Molecular identification of a phytoplasma associated with Ajwain (Trachyspermum ammi) in India

Abstract

A new disease of Trachyspermum ammi, commonly known as Ajwain in India, was observed in Lucknow, India. The symptoms included small chlorotic leaves, highly proliferating shoots, witches' broom appearance, shortened internodes and an overall stunted growth. Poor flower heads and fruit setting caused considerable yield losses for farmers. In transmission electron microscopy, pleomorphic bodies were detected in the phloem cells of diseased plants but not in those of healthy plants. The disease etiology was investigated using direct and nested polymerase chain reaction with phytoplasma-specific primers, DNA sequencing, and phylogenetic analysis. Phylogenetic analysis indicated that this phytoplasma clustered in the 16SrVI group. A 1,249 bp sequence (FJ970035) of the 16S rRNA gene from the phytoplasma showed 99% homology with the 16S rRNA gene, (FJ427295) of Ca. Phytoplasma trifolii strain A6 belonging to the phytoplasma group VI (reported from Iran). This is the first report of phytoplasma infection affecting Ajwain (T. ammi).