Viruses cause many severe plant diseases, resulting in immense losses of crop yield worldwide. Therefore, developing novel approaches to control plant viruses is crucial to meet the demands of a growing world population. Recently, RNA interference (RNAi) has been widely used to develop virus-resistant plants. Once genome replication and assembly of virion particles is completed inside the host plant, mature virions or sometimes naked viral genomes spread cell-to-cell through plasmodesmata by interacting with the virus-encoded movement protein (MP). We used the RNAi approach to suppress MP gene expression, which in turn prevented potato leafroll virus (PLRV) systemic infection in Solanum tuberosum cv. Khufri Ashoka. Potato plants agroinfiltrated with MP siRNA constructs exhibited no rolling symptoms upon PLRV infection, indicating that the silencing of MP gene expression is an efficient method for generating PLRV-resistant potato plants. Further, we identified novel ATPase motifs in MP that may be involved in DNA binding and translocation through plasmodesmata. We also showed that the ATPase activity of MP was stimulated in the presence of DNA/RNA. Overall, our findings provide a robust technology to generate PLRV-resistant potato plants, which can be extended to other species. Moreover, this approach also contributes to the study of genome translocation mechanisms of plant viruses.

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Inhibition of potato leafroll virus multiplication and systemic translocation by siRNA constructs against putative ATPase fold of movement protein.

Greenhouse peppers are one of the most important crops globally. However, as in any production activity, especially agricultural, they are subject to important risk factors such as price fluctuations, pests, or the use of bad quality water. This article aims to evaluate the viability of these types of crops by using discounted cash flows. Risk evaluation has been carried out through the analysis of pepper plantations for 2016 and 2017. The traditional application of this tool has significant limitations, such as the discount rate to be used or the estimation of future cash flows. However, by using discount functions that decrease over time in combination with decoupled net present value, these limitations are expected to improve. The use of decoupled net present value has permitted an increase in the accuracy and quantification of risks, isolating the main risks such as price drops (EUR 3720 ha−1 year−1) and structural risks (EUR 1622 € ha−1 year−1). The use of decreasing discount functions has permitted a more realistic investment estimation. Finally, the sensitivity analysis shows that decoupled net present value (DNPV) is little affected by changes in interest rates in contrast to traditional net present value (NPV).

The Financial Valuation Risk in Pepper Production: The Use of Decoupled Net Present Value

MOLECULAR CHARACTERIZATION OF A Tospovirus INFECTING BELL PEPPER (Capsicum annuum L.)

Potato is a major food crop that has the potential to feed the increasing global population. Potato is the fourth most important crop and a staple food for many people worldwide. The traditional breeding of potato poses many challenges because of its autotetraploid nature and its tendency toward inbreeding depression. Moreover, potato crops suffer considerable production losses because of infections caused by plant viruses. In this context, RNA silencing technology has been successfully applied in model and crop species. In this review, we describe the RNA interference (RNAi) mechanisms, including small-interfering RNA, microRNA, and artificial microRNA, which may be used to engineer resistance against potato viruses. We also explore the latest advances in the development of antiviral strategies to enhance resistance against potato virus X, potato virus Y, potato virus A, potato leafroll virus, and potato spindle tuber viroid. Furthermore, the challenges in RNAi that need to be overcome are described in this review. Altogether, this report would be insightful for the researchers attempting to understand the RNAi-mediated resistance against viruses in potato.

/pdf/advances-in-rna-silencing-related-resistance-against-viruses-26dyqcp9.pdf

Advances in RNA-Silencing-Related Resistance against Viruses in Potato

Plant viruses cause various disease in crops and are responsible for huge economic losses. Understanding their mode of infection and spread is crucial for developing control strategies. Genome packaging is an important step in the process of viral maturation. Three systems of viral genome packaging are known till date. The type I packaging system, found in most of the small plant viruses, involves co-condensation of nucleic acid with viral capsid proteins (CPs) leading to the assembly of virion particles without utilizing ATP. The type II and III packaging systems, present in phages and nucleo-cytoplasmic large DNA viruses, exhibit genome translocation inside the prohead by utilizing ATP. Discovery of the ATPase fold in the CPs of many small plant viruses and the requirement of other ATPases during genome encapsidation have changed the perception about genome packaging in the type I system. Based on recent studies, it seems that the genome packaging mechanisms of plant viruses such as potexvirus have nothing in common with those of other well-characterized passive, energy-independent type I systems. Moreover, these studies have suggested that in these plant viruses, the genome encapsidation process is more intricately coupled with energy utilization than in other systems. In this comprehensive review, we present a novel, expanded sub-classification system for the type I system on the basis of ATP employed.

