Time filter

Source Type

Adam Arsovski A.,London Research and Development Center | Yu K.,Greenhouse and Processing Crops Research Center
Molecular Plant Pathology | Year: 2016

Rsv1, a single dominant resistance locus in soybean, confers extreme resistance to the majority of Soybean mosaic virus (SMV) strains, but is susceptible to the G7 strain. In Rsv1-genotype soybean, G7 infection provokes a lethal systemic hypersensitive response (LSHR), a delayed host defence response. The Rsv1-mediated LSHR signalling pathway remains largely unknown. In this study, we employed a genome-wide investigation to gain an insight into the molecular interplay between SMV G7 and Rsv1-genotype soybean. Small RNA (sRNA), degradome and transcriptome sequencing analyses were used to identify differentially expressed genes (DEGs) and microRNAs (DEMs) in response to G7 infection. A number of DEGs, DEMs and microRNA targets, and the interaction network of DEMs and their target mRNAs responsive to G7 infection, were identified. Knock-down of one of the identified DEGs, the eukaryotic translation initiation factor 5A (eIF5A), diminished the LSHR and enhanced viral accumulation, suggesting the essential role of eIF5A in the G7-induced, Rsv1-mediated LSHR signalling pathway. This work provides an in-depth genome-wide analysis of high-throughput sequencing data, and identifies multiple genes and microRNA signatures that are associated with the Rsv1-mediated LSHR. © 2016 BSPP AND JOHN WILEY & SONS LTD.

Cerkauskas R.F.,Agriculture and Agri Food Canada | Ferguson G.,Greenhouse and Processing Crops Research Center | Macnair C.,Agriculture and Agri Food Canada
Canadian Journal of Plant Pathology | Year: 2015

Phytophthora blight (Phytophthora capsici) affecting greenhouse vegetable production in Canada is reported for the first time. Aspects of the epidemiology and management of P. capsici in relation to greenhouse and field vegetable production in Ontario are discussed. Identification of the pathogen was based on cultural, morphological and molecular approaches, the latter using primer set PC1/2. The pathogen caused 10% plant population losses in a greenhouse pepper operation in Leamington, ON in 2006-2007, and 5%, 5% and 10% losses in commercial greenhouse tomato operations at sites in 2007, 2008 and 2011, respectively, with 1000 greenhouse tomato plants affected in 2012. Phytophthora blight occurred in 2006 in Haldimand-Norfolk and Essex counties on field cucumber and pepper, respectively, and in Essex county in 2007 on field pepper, squash and tomato. The disease was not observed on field pepper, tomato or cucumber plants in fungicide efficacy trials near Harrow, ON in 2005-2006 or near St. Williams, ON in 2007 where the disease had occurred previously. Symptom development was most rapid on greenhouse cucumber and least rapid on greenhouse tomato. Virkon® disinfectant at 0.25%, 0.5%, 1% and 2% commercially formulated product was 100% effective in preventing zoospore germination of P. capsici while Chemprocide™ disinfectant was not fully effective at 0.04%, 0.4% and 4%, and Virucidal Extra® was intermediate in efficacy. The fungicides fluazinam, mandipropamid, cyazofamid and fluopicolide were effective in controlling P. capsici on greenhouse tomato, cucumber, and pepper plants for at least a 14-day period. Metalaxyl was less effective, possibly due to partial resistance in the fungus to this chemical. © 2015 © 2015 The contribution of Raymond F. Cerkauskas and Craig MacNair is authored as part of their employment by Agriculture and Agri-Food Canada (AAFC), and Gillian Ferguson as part of her employment by the Ontario Ministry of Agriculture, and copyright is asserted in the contribution by Her Majesty the Queen in Right of Canada.

Cerkauskas R.F.,Agriculture and Agri Food Canada | Ferguson G.,Greenhouse and Processing Crops Research Center
Canadian Journal of Plant Pathology | Year: 2014

