Northeastern Division: Detection of Peronospora variabilis in quinoa seeds
A. L. TESTEN (1), J. B. Ochoa (2), G. Plata R. (3), P. A. Backman (1). (1) Pennsylvania State University, University Park, PA, U.S.A.; (2) INIAP Ecuador, Quito, Ecuador; (3) PROINPA Foundation, Cochabamba, Bolivia
Quinoa (<i>Chenopodium quinoa</i>) is the most recent Andean crop to have global impact, but research on management of quinoa diseases is insufficient. Quinoa downy mildew, caused by <i>Peronospora variabilis</i> (formerly <i>Peronospora farinosa</i> f. sp. <i>chenopodii</i>), is the key disease of quinoa and can lead to severe yield losses. <i>P. variabilis</i> oospores can be seedborne and previous seed detection methods have relied on visual detection and seedling assays. However, these methods are time-consuming, prohibiting the screening of large numbers of seed. In this research, molecular methods were developed to detect <i>P. variabilis</i> in quinoa seeds. Thirty-three seed lots of domestic and imported quinoa, along with seed of <i>Chenopodium pallidicaule</i> and <i>Chenopodium album</i>, were analyzed using two PCR based detection methods. By using a sequencing-based detection method, <i>P. variabilis</i> was detected in 32 of 33 seed lots. A method that employed PCR with <i>P. variabilis</i> specific primers detected the pathogen in 31 of 33 seed lots. <i>P. variabilis</i> was never detected in <i>C. pallidicaule</i> or <i>C. album</i> seed lots. Seedborne oospores of <i>P. variabilis</i> likely contribute to downy mildew epidemics in Andean countries and have allowed the pathogen to spread to countries beyond South America. This research allows for rapid, high throughput detection of <i>P. variabilis</i> in quinoa seeds, which is the first step toward creating certified <i>P. variabilis</i>-free quinoa seed.
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