Detection and molecular characterization of a 16SrII group phytoplasma associated with ‘witches broom’ disease in cactus (Opuntia sp.)

Abstract

Objective/Background. Phytoplasmas are obligate plant pathogens that exhibit strong specificity with their hosts. Typical symptoms induced by these pathogens include stunted growth and general decline, among others, and they rarely lead to plant death. The aim of this research was to determine the phytoplasma associated with the ‘witch’s broom’ symptom in an ornamental cactus (Opuntia sp.). Materials and Methods. Four samples of ornamental cacti exhibiting ‘witch’s broom’ symptoms were collected from four commercial nurseries in Texcoco, State of Mexico. DNA extraction was performed on the samples, followed by PCR using specific primers for phytoplasmas (P1/P7 and R16F2n/R16R2). Phytoplasma determination was carried out through PCR, in vitro RFLP, sequencing, and phylogenetic analysis. Results. According to the various analyses conducted, it was determined that the phytoplasma associated with the ornamental cactus belongs to the subgroup 16SrII-C. Conclusion. Based on the obtained results, it is established that a phytoplasma from the 16SrII-C subgroup is associated with the ‘witch’s broom’ symptom in the ornamental cactus (Opuntia sp.).