Monitoring of Candidatus Liberibacter solanacearum in carrot seeds

Currently, in the Russian Federation there is an increase in the production of vegetable crops. Potatoes (Solanum tuberosum) and carrots (Daucus carota) are important crops for Russia, the yield of which has increased over the past few years. Candidatus Liberibacter solanacearum (Lso, Zebra chip disease) is a phytopathogen that poses a serious threat to the production of these crops in the world. According to the pest risk analysis, Lso was included in the Eurasian Economic Union (EAEU) Quarantine List in 2018. During the monitoring 30 different cultivars of carrot seeds of different Russian and foreign producers were tested as a scientific purpose and to control infection with the Lso. A preliminary germination of seeds was carried out under laboratory conditions in wet chambers in a thermostat. Carrot seedlings, seed coats and whole seeds of each sample were tested separately. Seven days after the emergence of seedlings, they were separated from the seed coat; seedlings, their seed coat and whole seeds were placed in PBS extraction buffer at a ratio of 1:10 and homogenized, after that DNA was extracted from each sample using the Proba-NK kit (Agrodiagnostica, Russia). The analysis of the extracted DNA samples was carried out by qPCR Fitoskrin reagent kit (Syntol, Russia) to detect the DNA of the Lso. As a result, Lso was detected in six samples: 'Touchon' whole seeds and seed coat, 'Chantenay Royal' whole seeds and seed coat, 'Nantaise amelioree' whole seeds and seed coat. All positive samples were of French origin. It should be noted that in seedlings grown from infected seeds, Lso has not been identified. Seeds of Russian origin were free from the Zebra chip disease. In case of the absence of pathogen transmission through seeds will be confirm in the future a new potential pathway for Ca. L. solanacearum is proposed. © 2021 International Society for Horticultural Science. All rights reserved.