A preliminary survey on the presence of Xylella fastidiosa in olive, citrus and grapevine groves in Morocco

Xylella fastidiosa, bactérie gram-négative, confinée au xylème, très polyphage, provoque diverses maladies sur plus de 300 plantes hôtes. Compte tenu de la récente détection confirmée de X. fastidiosa dans l'Union Européenne, cette bactérie est en train de devenir une menace sérieuse pour le secteur agricole marocain. Une enquête a été menée durant Mai-Septembre 2015 sur la présence de X. fastidiosa dans plusieurs plantations de l'olivier, des agrumes et de la vigne à  travers le pays. Des symptômes sévères qui pourraient être associés à  la bactérie ont été relevés. Un total de 900 échantillons de différentes cultures à  partir de différentes régions ont été collectés au hasard: 220 oliviers (cv. Picholine Marocaine) de deux régions, 410 arbres d'agrumes appartenant à  7 cultivars collectés dans 4 régions et 270 plants de vigne appartenant à  6 cultivars de 3 régions; tous ces échantillons ont été testés pour la présence de X. fastidiosa en utilisant un kit commercial ELISA. Les résultats obtenus ne montrent aucun échantillon positif. Ces résultats préliminaires sont considérés comme une bonne première indication, étant donné que X. fastidiosa n'a pas été détectée au Maroc. Cependant, des enquêtes continues à  grande échelle sont nécessaires pour empêcher son entrée dans le pays. Mots-clés: Maroc, Xylella fastidiosa, enquête, Olivier, agrumes, vigne, ELISA.The bacterium Xylella fastidiosa is gram negative, xylem-inhabiting, devastating pathogen which causes various diseases on more than 300 plant hosts. Given the recent confirmed findings of  X. fastidiosa in the European Union, this bacterium is becoming a serious threat to the Moroccan agricultural sector. A survey was conducted during May-September 2015 on the presence of X. fastidiosa in several commercial groves, covering olive, citrus and grapevine growing areas. In a few trees, severe symptoms which could be associated to the bacterium were observed. A total of 900 samples of different crops from different regions were randomly collected: 220 olive trees (cv. Picholine Marocaine) from two regions, 410 citrus trees belonging to 7 different cultivars collected in 4 regions and 270 grapevine plants belonging to 6 different cultivars from 3 regions; all these samples were tested for the presence of X. fastidiosa by using an ELISA commercial kit. The obtained results did not show any positive sample. These preliminary results are taken as an encouraging indication, considering that X. fastidiosa was not found in Morocco, at least in the surveyed crops. However, frequent extensive surveys in different regions are needed to prevent its entrance into the country. Keywords: Morocco, Xylella fastidiosa, survey, olive, citrus, grapevine, ELISA

Caractérisation moléculaire du virus des nervures jaunes nécrotiques de la betterave (BNYVV) infectant la betterave à sucre au Tadla

La betterave sucrière est la principale source de sucre au Maroc. Les principales zones de production de la betterave à  sucre sont Doukkala, Tadla, Gharb, et Moulouya. La rhizomanie, causée par le virus des nervures jaunes nécrotiques de la betterave (BNYVV, genre Benyvirus), a été décrite pour la première fois en Italie et s'est propagée dans la plupart des régions productrices de la betterave sucrière. Dans la région de Tadla, la rhizomanie est l'un des principaux problèmes phytosanitaires majeurs pour la culture de la betterave sucrière. En 2010, cinq isolats de différentes localités de la région de Tadla ont été collectés pour des études de caractérisation moléculaire par le séquençage du gène de protéine de la capside (CP). Les résultats obtenus ont montré que les isolats marocains étaient dans le groupe B de BNYVV; ces isolats ont montré une grande similarité nucléotidique avec l'isolat Belge B2 (AY696077), avec une homologie de séquence de 100 %. Au mieux de nos connaissances, il s'agit de la première caractérisation moléculaire des isolats de BNYVV au Maroc. Mots-clés: Rhizomanie, betterave sucrière, caractérisation moléculaire, gène de la protéine de la capside, Maroc.Sugar beet is the most important sugar crop in Morocco. The main production areas of sugar beet are Doukkala, Tadla, Gharb, and Moulouya. Rhizomania, caused by Beet necrotic yellow vein virus (BNYVV, genus Benyvirus), was first described in Italy and has spread in most sugar beet-growing areas of the world within a few decades. In the Tadla region, Rhizomania is one of the major phytosanitary problems for the sugar-beet industry. In 2010, five isolates from different locations in the Tadla region were collected for molecular characterization studies by sequencing the coat protein gene (CPg). The obtained results showed that all the sequenced isolates were in the B type of BNYVV and revealed the highest nucleotide similarity with the Belgian isolate B2 (AY696077), with a sequence homology of 100 %. To the best of our knowledge, this is the first molecular characterization of BNYVV isolates in Morocco. Keywords: Rhizomania, sugar beet, molecular characterization, coat protein gene, Morocco

