Laboratory methods for work with plant and soil nematodes

The Panel on Plant Health conducted a pest risk assessment for Bemisia tabaci and the viruses it transmits, including an evaluation of risk reduction options and an assessment of the effectiveness of the special requirements linked to B. tabaci and the viruses listed in Council Directive 2000/29/EC. B. tabaci and a large number of viruses transmitted by this polyphagous insect occur in subtropical and tropical climates around the world. Five entry pathways for B. tabaci and associated viruses were identified, with the plants for planting pathway being most significant and rated for entry of insects and viruses as likely and moderately likely, respectively. The most invasive B. tabaci species and several of its associated viruses responsible for severe diseases in major European food crops are established outdoors in coastal Mediterranean regions. Because of similar climate requirements and host plant preferences, B. tabaci and associated viruses currently not present in Europe are likely to establish within the temperature limits set for B. tabaci. Trade between European Member States allows B. tabaci to reach greenhouses in northern Europe, including those in areas with protected zone status. Because of the cool climate, establishment and spread outdoors of B. tabaci is rated unlikely for northern Europe. This situation is likely to continue even under a climatic scenario with an increase in temperature of +2 °C. B. tabaci -transmitted viruses cause severe diseases with major negative impact on crop production when risk reduction measures are not used. Risk reduction options will also apply to B. tabaci and viruses new to Europe. Risk reductions options are evaluated in terms of reducing B. tabaci populations, crop infestations, virus incidence and the impact of diseases. © European Food Safety Authority, 2013

Scientific Opinion on the risks to plant health posed by Bemisia tabaci species complex and viruses it transmits for the EU territory

Patchouli (Pogostemon cablin Benth.): Botany, agrotechnology and biotechnological aspects

Potyviruses are the largest group of plant infecting RNA viruses that cause significant losses in a wide range of crops across the globe. The majority of viruses in the genus Potyvirus are transmitted by aphids in a non-persistent, non-circulative manner and have been extensively studied vis-a-vis their structure, taxonomy, evolution, diagnosis, transmission, and molecular interactions with hosts. This comprehensive review exclusively discusses potyviruses and their transmission by aphid vectors, specifically in the light of several virus, aphid and plant factors, and how their interplay influences potyviral binding in aphids, aphid behavior and fitness, host plant biochemistry, virus epidemics, and transmission bottlenecks. We present the heatmap of the global distribution of potyvirus species, variation in the potyviral coat protein gene, and top aphid vectors of potyviruses. Lastly, we examine how the fundamental understanding of these multi-partite interactions through multi-omics approaches is already contributing to, and can have future implications for, devising effective and sustainable management strategies against aphid-transmitted potyviruses to global agriculture.

Aphid Transmission of Potyvirus: The Largest Plant-Infecting RNA Virus Genus.

Tomato chlorosis virus (ToCV) causes an important disease that primarily affects tomato, although it has been found infecting other economically important vegetable crops and a wide range of wild plants. First described in Florida (USA) and associated with a 'yellow leaf disorder' in the mid-1990s, ToCV has been found in 35 countries and territories to date, constituting a paradigmatic example of an emergent plant pathogen. ToCV is transmitted semipersistently by whiteflies (Hemiptera: Aleyrodidae) belonging to the genera Bemisia and Trialeurodes. Whitefly transmission is highly efficient and cases of 100% infection are frequently observed in the field. To date, no resistant or tolerant tomato plants are commercially available and the control of the disease relies primarily on the control of the insect vector. Taxonomy Tomato chlorosis virus is one of the 14 accepted species in the genus Crinivirus, one of the four genera in the family Closteroviridae of plant viruses. Virion and genome properties The genome of ToCV is composed of two molecules of single-stranded positive-sense RNA, named RNA1 and RNA2, separately encapsidated in long, flexuous, rod-like virions. As has been shown for other closterovirids, ToCV virions are believed to have a bipolar structure. RNA1 contains four open reading frames (ORFs) encoding proteins associated with virus replication and suppression of gene silencing, whereas RNA2 contains nine ORFs encoding proteins putatively involved in encapsidation, cell-to-cell movement, gene silencing suppression and whitefly transmission. Host range In addition to tomato, ToCV has been found to infect 84 dicot plant species belonging to 25 botanical families, including economically important crops. Transmission Like all species within the genus Crinivirus, ToCV is semipersistently transmitted by whiteflies, being one of only two criniviruses transmitted by members of the genera Bemisia and Trialeurodes. Disease symptoms Tomato 'yellow leaf disorder' syndrome includes interveinal yellowing and thickening of leaves. Symptoms first develop on lower leaves and then advance towards the upper part of the plant. Bronzing and necrosis of the older leaves are accompanied by a decline in vigour and reduction in fruit yield. In other hosts the most common symptoms include interveinal chlorosis and mild yellowing on older leaves. Control Control of the disease caused by ToCV is based on the use of healthy seedlings for transplanting, limiting accessibility of alternate host plants that can serve as virus reservoirs and the spraying of insecticides for vector control. Although several wild tomato species have been shown to contain genotypes resistant to ToCV, there are no commercially available resistant or tolerant tomato varieties to date.

