Silverleaf Nightshade (Solatium elaeagnifolium), a Reservoir Host for 'Candidates Liberibacter solanacearum', the Putative Causal Agent of Zebra Chip Disease of Potato

摘要

Zebra chip disease of potato is caused by the bacterial pathogen 'Candidate Liberibacter solanacearum' and is a growing concern for commercial potato production in several countries in North and Central America and New Zealand. 'Ca. L. solanacearum' is vectored by the potato psyllid Bac-tericera cockerelli, which transmits the pathogen to several cultivated and wild solanaceaous host plants. Silverleaf nightshade (SLN), Solatium elaeagnifolium, is a common weed in the Lower Rio Grande Valley of Texasand a host for both the potato psyllid and 'Ca. L. solanacearum'. SLN plants were successfully inoculated with 'Ca. L. solanacearum' under laboratory conditions. Retention studies demonstrated that 'Ca. L. solana-cearum'-infected SLN planted in the field in January 2013, concurrent with commercial potato planting, retained the pathogen under field conditions throughout the year despite extensive dieback during summer. Thepresence of 'Ca. L. solanacearum' was confirmed in leaves, roots, and stolons of SLN plants collected the following year using polymerase chain reaction. Acquisition assays using B. cockerelli adults also revealed that SLN retained the pathogen. Transmission studies determined that B. cockerelli can acquire 'Ca. L. solanacearum' within a 2-week acquisition access period on 'Ca. L. solanacearum'-infected SLN and subsequently transmit (he pathogen to potato. These results demonstrate that SLN plants can serve as a reservoir for 'Ca. L. solanacearum', providing a source of inoculum for B. cockerelli adults colonizing potato the next season. The presence of SLN plants all year round in the LRGV makes the weed an epidemiologically important host. These findings underscore the importance of eradicating or managing SLN plants growing in the vicinity of potato fields to prevent spread of 'Ca. L. solanacearum' and damage caused by zebra chip.