@article{blanco-meneses_ristaino_2011, title={Detection and Quantification of Peronospora tabacina Using a Real-Time Polymerase Chain Reaction Assay}, volume={95}, ISSN={["0191-2917"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-79959308900&partnerID=MN8TOARS}, DOI={10.1094/pdis-05-10-0333}, abstractNote={Peronospora tabacina is an obligate plant pathogen that causes blue mold of tobacco. The disease is difficult to diagnose before the appearance of symptoms and can be easily spread in nonsymptomatic tobacco seedlings. We developed a real-time polymerase chain reaction (PCR) assay for P. tabacina that uses 5' fluorogenic exonuclease (TaqMan) chemistry to detect and quantify pathogen DNA from diseased tissue. The primers and probe were designed using 5.8S ribosomal DNA sequences from 12 fungal and oomycete tobacco pathogens and 24 Peronospora spp. The PtabBM TaqMan assay was optimized and performed with a final concentration of 450 nM primers and 125 nM probe. The real-time TaqMan assay was assessed for sensitivity and the lower detection limit was 1 fg of DNA. The assay was specific for P. tabacina. None of the DNA from other tobacco pathogens, nonpathogens, or the host were amplified. The PtabBM TaqMan assay was useful for detection of P. tabacina in field samples, artificially inoculated leaves, roots, and systemically infected tobacco seedlings. The assay was used to quantify host resistance and it was possible to detect the pathogen 4 days postinoculation in both medium-resistant and susceptible tobacco cultivars. The real-time PCR assay for P. tabacina will be a valuable tool for the detection of the pathogen and of use to regulatory agencies interested in preventing the spread of blue mold.}, number={6}, journal={PLANT DISEASE}, author={Blanco-Meneses, Monica and Ristaino, Jean Beagle}, year={2011}, month={Jun}, pages={673–682} }
 @article{ristaino_johnson_blanco-meneses_liu_2007, title={Identification of the tobacco blue mold pathogen, Peronospora tabacina, by polymerase chain reaction}, volume={91}, ISSN={["1943-7692"]}, url={http://www.scopus.com/inward/record.url?eid=2-s2.0-34249085921&partnerID=MN8TOARS}, DOI={10.1094/PDIS-91-6-0685}, abstractNote={Tobacco blue mold, caused by the oomycete pathogen Peronospora tabacina, is a highly destructive pathogen of tobacco (Nicotiana tabacum) seed beds, transplants, and production fields in the United States. The pathogen also causes systemic infection in transplants. We used polymerase chain reaction (PCR) with the primers ITS4 and ITS5, sequencing, and restriction digestion to differentiate P. tabacina from other important tobacco pathogens, including Alternaria alternata, Cercospora nicotianae, Phytophthora glovera, P. parasitica, Pythium aphanidermatum, P. dissotocum, P. myriotylum, P. ultimum, Rhizoctonia solani, Sclerotinia sclerotiorum, Sclerotium rolfsii, Thielaviopsis basicola, and related Peronospora spp. A specific PCR primer, called PTAB, was developed and used with ITS4 to amplify a 764-bp region of DNA that was diagnostic for P. tabacina. The PTAB/ITS4 primers did not amplify host DNA or the other tobacco pathogens and were specific for P. tabacina on tobacco. DNA was detected to levels of 0.0125 ng. The PTAB primer was useful for detection of the pathogen in fresh, air-dried, and cured tobacco leaves. This primer will be useful for disease diagnosis, epidemiology, and regulatory work to reduce disease spread among fields.}, number={6}, journal={PLANT DISEASE}, author={Ristaino, Jean Beagle and Johnson, Andrea and Blanco-Meneses, Monica and Liu, Bo}, year={2007}, month={Jun}, pages={685–691} }