaluar la actividad cicatrizante de los extractos hidroalcohólicos de Peperomia congona Sodiro (congona), Annona muricata L. (guanábana), Urtica urens L. (ortiga),Ormosia coccinea (Aubl) Jacks (huayruro), Opuntia ficus-indica L. Mill. (tuna) y Musa acuminata Colla (plátano bellaco) en heridas incisas de Rattus norvegicus albinus (rata albina). Métodos: Estudio analítico experimental de tipo prospectivo y longitudinal. Se realizó el análisis fitoquímico preliminar de los 6 extractos. Se emplearon 80 ratas albinas machos, aleatorizadas y distribuidas en 8 grupos (n = 10). Se realizó una aplicación dermal durante 10 días consecutivos posteriores a la generación de heridas incisas que se realizaron en el dorso. Grupo I (cloruro de sodio al 0,9 %). Grupo II (gel cicatrizante comercial). Del Grupo III al VIII fueron tratados con extracto hidroalcohólico de congona, guanábana, ortiga, huairuro, tuna y plátano bellaco respectivamente. La evolución de la cicatrización fue seguida en los días 1, 5 y 11 y medida en milímetros. Resultados: Se detectó la presencia de alcaloides, compuestos fenólicos y flavonoides en los 6 extractos; además de cumarinas en congona, taninos en guanábana, ortiga, tuna y huayruro, y quinonas en guanábana y plátano bellaco. Se comprobó la actividad cicatrizante en los extractos de guanábana (69,77 %), tuna (66,27 %), plátano bellaco (64,38 %), ortiga (56,73 %), congona (55,74 %) y huayruro (54,50 %), comparados con un gel comercial (72,21 %). Conclusiones: El extracto hidroalcohólico de las hojas de Annona muricata L. (guanábana) presentó la mayor actividad cicatrizante en heridas incisas de ratas albinas machos. ; Introduction: In military medicine, natural healing agents against incision wounds are relevant in the treatment of the military. Objective: To evaluate the healing activity of the hydroalcoholic extracts of Peperomia congona Sodiro (congona), Annona muricata L. (guanabana), Urtica urens L. (ortiga), Ormosia coccinea (Aubl) Jacks (huairuro), Opuntia ficus-indica L. Mill. (tuna) and Musa acuminata Colla (platano bellaco) in incised wounds of Rattus norvegicus albinus (albino rat). Methods: Experimental analytical study of prospective and longitudinal type. The preliminary phytochemical analysis of the 6 extracts was carried out. We used 80 male albino rats, randomized and distributed in 8 groups (n = 10). A dermal application was made during 10 consecutive days after the generation of incised wounds that were made on the back. Group I (0.9% sodium chloride). Group II (commercial healing gel). From Group III to VIII they were treated with hydroalcoholic extract of congona, guanábana, ortiga, huairuro, tuna and platano bellaco respectively. The evolution of healing was followed on days 1, 5 and 11 and measured in millimeters. Results: The presence of alkaloids, phenolic compounds and flavonoids was detected in the 6 extracts;in addition to coumarins in congona, tannins in guanábana, nettle, tuna and huayruro, quinonas in guanábana and plantain bellaco. The healing activity was verified in the extracts of guanabana (69.77 %), tuna (66.27 %), platano bellaco (64.38 %), ortiga (56.73 %), congona (55.74 %) and huayruro (54.50 %), compared with a commercial gel (72.21 %). Conclusions: The hydroalcoholic extract of the leaves of Annona muricata L. (guanábana) showed the highest healing activity in incised wounds of male albino rats.

