Yellow Virus Research Articles

Integrated Pest Management in Action – Derogation for Use of the Neonicotinoid, Thiamethoxam in Sugar Beet in 2022

In his days as an employed person the author, working as an entomologist at Broom's Barn Sugar Beet Research Centre (1984–2006), his job was to assess the efficacy of the various neonicotinoid seed treatments that were coming through development from various companies. Subsequently the best of these, imidacloprid initially, followed a few years later by clothianidin and thiamethoxam, were registered for use in sugar beet, and they revolutionised pest control in that crop in the UK and across Europe. They displaced older chemicals such as the carbamate granules aldicarb, benfuracarb, carbofuran and furathiocarb; they displaced even older sprays such as the organochlorine, gamma HCH. They reduced the need for sprays to control aphids and other early season foliar pests such as leaf miners (Pegomya betae). Neonicotinoids effectively did him out of a job in the end, and his team was disbanded in 2006. However, he is not bitter. They helped the sugar beet industry take control of the myriad of pests that affected this vulnerable crop, and I felt it was a job well done. During the time that we were assessing these novel treatments, He tried very hard to persuade the sugar beet industry to consider an IPM approach to their use, partly because he was worried that the widespread use of the active ingredients as insurance treatments might result in selection for resistance in the targeted pests, especially the aphids. He even produced a model to support the approach, which would have allowed forecasts to be made as early as mid-February. Unfortunately, the powers that be at the time did not agree with him, and proceeded to introduce the seed treatments without consideration of need. Back then, the seed treatment process required the seed to be treated in December, or January at the latest, before any accurate forecast could be made, especially for control of aphids. The sugar beet crop back then was also grown on over 200,000 ha, double the hectarage of today. The decrease in area grown in the UK was due to changes in the EU sugar regime, that resulted in reduced prices, and greater competition from other crops, which gave and still give higher returns. How times change. Here we are 20 years later with better seed treatment technology in place that allows precisely what we were trying to do back in the 1990s, namely to make treated seed available only if the forecast for national virus yellows infection is above an acceptable threshold for use. He thinks it is ironical that it took an epidemic of virus yellows in 2020 to persuade the sugar beet industry that this could and should be done, and that neonicotinoids could be employed using IPM principles. Thankfully the government has agreed that this is an acceptable practice with a banned chemical when effective alternatives are not available.

The Virulence Factor p25 of Beet Necrotic Yellow Vein Virus Interacts With Multiple Aux/IAA Proteins From Beta vulgaris: Implications for Rhizomania Development.

Rhizomania caused by Beet necrotic yellow vein virus (BNYVV) is characterized by excessive lateral root (LR) formation. Auxin-mediated degradation of Aux/IAA transcriptional repressors stimulates gene regulatory networks leading to LR organogenesis and involves several Aux/IAA proteins acting at distinctive stages of LR development. Previously, we showed that BNYVV p25 virulence factor interacts with BvIAA28, a transcriptional repressor acting at early stages of LR initiation. The evidence suggested that p25 inhibits BvIAA28 nuclear localization, thus, de-repressing transcriptional network leading to LR initiation. However, it was not clear whether p25 interacts with other Aux/IAA proteins. Here, by adopting bioinformatics, in vitro and in vivo protein interaction approaches we show that p25 interacts also with BvIAA2 and BvIAA6. Moreover, we confirmed that the BNYVV infection is, indeed, accompanied by an elevated auxin level in the infected LRs. Nevertheless, expression levels of BvIAA2 and BvIAA6 remained unchanged upon BNYVV infection. Mutational analysis indicated that interaction of p25 with either BvIAA2 or BvIAA6 requires full-length proteins as even single amino acid residue substitutions abolished the interactions. Compared to p25-BvIAA28 interaction that leads to redistribution of BvIAA28 into cytoplasm, both BvIAA2 and BvIAA6 remained confined into the nucleus regardless of the presence of p25 suggesting their stabilization though p25 interaction. Overexpression of p25-interacting partners (BvIAA2, BvIAA6 and BvIAA28) in Nicotiana benthamiana induced an auxin-insensitive phenotype characterized by plant dwarfism and dramatically reduced LR development. Thus, our work reveals a distinct class of transcriptional repressors targeted by p25.

