Phytoplasmas, the Fast Spreading Vector Borne Pathogens of Flower Crops: Indian Scenario

Floriculture trade in India is one of the most lucrative fields, earning valuable forex to the national exchequer. Exchange of planting material via different modes plays a major role in spreading of the pathogen. Floriculture being an international industry, the transmission of pests or pathogens through live plants, seeds, cuttings and flowers etc., is very high. In recent years, the occurrence of phytoplasmal diseases in flower crops is increasing due to extensive exchange amongst many groups. The prominent symptoms of phytoplasma infection are the flowers turning into leafy structures called phyllody and the formation of sterile green flowers called virescence. In floricultural crops, these two symptoms are of major disadvantages as the flowers are the main economic product. The phyllody symptoms are most often mistaken for novel plant type and are multiplied unwittingly. Phytoplasmas are switch between plant and animal kingdoms. Phytoplasma spread in the field through leaf hoppers by inhabiting in their gut, haemolymph, salivary glands etc. Among the ornamental plants and flower crops, various groups of phytoplasma have been reported from India. More than 40 per cent of the infections are reported from the members of the Asteraceae family with 16SrI-B group, ‘Candidatus Phytoplasma asteris’.