https://bsppjournals.onlinelibrary.wiley.com/doi/pdf/10.1111/mpp.12847

Tomato chlorosis virus, an emergent plant virus still expanding its geographical and host ranges

In 2008, virus-like symptoms of yellowing, interveinal chlorosis, leaf curling and necrotic fleck were observed on greenhouse-tomato plants (Solanum esculentum) in Tochigi Prefecture. The symptomatology and the characteristics of the causal agent such as whitefly transmissibility and particle morphology are similar to those for Tomato infectious chlorosis virus (TICV) and Tomato chlorosis virus (ToCV), species of the genus Crinivirus in the family Closteroviridae. Sequencing of reverse transcription-polymerase chain reaction (RT-PCR) products using the degenerate primers for heat shock protein 70 homolog genes of closteroviruses and specific primers for TICV and ToCV indicated that the virus was ToCV, that has not previously been reported in Japan.

Yellowing disease of tomato caused by Tomato chlorosis virus newly recognized in Japan

This study was carried out to identify the virus associated with mosaic disease on patchouli in Indonesia. The diseased plant samples collected from Garut, Ciamis, Bogor (West Java) and West Pasaman (West Sumatera) strongly reacted with Potyvirus antiserum by enzyme-linked immunosorbent assay, but did not show any signal with antisera to Cucumber mosaic virus, Tobacco mosaic virus, Broad bean wilt virus 1 and Broad bean wilt virus 2; except the samples collected from Brebes (Central Java) which strongly reacted with Broad bean wilt virus 2 (Fabavirus) only. Besides that, the diseased plant samples collected from North Sumatera (Pakpak Bharat) did not react to any antiserum tested. The Potyvirus was then isolated. Positive results were obtained using a reverse transcriptase-polymerase chain reaction (RT-PCR) method to detect and identify Potyvirus from nucleic acid extracts of the symptomatic patchouli plants, using a pair of degenerate primers specific for Potyvirus CP gene. The sequence of this RT-PCR fragment, consisted of 800 bp, confirmed association of a Potyvirus with mosaic disease on patchouli plants in Indonesia. Potyvirus infecting patchouli plants in Indonesia are closely related to Telosma mosaic virus (TeMV) and Passionfruit woodiness virus (PaWP). This paper is the first report that TeMV, PaWP and Fabavirus are associated with mosaic disease on patchouli plants in Indonesia.

Potyvirus associated with mosaic disease on patchouli (Pogostemon cablin (Blanco) Benth.) plants in Indonesia.

