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Critical aspects of biologically relevant seed health assays

Valerie Verdier: IRD, Cirad, Univ Montpellier, IPME

<div>There is no question on the importance of preventing the spread of plant pathogens across the globe. This is facilitated by the creation and implementation of phytosanitary regulations, and the continuous improvement of seed health testing protocols. Our experience in developing an assay for detection of <em>Xanthomonas oryzae</em> pvs. <em>oryzae</em> and <em>oryzicola</em> rice seed contamination has shown us that this is not an easy task. Critical aspects of seed health assays are not only limited to the technical specifications of the detection method, such as sensitivity, selectivity, ruggedness, and reliability. In diagnostic PCR, the inclusion of test controls (i.e. internal amplification control, process controls, no template controls, positive controls, and non-target controls) are necessary to validate any result. Also, the simplicity of an assay is important for it to be useful. Is the required equipment commonly available or too specialized? Are the extraction steps simple and easy to carry out? In the final stages before protocol dissemination to users, the protocol should be audited by a higher body, such as the International Seed Testing Association (ISTA), and the accreditation of a protocol for universal use would depend on stringent evaluation by ISTA. Developing protocols for seed health testing should be done with the prime intention to create a method for easy adoption by quarantine laboratories across the globe.</div>