beet curly top virus
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2022 ◽  
Vol 12 ◽  
Author(s):  
Rajtilak Majumdar ◽  
Paul J. Galewski ◽  
Imad Eujayl ◽  
Rakesh Minocha ◽  
Eric Vincill ◽  
...  

Beet curly top virus (BCTV) mediated yield loss in sugar beets is a major problem worldwide. The circular single-stranded DNA virus is transmitted by the beet leafhopper. Genetic sources of BCTV resistance in sugar beet are limited and commercial cultivars rely on chemical treatments versus durable genetic resistance. Phenotypic selection and double haploid production have resulted in sugar beet germplasm (KDH13; 13 and KDH4-9; 4) that are highly resistant to BCTV. The molecular mechanism of resistance to the virus is unknown, especially the role of small non-coding RNAs (sncRNAs) during early plant–viral interaction. Using the resistant lines along with a susceptible line (KDH19-17; 19), we demonstrate the role of sugar beet microRNAs (miRNAs) in BCTV resistance during early infection stages when symptoms are not yet visible. The differentially expressed miRNAs altered the expression of their corresponding target genes such as pyruvate dehydrogenase (EL10Ac1g02046), carboxylesterase (EL10Ac1g01087), serine/threonine protein phosphatase (EL10Ac1g01374), and leucine-rich repeats (LRR) receptor-like (EL10Ac7g17778), that were highly expressed in the resistant lines versus susceptible lines. Pathway enrichment analysis of the miRNA target genes showed an enrichment of genes involved in glycolysis/gluconeogenesis, galactose metabolism, starch, and sucrose metabolism to name a few. Carbohydrate analysis revealed altered glucose, galactose, fructose, and sucrose concentrations in the infected leaves of resistant versus susceptible lines. We also demonstrate differential regulation of BCTV derived sncRNAs in the resistant versus susceptible lines that target sugar beet genes such as LRR (EL10Ac1g01206), 7-deoxyloganetic acid glucosyltransferase (EL10Ac5g12605), and transmembrane emp24 domain containing (EL10Ac6g14074) and altered their expression. In response to viral infection, we found that plant derived miRNAs targeted BCTV capsid protein/replication related genes and showed differences in expression among resistant and susceptible lines. The data presented here demonstrate the contribution of miRNA mediated regulation of metabolic pathways and cross-kingdom RNA interference (RNAi) in sugar beet BCTV resistance.


Plant Disease ◽  
2021 ◽  
Author(s):  
Hannah M. Rivedal ◽  
Cassandra Funke ◽  
Kenneth Frost

Hemp (Cannabis sativa) acreage in Oregon has increased by approximately 240 times in the last five years and a greater number of hemp diseases have been observed. This special report documents pathogens, particularly those causing virus and virus-like diseases, that have been detected from field and greenhouse-grown hemp crops in Oregon, based on plant samples submitted to the Hermiston Agricultural Research and Extension Center Plant Clinic of Oregon State University in 2019 and 2020. Symptoms and signs were used to evaluate disease types and determine diagnostic assays used on each submission. Plants with signs or symptoms of fungal or oomycete infection were cultured to isolate pathogenic organisms and plants with symptoms suspected to be caused by virus infection were assayed for the presence of Beet curly top virus (BCTV), viroids, and phytoplasmas using polymerase chain reaction (PCR), or reverse transcription (RT)-PCR. Diseases with fungal or oomycete, and virus causes accounted for 26.5%, and 42.9% of submissions, respectively; co-infection of viral and fungal or oomycete pathogens were detected from 6.1% of submissions between 2019 and 2020. BCTV, a curtovirus, and hop latent viroid (HLVd) were the predominant pathogens detected from field and indoor grown hemp. Worland-like strains of BCTV represented 93% of all curtovirus detections. Eighty percent of HLVd detections occurred from plants that originated from indoor growing facilities. Based on BCTV vector, beet leafhopper, prevalence, field-grown hemp in western production regions may be affected by curly top and increasing hemp acreage in the landscape may have potential implications on other crops affected by curtoviruses. Virus and virus-like diseases could be a limiting factor for hemp production in some regions of the United States.