This study was conducted to evaluate the effectiveness of plant growth promoting rhizobacteria (PGPR) in protecting chillipepper plant from infection of cucumber mosaic virus (CMV) and chilli veinal mottle virus (ChiVMV) Seven isolates of PGPR, ie BC1, BTP2H, BTP3G, BTP3O BTP1, BTP2D, and T1F were applied as seed treatment and soil drench Plants height, number of branch, and fruits weight were measured every one and ten weeks after virus inoculation Virus concentration in plants and disease incidence were confirmed by enzyme-linked immunosorbant assay (ELISA) Results showed that inoculation with PGPR improved the seed germination Eight days after sowing, the percentage of PGPR treated seed germination reached 50-84%; whereas those of untreated seed reached only 18% In general, PGPR treatment significantly reduced (p < 005) the effect of virus infection on plant growth Two PGPR isolates, ie BTP1 and BTP2H, maintained fruit weight of infected plants as good as those of healthy plants Based on ELISA, PGPR was able to inhibit the disease incidence The BTP3O and BTP2D isolates even protected the plant from ChiVMV infection Concentration of salicylic acid and peroxidase were relatively higher on plants treated with PGPR than those without PGPR treatment This gave an indication that PGPR may act as induction agents for systemic acquired resistance Therefore, PGPR treatment is a promising strategy to control viral diseases on chillipepper

Kajian Plant Growth Promoting Rhizobacteria sebagai Agens Proteksi Cucumber Mosaic Virus dan Chilli Veinal Mottle Virus pada Cabai

Recently, field surveys were conducted in several orchid nurseries in Bogor (West Java), Magelang (Central Java) and Malang (East Java). We found that most of the commercially orchids sampled from Bogor was infected by virus-like disease. The symptoms depend on the orchid species. Thus, the symptoms varied such as mottle, mosaic and necrotic flecks either on the leaves or on the flowers. Similiar symptoms were not found in samples obtained from Central Java and East Java. A Tobamo-like virus was inferred to be possible cause of the viral disease-like symptoms. Serological test of the samples by ELISA showed positive against Odontoglosum Ringspot Virus (ORSV) antibody and was negative against Cymbidium Mosaic Virus (CyMV) antibody. Total RNA was extracted from symptomatic plants and RT-PCR was carried out by using a pair of coat protein (CP) gene primer of ORSV.  It was successfully amplified a 500 bp of DNA fragment and it was directly sequenced. The nucleotide sequence of CP gene had confirmed the identity of ORSV. Phylogenetic analysis based on the CP nucleotide sequences were grouped into only one major cluster.  The ORSV isolate from Bogor (Sd 21) and the other isolates were clustered in the same group and had highest nucleotide homology (99%). These results provide first evidence of ORSV infecting orchids in Bogor, Indonesia.

https://repository.ipb.ac.id/bitstream/handle/123456789/42708/Irwan%20Lakani.pdf?sequence=1&isAllowed=y

Identification and Molecular Characterization of Odontoglosum Ringspot Virus (ORSV) from Bogor, Indonesia

Branched tuber disease is a new problem on carrot cultivation in Indonesia. The disease may reduce the quantity and quality of the tubers and causing significant yield losses. Meloidogyne spp . has been identified as the primary cause of branched or forked disease of carrot in West Java. Similar disease was observed in carrot field in Dieng Plateau, Central Java. The study was conducted at three locations in the Dieng Plateau having different elevation. Nematode species identification was done by observing the perinneal pattern of 150 samples of female nematode and obtained four Meloidogyne species, namely M. arenaria, M. hapla, M. incognita, and M. javanica . All four species were found associated with branched tuber disease in three locations with M. incognita as a dominant species having prevalence levels of 50% to 58%. Key words: branched tuber disease, carrots, Meloidogyne , species identification

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Gede Suastika

Papers

Yellowing disease of tomato caused by Tomato chlorosis virus newly recognized in Japan

Potyvirus associated with mosaic disease on patchouli (Pogostemon cablin (Blanco) Benth.) plants in Indonesia.

Kajian Plant Growth Promoting Rhizobacteria sebagai Agens Proteksi Cucumber Mosaic Virus dan Chilli Veinal Mottle Virus pada Cabai

Identification and Molecular Characterization of Odontoglosum Ringspot Virus (ORSV) from Bogor, Indonesia

Identifikasi Meloidogyne Penyebab Penyakit Umbi Bercabang pada Wortel di Dataran Tinggi Dieng