Graft-transmissible Diseases Research Articles

Identification and Detection of Citrus Psorosis Virus (CPsV) In Citrus Varieties And Rootstocks Cultivated In Mitidja Region, Algeria

Abstract Psorosis is one of major graft-transmissible diseases of Citrus; the virus was reported to occur in different Citrus cultivated areas and constitutes a serious threat to Citrus establishment and development. This study focuses on the identification of Citrus Psorosis Virus (CPsV) by tow diagnostic methods; biological indexing in indicator seedling and serological test (DAS-ELISA). Thereby, different varieties of sweet orange (Citrus sinensis (L.) Osbeck), mandarin (Citrus × Deliciosa), lemon (Citrus × limon), Grapefruits (Citrus × Paradisi), clementine (Citrus × Clementine) and tow rootstocks sour orange (Citrus × aurantium L.) and trifoliate orange (Poncirus trifoliata) that exhibit typical symptoms of Psorosis disease have been detected and collected from five different orchards located in the regions of Mitidja (Algeria). All collected samples were subjected to biological testing and double antibody sandwich ELISA (DASELISA) as diagnostic tests. The serological method, specifically DAS-ELISA, yielded positive results on varieties from the prospect station, indicating the presence of psorosis in Algeria. The typical symptoms of psorosis were observed through the indexed seedlings and grafts.

PM 4/17 (3) Certification scheme for olive trees and rootstocks

<scp>PM</scp> 4/17 (3) Certification scheme for olive trees and rootstocks

Graft-Transmissible Diseases of Ribes - Pathogens, Impact, and Control.

This article provides an up-to-date review of disease-causing viruses and phytoplasmas of currants including symptoms, transmission, detection, economic impact, and control measures. Currants are widely cultivated in more than 30 countries in the temperate zones of Europe, Asia, South America, Australia, and New Zealand. Ribes spp. can be infected by more than 20 virus species and four Candidatus Phytoplasma species, with more to be described in the future. High-throughput sequencing opened a new era of deciphering virus variants and mixed infections, leading to the characterization of several new species. The use of clean propagation material is the basis for control of Ribes graft-transmissible diseases, but this has become a challenging task given the ever-growing number of newly discovered pathogens.

Managing biosecurity risks to Australian citrus

Author(s): Donovan, Nerida; Herrmann, Tim; Jelinek, Sylvia M | Abstract: The high health status of Australian citrus germplasm has been maintained largely due to a successful quarantine system and propagation scheme. Most endemic graft transmissible diseases are rarely observed in Australian orchards due to the use of high health status propagation material supplied by Auscitrus. Citrus tristeza virus is present throughout the citrus growing areas although mild strain cross protection has been effectively managing grapefruit stem pitting in white grapefruit varieties for over 40 years. However, diseases like huanglongbing and canker are ever present threats to the biosecurity of the Australian citrus industry. The introduction of mandatory nursery registration and compulsory use of pathogen tested propagation material would provide greater security to the industry in the face of increasing biosecurity threats.

Principles for supplying virus-tested material.

Production of virus-tested material of vegetatively propagated crops through national certification schemes has been implemented in many developed countries for more than 60 years and its importance for being the best virus control means is well acknowledged by growers worldwide. The two most important elements of certification schemes are the use of sensitive, reliable, and rapid detection techniques to check the health status of the material produced and effective and simple sanitation procedures for the elimination of viruses if present in candidate material before it enters the scheme. New technologies such as next-generation sequencing platforms are expected to further enhance the efficiency of certification and production of virus-tested material, through the clarification of the unknown etiology of several graft-transmissible diseases. The successful production of virus-tested material is a demanding procedure relying on the close collaboration of researchers, official services, and the private sector. Moreover, considerable efforts have been made by regional plant protection organizations such as the European and Mediterranean Plant Protection Organization (EPPO), the North American Plant Protection Organization (NAPPO), and the European Union and the USA to harmonize procedures, methodologies, and techniques in order to assure the quality, safety, and movement of the vegetatively propagated material produced around the world.

Huanglongbing or yellow shoot, a disease of Gondwanan origin: Will it destroy citrus worldwide?