Viruses are considered as major constraints to the exchange of germplasm, genetic improvement and breeding of banana and plantain (Musa spp) through the world. To date, six viruses are recognized to affect Musa spp: Banana bunchy top virus (BBTV), Banana streak viruses (BSV), Cucumber mosaic virus (CMV), Banana bract mosaic virus (BBrMV), Banana mild mosaic virus (BanMMV), Banana virus x (BVX). BBTV, the most devastating virus of banana, is currently spread in 14 countries of Africa including the Democratic Republic of Congo (DRC), where the virus was observed for the first time in 1950 in Yangambi, Kisangani region. The situation of others banana viruses remains unknown however, some of these viruses were observed in DRC bordering countries. The main aim of this work was to elucidate the epidemiological situation, the genetic variability and the origin of banana viruses in Democratic Republic of Congo. Epidemiological surveys were conducted in southwestern part of DRC, with a special emphasis on Bas Congo province, in order to search major banana viruses. Up to 666 samples were collected from at least 122 locations and analysed using PCR based method. BBTV is a multi component virus, which possesses six DNA components named DNA-R, M, N, C, U3, S. To understand the BBTV epidemiology, 52 complete sequences of DNA-R and 30 full sequences of DNA-R, U3, M, N, C, S were study. Phylogenetic analysis was carried out by isolates nucleotides sequences comparison, for all viruses detected (BBTV, BSV, CMV). Result show that BBTV is the most widespread banana virus in DRC. The main factor contributed to the spread of this threat is the human exchange of infected planting material. Data reveals a low genetic variability of BBTV isolates, which are grouped in South Pacific group. Theses BBTV isolates are close between them and with those of other sub-Saharian Africa countries. The earliest report of BBTV in Africa relates to an isolate described in Egypt in 1901. Since the earliest BBTV report in sub-Saharian Africa was in Democratic Republic of Congo in 1950, it is likely that Banana bunchy top virus spread from DRC to other SSA countries rather than from Egypt and that at least two Banana bunchy top virus introductions occurred in Africa from Java and Taiwan respectively. However, at a global scale, molecular analyses support infrequent Banana bunchy top virus dispersal events among continents. Democratic Republic of Congo seems to be the primary center of Banana bunchy top virus spread in Africa. Haplotypes analysis based on the coding region m-Rep protein showed 39 haplotypes (H1 to H39) (haplotype diversity value of 0.944±0.013). The most frequent haplotypes were H17, H9, H7 and H24 representing 31.6, 21.1, 21.1 and 27% of the BBTV isolates, respectively. Symptoms of banana streak disease including yellow streak, splitting of pseudo-stem, death of cigar leaf, were associated to the presence of Banana streak virus species (frequency = 20 %). The most widespread was Banana streak GF virus (BSGFV) (frequency = 68%) and Banana streak OL virus (BSOLV)(frequency = 25.5%). Musa acuminata cultivars are infected although no banana streak disease epidemic was reported any more, since the study revealed the transmission of BSV species from plantain (B genome) to banana (A genome). The frequency of mealybugs was about 9.3%, suggesting transmission of the disease. The sequenced isolate of BSGFV and BSOLV gather in the clade I, recognized to gathering the BSV species with endogenous counterpart. Cucumber mosaic virus was detected (frequency = 9.3%) mainly on asymptomatic samples collected. Genetic diversity analysis reveals the high similarity between Congolese CMV isolates and with South African isolates. These results suggest the hypothesis of the existence of the Cucumber mosaic virus single strain that dispersed througthout the study area. Banana bract mosaic virus was not detected in the collected samples despite the targeted sampling approach developed. The result suggests that the virus still absent in Bas Congo, Democratic Republic of Congo. ; Les virus constituent une contrainte majeure à l'amélioration et aux échanges de germplasm du bananier et plantain (Musa spp) dans le monde. Les études récentes rapportent que six virus affectent le bananier et plantain (Musa spp) dont le Banana bunchy top virus (BBTV), le Banana streak virus (BSV), Cucumber mosaic virus (CMV), Banana bract mosaic virus (BBrMV), Banana mild mosaic virus (BanMMV), le Banana virus x (BVX). Le BBTV est considéré comme le virus le plus dévastateur présent dans au moins 14 pays africains y compris la République démocratique du Congo (RDC) où il a été détecté pour la première fois, en 1950, à Yangambi dans la région de Kisangani. La situation des autres virus du bananier demeure inconnue malgré que certains d'entre eux aient été détectés dans les pays limitrophes de la RDC. Le principal objectif de cette thèse a été d'élucider la présence des virus impactant la culture du bananier (Musa spp.) en RDC, leurs origines et leurs diversités génétiques. Les enquêtes épidémiologiques ont été menées en vue de rechercher les principaux virus du bananier. Un accent particulier a été mis sur les zones moins investiguées en RDC, particulièrement la province du Bas Congo, à cause de sa position géographique, pour la recherche des nouveaux virus. Plus de 666 échantillons de feuilles de bananier ont été collectés dans 122 sites et analysés en utilisant la PCR comme base technique. Le BBTV est un virus à génome multipartite composé d'au moins six ADN nommés ADN-R, M, N, C, U3, S. Au total 52 séquences complètes d'ADN-R et 30 séquences complètes de M, N, C, U3, S ont été étudiées en vue de comprendre son épidémiologie. Les analyses phylogénétiques et la comparaison des séquences nucléotidiques ont été réalisées pour tous les virus détectés (BBTV, BSV, CMV). Les résultats indiquent que le BBTV est le virus du bananier le plus répandu en RDC. Le facteur humain constitue le principal moteur de dispersion de ce virus, particulièrement à travers l'échange de matériel de plantation infecté. Les données indiquent une faible variabilité génétique des isolats BBTV et leur regroupement dans le sous-groupe Sud Pacifique. Les isolats congolais de BBTV sont proches entre eux et aussi proches de ceux des autres pays d'Afrique sub-Saharienne (SSA). Les résultats confirment aussi que l'Afrique aurait subi une double introduction du BBTV venant respectivement de Java et de Taiwan. La première introduction du BBTV fut en Egypte en 1901 et la seconde en RDC en 1950. Au niveau moléculaire, les données supportent une distribution sur le continent africain - la RDC semble être un foyer primaire de dispersion en Afrique. L'analyse des haplotypes basée sur la région codante de la protéine m-Rep montre la présence de 39 haplotypes (H1 à H39) avec des valeurs de diversité de 0,944±0,013 dont les plus répandus sont H17, H9, H7 et H24, représentant respectivement 31,6 ; 21,1 ; 21,1 et 27,0 % des isolats BBTV. Les symptômes de banana streak disease incluant les stries jaunes, l'éclatement du pseudo-tronc, le dépérissement de la feuille cigare ont été associés à la présence des espèces Banana streak virus (fréquence de 20 %). Les espèces BSV les plus répandues sont Banana streak GF virus (BSGFV) (fréquence = 68 %) et Banana streak OL virus (BSOLV) (fréquence = 25,5 %). Les bananiers à génome Musa acuminata sont les plus infectés par le BSV, ce qui suggère le développement d'une épidémie BSV suite à la transmission du virus des hybrides interspécifiques (génome B) vers le bananier dessert (génome A). La fréquence de la cochenille a été évaluée à 9,3 %, ce qui renforce l'hypothèse d'une transmission de Banana streak virus. Les isolats de BSGFV et ceux de BSOLV séquencés, se groupent dans le clade I reconnu comme un clade ressemblant les espèces BSV ayant une contrepartie endogène. Cucumber mosaic virus a été détecté (fréquence = 9,3%) principalement sur les échantillons asymptomatiques. L'analyse de la diversité génétique révèle une similarité élevée entre les isolats de la RDC. Ce qui appuie l'hypothèse de l'existence d'une unique souche de CMV qui se disperse à travers le pays. Malgré l'approche de collecte d'échantillons utilisée, Banana bract mosaic virus n'a pas été détecté dans les échantillons collectés. Ces résultats suggèrent que Banana bract mosaic virus demeure absent du Bas Congo, RDC. ; (AGRO - Sciences agronomiques et ingénierie biologique) -- UCL, 2016

