The first survey of pome fruit viruses in Morocco

Considering the limited information on the presence and incidence of pome fruit virus and viroid diseases in Morocco, a preliminary assessment of the presence of pome fruit viruses in Morocco was carried out. Twenty orchards and nurseries were surveyed in the regions of Midelt, Meknès and Azilal. A total of 100 samples (apples and pears) were collected and tested. Biological indexing was made in a acclimatised greenhouse using the following indicators: Malus pumila cvs. ‛Spy 227’, ‛Radiant’ and ‛R 12740 7A’, and Pyrus communis cv. ‛LA/62’. All samples were also tested by ELISA for the presence of Apple chlorotic leaf spot virus (ACLSV), Apple stem grooving virus (ASGV), Apple stem pitting virus (ASPV) and Apple mosaic virus (ApMV). The prevailing viruses infecting apple were ACLSV (71%) and ASPV (58%), whereas ASGV was found in 12 tested trees. The same viruses were present, but less frequently, in pear: ACLSV (61%), Pear Vein Yellows Virus (PVYV) (25%) and ASGV (18%). Only four apple trees were found to be infected by ApMV. Additional RT-PCR testing confirmed the high incidence of ACLSV and ASPV.This was the first report of the presence of pome fruit viruses in Morocco, indicating the high infection rate worsened by the recent report of the presence of fire blight (Erwinia amylovora) in the country. Moreover, a total of 168 apples and 81 pears were sampled and tested for pome fruit viroids Apple scar skin viroid (ASSVd), Apple dimple fruit viroid (ADFVd) and Pear blister canker viroid (PBCVd) by tissue printing hybridization. No viroids were detected. Keywords: pome fruit, viruses, viroids, Morocco, ELISA, Tissue printing hybridization, PC

La inoculación con bacterias del ácido acético mejora la calidad de las aceitunas de mesa verdes naturales

This study aims to develop a method for the preparation of natural table olives using locally selected microorganisms and without resorting to the usual techniques which employ lye treatment and acids. The effects of parameters, such as lye treatment, inoculation with yeasts, substitution of organic acids with vinegar and/or acetic acid bacteria, and finally alternating aeration have been assessed. Four different combinations were applied to the “Picholine marocaine” olive variety using indigenous strains, namely Lactobacillus plantarum S1, Saccharomyces cerevisiae LD01 and Acetobacter pasteurianus KU710511 (CV01) isolated respectively from olive brine, Bouslikhen dates and Cactus. Two control tests, referring to traditional and industrial processes, were used as references. Microbial and physicochemical tests showed that the L3V combination (inoculated with A. pasteurianus KU710511 and L. plantarum S1 under the optimal growth conditions of the Acetic Acid Bacteria (AAB) strain with 6% NaCl) was found to be favorable for the growth of the Lactic Acid Bacteria (LAB) strain which plays the key role in olive fermentation. This result was confirmed by sensory evaluation, placing L3V at the top of the evaluated samples, surpassing the industrial one where a chemical debittering treatment with lye was used. In addition, alternating aeration served to increase the microbial biomass of both AAB and LAB strains along with Saccharomyces cerevisiae LD01 strain, but also to use lower concentration of NaCl and to reduce the deterioration of olives compared to the anaerobic fermentation process. Finally, a mixed starter containing the three strains was prepared in a 10-L Lab-fermenter from the L3V sample in order to improve it in subsequent studies. The prepared starter mixture could be suitable for use as a parental strain to prepare table olives for artisan and industrial application in Morocco.Este estudio tiene como objetivo desarrollar un método para la preparación de aceitunas de mesa naturales utilizando microorganismos seleccionados localmente y sin recurrir a las técnicas habituales que utilizan el tratamiento con lejía y ácidos. Se han evaluado los efectos de parámetros como el tratamiento con lejía, la inoculación con levaduras, la sustitución de ácidos orgánicos por bacterias de vinagre y/o ácido acético, y finalmente la aireación alterna. Se ensayaron cuatro combinaciones diferentes en la variedad de aceituna «Picholine marocaine» utilizando cepas autóctonas, como Lactobacillus plantarum S1, Saccharomyces cerevisiae LD01 y Acetobacter pasteurianus KU710511 (CV01) aisladas respectivamente de salmuera de aceitunas, Bouslikhen y Cactus. Se utilizaron como referencia dos pruebas de control, referidas a procesos tradicionales e industriales. Las pruebas microbianas y fisicoquímicas mostraron que la combinación L3V (inoculada con A. pasteurianus KU710511 y L. plantarum S1 en las condiciones óptimas de crecimiento de la bacteria del ácido acético (AAB) con NaCl al 6%) resultó ser favorable para el crecimiento del Láctico. Las cepas de bacterias ácidas (LAB) juegan un papel clave en la fermentación de las aceitunas. Este resultado fue confirmado por la evaluación sensorial colocando L3V en la parte superior de las muestras evaluadas, superando a la industrial, donde se usó un tratamiento de eliminación química con lejía. Además, la aireación alterna permitió aumentar la biomasa microbiana de las cepas AAB y LAB junto con la cepa Saccharomyces cerevisiae LD01, también usar una concentración más baja de NaCl y reducir el deterioro de las aceitunas, en comparación con la operación de fermentación anaerobia. Finalmente, se preparó un iniciador mixto que contenía las tres cepas en un fermentador de laboratorio de 10-L a partir de la muestra L3V con el objeto de mejorarlo en los estudios posteriores. El iniciador de mezcla preparado podría ser adecuado para usarse como una cepa parental para preparar aceitunas de mesa para aplicaciones artesanales e industriales en Marruecos