Plant Disease ◽  
2021 ◽  
Author(s):  
Kylie D. Swisher Grimm ◽  
James Crosslin ◽  
Rodney Cooper ◽  
Kenneth Frost ◽  
Lindsey J. du Toit ◽  
...  

Two fields of coriander (Coriandrum sativum L.) seed crops of proprietary cultivars were observed in the Columbia Basin of Washington in July 2020 with 40 and 90% incidence of plants showing stunting and leaf and stem discoloration, sometimes with mild leaf curl. Foliar discoloration ranged from yellow to red and purple. Sweep-netting along the field edges collected one beet leafhopper (Circulifer tenellus Baker; BLH), the known vector of Beet curly top virus (BCTV), Beet leafhopper transmitted virescence agent (BLTVA) phytoplasma, and Spiroplasma citri, all of which affect Solanaceae and Apiaceae crops in Washington (Crosslin et al. 2006; Johnson and Martin 1998; Lee et al. 2006). Nucleic acids extracted from leaves and petioles of 12 coriander plants (8 from Field 1 and 4 from Field 2) using the Dellaporta method, and from the BLH using the CTAB method (Crosslin et al. 2006) were subjected to PCR assays to detect the BLH-transmitted pathogens which cause yellow and purple discoloration in potato (Solanum tuberosum L.) and carrot (Daucus carota subsp. sativus (Hoffm.) Arc.) in this region. BLTVA was targeted using a species-specific nested PCR assay with primers P1 and P7, followed by primers FU5 and BLTVA-int (Crosslin et al. 2006); S. citri was targeted using primers P89-F and P89-R (Yokomi et al. 2008); and BCTV was targeted using curtovirus primers BCTV2-F and BCTV2-R (Strausbaugh et al. 2008). BLTVA and S. citri were not detected in the plants, but curtovirus was detected in 10 of the 12 plants. All three pathogens were detected from the single BLH. A 519 bp region of the curtovirus capsid protein gene was amplified from seven plants (5 from Field 1 and 2 from Field 2) and the BLH, and cloned into TOP10 Escherichia coli cells using the pCR-2.1 TOPO vector (Invitrogen, Carlsbad, CA). Three clones were sequenced from each sample. For each of six plant samples and the BLH, the three clones were identical and consensus sequences were generated (GenBank Accessions MW234419 to MW234425). For the seventh plant, two clones were identical in sequence (MW234426) and the third contained 12 single nucleotide polymorphisms (MW234427). All sequences were subjected to an NCBI BLASTn analysis and showed 98.3 to 99.8% identity with BCTV sequences. Additional PCR assays with primers BMCTV-C1 2213F and BMCTV-C1 2609R (Strausbaugh et al. 2008), targeting the C1 gene of the Worland strain of BCTV, detected BCTV-Worland-like strains in all plants and the BLH, confirming that BCTV was present and indicating that the strain-specific primer pair was more sensitive than the universal curtovirus primers. Yield losses in the two fields were approximately 60%, with reduced seed size but not seed quality. BCTV infections in coriander crops have been observed in the Columbia Basin in 2002, 2005, 2008, and 2013, with yield losses ranging from 10 to 100% per field, though official reports were not made following the diagnoses (Crosslin, du Toit, and Frost, unpublished data). BCTV has caused millions of dollars of losses in the U.S. in crops such as sugar beet (Beta vulgaris subsp. vulgaris L.), tomato (S. lycopersicum L.), and pepper (S. annuum L.) (Johnson and Martin 1998). This is the first publication of BCTV affecting seed production of the specialty crop C. sativum. The observation of 90% incidence of symptoms in one field suggests that resistant cultivars and/or insect pest management practices are needed to prevent significant impacts of BCTV on coriander seed production in this semi-arid region.


