Development of specific secA-based diagnostics for the 16SrXI and 16SrXIV phytoplasmas of the Gramineae

Abstract

Phytoplasmas are responsible for a range of diseases in the Gramineae in Sub-Saharan Africa and Asia including sugarcane grassy shoot (white leaf), rice yellow dwarf, napier grass stunt and Bermuda grass white leaf. In previous work, we have designed universal nested PCR primers based on the secA gene for amplification of DNA from phytoplasmas in most 16Sr groups. However, these primers did not appear to work well on phytoplasmas in the 16SrXI and XIV groups. In this work, we have designed specific sets of primers based on the secA gene that can be used in a nested PCR assay to amplify either the napier grass stunt phytoplasma or the sugarcane phytoplasma or the rice/bermudagrass phytoplasmas. These assays and secA sequences have also been used to redefine the taxonomic relationships between these phytoplasmas.