Phytoplasma of the 16SrIII-J subgroup associated with cabbage stunt and spatial pattern analysis of the disease

Abstract

The aim of this study is the molecular characterization of a phytoplasma associated with cabbage stunt and spatial analyses of symptomatic plants in the field. Detection by nested PCR, sequencing of 16S rRNA gene and conventional and virtual RFLP, as well as phylogenetic analysis revealed that a 16SrIII-J phytoplasma was associated with cabbage plants that exhibited stunting, reduced size, malformation or failure to form head, reddening leaves, sprout proliferation and vessel necrosis. The spatial analyses demonstrated that the dispersion pattern of symptomatic plants was aggregated and the pathogen introduced from adjacent areas. Phytoplasmas of 16SrIII group were also detected in leafhoppers of the species Atanus nitidus collected from cabbage fields and adjacent areas, evidencing that these insects are possibly potential vectors of this fastidious bacteria found in cabbage plants. These findings confirmed that a subgroup 16SrIII-J phytoplasma is associated with cabbage stunt. In addition, the spatial analyses indicated that the disease emerges from primary foci located in external areas and progress toward the center of the fields. The discovery of the etiological agent of the cabbage stunt together with the type of dispersion of the disease represent a relevant contribution to improve the management strategies aiming harm reduction.