JosephM. Bovewas born in Luxemburg, 1929. French citizen since 1968. Higher education: School of Agronomy and University, Paris, France (1950-1955), University of California, Berkeley (1956-1955). Doctorate on in vitro synthesis of plant viral RNA (1967). Researcher at the French Institute for Citrus and Tropical fruit Research (1959-1970) at Versailles, France. Director of research at INRA (French National Institute for Agricultural Research), at INRA campus of Bordeaux, France (1971-1975) and professor of microbiology at University of Bordeaux (1976-1997). Head of Laboratory for Cellular and Molecular Plant Biology (1974-1994). President of INRA-Bordeaux (19841994). FAO consultant for citrus diseases (1981-1993). Consultant at Fundecitrus, Sao Paulo State, Brazil, for graft-transmissible diseases of citrus (1998-2014). Research. (i) Photosynthetic phosphorylation, laboratory of Prof. D.I. Arnon, University of California at Berkeley (1956-1959). (ii) Replication of plant virus RNA, Versailles and Bordeaux (1959-1986). (iii) Discovery and study of pathogenic, phloem-restricted bacteria of citrus: Spiroplasma citri, agent of stubborn disease, Candidatus Liberibacter spp., associated with huanglongbing, Candidatus Phytoplasma aurantifolia, associated with witches’ broom disease of lime, as well as of xylem-restricted bacteria: Xylella fastidiosa, agent of citrus variegated chlorosis (1969-1999). (iv) Etiology and management of citrus diseases in Brazil: Variegated chlorosis (1989-1993), Sudden Death (19982005), Huanglongbing 2005-2014). J.M. Bove is member of the French Academy of Agriculture (1992), corresponding member of the French Academy of Science (1993), member of the Brazilian Academy of Science (2002), Fellow of the American Phytopathological Society (1994), Fellow of the International Organization of Citrus Virologists (2004). Phytoparasitica DOI 10.1007/s12600-014-0415-4

DETECTION OF Citrus psorosis ophiovirus IN CITRUS CV. NAVEL ORANGE IN EGYPT

Citrus is one of the most important fruit crops worldwide. Most of the citrus cultivars are grown as grafted plants. Virus pathogens transmitted by grafting as well as insect vectors could cause economic problems. Among graft transmissible diseases that have been reported from Egypt as well as in the rest of the Mediterranean countries; citrus psorosis disease that is of the most serious and remain the most spread disease in Egypt (Roistacher, 1991; Sofy, 2008). In infected trees, scaly bark symptoms appears on the trunk, staining of interior wood of branch and gummy as well as shortened leaf internodes and mottling patterns on leaves (Ghazal et al., 2008; El-Dougdoug et al., 2009). Citrus psorosis virus (CPsV), the type species of the genus Ophiovirus (Vaira et al., 2005), is the putative causal agent of psorosis, a major graft-transmissible disease of citrus (Roistacher, 1993). Virus particles are formed by three single-stranded, negative sense RNAs and a coat protein (CP) of 48 kDa (Derrick et al., 1988; Marti´n et al., 2005). RNA1 contains 8184 bp and its complementary strand has two ORFs potentially encoding a 24 kDa protein of unknown function and a 280 kDa protein with motifs characteristic of RNA-dependent RNA polymerases (RdRp). RNA2 contains 1644 bp and its complementary strand encodes a 54 kDa protein without similarities to other known proteins and RNA3 contains 1454 bp and its complementary strand encodes the CP (Barthe et al., 1998; Sa´nchez de la Torre et al., 1998 & 2002; Naum-Ongani´a et al., 2003; Marti´n et al., 2005). The sensitive, reliable and rapid identification of plant viruses is essential for effective disease control. For many years, laborious and costly indexing on citrus indicators was the only diagnostic method available (Roistacher, 1993). The first breakthrough in the development of a laboratory diagnostic testing technique came in 1977 with the development of the ELISA (Clark and Adams, 1977). DAS-ELISA (Garcia et al., 1997) and TAS-ELISA (Alioto et al., 1999) are methods developed and applied for psorosis diagnosis in field trees. Polymerase chain reaction (PCR) was developed in the early 1990’s and has the ability to selectively amplify a part of the target deoxyribonucleic acid (DNA). Reverse transcription-polymerase chain reaction (RT-PCR) (Garcia et al., 1997; Legarreta et al., 2000; D’Onghia et al., 2001), are now being utilized and several primers have been designed for the CPsV detection by the RT-PCR providing an alternative method for diagnosis (Barthe et al., 1998; Legarreta et al., 2000). This study aimed to detect CPsV in citrus trees cv. Navel orange via biological, serological and molecular methods.