Viruses are considered as major constraints to the exchange of germplasm, genetic improvement and breeding of banana and plantain (Musa spp) through the world. To date, six viruses are recognized to affect Musa spp: Banana bunchy top virus (BBTV), Banana streak viruses (BSV), Cucumber mosaic virus (CMV), Banana bract mosaic virus (BBrMV), Banana mild mosaic virus (BanMMV), Banana virus x (BVX). BBTV, the most devastating virus of banana, is currently spread in 14 countries of Africa including the Democratic Republic of Congo (DRC), where the virus was observed for the first time in 1950 in Yangambi, Kisangani region. The situation of others banana viruses remains unknown however, some of these viruses were observed in DRC bordering countries. The main aim of this work was to elucidate the epidemiological situation, the genetic variability and the origin of banana viruses in Democratic Republic of Congo. Epidemiological surveys were conducted in southwestern part of DRC, with a special emphasis on Bas Congo province, in order to search major banana viruses. Up to 666 samples were collected from at least 122 locations and analysed using PCR based method. BBTV is a multi component virus, which possesses six DNA components named DNA-R, M, N, C, U3, S. To understand the BBTV epidemiology, 52 complete sequences of DNA-R and 30 full sequences of DNA-R, U3, M, N, C, S were study. Phylogenetic analysis was carried out by isolates nucleotides sequences comparison, for all viruses detected (BBTV, BSV, CMV). Result show that BBTV is the most widespread banana virus in DRC. The main factor contributed to the spread of this threat is the human exchange of infected planting material. Data reveals a low genetic variability of BBTV isolates, which are grouped in South Pacific group. Theses BBTV isolates are close between them and with those of other sub-Saharian Africa countries. The earliest report of BBTV in Africa relates to an isolate described in Egypt in 1901. Since the earliest BBTV report in sub-Saharian Africa was in Democratic Republic of Congo in 1950, it is likely that Banana bunchy top virus spread from DRC to other SSA countries rather than from Egypt and that at least two Banana bunchy top virus introductions occurred in Africa from Java and Taiwan respectively. However, at a global scale, molecular analyses support infrequent Banana bunchy top virus dispersal events among continents. Democratic Republic of Congo seems to be the primary center of Banana bunchy top virus spread in Africa. Haplotypes analysis based on the coding region m-Rep protein showed 39 haplotypes (H1 to H39) (haplotype diversity value of 0.944±0.013). The most frequent haplotypes were H17, H9, H7 and H24 representing 31.6, 21.1, 21.1 and 27% of the BBTV isolates, respectively. Symptoms of banana streak disease including yellow streak, splitting of pseudo-stem, death of cigar leaf, were associated to the presence of Banana streak virus species (frequency = 20 %). The most widespread was Banana streak GF virus (BSGFV) (frequency = 68%) and Banana streak OL virus (BSOLV)(frequency = 25.5%). Musa acuminata cultivars are infected although no banana streak disease epidemic was reported any more, since the study revealed the transmission of BSV species from plantain (B genome) to banana (A genome). The frequency of mealybugs was about 9.3%, suggesting transmission of the disease. The sequenced isolate of BSGFV and BSOLV gather in the clade I, recognized to gathering the BSV species with endogenous counterpart. Cucumber mosaic virus was detected (frequency = 9.3%) mainly on asymptomatic samples collected. Genetic diversity analysis reveals the high similarity between Congolese CMV isolates and with South African isolates. These results suggest the hypothesis of the existence of the Cucumber mosaic virus single strain that dispersed througthout the study area. Banana bract mosaic virus was not detected in the collected samples despite the targeted sampling approach developed. The result suggests that the virus still absent in Bas Congo, Democratic Republic of Congo. ; Les virus