Complete genome sequence of Lettuce Witches’-Broom phytoplasma isolate LWB: a 16SrIII-X subgroup with expanding relevance in South America

Abstract

Phytoplasmas are non-cultivable, cell wall-less bacteria associated with a wide range of plant diseases worldwide and are transmitted by phloem-feeding insect vectors (Lee et al. 2000; Bertaccini et al. 2022). Traditionally, their classification has relied on restriction fragment length polymorphism (RFLP) analysis of a ~ 1.2 kb fragment of the 16S rRNA gene (Lee et al. 1998), which led to the establishment of the 16Sr group system. To date, close to 40 distinct 16Sr groups have been described, providing a practical but limited framework to assess phytoplasma diversity (Bertaccini et al. 2022). Among them, the X-disease group (16SrIII group) stands out as one of the most diverse and geographically widespread groups, especially in the Americas, where members of this group have been detected in a wide range of hosts, including fruit crops, vegetables, ornamentals, and native trees (Galdeano et al. 2013; Montano et al. 2024).