Legislatively Establishing a Health Certification Programme for Citrus

Many countries have implemented plant material certification programmes to preserve or rebuild certain agricultural sectors. These programmes aim to produce and distribute high quality planting materials that are free from systemic diseases and pests. Certification programmes generally requirements for nurseries, growers and other purveyors of plants. Only those varieties of plants that have been registered and approved by the competent national authority; that have been evaluated, indexed and found free from any systemic diseases; and that thrive in the region may be certified. Generally, the agricultural ministry administers certification programmes, although the competent authority will vary by country. Many different crops throughout the world are subject to certification. Citrus is one of the major cultivated fruit crops in the world, grown in more than 100 countries throughout the tropical, sub-tropical and Mediterranean climate regions. For most of these countries, citrus is a significant export. South Africa, for example, exported over one million metric tonnes of oranges in the 2008/2009 marketing year, whereas the world export total was over three million tonnes. Citrus is also one of the crops most susceptible to and most easily harmed by pathogens transmitted through plant propagation, a type of plant reproduction whose object is to preserve the unique characteristics of a desirable plant from one generation to the next. Different types of plant propagation include grafting (uniting two plants to make them grow as a single plant by inserting one or more buds of one plant – the scion – into the rootstock or stock of the other) and budding (common for propagating young citrus trees: here the scion, consisting of a single bud, is attached just underneath the bark). As will be discussed in more detail below, citrus diseases range from prokaryotic (bacteria and mollicute, i.e. without a cell wall) to fungal (true fungi and oomycetes, i.e. pathogens that look like fungi but on a molecular level more closely resemble algae) to viral (true viruses and viroids, i.e. viruses without proteins). Some diseases, such as citrus tristeza, huanglongbing and witches’ broom, are so serious that they can cripple, debilitate or even destroy a citrus industry in a country or region. A citrus certification programme producing disease tested propagative material is one of the most efficient ways to eliminate or contain graft transmissible and other citrus diseases. This paper is designed as a resource for national or sub-national governments that are interested in designing and implementing a citrus certification programme. The paper first provides a background to the diseases and transmission vectors to which citrus species are susceptible. It then outlines examples of certification programmes, voluntary and mandatory, and then provides a detailed description of the specific elements of a certification programme and the legislation needed to put it in place.

Pathogen‐tested material of grapevine varieties and rootstocks

Pathogen‐tested material of grapevine varieties and rootstocks

Polyvalent Degenerate Oligonucleotides Reverse Transcription-Polymerase Chain Reaction: A Polyvalent Detection and Characterization Tool for Trichoviruses, Capilloviruses, and Foveaviruses

ABSTRACT A polyvalent nested reverse transcription-polymerase chain reaction (RT-PCR) test using degenerate primers containing inosine (polyvalent degenerate oligonucleotides [PDO]) was developed for filamentous fruit tree viruses belonging to the genera Trichovirus, Capillovirus, and Foveavirus. The 362-bp product was amplified from nucleic acid extracts obtained from Prunus and Malus leaf samples. All the viruses targeted were detected, demonstrating the polyvalence of the test. The variability of a collection of Apple chlorotic leaf spot virus isolates was analyzed using the sequence of the PDO RT-PCR amplified cDNAs. The technique was also used to screen stone fruit materials infected with known agents or with virus-like graft-transmissible diseases of unknown etiology. The results obtained further validated the broad specificity of the assay, with positive amplification obtained for uncharacterized or partially characterized viruses associated with cherry and peach disorders. Sequencing the amplified PCR products either directly or after cloning allowed the identification of variants of known agents and the tentative identification of two new agents, a Trichovirus and a Foveavirus. In addition, sequence comparisons demonstrated that the sequence of the targeted region is phylogenetically informative and of predictive taxonomic value.

Nucleotide sequence and genome structure of grapevine rupestris stem pitting associated virus-1 reveal similarities to apple stem pitting virus.

Rupestris stem pitting (RSP), a component of the rugose wood complex, is one of the most widespread graft-transmissible diseases of grapevines. Here we report on the consistent association of a high molecular mass dsRNA (ca. 8.7 kbp) with RSP. The dsRNA was reverse-transcribed and cDNAs generated were cloned into Lambda ZAP II. Sequence analysis of the cDNA clones showed that the dsRNA was of viral origin and the putative virus was designated rupestris stem pitting associated virus-1 (RSPaV-1). The genome of RSPaV-1 consists of 8726 nt excluding a poly(A) tail at the 3' terminus. It has five potential open reading frames which have the capacity to code for the replicase (ORF1), the triple gene block (ORF2-4) and the coat protein (ORF5). Comparison of the genome structure and nucleotide and amino acid sequences indicated similarities of RSPaV-1 to apple stem pitting virus, and to a lesser extent, to potato virus M carlavirus. The possibility that different strains of RSPaV-1 or other viruses are associated with RSP is discussed.