Synergy between an emerging monopartite begomovirus and a DNA-B component

In recent decades, a legion of monopartite begomoviruses transmitted by the whitefly Bemisia tabaci has emerged as serious threats to vegetable crops in Africa. Recent studies in Burkina Faso (West Africa) reported the predominance of pepper yellow vein Mali virus (PepYVMLV) and its frequent association with a previously unknown DNA-B component. To understand the role of this DNA-B component in the emergence of PepYVMLV, we assessed biological traits related to virulence, virus accumulation, location in the tissue and transmission. We demonstrate that the DNA-B component is not required for systemic movement and symptom development of PepYVMLV (non-strict association), but that its association produces more severe symptoms including growth arrest and plant death. The increased virulence is associated with a higher viral DNA accumulation in plant tissues, an increase in the number of contaminated nuclei of the phloem parenchyma and in the transmission rate by B. tabaci. Our results suggest that the association of a DNA-B component with the otherwise monopartite PepYVMLV is a key factor of its emergence.

Complete genome sequence of a distinct rosadnavirus isolated from Viola plants in China.

In 2019, plants of the genus Viola showing yellow mottling symptoms were collected in Liaoning, China. RNA sequencing and PCR both confirmed the presence of a reverse-transcribing DNA virus. The novel virus was named "viola yellow mottle virus" (VYMV), and its 9,872-bp genome was found to contain eight open reading frames. The polymerase (RT+RNase H) gene shared the most similarity (31.6% nucleotide and 41.6% amino acid sequence identity) with that of rose yellow vein virus (RYVV, NC_020999), which is currently the only member of the genus Rosadnavirus. Phylogenetic analysis indicated a close relationship between these viruses, suggesting that VYMV should be considered a new member of the genus Rosadnavirus.

A Method for Developing RNAi-Derived Resistance in Cowpea Against Geminiviruses.

In plants, RNA interference (RNAi) is triggered by double-stranded RNA (dsRNA). Accordingly, various RNA silencing technologies involving hpRNA, artificial microRNA (miRNA), and virus-induced gene silencing (VIGS) are used for controlling the expression of genes. Such manipulations help understanding gene functions and crop improvement biotechnology. A typical hpRNA construct is comprised of an intron splicable perfect inverted repeat of the target gene sequences under the control of a strong promoter. Geminiviruses, especially Mungbean Yellow Mosaic India Virus (MYMIV) cause devastating diseases in legume plants including cowpea, incurring severe crop loss. RNAi, involving hpRNA construct as transgene, is used to control these diseases at the early stages of geminivirus infection in the host, preventing symptom development and viral DNA accumulation. In this chapter, we describe a detailed protocol for the identification of geminivirus isolates from the filed grown cowpea plants, characterization of virus isolates under the laboratory conditions, design and construct RNAi vectors for effective suppression of viral target genes, and consequent development of transgenic cowpea using Agrobacterium-mediated transformation protocol. These transgenics are subsequently evaluated for resistance to MYMIV.

IDENTIFICATION OF CHILLI PLANTS PLANTING ORGANISMS IN TEKO VILLAGE, LOMBOK TIMUR

The main objective of this research is to identify and introduce various types of pests to farmers in Teko Village, Pringgebaya District. The method used is a survey method with a data collection approach in the form of direct observation on the expanse of chili plants and questionnaires as a guide for interviews with respondent farmers. Identification of pests on chili plants in Teko Village, namely: yellow virus, anthracnose fruit rot, fruit and leaf rot, whitefly, weeds (puzzle grass, spinach, and grass weeds).

