Wheat streak mosaic virus (WSMV) causes sporadic epidemics in Montana, which can threaten profitability of the state’s small grains production. One challenge for WSMV management in Montana is that ...most commercially available wheat and barley cultivars are susceptible to WSMV or their performance under WSMV pressure is unknown. In a 3-year field study from 2017 to 2019 winter wheat, spring wheat, and barley cultivars were evaluated for their susceptibility to WSMV and yield performance under WSMV pressure. Plants were mechanically inoculated, and WSMV incidence was assessed using double antibody sandwich ELISA. There was effective resistance to WSMV in breeding line CO12D922, which had consistently low WSMV incidence, highlighting promising efforts in the development of WSMV-resistant winter wheat cultivars. Moderate WSMV incidence and minor yield losses were observed from WSMV infection of commercial winter wheat ‘Brawl CL Plus’ and Montana State University breeding line MTV1681. Spring wheat cultivars in this study had high WSMV incidence of up to 100% in ‘Duclair,’ ‘Egan,’ and ‘McNeal.’ High WSMV incidence was associated with severe yield losses as high as 85% for Duclair and ‘WB9879CLP’ in 2019, demonstrating a high degree of susceptibility to WSMV inoculation. Barley cultivars had considerably lower WSMV incidence compared with spring and winter wheat. Grain yield response to WSMV inoculation was variable between barley cultivars. The study provided an experimental basis for cultivar recommendations for high WSMV pressure environments and identified breeding lines and cultivars with potential resistance traits of interest to breeding programs that aim to develop WSMV-resistant cultivars.
Plants infected with pathogens often attract the pathogens’ vectors, but it is not clear if this is advantageous to the vectors. We therefore quantified the direct and indirect (through the host ...plant) effects of a pathogen on its vector. A positive direct effect of the plant‐pathogenic Tomato spotted wilt virus on its thrips vector (Frankliniella occidentalis) was found, but the main effect was indirect; juvenile survival and developmental rate of thrips was lower on pepper plants that were damaged by virus‐free thrips than on unattacked plants, but such negative effects were absent on plants that were damaged and inoculated by infected thrips or were mechanically inoculated with the virus. Hence, potential vectors benefit from attacking plants with virus because virus‐infected plants are of higher quality for the vector's offspring. We propose that plant pathogens in general have evolved mechanisms to overcome plant defences against their vectors, thus promoting pathogen spread.
Flexuous (potexvirus-like) and rod-shaped (tobamovirus-like) particles observed in leaf-dip preparations by transmission electron microscopy RT-qPCR analyses using the ToBRFV-specific primer sets ...CaTa28 and CSP1325 (International Seed Federation, 2020) gave strong positive results with Cq values of 8.4 and 10.8, respectively. After removal of the plants, cleaning of the infrastructure and steam disinfection of the soil, an initial surface analysis using 245 cotton swabs showed high virus titre in samples collected on the fruit packing machines, scissor lifts and overhead heaters. ...an additional cleaning was performed, followed by disinfection with commercial benzoic acid (MENNO Florades) before a second surface analysis. ...the 2022 production will switch entirely to hydroponics in order to reduce the risk of the outbreak restarting from infected plant debris in the soil.
Tomato leaf curl New Delhi virus (ToLCNDV) is a severe threat for cucurbit production worldwide. Resistance has been reported in several crops, but at present, there are no described accessions with ...resistance to ToLCNDV in cucumber (
).
var.
accessions were mechanically inoculated with ToLCNDV and screened for resistance, by scoring symptom severity, tissue printing, and PCR (conventional and quantitative). Severe symptoms and high load of viral DNA were found in plants of a nuclear collection of Spanish landraces and in accessions of
from different geographical origins. Three Indian accessions (CGN23089, CGN23423, and CGN23633) were highly resistant to the mechanical inoculation, as well as all plants of their progenies obtained by selfing. To study the inheritance of the resistance to ToLCNDV, plants of the CGN23089 accession were crossed with the susceptible accession BGV011742, and F
hybrids were used to construct segregating populations (F
and backcrosses), which were mechanically inoculated and evaluated for symptom development and viral load by qPCR. The analysis of the genetic control fit with a recessive monogenic inheritance model, and after genotyping with SNPs distributed along the
genome, a QTL associated with ToLCNDV resistance was identified in chromosome 2 of cucumber.