Production Systems of Fruit Tree Nurseries to Control Graft-Transmissible Diseases.

Graft transmissible diseases of fruit crops are very important because of the large production losses and the transmission of pathogens to propagated clones. Virus, viroid and prokaryote organisms have been found as the causal agents of many diseases. However, unidentified pathogens still remain in many fruit crops. ELISA, electrophoreses and PCR can detect the characterized pathogens rapidly, but plant indexing is necessary for undermined pathogens. To obtain pathogen-free plants, a heat-treatment is effective to eliminate various pathogens from infected plants, but usually not viroids. Apical shoot-tip-culture or grafting can eliminate viroids as well as other pathogens, except for capillovirus. Methods combining pre-heat treatment and subsequent shoot-tip culture/grafting have been demonstrated for the elimination of known pathogens. Pathogen-free stock plants are usually preserved in protective screen houses. However, additional propagation and nursery production have been accomplished in fields in Japan. Thus, periodic checks or indexing of the mother stocks are needed. Pre-inoculation of bud-sources with protective mild strains of virus has been proved effective to control citrus stem pitting disease caused by aphid-vectored CTV. Disinfection of cutting tools is recommended to prevent viroid transmission, especially in nursery production.

Occurrence of Graft-Transmissible Diseases of Citrus in the Highlands of Northern Luzon, Philippines

Occurrence of Graft-Transmissible Diseases of Citrus in the Highlands of Northern Luzon, Philippines

Agro-ecology and Centers of Origin of Graft-transmissible Diseases of Citrus

Agro-ecology and Centers of Origin of Graft-transmissible Diseases of Citrus

Three graft-transmissible diseases and a variegation disorder of small fruit in New Zealand

Abstract The presence in New Zealand of the reversion disease of black currants was demonstrated by the development of typical symptoms in susceptible cultivars after graft inoculation. Reversion appears to be responsible for the serious crop losses occurring in Otago and Southland regions. It is not restricted to those areas, but occurs at a low incidence in Canterbury and Nelson regions. Spread has occurred through the use of infected cuttings during propagation, and probably also by the gall mite vector. Red currant vein banding disease was detected in several red currant cultivars by graft inoculation to red currant seedlings, and to the indicator B1385/81, but is of low incidence. The disease boysenberry decline, possibly caused by a mycoplasma-like organism, occurs in the northern half of the North Island. During the 1980s it appeared to be spreading rapidly until the removal of most infected plantings greatly reduced its incidence. The boysenberry leatbopper is a possible vector, but in controlled ...

Cytological and Histological Aberrations in Woody Plants Following Infection with Viruses, Mycoplasmas, Rickettsias, and Flagellates

INTRODUCTION To understand how a disease is produced by a systemic, intracellular submi­ croscopic (below ca 0.3,.. ) agent, it is necessary to study the complete se­ quence of pathological aberrations and host responses that occur following infection. In such studies of pathogenesis or pathogeny (113) one gathers in­ formation about: (a) how and where the causal agent enters the host; (b) which are infected and how they are affected by the initial infection; (c) the effect of infected on adjacent noninfected cells in producing dis­ eased tissues; (d) the host response to the diseased tissues such as formation of wound periderm or tyloses; and (e) the maleffects of the tissues on other parts and functions of the plant. A standard set of steps in pathogenesis cannot be formulated for all diseases because the steps vary with the disease, the host, and the vector. Most plant pathologists do not consider all of these steps but rather spe­ cialize in certain well defined areas of experimentation such as: (a) infection processes (93, 100) ; (b) synthesis of virus particles (5, 72, 82); (c) translo­ cation of the agent (93); etc. This paper will consider cytological and ana­ tomical aspects of pathogeny beginning with the first appearances of the agent and! or with the first pathologic changes in the host that are detectable with the light or electron microscope. Until Doi et a1 (17) discovered mycoplasma associated with several plant diseases, and Goheen et al (40) discovered Rickettsia-like organisms associ­ ated with Pierce's disease, all graft-transmissible diseases with submicro-