Detection by tissue printing hybridization of Pome fruit viroids in the mediterranean basin

Available data on the incidence and biodiversity of pome fruit viroids in the Mediterranean basin are limited. Before starting a research survey to fill this gap, a tissue-printing hydridization (TPH) method to detect Apple scar skin viroid (ASSVd), Pear blister canker viroid (PBCVd) and Apple dimple fruit viroid (ADFVd) has been developed and validated. Afterward, TPH was used in large-scale indexing of pome fruit viroids in Bosnia and Herzegovina, Malta, Lebanon and Turkey. A total of about 1,000 trees was randomly collected and tested. Positive results obtained by TPH were confirmed by at least one additional detection method (RT-PCR and/or Northern-blot hybridization) and viroids were finally identified by sequencing full-length cDNA clones. PBCVd was detected in 13%, 12.4% and 5.4% of the tested pear trees in Bosnia and Herzegovina, Malta and Turkey, respectively, showing a wider diffusion of this viroid than expected. In contrast, ASSVd was never detected and ADFVd was only found in symptomatic trees (cv. Starking Delicious) in Lebanon, confirming a restricted presence of these viroids in the Mediterranean basin. Altogether, these data support the use of TPH as an easy and valuable tool for exploring pome fruit viroid spread. Keywords: Viroid disease, viroid spread, pome fruit trees, detection methods, molecular hybridizatio

Certification scheme for fig plants (Ficus carica L.) in Morocco

Certification and sanitation programs for pathogen-tested material of the fig tree have the aim of providing plants that are true-to-type, free from virus and substantially free from other pests. In Morocco, this certification scheme provides detailed guidance on the production of vegetatively propagated fig plants. The organization of certification through its steps is detailed and the agencies involved in the sanitary controls, which guarantee the freedom of certified stocks from virus causing mosaic on fig plants are described. This program involves the sectors of research, public institutions and Moroccan nurseries in order to set up a system of sanitary certification of fig tree in Morocco

