Seeds can be important vehicles for long-range virus transmission because of their international trade and the exchange of germplasm used in breeding programs. Besides, they can serve as a bridge for virus survival between growing seasons. Up to 231 diseases caused by viruses or viroids are reported to be transmitted by seeds (Sastry, 2013).
Official agencies have reference protocols for viruses detection in seeds, mainly based on ELISA. However, this technique requires to test a high number of seeds per batch as has lower sensitivity than other techniques and could lead to wrong results as virus concentration in seeds is lower than in other plant tissues (Zhang et al., 2011). Therefore, efforts are needed to improve sensitivity and specificity of virus detection techniques in seeds. Abiopep has developed a real-time PCR (RT-qPCR) assay based on the use of TaqMan probes for the detection of three cucurbit seed-transmitted viruses: cucumber green mottle mosaic virus (CGMMV), melon necrotic spot virus (MNSV) and squash mosaic virus (SqMV) (Torre et al., 2019). This technique has proven to be very specific and far more sensitive in seeds than ELISA.
The TaqMan technology is an effective method for the analysis of viruses in seeds, allowing to reduce the number of subsamples to be analyzed per batch, the materials and time, reducing significantly the costs of the assay.
Our RT-qPCR assays have proven to be highly suitable for analyses of seeds batches, and the possibility of their implementation into certification programs should be taken into consideration.
In Abiopep we have also a diagnostic set based on TaqMan probes for the detection of tomato leaf curl New Delhi virus, (ToLDNDV), a virus that affects both tomatoes and cucurbits and that recently has been proposed to be transmitted by seeds (Kil et al., 2020).
Kil, E. J., Bich Vo, T. T., Fadhila, C., Thi Ho, P., Lal, A., Troiano, E., Parrella, G. and Lee, S. (2020) «Seed transmission of tomato leaf curl new delhi virus from zucchini squash in italy», Plants, 9(5), pp. 5-11. doi: 10.3390/plants9050563.
Sastry, K. S. (2013) Seed-borne plant virus diseases, Seed-borne plant virus diseases. India: Springer India. doi: 10.1007/978-81-322-0813-6.
Torre, C., Agüero, J., Gómez-Aix, C. and Aranda, M. A. (2019) «Comparison of DAS-ELISA and qRT-PCR for the detection of cucurbit viruses in seeds», Annals of Applied Biology, 176(2). doi: 10.1111/aab.12543.
Zhang, Y., Zhao, W., Li, M., Chen, H., Zhu, S. and Fan, Z. (2011) «Real-time TaqMan RT-PCR for detection of maize chlorotic mottle virus in maize seeds», Journal of Virological Methods, 171(1), pp. 292-294. doi: 10.1016/j.jviromet.2010.11.002.