Diagnosis of <I>Candidatus</I> Liberibacter solanacearum Associated with Imported Seed Potatoes

Abstract

Zebra chip disease in potatoes is caused by the bacterium Candidatus Liberibacter solanacearum, poses a serious threat to potato production in Thailand. Although the disease has not yet been reported in the country, outbreaks have occurred in seed potato-exporting countries. Therefore, interception and preventive measures are essential to prevent the introduction of this pathogen and its potential damage on the domestic potato industry. In this study, a total of 134 imported seed potato samples from six countries — Australia, Canada, the Netherlands, New Zealand, Scotland, and the United States — were examined during 2021–2023. Diagnosis was conducted using accurate and rapid molecular techniques (nested-PCR) in combined with visual inspection for zebra chip symptoms on seed tubers. In addition, field surveys were conducted in potato-growing areas of several provinces in Thailand, including Chiang Rai, Chiang Mai, Tak, Phayao, Sakon Nakhon, and Nakhon Phanom. The results revealed no detection of either Ca. L. solanacearum or zebra chip symptoms in imported seed potatoes samples or in field surveys. These findings provide an important reference for establishing import regulations for seed potatoes, and contribute to the prevention and control the potential introduction and spread of this destructive pathogen in Thailand.