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Ceglie Messapica, Italy

Laala S.,Cncc Center National Of Controle Et Of Certification Des Semences Et Plants | Manceau C.,Laboratoire Of La Sante Des Vegetaux | Valentini F.,Mediterranean Agronomic Institute MAIB | Kerkoud M.,Diag Gene | Kheddam M.,Cncc Center National Of Controle Et Of Certification Des Semences Et Plants
Journal of Plant Pathology

During field surveys conducted in Spring and Summer 2010-2011, typical fire blight symptoms were observed on twigs and branches of pear (Pyrus communis) and apple (Malus domestica) in Algerian commercial orchards located in the areas of Algiers, Blida, Tipaza and Boumerdes. The disease was observed in 284 orchards, mainly on pear cv. Santa Maria and on apple cvs Royal gala and Golden delicious. Bacterial colonies were isolated on King's medium B (KB) and the semi-selective medium CCT (cycloheximide, cristal violet and thallium nitrate). Bacterial isolates displayed biochemical patterns typical of Erwinia amylovora and reacted positively in a serological slide agglutination test. Pathogenicity of bacterial isolates was confirmed by inoculating immature pear fruits of cv. Conference. The identity of the isolates was further confirmed by nested-PCR, and rep-PCR. A sequenced DNA fragment (713 bp) of the recA gene (accession No. JN812979) matched with 100% identity all E. amylovora recA DNA sequences available in GeneBank. Source

Digiaro M.,Mediterranean Agronomic Institute MAIB
Acta Horticulturae

A brief account is given on the situation of Sharka disease in the Mediterranean countries. The recent developments in the domain of virus characterization, diagnosis, epidemiology, genetic resistance and control measures are briefly reviewed. The necessity to intensify and extend the territorial monitoring activity and the use of certified plant propagating material of stone fruits is strongly recommended. Source

Yahiaoui D.,Mediterranean Agronomic Institute MAIB | Djelouah K.,Mediterranean Agronomic Institute MAIB | D'Onghia A.M.,Mediterranean Agronomic Institute MAIB | Catara A.,University of Catania
Acta Horticulturae

Citrus tristeza closterovirus (CTV), an insect-borne virus transmitted in nature by several aphid species in a semi-persistent manner, has historically posed a serious threat to the citrus industry worldwide. Up to date, the virus characterization and virus-vector relationship have been a key factor in understanding the disease epidemiology. The present research investigated the genetic variability generated within specific genomic regions of selected CTV isolates throughout the transmission by aphids. Isolates showing different genotype profiles and originating from Italy and Egypt were subjected to experimental transmission trials by a local biotype of Aphis gossypii (Glover) species, onto Mexican lime [Citrus aurantifolia (Christm.) Swingle] seedlings. The genotypes belonging to these CTV isolates were studied by using simultaneously multiple molecular markers (MMM) analysis, partial genome sequencing on CPg and single strand conformation polymorphism (SSCP) assays flanking the p18 and p20 genomic regions. The SSCP patterns obtained from the different sub-isolates were compared to those associated with their parental inoculum sources. In the present work, screening of slight CTV genomic variations in the aphid derived sub-isolates indicated variable changes in the studied proteins, regardless of the transmission abilities of the CTV isolates. Source

Abou Kubaa R.,Mediterranean Agronomic Institute MAIB | Yahiaoui D.,Mediterranean Agronomic Institute MAIB | Djelouah And K.,Mediterranean Agronomic Institute MAIB | D'Onghia A.M.,Mediterranean Agronomic Institute MAIB | Saponari M.,CNR Institute of Plant virology
Acta Horticulturae

Citrus tristeza virus (CTV) has been considered a heavily destructive pathogen to the world's citrus industries. In the Mediterranean basin, despite the eradication programmes that have been undertaken in many countries, CTV is still a serious threat due to its wide dissemination and the predominant use of the susceptible sour orange as rootstock. Sixteen CTV isolates collected from Algeria, Italy, Montenegro and Palestine, maintained at the Mediterranean Agronomic Institute of Bari (MAIB), were characterized by using a set of primers encompassing similar sized DNA fragments from four reference strains (T30, T36, VT and T3). Among the studied CTV isolates, 10 were apparently pure and showed T30, T36 and VT genotypes, while the remaining isolates proved to be genotype mixture including VT-T3; T36-T30 and VTT36 groups. This finding highlighted the wide distribution of T30 genotype throughout the Mediterranean area and the occurrence of severe strains. Source

D'Onghia A.M.,Mediterranean Agronomic Institute MAIB | Di Terlizzi B.,Mediterranean Agronomic Institute MAIB
Acta Horticulturae

Fruit trees in the Mediterranean area can be seriously compromised by pests and pathogens, which can be widely distributed or only localized in some countries or areas. Due to the climate change, new emerging pathogens may become dangerous for fruit tree crops. Furthermore, a number of destructive pests and pathogens are not yet present in the Mediterranean area and their potential entrance and spread can represent a serious threat for the sustainability of these crops. Within this context, the improvement of the quality of propagating materials of fruit tree species represents a fundamental option in the framework of the outcomes of the Barcelona declaration (1995), since it reduces dissemination of pests and pathogens among the countries through the free exchange of plant materials. The strategy conducted by CIHEAM/ MAIB, through the IPM Division, is aimed at facilitating the Barcelona process in the Region for propagating materials involving political organizations, scientific institutions, professional associations and farmers. Several important results were achieved through the training of executives, research and network actions in the region thereby implementing international cooperation programmes. Dedicated research networks were activated for the harmonization of technical protocols, procedures and regulations and for acquiring updated information on the sanitary status of fruit crops in most of the countries. Co-operation projects were promoted for the improvement of the fruit tree industry through the enhancement of the quality of nursery productions in different Mediterranean countries. Apart from international cultivars, several local genotypes of fruit tree crops have been clonally and sanitarily selected, thus contributing to the free exchange of this germplasm in the region. Through this long process, the free trade area of plant materials can be now envisaged among some countries in the Region. Source

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