|Duressa, Dechassa - Former ARS Employee|
|Koike, Steven - University Of California - Cooperative Extension Service|
|Maruthachalam, Karunakaran - University Of California|
|Subbarao, Krishna - University Of California|
Submitted to: Acta Phytopathologica Sinica
Publication Type: Abstract Only
Publication Acceptance Date: 2/26/2013
Publication Date: 8/25/2013
Citation: Duressa, D., Rauscher, G.M., Koike, S.T., Mou, B., Hayes, R.J., Maruthachalam, K., Subbarao, K.V., Klosterman, S.J. 2013. Detection and quantification of Verticillium dahliae in spinach seed. Acta Phytopathologica Sinica. 43 (supplement):245.
Technical Abstract: Verticillium dahliae is a soilborne fungus that causes Verticillium wilt on multiple crops in central coastal California. Although spinach crops grown in this region for fresh and processing commercial production do not display Verticillium wilt symptoms, spinach seeds produced in the United States and Europe are commonly infected with V. dahliae, and may contribute to Verticillium wilt epidemics on crops grown in rotation with spinach. A sensitive, rapid, and accurate method for quantification of V. dahliae in spinach seed may help identify highly infected lots and curtail their planting, and thereby minimize the spread of exotic strains via spinach seed. A quantitative real-time polymerase chain reaction (qPCR) assay was employed for detection and quantification of V. dahliae in spinach germplasm and commercial spinach seed lots. The assay used V. dahliae-specific primer pair (VertBt-F and VertBt-R) and an analytical mill for grinding the tough spinach seed for DNA extraction. The assay enabled quantification of V. dahliae in spinach seed, with a sensitivity limit of ˜1 infected seed per 100 (1.3% infection in a seed lot). Quantification was reproducible between replicate samples of a seed lot among different real-time PCR thermocyclers. A pathogen DNA content corresponding to a quantification cycle value of =31 corresponded with a percent seed infection of =1.3% when tested on commercial seed lots. The assay is useful in qualitatively assessing seed lots for V. dahliae infection levels, and the results of the assay can be helpful to guide decisions on whether to apply seed treatments.