Considering the availability of serological and molecular biological methods, the bioassay has been paled into insignificance, although it is the only experimental method that can be used to ...demonstrate the infectivity of a virus. We compared goodness-of-fit and predictability power of five models for the quantification of tomato brown rugose fruit virus (ToBRFV) based on local lesion assays: the Kleczkowski model, Furumoto and Mickey models I and II, the Gokhale and Bald model (growth curve model), and the modified Poisson model. For this purpose, mechanical inoculations onto
L. cv. Xanthi nc and
L. with defined virus concentrations were first performed with half-leaf randomization in a Latin square design. Subsequently, models were implemented using Python software and fitted to the number of local lesions. All models could fit to the data for quantifying ToBRFV based on local lesions, among which the modified Poisson model had the best prediction of virus concentration in spike samples based on local lesions, although data of individual indicator plants showed variations. More accurate modeling was obtained from the test plant
than from
cv. Xanthi nc. The position of the half-leaves on the test plants had no significant effect on the number of local lesions.
A method for mechanical inoculation of soybean and pea plants with soybean dwarf virus (SbDV) was developed. Soybean and pea seedlings were inoculated with SbDV RNA transcript via pricks made with ...fine stainless steel wire. After 2–3 weeks, more than 50% of inoculated plants were systemically infected with SbDV. Further analysis using this method to inoculate plants with a mutated SbDV revealed that the readthrough domain of SbDV is not essential for viral long-distance movement in host plants.
In 2021, yellowing disease of tomatoes caused by tomato chlorosis virus (ToCV, a crinivirus) was found in two production areas in Kyoto Prefecture, Japan. The disease is emerging as a serious problem ...for field and greenhouse growers. The virus is known to be transmitted by whiteflies (Bemisia spp. and Trialurodes vaporariorum) and has been assumed to not be mechanically transmissible. For developing management methods for diseases caused by whitefly-transmitted viruses, a mechanical inoculation method is desirable. Here we thus developed a method for mechanical inoculation using a toothbrush that had been dipped in an extract of leaves ground in 4 volumes of 100 mM potassium phosphate buffer (pH 7.0) containing 0.1% (v/v) 2-mercaptoethanol. After 17 days, characteristic symptoms appeared on tomato plants, and ToCV was confirmed in leaf tissue using a one-step reverse transcription-polymerase chain reaction. Transmission efficiency using the method was 81.0%. This finding is the first report of sap transmission for ToCV.
Yellow leaf curl disease of tomato caused by tomato yellow leaf curl virus (TYLCV: a begomovirus) causes severe damage. In general, the virus is transmitted by the whitefly Bemisia tabaci (Gennadius) ...(Hemiptera: Aleyrodidae) and has been assumed not to be mechanically transmissible. Because mechanical inoculation has great practical uses, e.g., screening for resistant tomato varieties, here we developed a method using a toothbrush to inoculate plants of susceptible tomato cv. House-Momotaro with TYLCV. The inoculum solution (buffer ingredients, molarity, pH, dilution of viruliferous leaf sap) were optimized to achieve the highest infection rates. After 35 days, characteristic symptoms appeared on the inoculated tomato plants, and infection of TYLCV was confirmed in non-inoculated upper leaves by polymerase chain reaction. The highest infection rate (73.3%) was obtained using 100 mM potassium phosphate buffer (pH 7.0) containing 0.1% (v/v) 2-mercaptoethanol at a 1000-fold volume of macerated infected leaf tissue. TYLCV was transmitted mechanically at 73.3 % infectivity in proportion of plants inoculated.
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