Polymorphism among thermotolerant and sensitive genotypes of wheat (Triticum aestivum L.) using DNA markers
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Date
2009
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Publisher
CCSHAU
Abstract
Wheat is one of the most important staple food crops and is
cultivated throughout the world. High-temperature stress is one of the major
constrains to wheat production world wide. This study was undertaken with the
objective to assess polymorphism among 10 thermosensitive and 10
thermotolerant genotypes of wheat. DNA extracted from young leaves of 20
wheat genotypes was amplified by using 20 ISSR and 25 RAPD primers. Out of
these primers, 11 ISSR and 18 RAPD primers were showing amplification and
were selected for present investigation. For ISSR and RAPD assays, data was
analyzed to calculate various parameters such as the number of total bands,
number of polymorphic bands, per cent polymorphism, bands per primer,
polymorphic bands per primer, similarity matrices and dendrogram. Both RAPD
and ISSR generated a moderate level of average percentage of polymorphism i.e.
60.3% and 48.4% respectively. The ISSR primers yielded average 8.64 bands per
primer while RAPD primers amplified average 7 bands per primer. The average
number of polymorphic bands was higher in case of RAPDs (4.22) as compared
to that in ISSRs (4.18). Overall size of PCR amplified products ranged between
220 bp and 3500 bp for ISSR primers and between 280 bp and 4000 bp for
RAPD primers. Based on ISSR similarity matrix data, the value of similarity
coefficient ranged from 0.69 to 0.94 with an average genetic similarity of 0.81.
RAPD similarity matrices between different genotypes ranged from 0.63 to 0.89
with average similarity coefficient of 0.78. Dendrograms generated using RAPD
and ISSR markers separated genotypes into two major clusters which were
further divided into sub clusters. However, dendrogram based on RAPD markers
was not in accord with dendrogram based on ISSR markers.ISSR-41 primers
amplified a ≈2800 bp band which was present in all the 10 thermotolerant
genotypes and absent in all thermosensitive genotypes except one (genotype S5).
The marker identified using ISSR-41 primer may probably be thermotolerance
specific and may have potential for use in marker assisted selection programs for
wheat production improvement.
Description
Keywords
Wheats, Genotypes, Genetics, DNA, Rapd, Polymorphism, Genomes, Planting, Genetic structures, Genetic polymorphism