Phytoplasmas cause significant diseases in many plant species worldwide and emergence of new disease reports are being
reported regularly or new outbreaks of already known ones noticed in India. Phytoplasmas are phloem-limited plant pathogens
that are spread by sap-sucking insect vectors belonging to the families Cicadellidea (leafhoppers) and Fulgoridea (plant hoppers).
Phytoplasmas may over winter in infected vectors, as well as in perennial plants that serve as reservoirs for phytoplasmas.
Additionally, phytoplasmas can be spread by vegetative propagation through cuttings, storage tubers, rhizomes, or bulbs. The
distribution, incidence and severity of plant diseases are influenced by many interacting factors including host susceptibility,
cropping systems, management strategies and environmental conditions. In order to determine the phytoplasma diversity in
India, symptomatic and asymptomatic samples collected from different locations were used for total genomic DNA extraction
from healthy and infected plants. The samples were assayed for the presence of phytoplasma using polymerase chain reaction
(PCR) with universal phytoplasma primers for amplification of ribosomal 16S rDNA. Cloning, Sequencing and comparative
analysis of cloned PCR product has indicated several phytoplasma diseases have been associated with different phytoplasma
groups showing a wide genetic diversity. Comparative and phylogenetic analyses of 16S rRNA gene sequences indicated that
an overwhelming majority of the phytoplasmas under study belonged to the aster yellows phytoplasma group (16SrI) is the
predominant one which affects ornamentals, tree species, vegetables, fruits, sugarcane, and pulses in India. Nucleotide sequence
analysis of 16S rDNA have shown that the ?Candidatus Phytoplasma asteris?, ?Ca.P. aurantifolia?, ?Ca. P. ulmi?, 'Ca. P. trifolii', ?Ca. P.
phoenicium?, ?Ca. P. oryzae?, ?Ca. P. cynodontis?, belonging to 16SrI, 16SrII, 16SrV, 16SrVI, 16SrIX, 16SrXI and 16SrXIV groups are
the major Phytoplasma groups associated with different plant species in India. The findings have implications for relationships
between ecosystem distribution and the emergence of group 16SrI subgroup diversity
M Krishna Reddy received his M.Sc. (Ag) and Ph.D. in plant pathology (virology) from the Indian Agricultural Research Institute, New Delhi, India.
He then joined as a scientist at the Indian Institute of Horticultural Research (IIHR) of Indian Council of Agricultural Research (ICAR) at Bangalore,
India. He has published more than 65 papers in reputed journals of National and International and serving as an editorial board member of repute
Journals. As a plant virologist, he continues to work on viruses of fruits, vegetables, and ornamental crops which includes molecular characterization
and diagnosis of plant viruses, viroids, phytoplasma etc, control of viral diseases of horticultural crops; development of environmentally friendly and
sustainable IPM strategies for reducing the impact of destructive viral diseases; development of virus-resistant varieties/hybrids in vegetable crops;
capacity building in SAU?s and Agricultural departments and technology transfer. He currently serves as principal scientist and head of the Division of
Plant Pathology, IIHR, Bangalore and provides leadership to the research, extension, and training programs in plant pathology in horticultural crops.
He has 25 years of research experience on plant viruses, guided 12 research students and handled several National and International projects on
plant viruses. He is recipient of M. J. Narashimhan academic merit award (1991), Fellowship of the United Nations University (UNU), Tokyo, Japan
and ICAR award for Outstanding Interdisciplinary team research for the biennium 2007-2008, India.
Peer Reviewed Journals
Make the best use of Scientific Research and information from our 700 + peer reviewed, Open Access Journals