BMC Genomics ◽  
2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Carl Michael Deom ◽  
Magdy S. Alabady ◽  
Li Yang

Abstract Background The Beet curly top virus C4 oncoprotein is a pathogenic determinant capable of inducing extensive developmental abnormalities. No studies to date have investigated how the transcriptional profiles differ between plants expressing or not expressing the C4 oncoprotein. Results We investigated early transcriptional changes in Arabidopsis associated with expression of the Beet curly top virus C4 protein that represent initial events in pathogenesis via a comparative transcriptional analysis of mRNAs and small RNAs. We identified 48 and 94 differentially expressed genes at 6- and 12-h post-induction versus control plants. These early time points were selected to focus on direct regulatory effects of C4 expression. Since previous evidence suggested that the C4 protein regulated the brassinosteroid (BR)-signaling pathway, differentially expressed genes could be divided into two groups: those responsive to alterations in the BR-signaling pathway and those uniquely responsive to C4. Early transcriptional changes that disrupted hormone homeostasis, 18 and 19 differentially expressed genes at both 6- and 12-hpi, respectively, were responsive to C4-induced regulation of the BR-signaling pathway. Other C4-induced differentially expressed genes appeared independent of the BR-signaling pathway at 12-hpi, including changes that could alter cell development (4 genes), cell wall homeostasis (5 genes), redox homeostasis (11 genes) and lipid transport (4 genes). Minimal effects were observed on expression of small RNAs. Conclusion This work identifies initial events in genetic regulation induced by a geminivirus C4 oncoprotein. We provide evidence suggesting the C4 protein regulates multiple regulatory pathways and provides valuable insights into the role of the C4 protein in regulating initial events in pathogenesis.


2021 ◽  
pp. 224-243
Author(s):  
Shou-Hua Wang

Abstract A systemic disease is defined as one where a pathogen infects a plant systemically or affects the plant as a whole. There are certain types of diseases in hemp and cannabis crops that are viewed more as systemic rather than localized, based on both infection behaviour and symptom development. This chapter deals with diagnosing systemic diseases of cannabis crops, including vascular wilt caused by Fusarium Species, witches' broom caused by phytoplasmas, leaf curl caused by Beet curly top virus, plant stunting caused by Hop latent viroid, leaf chlorosis caused by Lettuce chlorosis virus and other viral diseases. Field diagnosis through symptom observation, problem classification, sampling, laboratory diagnosis by visual and microscopic examinations, isolation and colony observation, identification (PCR/DNA-based, morphological, ELISA), pathogenicity test, and key diagnostic evidence are described. Systemic disease management measures are discussed, focusing on inoculum prevention and vector control, monitoring mother plant health, managing insect vectors, controlling weeds, use of resistant varieties, avoiding contact transmission and reducing abiotic stresses.


Plant Disease ◽  
2020 ◽  
Author(s):  
Jiahuai Hu ◽  
Robert Masson ◽  
Laura Dickey

