Review article: Phytoplasma diseases affecting various plant species in India

Abstract

In India recent evidences showed that phytoplasma associated with plants including crops, fruits, trees, ornamental, sugarcane, grasses and weeds increasing at alarming rate. Phytoplasma cause diseases in several plant species and resulted in serious threat as a source of alternative natural host for the spread of phytoplasma pathogen to other economically important plants and thereby chances of causing severe losses. In earlier days very few phytoplasma diseases were identified in India merely on the basis of bright-field, fluorescence, electron microscope observations, tetracycline treatment and to a lesser extent by serological assays. Among these, microscopic methods do not attain pathogen identification, and all of them are not always sufficiently sensitive to detect phytoplasma infections in low-titer hosts. Today detection of phytoplasma based on molecular genetic methods including PCR assays are efficiently carried out in India and on that basis several plant species are reported to have phytoplasma infections. So far more than 37 plant species have been reported to be associated with phytoplasma infections from all over India. The “Candidatus Phytoplasma asteris”, “Candidatus Phytoplasma aurantifolia”, “Candidatus Phytoplasma trifolii” and “Candidatus Phytoplasma cynodontis” belong to 16SrI, 16SrII, 16SrVI and 16SrXIV group of phytoplasmas are the major groups associated with different species reported to be infected with phytoplasma throughout India. In this paper, we have discussed overall progress on phytoplasma disease on plant species in India in terms of taxonomy, symptomatology, economic significance, transmission and characterization.