Reassessing the mechanism of genome packaging in plant viruses with lessons from ATPase fold

Pepper (Capsicum annuum L), an important vegetable crop in Thailand, is affected by several viral diseases This research was conducted to determine the occurrence and incidence of tospovirus on pepper in Southern Thailand One hundred and thirty symptomatic leaf samples of pepper were collected from pepper production areas in three provinces of Southern Thailand during the summer of 2012 Serological diagnosis was defined by directed antigen coating enzyme-linked immunosorbent assay (DAC-ELISA) using specific polyclonal antibodies to Capsicum chlorosis virus (CaCV), Watermelon silver mottle virus (WSMoV), Melon yellow spot virus (MYSV) and Tomato necrotic ringspot virus (TNRV) The highest virus incidence among the surveyed provinces was recorded in Nakhon Sri Thammarat (846%), followed by Songkhla (692%) and Patthalung (153%) Virus incidence in decreasing order was MYSV (1692%), TNRV (1308%), WSMoV and CaCV (154%) Furthermore, the virus was also detected in two weed species (Amaranthus lividus Linn and Heliotropium indicum Linn) by using tospovirus serogroup IV antiserum This is the first report of tospovirus in pepper in Southern Thailand To identify the species of tospovirus infecting pepper in the area, further biological and molecular characterization is needed Key Words: Capsicum annuum L, disease incidence, pepper, tospovirus Abbreviations: CaCV - Capsicum chlorosis virus, DAC-ELISA - direct-antigen coating enzyme-linked immunosorbent assay, GBNV - Groundnut bud necrosis virus, MYSV - Melon yellow spot virus, PBS - phosphate buffer saline, rpm - round per minute, TNRV - Tomato necrotic ringspot virus, WSMoV - Watermelon silver mottle virus

The Occurrence and Disease Incidence of Tospovirus Infecting Pepper (Capsicum annuum L.) in Southern Thailand

Viruses in plants have to accomplish two movement stages: cell-to-cell transfer from infected cells to neighboring healthy cells and long-distance transport from source to sink via the vascular system to establish systemic infection. Plants also activate defense mechanisms to combat viral invasion. Recent advances in three main aspects of virus interaction with the host plant are focal in this review: first, the viral distribution in host plants including the essential components required for viral movement; second, indications that the molecular defense mechanism known as RNA silencing plays an important role in controlling those viral distributions and is counteracted by virus-encoded suppressor proteins; and third, accumulated current knowledge on how viral resistance by RNA silencing relates to developing disease-free tissues during the infection period. Although one potential control of viral diseases in crops is to use virus-tolerant cultivars, a knowledge of viral distributions and the interactions between RNA silencing and virus-encoded counter-defenses is valuable. Key Words: plant defense, RNA silencing, silencing suppressor, siRNA, viral distribution, viral movement Abbreviations: CMV – Cucumber mosaic virus, DCL – Dicer-Like Protein, DGI – dark green islands, dsRNA – double- stranded RNA, HC-Pro – helper component proteinase, MPs – movement proteins, PD – plasmodesmata, PTGS – post- transcriptional gene silencing, RDR – RNA-dependent RNA polymerase, RISC – RNA-induced silencing complex, RNA – ribonucleic acid, SEL – size exclusion limit, siRNA – small interfering RNA, ssRNA – single-stranded RNA, TMV – Tobacco mosaic virus, TSWV – Tomato spotted wilt virus, TYLCV – Tomato yellow leaf curl virus, vRNP – viral ribonucleoprotein, YTs – yellow green tissues

Sunpapao Anurag

Papers

The Occurrence and Disease Incidence of Tospovirus Infecting Pepper (Capsicum annuum L.) in Southern Thailand

Virus-Induced Symptoms in Plants: A Review of Interactions Between Viral Trafficking and RNA Silencing