Molecular characterization of Beet necrotic yellow vein virus (BNYVV) infecting sugar beet in Tadla

Sugar beet is the most important sugar crop in Morocco. The main production areas of sugar beet are Doukkala, Tadla, Gharb, and Moulouya. Rhizomania, caused by Beet necrotic yellow vein virus (BNYVV, genus Benyvirus), was first described in Italy and has spread in most sugar beet-growing areas of the world within a few decades. In the Tadla region, Rhizomania is one of the major phytosanitary problems for the sugar-beet industry. In 2010, five isolates from different locations in the Tadla region were collected for molecular characterization studies by sequencing the coat protein gene (CPg). The obtained results showed that all the sequenced isolates were in the B type of BNYVV and revealed the highest nucleotide similarity with the Belgian isolate B2 (AY696077), with a sequence homology of 100%. To the best of our knowledge, this is the first molecular characterization of BNYVV isolates in Morocco

A preliminary survey on the presence of Xylella fastidiosa in olive, citrus and grapevine groves in Morocco

The bacterium Xylella fastidiosa is gram negative, xylem-inhabiting, devastating pathogen which causes various diseases on more than 300 plant hosts. Given the recent confirmed findings of X. fastidiosa in the European Union, this bacterium is becoming a serious threat to the Moroccan agricultural sector. A survey was conducted during May-September 2015 on the presence of X. fastidiosa in several commercial groves, covering olive, citrus and grapevine growing areas. In a few trees, severe symptoms which could be associated to the bacterium were observed. A total of 900 samples of different crops from different regions were randomly collected: 220 olive trees (cv. Picholine Marocaine) from two regions, 410 citrus trees belonging to 7 different cultivars collected in 4 regions and 270 grapevine plants belonging to 6 different cultivars from 3 regions; all these samples were tested for the presence of X. fastidiosa by using an ELISA commercial kit. The obtained results did not show any positive sample. These preliminary results are taken as an encouraging indication, considering that X. fastidiosa was not found in Morocco, at least in the surveyed crops. However, frequent extensive surveys in different regions are needed to prevent its entrance into the country

Prospection et première caractérisation moléculaire de l’exocortis (Citrus exocortis viroid, CEVd) dans la région du Gharb

Viroids are graft and mechanically transmissible agents, disseminated through budding. A field survey was conducted, during July 2013, for citrus viroids in the Gharb region. A total of 53 samples were collected and used for inoculation of ‘Etrog’ lemon before being tested by RT-PCR for the detection of exocotris (Citrus exocortis viroid, CEVd). The results showed that CEVd was widespread in the region with an infection rate of 84.9% in the analyzed samples. After genomic sequencing, a study of the genetic diversity was conducted on three representative local isolates of CEVd. The comparison between the nucleotide sequences of Moroccan CEVd isolates revealed a genetic diversity of less than 3%