constituent une contrainte majeure à l'amélioration et aux échanges de germplasm du bananier et plantain (Musa spp) dans le monde. Les études récentes rapportent que six virus affectent le bananier et plantain (Musa spp) dont le Banana bunchy top virus (BBTV), le Banana streak virus (BSV), Cucumber mosaic virus (CMV), Banana bract mosaic virus (BBrMV), Banana mild mosaic virus (BanMMV), le Banana virus x (BVX). Le BBTV est considéré comme le virus le plus dévastateur présent dans au moins 14 pays africains y compris la République démocratique du Congo (RDC) où il a été détecté pour la première fois, en 1950, à Yangambi dans la région de Kisangani. La situation des autres virus du bananier demeure inconnue malgré que certains d'entre eux aient été détectés dans les pays limitrophes de la RDC. Le principal objectif de cette thèse a été d'élucider la présence des virus impactant la culture du bananier (Musa spp.) en RDC, leurs origines et leurs diversités génétiques. Les enquêtes épidémiologiques ont été menées en vue de rechercher les principaux virus du bananier. Un accent particulier a été mis sur les zones moins investiguées en RDC, particulièrement la province du Bas Congo, à cause de sa position géographique, pour la recherche des nouveaux virus. Plus de 666 échantillons de feuilles de bananier ont été collectés dans 122 sites et analysés en utilisant la PCR comme base technique. Le BBTV est un virus à génome multipartite composé d'au moins six ADN nommés ADN-R, M, N, C, U3, S. Au total 52 séquences complètes d'ADN-R et 30 séquences complètes de M, N, C, U3, S ont été étudiées en vue de comprendre son épidémiologie. Les analyses phylogénétiques et la comparaison des séquences nucléotidiques ont été réalisées pour tous les virus détectés (BBTV, BSV, CMV). Les résultats indiquent que le BBTV est le virus du bananier le plus répandu en RDC. Le facteur humain constitue le principal moteur de dispersion de ce virus, particulièrement à travers l'échange de matériel de plantation infecté. Les données indiquent une faible variabilité génétique des isolats BBTV et leur regroupement dans le sous-groupe Sud Pacifique. Les isolats congolais de BBTV sont proches entre eux et aussi proches de ceux des autres pays d'Afrique sub-Saharienne (SSA). Les résultats confirment aussi que l'Afrique aurait subi une double introduction du BBTV venant respectivement de Java et de Taiwan. La première introduction du BBTV fut en Egypte en 1901 et la seconde en RDC en 1950. Au niveau moléculaire, les données supportent une distribution sur le continent africain - la RDC semble être un foyer primaire de dispersion en Afrique. L'analyse des haplotypes basée sur la région codante de la protéine m-Rep montre la présence de 39 haplotypes (H1 à H39) avec des valeurs de diversité de 0,944±0,013 dont les plus répandus sont H17, H9, H7 et H24, représentant respectivement 31,6 ; 21,1 ; 21,1 et 27,0 % des isolats BBTV. Les symptômes de banana streak disease incluant les stries jaunes, l'éclatement du pseudo-tronc, le dépérissement de la feuille cigare ont été associés à la présence des espèces Banana streak virus (fréquence de 20 %). Les espèces BSV les plus répandues sont Banana streak GF virus (BSGFV) (fréquence = 68 %) et Banana streak OL virus (BSOLV) (fréquence = 25,5 %). Les bananiers à génome Musa acuminata sont les plus infectés par le BSV, ce qui suggère le développement d'une épidémie BSV suite à la transmission du virus des hybrides interspécifiques (génome B) vers le bananier dessert (génome A). La fréquence de la cochenille a été évaluée à 9,3 %, ce qui renforce l'hypothèse d'une transmission de Banana streak virus. Les isolats de BSGFV et ceux de BSOLV séquencés, se groupent dans le clade I reconnu comme un clade ressemblant les espèces BSV ayant une contrepartie endogène. Cucumber mosaic virus a été détecté (fréquence = 9,3%) principalement sur les échantillons asymptomatiques. L'analyse de la diversité génétique révèle une similarité élevée entre les isolats de la RDC. Ce qui appuie l'hypothèse de l'existence d'une unique souche de CMV qui se disperse à travers le pays. Malgré l'approche de collecte d'échantillons utilisée, Banana bract mosaic virus n'a pas été détecté dans les échantillons collectés. Ces résultats suggèrent que Banana bract mosaic virus demeure absent du Bas Congo, RDC. ; (AGRO - Sciences agronomiques et ingénierie biologique) -- UCL, 2016

