d(GC) - Association of Biotechnology and Pharmacy

Current Trends in Biotechnology and Pharmacy
Vol. 6 (2) 173-182 April 2012, ISSN 0973-8916 (Print), 2230-7303 (Online)
the same ancestral gene. Future work regarding
the function and evolution of the avirulence genes
that correspond to the resistance genes at the
Pik locus will help reveal part of the history of
rice cultivar–blast fungus arms race. Although the
number of isolates analyzed in this research is
too small and their geographic origin is too
limited, our results demonstrate the potential of
the Vegetative Compatibility Group (VCG)
analysis to differentiate even closed related
isolates of P. grisea. Population structure
analyses of M. grisea using molecular markers
have contributed to the knowledge on
evolutionary dynamics. Studies on genetic
structure of M. grisea population using MGM
markers SSR based fingerprinting showed that
even though each isolate had a unique
fingerprint, they could be grouped into distinct
lineages Thus; P. grisea may represent a
reticulate species in which there may be periodic
vertical and horizontal gene transfer over time
(35). Addressing such hypotheses about the true
nature of genetic variability and population
structure with P. grisea in the future will likely
benefit from the use of marked field strains (36)
combined with following the dynamics of specific
pieces of DNA such as avirulence genes (37, 38)
within and between field populations. A better
understanding of these factors and the
mechanisms that control population dynamics
may reveal how we can most effectively manage
this important plant pathogen.
Conclusion
The present study with genome specific
microsatellite markers helped to understand the
population diversity precisely. The concomitant
grouping of the isolates collected on the
differential varieties with the predominant isolates
collected from the diverse agro climatic regions
of India, helped in precise prediction of virulence
genes spectra in the hotspot regions of India. The
recent progress in genomics and sequence
availability of rice and M. grisea can be extended
further to determine the spectra of AVR genes of
Madhan Mohan et al
180
major blast isolates which can in turn offer a
major clue in deployment of blast resistance
genes in rice improvement programmes. It is
anticipated that this study will lead to a better
understanding of the diversity and distribution of
blast pathogens both from rice and non-rice hosts
and to its potential application in rice breeding
programs aiming at development of durable
blast-resistant rice cultivars.
Acknowledgement
We thank the Project Director, DRR, for
providing facilities and the Department of
Biotechnology, Government of India, New Delhi
for financial support. The authors also thank Dr.
R. M. Sundaram for critical reading and
suggestions to improve the manuscript.
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