Cucumber powdery mildew (Podosphaera xanthii) causes significant annual yield and quality losses in greenhouse production in Canada. Management of the disease was evaluated in various research trials conducted at Harrow, ON from 1999-2007 and at two commercial greenhouse operations in Leamington, ON in 2005-2006. Products evaluated included biological control agents, new classes of fungicides, and materials derived from natural products as well as several traditional fungicides with multi-site modes of action. Best control in the research greenhouse was obtained with applications of Nova, Quintec, strobilurin derivatives (Quadris, Flint, Sovran), Procure, Pristine, JMS Stylet-Oil ®, V-10118, Prev-AM, copper soap, Actigard and sulphur. Disease control was also obtained with Milstop, two fermented milk by-products (Lactosan, Yo-K-San) + surfactant formulations (Agral 90), and Agral 90 only. Applications of K2HPO4 + Agral 90, CaCl2 + Agral 90, and Siliforce were significantly better than the water check while fumed silica was not effective. Among biological control products, Sporodex (Pseudozyma flocculosa) was effective in control of P. xanthii while Serenade (Bacillus subtilis) was not. Actinovate (Streptomyces lydicus) provided control also. Under commercial greenhouse conditions, Milstop, and Lactosan + Agral 90 when applied weekly suppressed powdery mildew development at least equal to that of Nova. Resistance in P. xanthii to high rates of Nova and Pristine was detected in 3 of 17 and 2 of 8 commercial greenhouse cucumber operations, respectively, near Leamington. None of the locations had resistance to both fungicides at commercial rates of application, although one site showed consistently greater resistance of P. xanthii to both fungicides. © 2014 The contribution of Raymond F. Cerkauska.

Hao X.,Agriculture and Agri Food Canada | Wen G.,Agriculture and Agri Food Canada | Papadopoulos A.P.,Agriculture and Agri Food Canada | Khosla S.,Greenhouse and Processing Crops Research Center
HortTechnology | Year: 2010

A high-wire system, in which the plant is trained into a single stem, is gaining popularity in year-round greenhouse cucumber (Cucumis sativus) production, especially with supplemental lighting, as it allows for uniform foliar and light distribution and higher yield and quality. However, this system requires much higher plant densities than the conventional umbrella system, resulting in increased crop start-up costs. A technique for raising twin-head transplants and a twin-head "V" high-wire cucumber system were developed to address this issue. The twin-head transplants were raised by topping the seedlings after the appearance of the fourth true leaf and then two strong lateral shoots were allowed to develop and be trained into a "V" system after planting. The twin-head system achieved similar plant growth and fruit yield as the conventional single-head system on two long English seedless cucumber cultivars (Bodega and Myrthos) and two breeding lines (2005A and 24-119) tested over 2 years. The twin-head system also improved the fruit grades in 'Bodega' by increasing the percentage of fruit in medium size while reducing the percentage of fruit in small size. Because the twin-head system achieved the same fruit yield as the conventional single-head system while using only half the number of transplants, we can conclude that the twin-head "V" high-wire system is a more cost-effective high-wire system for year-round greenhouse cucumber production.

Cerkauskas R.F.,Agriculture and Agri Food Canada | Ferguson G.,Greenhouse and Processing Crops Research Center | Banik M.,Agriculture and Agri Food Canada
Canadian Journal of Plant Pathology | Year: 2011

Leveillula taurica was observed on field pepper at various sites in south-western Ontario in 2005-2007. The field isolates collected from these sites were similar to a greenhouse isolate based on morphological observations. Host range of greenhouse and field isolates was similar, with minor sporulation on potato, carrot and several weeds. The greenhouse pepper cultivar Samanta was the most susceptible to L. taurica while Triple 4, Duplo and Bosanova were the least susceptible to infection. Best control of pepper powdery mildew in the greenhouse was obtained with applications of myclobutanil, triflumizole, pyraclostrobin+boscalid, quinoxyfen, strobilurin derivatives (azoxystrobin, trifloxystrobin, kresoxim-methyl), copper soap, JMS Stylet-Oil ®, Valent-10118, acibenzolar-S-methyl and sulphur. Disease reduction was also obtained with applications of potassium bicarbonate, citrus oil+borax, Bacillus subtilis and a fermented milk byproduct+surfactant. K 2HPO 4+surfactant was effective in reducing disease whereas CaCl 2+surfactant, fumed silica and Sporothrix flocculosa were not effective. In field plots, best disease control was achieved with applications of myclobutanil and the fermented milk byproduct+surfactant in 2006 whereas in 2007, citrus oil+borax and potassium bicarbonate were most effective. There were no significant differences in pepper yield among the treatments in field plots. In vitro survival studies showed that the fungus was able to survive in infected pepper leaves after exposure to temperatures of 10°C for 2 months. © 2011 The Canadian Phytopathological Society.

Discover hidden collaborations