Double Channel CNN Based Tomato Plant Leaf Disease Detection

Early blight, late blight, bacterial spot, leaf mold, spider mites, yellow leaf curl virus and Septoria leaf spot are the most common diseases of tomato plant which cause major loss to agriculture sector. Diagnosis and prognosis at early stage are prime challenges to save life of tomato crop. This research presents a state-of-the-art Double-Channel Convolution Neural Network (D-CNN) model for diagnoses of 8 different Classes of Tomato Plant Leaves. The proposed model integrates two separate Convolutional Neural Network (CNN) channels with similar number of Conv Layers and Parameters. One Channel processes the pre-processed Red-Green-Blue (RGB) data, whereas the second channel processes the region segmented data obtained by applying a Multi-Otsu Thresholding algorithm. We verified the proposed model on the Plant Village dataset which consists of more than 16,000 images of tomato plant leaves. The proposed model attains an overall accuracy of 94% after 200 iterations, comparatively 3.2% faster than Support Vector Machine (SVM), 2.2% faster than Probabilistic Neural Network (PNN), and 8% faster than Residual Neural Network (ResNet-50).

Preliminary Study of Viruses Infecting Strawberry (Fragaria spp.) in the Midsouthern United States

Strawberry is an important economic crop in the midsouthern United States; however, limited information is known about the viruses present in strawberry fields in Arkansas, Missouri, Oklahoma, and Texas. The purpose of this study was to determine the presence of particular viruses infecting strawberry crops in these four states. A total of 816 strawberry leaf samples were randomly collected from growers’ fields during the 2014 and 2016 growing seasons and tested by dot-immunobinding assay against antisera of eight available viruses: apple mosaic virus (ApMV), arabis mosaic virus (ArMV), raspberry bushy dwarf virus (RBDV), raspberry ringspot virus, strawberry mild yellow edge virus (SMYEV), tobacco necrosis virus, tomato black ring virus, and tomato ringspot virus (ToRSV). Of the eight viruses, ApMV, RBDV, and SMYEV had the highest infection rates in 2014, whereas ApMV, ArMV, ToRSV and SMYEV were the most prevalent viruses in 2016. Mixed infection of more than one virus was very common in samples collected from all four states. Our preliminary results showed that the distribution of virus relative frequencies differed significantly among seven sample locations across the states within a sample year, but we could not show statistical differences among the years based on our sample sizes. Mixed infections in strawberries were higher than expected in 2014 and lower than expected in 2016 based on viruses being independent infections. Overall, the occurrence of the viruses in strawberry crops could have important potential impacts for strawberry production in the midsouthern states.

Effects of plant growth regulators on transient expression of foreign gene in Nicotiana benthamiana L. leaves

BackgroundIn the last decades, replicating expression vectors based on plant geminivirus have been widely used for enhancing the efficiency of plant transient expression. By using the replicating expression vector derived from bean yellow dwarf virus and green fluorescent protein as a reporter, we investigated the effects of α-naphthalene acetic acid, gibberellins3, and 6-benzyladenine, as three common plant growth regulators, on the plant biomass and efficiency of transient expression during the process of transient expression in Nicotiana benthamiana L. leaves.ResultsWith the increase of the concentration of α-naphthalene acetic acid, gibberellins3, and 6-benzyladenine (from 0.1 to 1.6 mg/L), the fresh weight, dry weight, and leaf area of the seedlings increased first and then returned to the levels similar to the controls (without chemical treatment). The treatment with α-naphthalene acetic acid at 0.2 and 0.4 mg/L can enhance the level of transient expression of green fluorescent protein, which peaked at 0.4 mg/L α-naphthalene acetic acid and was increased about by 19%, compared to the controls. Gibberellins3 at 0.1–0.4 mg/L can enhance the level of transient expression of green fluorescent protein, which peaked at 0.2 mg/L gibberellins3 and was increased by 25%. However, the application of 6-benzyladenine led to decrease in the level of transient expression of green fluorescent protein.ConclusionsThe appropriate plant growth regulators at moderate concentration could be beneficial to the expression of foreign genes from the Agrobacterium-mediated transient expression system in plants. Thus, appropriate plant growth regulators could be considered as exogenous components that are applied for the production of recombinant protein by plant-based transient expression systems.

