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Maize Genomics and Genetics 2012, Vol.3, No.3, 13
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protein-coding genes) expressed in the endosperm to
be imprinted, with 68 of them showing maternal
preferential expression and 111 paternal preferential
expressions. Zhang et al (2011) has identified two
PEGs
VIM5
and
Yuc10
in maize.
6 Conclusion and our views
Genetic imprinting is observed only in the triploid
endosperm of the angiosperms in the plant kingdom
and around thirteen imprinted genes have been reported
in maize. Hundreds of imprinted genes are being
added to the list through deep sequencing technologies,
but the functional role is yet to be elucidated. DNA
methylation and histone modifications are the two
important process involved in exertion and mainte-
nance of imprinting. Genetic imprinting is found to
have major role in many key developmental processes
and genome dosage is one of the factors contributing
to the imprinting. Genome dosage has reported to
have direct implication on the seed size in maize.
Though we can speculate that the role of imprinting in
the maintenance of the genome dosage imbalance in
the cross-pollinated plants, its role in self-pollinated
plants is yet to be discerned. To date, the scientific
community is still debating on its role in evolution and
significance in the process of crop improvement.
Advanced technologies like genome-wide approaches
may contribute in helping the researchers to unravel
the potential mechanism of genetic imprinting and its
possible benefits to crop improvement.
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