Pest risk analysis on Xylella fastidiosa in Morocco

Morocco is basically an agricultural country; almost 40% of the workforce is employed in this sector. Xylella fastidiosa is a xylem-inhabiting pathogen which can infect more than 300 plant species, although most host species are symptomless. Until relatively recently, X. fastidiosa was primarily limited to North and South America, but in 2013 a widespread epidemic of olive quick decline syndrome caused by this fastidious pathogen appeared in southeastern Italy, and later several cases of X. fastidiosa outbreaks have been reported in other European countries (France, Germany and Spain). Following these recently confirmed findings of X. fastidiosa in the European Union, this bacterium has become a serious threat to the Moroccan flora. The national phytosanitary authorities have adopted several measures to prevent the introduction of X. fastidiosa into the national territory by deciding, inter alia, to suspend importation of host plant species to the bacterium from infected areas. This paper presents the phytosanitary risk of this bacterium in Morocco

The importance, biology and management of cereal cyst nematodes (Heterodera spp.)

Cereals are exposed to biotic and abiotic stresses. Among the biotic stresses, plant-parasitic nematodes play an important role in decreasing crop yield. Cereal cyst nematodes (CCNs) are known to be a major constraint to wheat production in several parts of the world. Significant economic losses due to CCNs have been reported. Recognition and identification of CCNs are the first steps in nematode management. This paper reviews the current distribution of CCNs in different parts of the world and the recent advances in nematode identification. The different approaches for managing CCNs are also discussed

Assessing the prevalence of citrus virus and virus-like diseases in Berkane area

Les phytovirus constituent un sujet de préoccupation majeur aussi bien au niveau mondial que national. L’efficacité des mesures de contrôle des phytovirus repose sur une bonne compréhension de leur étiologie et de leur épidémiologie. C’est dans ce contexte que la prévalence des viroses des agrumes, causées par des phytovirus et des microorganismes similaires aux virus, a été étudiée dans la région de Berkane. Un total de 277 échantillons a été prélevé dans 3 pépinières et 27 exploitations agrumicoles entre 2018 et 2019. Ces échantillons ont été testés contre des anticorps monoclonaux spécifiques pour citrus tristeza virus (CTV), citrus psorosis virus (CPsV), et Spiroplasma citri, moyennant Double Antibody Sandwich-Enzyme Linked-Immunosorbent Assay (DAS-ELISA). Seul CPsV a été détecté avec une prévalence de 18% (51/277). Nos résultats révèlent que les profils d’infection par CPsV sont significativement différents entre tous les sites prospectés et que ce virus est présent aussi bien sur oranger (24%) que sur clémentinier (15%). Des tests préliminaires de Reverse Transcription-Polymerase Chain Reaction (RT-PCR) ont permis de confirmer les résultats obtenus par DAS-ELISA pour CPsV et ont révélé également la présence de citrus exocortis viroid (CEVd) et hop stunt viroid (HSVd). Ces résultats contribueraient dans la formulation de pratiques viables de gestion des phytovirus et des microorganismes similaires aux virus dans la région de Berkane.Plant viruses represent serious threats to crop plants, particularly in intensive farming. They are responsible for tremendous losses in crop production and quality all over the world. The efficiency of their control relies on a good understanding of both their etiology and epidemiology. In this context, a survey of citrus virus and virus-like diseases was undertaken in the northeast of Morocco (Berkane area). 277 leaf samples were collected from citrus nurseries plants and orchards trees between 2018 and 2019 and were tested with Double-Antibody Sandwich-Enzyme Linked Immunosorbent Assay (DAS-ELISA) to detect citrus tristeza virus (CTV), citrus psorosis virus (CPsV), and Spiroplasma citri. Only CPsV was detected with an average prevalence of 18% (51/277). CPsV infection patterns were significantly different between all the surveyed orchards, and the virus was detected on both orange and clementine trees with an average prevalence of 24% and 15%, respectively. Preliminary Reverse Transcription-Polymerase Chain Reaction (RT-PCR) tests have confirmed the serological results obtained for CPsV and also allowed the detection of two viroids, citrus exocortis viroid (CEVd) and hop stunt viroid (HSVd). These results will help improve citrus virus and virus-like diseases control strategies in the Berkane area