Published online: 20 September 2017 ; Taxonomy Bacteria; Phylum Proteobacteria; Class Gammaproteobacteria; Order Xanthomonadales; Family Xanthomonadaceae; Genus Xanthomonas; currently classified as X. campestris pv. musacearum (Xcm). However, fatty acid methyl ester analysis and genetic and genomic evidence suggest that this pathogen is X. vasicola and resides in a separate pathovar. Isolation and Detection Xcm can be isolated on yeast extract peptone glucose agar (YPGA), cellobiose cephalexin agar and yeast extract tryptone sucrose agar (YTSA) complemented with 5-fluorouracil, cephalexin and cycloheximide to confer semi-selectivity. Xcm can also be identified using direct antigen coating enzyme-linked immunosorbent assay (DAC-ELISA), species-specific polymerase chain reaction (PCR) using GspDm primers and lateral flow devices that detect latent infections. Host range Causes Xanthomonas wilt on plants belonging to the Musaceae, primarily banana (Musa acuminata), plantain (M. acuminata × balbisiana) and enset (Ensete ventricosum). Diversity There is a high level of genetic homogeneity within Xcm, although genome sequencing has revealed two major sublineages. Symptoms Yellowing and wilting of leaves, premature fruit ripening and dry rot, bacterial exudate from cut stems. Distribution Xcm has only been found in African countries, namely Burundi, Ethiopia, Democratic Republic of the Congo, Kenya, Rwanda, Tanzania and Uganda. Ecology and Epidemiology Xcm is transmitted by insects, bats, birds and farming implements. Long-distance dispersal of the pathogen is by the transportation of latently infected plants into new areas. Management The management of Xcm has relied on cultural practices that keep the pathogen population at tolerable levels. Biotechnology programmes have been successful in producing resistant banana plants. However, the deployment of such genetic material has not as yet been achieved in farmers' fields, and the sustainability of transgenic resistance remains to be addressed.

TAXONOMY: Bacteria; Phylum Proteobacteria; Class Gammaproteobacteria; Order Xanthomonadales; Family Xanthomonadaceae; Genus Xanthomonas; currently classified as X. campestris pv. musacearum (Xcm). However, fatty acid methyl ester analysis and genetic and genomic evidence suggest that this pathogen is X. vasicola and resides in a separate pathovar. ISOLATION AND DETECTION: Xcm can be isolated on yeast extract peptone glucose agar (YPGA), cellobiose cephalexin agar and yeast extract tryptone sucrose agar (YTSA) complemented with 5‐fluorouracil, cephalexin and cycloheximide to confer semi‐selectivity. Xcm can also be identified using direct antigen coating enzyme‐linked immunosorbent assay (DAC‐ELISA), species‐specific polymerase chain reaction (PCR) using GspDm primers and lateral flow devices that detect latent infections. HOST RANGE: Causes Xanthomonas wilt on plants belonging to the Musaceae, primarily banana (Musa acuminata), plantain (M. acuminata × balbisiana) and enset (Ensete ventricosum). DIVERSITY: There is a high level of genetic homogeneity within Xcm, although genome sequencing has revealed two major sublineages. SYMPTOMS: Yellowing and wilting of leaves, premature fruit ripening and dry rot, bacterial exudate from cut stems. DISTRIBUTION: Xcm has only been found in African countries, namely Burundi, Ethiopia, Democratic Republic of the Congo, Kenya, Rwanda, Tanzania and Uganda. ECOLOGY AND EPIDEMIOLOGY: Xcm is transmitted by insects, bats, birds and farming implements. Long‐distance dispersal of the pathogen is by the transportation of latently infected plants into new areas. MANAGEMENT: The management of Xcm has relied on cultural practices that keep the pathogen population at tolerable levels. Biotechnology programmes have been successful in producing resistant banana plants. However, the deployment of such genetic material has not as yet been achieved in farmers' fields, and the sustainability of transgenic resistance remains to be addressed.