IOT BASED MOLECULAR MARKERS FOR DISEASE RESISTANCE STUDIES IN RICE - STRATEGY AND CHALLENGES

Rice production is constrained by diseases of fungal, bacterial and viral origin. The Internet of Things (IoT) – network of interconnected devices - is an application for disease related uses, collection of data, processing for testing and monitoring. This review article aims about how IoT can track and allows disease resistance studies in in Oryza species. Among them Xanthomonas oryzae, Magnaporthe grisea, RYMV (Rice yellow mottle virus), and brown planthopper causes the high yield losses. Disease resistance genes are identified and they are screened by the SSR (simple sequence repeats), RAPD (Randomly Amplified Polymorphic DNA) and RFLP (restriction fragment length polymorphisms) analysis.

Virus Yellows in sugar beet – possibilities to achieve virus resistance

Virus yellows in sugar beet is caused by different virus species. Monitoring has shown that Beet yellows virus (BYV), Beet mild yellowing virus (BMYV), Beet chlorosis virus (BChV) are common and widespread, while Beet mosaic virus (BtMV) is less prevalent. The green peach aphid (Myzus persicae) is considered the main vector of these viruses. Sugar beet varieties with resistance or tolerance traits are currently not available to practical growers, therefore it is imperative to support breeding efforts with improved strategies to achieve virus resistance. For this purpose, a field test was established in which yield differences between susceptible and tolerant varieties can be generated by a 3% inoculation with BMYV-carrying aphids. A greenhouse bioassay has also been developed to distinguish susceptible and tolerant genotypes following BYV infection. Both assays pave the way for future use of natural resources such as wild forms and other breeding material to screen for virus resistance. In addition, molecular biology approaches are used to identify plant susceptibility factors of the plant-virus interaction, which will be knocked out via modern precision breeding methods to generate recessive virus resistance. Consequently, genotypes with naturally occurring mutations in the appropriate factors can be used for crossbreeding processes into elite breeding material.

Association of tomato yellow leaf curl virus — Oman strain with the leaf curl and yellow mosaic symptoms on papaya and wild poinsettia in Oman

Begomoviruses (Geminiviridae) cause severe diseases in several crops, often causing significant losses due to reduced yield and quality. These viruses are easily transmitted by the whitefly (Bemisia tabaci) vector. Begomovirus-like symptoms were observed in wild poinsettia (Euphorbia cyathophora) and cultivated papaya (Carica papaya) plants in the Nizwa, Al-Dakhliya and Al-Batinah regions of Oman, where papaya is grown extensively. The aim of this study was to identify the suspected viral causal agent associated with yellow mosaic and leaf curl symptoms in the poinsettia and papaya plants. Symptomatic leaf samples were collected and subjected to DNA isolation followed by PCR amplification with begomovirus-coat protein specic primers. An amplicon of betasatellites was also amplified using betasatellite-specific primers. The amplicons were cloned and sequenced bi-directionally. The full-length begomoviral genome was determined to be 2766 and 2752 bp in length for the wild poinsettia and papaya isolates, respectively. The respective betasatellites were found to be 1354 and 1370 bp. Sequence analysis indicated that the papaya isolate, herein tomato yellow leaf curl virus (TYLCV)-Pap-Oman, shared 95.0% nucleotide identity with the wild poinsettia isolate, herein TYLCV-Poin-Oman, followed by 93.5% identity with TYLCV-Iran (GU076448). Phylogenetic analysis grouped TYLCV-Pap-Oman and TYLCV-Poin-Oman with TYLCV isolates previously reported from Iran, Saudi Arabia and Sudan, whereas the two betasatellites grouped them with TYLCB isolates previously reported from Oman. Based on the nucleotide sequence identity and phylogenetic tree analysis, the Begomovirus identified from papaya and wild poinsettia is considered an isolate of TYLCV from plant host species previously reported in the Arabian Peninsula.

