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THE METHYLATION-SENSITIVE AMPLIFICATION POLYMORPHISM IN JUVENILE
AND ADULT PHASE CRAB APPLE (MALUS MICROMALUS)
ISHFAQ A. HAFIZ, NADEEM A. ABBASI, AZHAR HUSSAIN, ABDUL WAHEED* AND
S.M. SAQLAN NAQVI**
Abstract: Cytosine methylation has been implicated in regulation of gene expression,
genomic imprinting and chromatin remodeling, resulting both in temporal
and developmental regulation. Keeping in view its importance in development,
this study was carried out to explore the methylation-sensitive amplification
polymorphism (MSAP) associated with the transition from juvenile to
adult phase in Malus micromalus. For detection of methylation
in the genome of M. micromalus, a pair of restriction endo-nucleases
HpaII-MspI was used. Genomic DNA from juvenile and adult phase leaves
of the seedling tree, that was undigested (control) and digested with
each enzyme HpaII and MspI, was amplified using selected primers. In
total 72 bands were amplified with the help of 12 primers. Post amplification
digestion of these bands with MspI or HpaII revealed 35 bands containing
CCGG. Ten bands absent in amplified profiles from J phase digested DNA,
appeared in amplified products from digested A phase DNA, indicating
de novo methylation at CCGG. Five bands disappeared in A phase
while these bands were present in J phase DNA amplified profiles, revealing
presence of restriction site without methylation in A phase. These results
are suggestive that demethylation may have occurred in A phase. Seventeen
motifs of DNA methylation at CCGG remaining similar in both phases seem
to have been maintained from basal to crown part of the seedling tree.
Amplified profiles produced from restricted DNA from both phases showed
polymorphism due to differential methylation.
Department of Horticulture, University of Arid Agriculture, Rawalpindi,
Pakistan.
* Department of Botany, University of Arid Agriculture Rawalpindi,
Pakistan.
** Department of Biochemistry, University of Arid Agriculture Rawalpindi,
Pakistan.
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