"Candidatus Liberibacter solanacearum” infection of commercial tomatillo, Physalis ixocarpa Brot. (Solanales: Solanaceae) in Saltillo, Mexico

Authors: REYES CORRAL, CESAR - University Of Idaho; Cooper, William - Rodney; KARASEV, ALEXANDER - University Of Idaho; DELGADO-LUNA, CAROLINA - University Of Idaho; SANCHEZ-PENA, SERGIO - Universidad Autonoma Agraria Antonio Narro

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/2/2020
Publication Date: 1/16/2021
Citation: Reyes Corral, C., Cooper, W.R., Karasev, A.V., Delgado-Luna, C., Sanchez-Pena, S. 2021. "Candidatus Liberibacter solanacearum” infection of commercial tomatillo, Physalis ixocarpa Brot. (Solanales: Solanaceae) in Saltillo, Mexico. Plant Disease. 105(9):2560-2566. https://doi.org/10.1094/PDIS-10-20-2240-RE.
DOI: https://doi.org/10.1094/PDIS-10-20-2240-RE

Interpretive Summary: The potato psyllid is a pest of certain crops such as tomato and potato because it causes feeding damage called psyllid yellows and transmits a bacterial plant pathogen called Liberibacter solanacearum. The psyllids and Liberibacter both occur as distinct haplotypes that differ in biological traits. In 2019, plants within a potato psyllid-infested tomatillo plot near Saltillo, Mexico developed yellow leaves that is similar to both psyllid yellows and Liberibacter-infection. Researchers at the USDA-ARS in Wapato, WA, University of Idaho in Moscow, ID, and Universidad Autonoma Agraria Antonio Narro in Saltillo, Mexico determined that the foliar symptoms were caused by Liberibacter infection. Two haplotypes of potato psyllid were present in this plot, as were two different haplotypes of Liberibacter with the more damaging Liberibacter haplotype being most common. Results of molecular gut content analysis indicated that the Liberibacter-infected psyllids had arrived in the tomatillo plot from non-crop weeds, and that many of the psyllids had also previously fed upon potato, which is also susceptible to Liberibacter. This report provides important information that could aid in the development of landscape-level management of potato psyllid and Liberibacter in this region

Technical Abstract: The potato psyllid, Bactericera cockerelli (Šulc), (Hemiptera: Triozidae) is a pest of Solanaceous crops (Solanales) including potato (Solanum tuberosum L.) and tomato (S. lycopersicum L.). Feeding by high populations of nymphs causes psyllid yellows while adults are vectors of the plant pathogen, “Candidatus Liberibacter solanacearum” (Lso). Foliar symptoms that were consistent with either Lso-infection or psyllid yellows were observed in 2019 on tomatillo (Physalis ixocarpa Brot.; Solanaceae) grown within an experimental plot located near Saltillo, Mexico. This study had three primary objectives: 1) determine whether the observed foliar symptoms observed on tomatillo in 2019 were caused by Lso infection, 2) identify the haplotypes of Lso and potato psyllids present in the symptomatic plot, and 3) use gut content analysis to infer the plant sources of Lso-infected psyllids. Results confirmed that 71% of symptomatic plants and 71% of psyllids collected from the plants were infected with Lso. All infected plants and insects harbored the more virulent Lso haplotype B, but one psyllid was also co-infected with haplotype A. The potato psyllids were predominately of the central haplotype but one psyllid was identified as the western haplotype. Molecular gut content analysis of psyllids confirmed the movement of psyllids between non-crop habitats and tomatillo and indicated that Lso infection of psyllids was associated with increased plant diversity in their diet