A rapid, simple, and highly efficient method for VIGS and in vitro-inoculation of plant virus by INABS applied to crops that develop axillary buds and can survive from cuttings

BackgroundVirus-induced gene silencing (VIGS) is one of the most convenient and powerful methods of reverse genetics. In vitro-inoculation of plant virus is an important method for studying the interactions between viruses and plants. Agrobacterium-based infiltration has been widely adopted as a tool for VIGS and in vitro-inoculation of plant virus. Most agrobacterium-based infiltration methods applied to VIGS and virus inoculation have the characteristics of low transformation efficiencies, long plant growth time, large amounts of plant tissue, large test spaces, and complex preparation procedures. Therefore, a rapid, simple, economical, and highly efficient VIGS and virus inoculation method is in need. Previous studies have shown that the selection of suitable plant tissues and inoculation sites is the key to successful infection.ResultsIn this study, Tobacco rattle virus (TRV) mediated VIGS and Tomato yellow leaf curl virus (TYLCV) for virus inoculation were developed in tomato plants based on the agrobacterium tumefaciens-based infiltration by injection of the no-apical-bud stem section (INABS). The no-apical-bud stem section had a “Y- type” asymmetric structure and contained an axillary bud that was about 1–3 cm in length. This protocol provides high transformation (56.7%) and inoculation efficiency (68.3%), which generates VIGS transformants or diseased plants in a very short period (8 dpi). Moreover, it greatly reduces the required experimental space. This method will facilitate functional genomic studies and large-scale disease resistance screening.ConclusionsOverall, a rapid, simple, and highly efficient method for VIGS and virus inoculation by INABS was developed in tomato. It was reasonable to believe that it can be used as a reference for the other virus inoculation methods and for the application of VIGS to other crops (such as sweet potato, potato, cassava and tobacco) that develop axillary buds and can survive from cuttings.

Resistance status of mungbean (Vigna radiata (L.) Wilczek) advanced breeding materials against mungbean yellow mosaic India virus

Seventy-one advanced breeding lines of mungbean were screened under epiphytotic conditions in the field for resistance against yellow mosaic disease (YMD) using infector technique during Kharif of 2016–2019 at Main Research Farm of IIPR, Kanpur. The identity of the YMD causing virus species was confirmed by PCR using specific primers and found to be as Mungbean yellow mosaic India virus. The average disease rating score recorded for test genotypes ranged from 1–4 as against 7.75 (1–9 disease rating scale) of susceptible check (DGGV-2). Of the 71 test genotypes, 48 showed a good level of resistance (1–2 scale) and of them, genotypes- IPM1205-2, IPM14-49-5, IPM14-10, IPM411-9, IPM709-5-2, IPM14-12-3, IPM14-2, IPM526-11 and IPM 08-11 consistently showed a high level of resistance against YMD for 3 or 4 years with a disease rating score of 1. These genotypes can be exploited as donors for YMD resistance.

Effect of Fermentation Extracts against Bemisia tabaci on Chilli Pepper (Capsicum annuum)

This experiment was aimed to determine the effects of application of fermentation extracts on the development of pepper yellow leaf curl and whitefly on chilli. Experiment arranged in a completely randomized block design with four treatments (water as control, fermentations extracts named TSNGlu, BP4, and BP4Glu). The results showed symptoms in the form of curling of young leaves. The color of the leaves was relatively green. Yellow symptoms commonly found when severe were not found in the experiment. The symptoms of severe disease are marked in yellow at the top of the leaf and remain green at the bottom. The laboratory used 350 lux (underexposed light) so the symptoms become slight. ack of light intensity made plants etiolated and could not carry out photosynthesis properly. Each experiment consisted of 4 fermentation extract treatments. Each treatment. Overall, all treatments without fermentation and also AUDPC of the disease did not significantly affect the treatment of fermented extract both the incidence and severity of the low pepper yellow leaf curl virus. The treatment by spraying did not significantly affect the population of whitefly, except at 7 days after infestation, inversely proportional to the spraying treatment by means of discharge significantly affected from 14 days after infestation. The increase in plant height spray treatment did not have a significant effect and for spraying treatment with extraction of fermentation did not significantly affect the canopy area of ​​the plant canopy.

