Identification of potential leafhoppers vectors of phytoplasmas (16SrIII group) associated with broccoli stunt disease in Brazil

Recently, disease in broccoli plants (Brassica oleracea var. italica) was associated with three distinct phytoplasmas in Brazil. The disease named broccoli stunt (BS) has caused significant economic losses in So Paulo State. Group 16SrIII phytoplasmas is the most common group that have been associated with BS. The BS disease is still poorly understood, and the lack of information about the vectors further impairs its management. In this study, leafhoppers belonging to 18 different species were collected from weeds thriving near broccoli fields that were affected by group 16SrIII phytoplasmas. Specific primers revealed the presence of group 16SrIII phytoplasmas in five leafhoppers: Empoasca spp., Agallia albidula Uhler, Agalliana sticticollis (StAyenl), Planicephalus flavicosta (StAyenl), and Atanus nitidus (Linnavuori). The identity of the phytoplasmas was confirmed through DNA sequencing analysis. The leafhoppers were infected by phytoplasmas of the 16SrIII group (proposed Candidatus Phytoplasma pruni species) and are phylogenetically related to the broccoli stunt phytoplasma (BSP) strains detected in the study area and, thus, are considered potential vectors of group 16SrIII phytoplasmas to broccoli plants.