"Plant Epigenetics and Viral Pathogenesis"

The epigenetic modifications of plants are essential for their growth, development, survival and reproduction even during adverse conditions. The modifications at the DNA level, histone proteins, and non-coding RNA have made plants evolve against various abiotic and biotic stress factors. The change in the phenotype without any change in the genotype was first proposed by Conrad Hal Waddington in 1942, a leading evolutionary British biologist. Epigenetic trait has been defined as a “stably heritable phenotype resulting from changes in a chromosome without alterations in the DNA sequence” (Berger et al. 2009). They are the important source of phenotypic variation in natural populations. Unlike mammals in which epigenetic modification occurs during embryonic development, plants undergo epigenetic modification throughout their life cycle due to the presence of self-replicative stem cells called meristems. Plant viruses use the host machinery for their survival, whose multifunctional protein indeed acts as pathogenecity determinants though not all the factors involve in pathogenesis necessarily involves in essential process of life cycle. The replication, movement, encapsidation and transmission plays a crucial role in viral pathogenesis. The plants have evolved many mechanisms to defend itself from many pathogens, among which epigenetic modification enables them to combat many pathogens including plant viral infections. The availability of many new advanced technologies has led to a deeper understanding of the regulation of gene expression through epigenetic modifications. DNA methylation is well-studied and well understood phenomenon of epigenetic modifications which can be traced using techniques like sodium bisulfite sequencing (Frommer et al, 1994), chromatin immunoprecipitation and next generation sequencing. Thus, the understanding of epigenetic modification grows rapidly in search of novel crop improvement and crop protection strategies.