Detection of Candidatus Phytoplasma trifolii in dry chili plants with big bud symptoms

Chili crop in the north-central Mexico is damaged by infection caused by Candidatus Phytoplasma trifolii. Disease symptoms include chlorosis, leaf deformation, dwarfism and floral overdevelopment (big bud) with pistil and anther necrosis. The distribution of big buds on the plant is irregular. This suggests that the pathogen or its effectors move irregularly within the plant. Therefore, the objective of this work was to determine the presence of Candidatus Phytoplasma trifolii in different organs of chili plants with big bud symptoms. Diseased Mirasol type chili plants were collected from a commercial field in Zacatecas, Mexico, and their roots, stems, leaves, fruits and big buds were analyzed by universal and nested PCR for the presence of the phytoplasma. The pathogen was detected in five of eight plants tested, in at least one organ of each plant; however, its distribution within plants was irregular. The percentage of detection was 33.3, 62.5, 70, 80, and 100 % in roots, leaves, stems, fruits, and large buds, respectively. In fruits of chili plants symptomatic to big buds, the phytoplasma was detected in the peduncle, placenta, and seeds.