For decades, Xanthomonas vasicola pv. musacearum (Xvm) has been an economically important bacterial pathogen on enset in Ethiopia. Since 2001, Xvm has also been responsible for significant losses to banana crops in several East and Central African countries, with devastating consequences for smallholder farmers. Understanding the genetic diversity within Xvm populations is essential for the smart design of transnationally reasoned, durable, and effective management practices. Previous studies have revealed limited genetic diversity in Xvm, with East African isolates from banana each falling into one of two closely related clades previously designated as sublineages SL 1 and SL 2, the former of which had also been detected on banana and enset in Ethiopia. Given the presumed origin of Xvm in Ethiopia, we hypothesized that both clades might be found in that country, along with additional genotypes not seen in Central and East African bananas. Genotyping of 97 isolates and whole-genome sequencing of 15 isolates revealed not only the presence of SL 2 in Ethiopia, but additional diversity beyond SL 1 and SL 2 in four new clades. Moreover, SL 2 was detected in the Democratic Republic of Congo, where previously SL 1 was the only clade reported. These results demonstrate a greater range of genetic diversity among Xvm isolates than previously reported, especially in Ethiopia, and further support the hypothesis that the East/Central Africa xanthomonas wilt epidemic has been caused by a restricted set of genotypes drawn from a highly diverse pathogen pool in Ethiopia.

Viral diseases of banana are one of the major constraints to the production and distribution of germoplasm of banana in the world. To date, six viruses have been listed on banana: Banana bunchy top virus (BBTV), Banana streak virus (BSV), Banana bract mosaic virus (BBrMV), Cucumber mosaic virus (CMV), Banana mild mosaic virus (BMMV), Banana virus x (BVX). In Democratic Republic of Congo (DRC), the first viral disease of banana was found, for the first time, in 1950 in Yangambi, Kisangani region. To date, the distribution of BBTV remains mostly unknown and other banana viruses (BSV, CMV, BBrMV, BMMV, BVX) have not yet been reported. With the aim to describe and establish the frequency of the viruses involved to major viral diseases on banana (Banana bunchy top virus, Banana streak virus, Banana bract mosaic virus, Cucumber mosaic virus) in the Democratic Republic of Congo, epidemiological surveys were conducted in 2011, 2012 and 2013 in the South West of the Democratic Republic of Congo. For BBTV at least 216 samples were collected in 2011 and 2012, for BS, CMV, BBrMV and 450 samples were collected and 306 samples were analyzed using PCR, IC - PCR, IC-One-step-RT-PCR and RT - PCR techniques to detect respectively BBTV, BSV, CMV, and BBrMV. Results indicate that Banana bunchy top virus is the most prevalent virus of banana, in South Western of Democratic Republic of Congo (frequency = 44,6%). The highest frequency was observed in Bas Congo province of Bas Congo with a frequency of 17.8% in contrast, the lowest frequency was observed in Katanga province. Banana streak virus exists in natural condition and express symptoms of Banana streak disease. The most widespread BSV specie is Goldfinger (BSGFV) with a frequency of 64%. This study reveals that there is a transmission of Banana streak virus from banana containing genome B with eBSV integration to Musa acuminata strict, without integrated sequences. Furthermore, the frequency of vector is 9.3%. These results suggest an emergence of Banana streak disease in the study area. Analysis of the frequency of the Cucumber mosaic virus shows that the virus is widespread in all types of cropping systems including vegetables spaces whose N'Djili brasserie, Kimpoko and Kisantu. Very surprisingly CMV is missing from Mbanzangungu one of the largest vegetable crop production site. Performant analyses for the detection of Banana bract mosaic virus have proved negative. These results suggest that the BBrMV remains absent from the study area.