Complete genome sequence of a putative new and distinct caulimovirus from Metaplexis japonica (Thunb.) Makino in China

In 2019, a new disease characterized by yellow mottling on leaves was observed on Metaplexis japonica (Thunb.) Makino plants in Liaoning, China. Using RNA sequencing and PCR with overlapping primers, the complete nucleotide sequence of the circular double-stranded DNA genome of a new virus similar to caulimoviruses in diseased samples was determined. The genome comprised 7733 base pairs and was predicted to encode six proteins. It had the closest relationship to a caulimovirus, strawberry vein banding virus, based on sequence comparisons and phylogenetic analysis. Species-level sequence divergences from caulimoviruses were also observed in the conserved genomic regions. A complete episomal viral genome sequence in symptomatic M. japonica plants was identified, and the name "metaplexis yellow mottle-associated virus" is proposed for this virus.

Enhanced Age-Related Resistance to Tomato Yellow Leaf Curl Virus in Tomato Is Associated With Higher Basal Resistance.

Tomato yellow leaf curl virus (TYLCV) is one of the most notorious plant pathogens affecting the production of tomato worldwide. While the occurrence of age-related resistance (ARR) against TYLCV has been reported, the factors impacting its development remain unknown. We conducted a series of experiments with three tomato cultivars that vary in basal resistance to TYLCV to explore factors involved in the development of ARR. Our data indicate that ARR is more pronounced in tomato cultivars with higher basal resistance. Additionally, increased plant biomass in older plants does not contribute to ARR. Virus source plants with a younger age at initial inoculation facilitates virus acquisition by whiteflies. Finally, an analysis on plant hormones suggests that salicylic acid (SA) may play a major role in the development of ARR in tomato against TYLCV. These findings provide new insights into the developmental resistance in tomato against TYLCV as well as clues for the deployment of ARR in the management of diseases caused by TYLCV.

Fungal F8-Culture Filtrate Induces Tomato Resistance against Tomato Yellow Leaf Curl Thailand Virus

Tomato (Solanum lycopersicum) is an important economic crop worldwide. However, tomato production is jeopardized by the devastating tomato yellow leaf curl disease caused by whitefly-transmitted begomoviruses (WTBs). In this study, we evaluated the efficacy of our previously developed plant antiviral immunity inducer, fungal F8-culture filtrate, on tomato to combat tomato yellow leaf curl Thailand virus (TYLCTHV), the predominant WTB in Taiwan. Our results indicated that F8-culture filtrate treatment induced strong resistance, did not reduce the growth of tomato, and induced prominent resistance against TYLCTHV both in the greenhouse and in the field. Among TYLCTHV-inoculated Yu-Nu tomato grown in the greenhouse, a greater percentage of plants treated with F8-culture filtrate (43–100%) were healthy-looking compared to the H2O control (0–14%). We found that TYLCTHV cannot move systemically only on the F8-culture filtrate pretreated healthy-looking plants. Tracking the expression of phytohormone-mediated immune maker genes revealed that F8-culture filtrate mainly induced salicylic acid-mediated plant immunity. Furthermore, callose depositions and the expression of the pathogen-induced callose synthase gene, POWDERY MILDEW RESISTANT 4 were only strongly induced by TYLCTHV on tomato pretreated with F8-culture filtrate. This study provides an effective way to induce tomato resistance against TYLCTHV.

Asclepias yellow vein virus: a proposed new potyvirus in milkweed in the USA

Asclepias yellow vein virus: a proposed new potyvirus in milkweed in the USA

Simultaneous detection of virus infecting tobacco plant using multiplex-PCR in Klaten, Indonesia

Tobacco is one of the important plantation commodities in Indonesia. The multiple virus attack in the field causes crop damage to crop failure. Therefore, detection is needed quickly and accurately as a basis for control strategies. This study aimed to determine the viruses that attack tobacco plants in Klaten, Indonesia through simultaneous detection using multiplex-PCR. The study was conducted by observation in the field then detection in the Laboratory. Based on Multiplex-PCR detection results using primers of MJ 1/MJ 2, Krusty/Homer, and CMV P1/P2 showed that tobacco plants infected with several viruses from the genus Potyvirus, Begomovirus and Cucumovirus. Based on the results of the nucleotide sequencing blast, it was found that the tobacco isolate was positively infected by the Tomato yellow leaf curl Kanchanaburi virus (TYLCV), Cucumber mosaic virus (CMV) and Potato virus (PVY).