Parameters of the accelerated aging test to determine the vigor of tobacco seeds

The establishment of tobacco is performed through seedling transplant, and the initial step to promote a uniform plant stand and ensure a good yield of the tobacco crop is the use of good quality seedlings, for this, the use of seeds of the highest quality is necessary. In this sense, vigor tests are very important to obtain additional information to the standard germination test and can assist in decision-making. Thus, the aim of this work was to determine accelerated aging test methodologies for the evaluation of vigor in tobacco seeds. For the study, ten lots of tobacco seeds were used. The initial quality of the tobacco seeds was determined through the germination test, first germination count, germination speed index, emergence of seedlings at 7, 14 and 21 days after sowing, emergence speed index and the accelerated aging with water conducted as proposed by the AOSA. After the determination of the initial quality of the seeds, the accelerated aging test was carry out in the following methods: accelerated aging with water, saturated saline solution (40g NaCl 100mL-1 water) and unsaturated saline solution (11g NaCl 100mL-1 water), submitted to temperature of 45 and 41°C, for periods of exposure of 24, 48 and 72 hours. The assay was conducted in a randomized block designed, the averages obtained per lot at each evaluation were compared by the Scott-Knott test at a 5% probability level and a linear correlation analysis was performed. According to the results, it is concluded that the accelerated aging test with water conducted under a temperature of 45°C combined with a 24 - hour exposure period is adequate for evaluating the vigor of tobacco seeds.Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPqO estabelecimento da lavoura de tabaco se dá através do transplante de mudas, e o passo inicial para promover um estande uniforme de plantas e garantir uma boa produtividade da lavoura de tabaco é a utilização de mudas de boa qualidade, para isso, é necessário a utilização de sementes de altíssima qualidade. Neste sentido, os testes de vigor são muito importantes para obtenção de informações adicionais ao teste de germinação e podem auxiliar na tomada de decisão. Assim, objetivou-se com o presente trabalho determinar metodologias do teste de envelhecimento acelerado para avaliação do vigor em sementes de tabaco. Para o estudo, foram utilizados dez lotes de sementes de tabaco. Inicialmente determinou-se a qualidade inicial das sementes de tabaco através dos testes de germinação, primeira contagem de germinação, índice de velocidade de germinação, emergência de plântulas avaliadas aos 7, 14 e 21 dias após semeadura, índice de velocidade de emergência e envelhecimento acelerado com água conduzido conforme proposto pela AOSA. Após a determinação da qualidade inicial das sementes, estudou se o teste de envelhecimento acelerado nas metodologias: envelhecimento acelerado com água, solução salina saturada (40g de NaCl.100mL-1 de água) e solução salina não saturada (11g de NaCl.100mL-1 de água), submetidas a temperatura de 45 e 41⁰C, por períodos de exposição de 24, 48 e 72 horas. O ensaio foi conduzido em delineamento de blocos ao acaso, as médias obtidas por lote, em cada avaliação, foram comparadas pelo teste de Scott-Knott em nível de probabilidade de 5% e foi realizada análise de correlação linear. De acordo com os resultados obtidos, conclui - se que o teste de envelhecimento acelerado com água conduzido sob temperatura de 45ºC combinado com período de exposição de 24 horas mostra-se adequado para avaliação do vigor de sementes de tabaco

A preliminary survey on the presence of Xylella fastidiosa in olive, citrus and grapevine groves in Morocco

The bacterium Xylella fastidiosa is gram negative, xylem-inhabiting, devastating pathogen which causes various diseases on more than 300 plant hosts. Given the recent confirmed findings of X. fastidiosa in the European Union, this bacterium is becoming a serious threat to the Moroccan agricultural sector. A survey was conducted during May-September 2015 on the presence of X. fastidiosa in several commercial groves, covering olive, citrus and grapevine growing areas. In a few trees, severe symptoms which could be associated to the bacterium were observed. A total of 900 samples of different crops from different regions were randomly collected: 220 olive trees (cv. Picholine Marocaine) from two regions, 410 citrus trees belonging to 7 different cultivars collected in 4 regions and 270 grapevine plants belonging to 6 different cultivars from 3 regions; all these samples were tested for the presence of X. fastidiosa by using an ELISA commercial kit. The obtained results did not show any positive sample. These preliminary results are taken as an encouraging indication, considering that X. fastidiosa was not found in Morocco, at least in the surveyed crops. However, frequent extensive surveys in different regions are needed to prevent its entrance into the country