Industrial hemp (Cannabis sativa) is an emerging crop in Arizona, with many uses, including fiber, cosmetic products, and health food. In 2020, severe curly top disease outbreaks were observed in several hemp fields in Yuma and Graham Counties, Arizona, where disease incidence and severity were considerably high, up to 100% crop loss occurring in some fields. A wide range of symptoms have been observed at different infection stages and plant growth stages at the time of infection. Early stage symptoms manifest as light green-to-yellowing of new growth, similar to sulfur or micronutrient deficiency, usually combined with older leaves with dark green “blotchy” mosaic mottling overlaying light green chlorosis. Mosaic mottling of older leaves continues into mid-growth stage, and is coupled with more severe yellowing and witch’s broom (stunted leaves and shortened internode length of stem) of apical meristematic tissue. Curling and twisting of new leaves has also been observed. Symptoms often appear to be isolated to individual branches, with other branches showing no visual symptoms, often outgrowing and covering affected branches until harvest. Late stage symptoms include severe leaf curling with or without twisting, continued stunting, and necrosis of yellow leaves, resulting in significant yield reduction. Severely affected plants dwarfed by the virus experienced high mortality rates later into the season, most likely attributed to reduced ability to overcome abiotic stress conditions. These symptoms indicated the likelihood of curly top caused by Beet curly top virus (BCTV), which has been recently reported in Colorado (Giladi et al., 2020). Shoots were collected from thirty-eight symptomatic and nine asymptomatic hemp plants from July to August, 2020. Leaves were also collected as positive control from four chili pepper plants with or without curly top symptoms in Cochise County. Genomic DNA was extracted using DNeasy Plant Pro Kit (Qiagen Inc., Valencia, CA) according to the manufacturer’s instructions. BCTV-specific primers BCTV1 and BCTV2 were used to detect BCTV following a method by Rondon (Rondon et al., 2016). A 500 bp DNA fragment, indicative of BCTV, was amplified from all symptomatic hemp and chili pepper samples, but not from asymptomatic samples. Sequence analysis of this 500 bp DNA fragment revealed 98.99 % identity with GenBank accession MK803280, which is Beet curly top virus isolate from hemp identified in Western Colorado (Giladi et al., 2020). The full-length genomes of BCTV isolates from hemp and chili peppers were generated with additional primers 328F/945R (620bp), 455F/ 945R (490bp), OutR/ 2213F (1,190bp), 2609R/ 1278R (1,340bp), BCTV2/ 2609R (1,890bp) (Rondon et al., 2016, Strausbaugh et al., 2008). The complete nucleotide sequence (MW182244) from hemp was 2,929 bp and had 99.35% sequence identity with GenBank accession KX867055, which was a Worland strain of Beet curly top virus isolated from an Idaho sugar beet plant (Strausbaugh et al., 2017). Our hemp BCTV genome sequences shared 96.08% identity with the hemp strain of BCTV from Colorado (MK803280) and 99.50% identity with the BCTV isolate (MW188519) from chili pepper identified in this study. BCTV was reported on outdoor hemp in Western Colorado, in 2020 (Giladi et al., 2020). This is the first report of BCTV in Arizona causing curly top of industrial hemp in the field. In Arizona, BCTV is widespread on many agronomic crops including chili peppers and spread primarily by the phloem-feeding beet leafhoppers: Circulifer tenellus (Hemiptera: Cicadellidae) (Bennett, 1967). Due to the wide distribution of beet leafhoppers and abundant range of host plants for the virus, BCTV may become one of the most yield-limiting factors affecting the emerging industrial hemp production systems in Arizona.


Plant Disease ◽  
2020 ◽  
Vol 104 (3) ◽  
pp. 999-999 ◽  
Author(s):  
Y. Giladi ◽  
L. Hadad ◽  
N. Luria ◽  
W. Cranshaw ◽  
O. Lachman ◽  
...  

2020 ◽  
Vol 21 (1) ◽  
pp. 71-76
Author(s):  
Erik Lehnhoff ◽  
Rebecca Creamer

Curly top is an important widespread disease in semiarid regions that can be caused by several Curtovirus and Becurtovirus species. The strains of beet curly top virus (BCTV) have been some of the most widely reported to be associated with curly top. The viruses causing curly top are phloem limited and transmitted by the beet leafhopper (BLH), Circulifer tenellus Baker (Hemiptera: Cicadellidae). The BLH can also transmit other important pathogens such as phytoplasmas. Both the virus and insect vector have a broad host range of crops and weeds, including the winter annual weed London rocket (Sisymbrium irio L.). Prior prediction of disease would allow growers a window of opportunity to make informed management choices. A prediction model of BLH abundance was developed for southern New Mexico based on fall precipitation, which corresponds with London rocket emergence, and BLH sticky trap catch data for 2001 to 2018. Regression analyses showed positive associations between BLH numbers and October + November rainfall (P < 0.001) for two areas within southern New Mexico. A third area, where good weed management was used, had lower BLH numbers, and the relationship with precipitation was not significant (P = 0.190). Cumulative-season BLH abundance was correlated with BLH abundance in late April (r = 0.43) and late May (r = 0.56), indicating that early season knowledge of BLH abundance is useful for planning later season management. Although models based on October + November precipitation are good predictors of BLH abundance through June, they may not predict year-long BLH abundance because other environmental and biological factors contribute to subsequent BLH success and movement.


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