Genomic
sequence derived simple sequence repeats markers
A
case study with Medicago spp.
Viswanathan Mahalakshmi
International Crops Research
Institute for the Semi-Arid Tropics (ICRISAT)
Patancheru, 502 324
Andhra Pradesh, India
Tel: 91 40 3296161
Fax: 91 40 3241329
E-mail: v.mahalakshmi@cgiar.org
P. Aparna
International Crops Research
Institute for the Semi-Arid Tropics (ICRISAT)
Patancheru, 502 324
Andhra Pradesh, India
Tel: 91 40 3296161
Fax: 91 40 3241329
E-mail: aparna_pr@yahoo.com
S. Ramadevi
International Crops Research
Institute for the Semi-Arid Tropics (ICRISAT)
Patancheru, 502 324
Andhra Pradesh, India
Tel: 91 40 3296161
Fax: 91 40 3241329
E-mail: rama@gvkbio.com
Rodomiro Ortiz * #
International Institute of
Tropical Agriculture (IITA)
Oyo Road, PMB 5320, Ibadan, Oyo State, Nigeria
Tel: 234 2 2412626
E-mail: r.ortiz@cgiar.org
* Corresponding author
Keywords: bioinformatics,
genetic markers, repeat motifs, simple sequence repeats, SSR.
Present address: # IITA, c/o Lambourn and Co., Carolyn House,
26 Dingwall Road, Croydon, CR9 3EE, United Kingdom.
Simple sequence repeats
(SSR) or micro-satellites are becoming standard DNA markers for plant
genome analysis and are being used as markers in marker assisted breeding.
De novo generation of micro-satellite markers through laboratory-based
screening of SSR-enriched genomic libraries is highly time consuming
and expensive. An alternative is to screen the public databases of related
model species where abundant sequence data is already available. All
the genomic sequences of Medicago from the public domain database
were searched and analysed of di, tri, and tetra nucleotide repeats.
Of the total of about 156,000 sequences which were searched, 7325 sequences
were found to contain repeat motif and may yield SSR which will yield
product sizes of around 200 bp. Of these the most abundantly found repeats
were the tri-nucleotide (5210) group. Except for a very small proportion
(436), these link to the gene annotation database at TIGR (http://www.tigr.org). To facilitate further exploration
of this resource, a dynamic database with options to search and link
to other resources is available at (http://www.icrisat.org/text/research/grep/homepage/genomics/medssrs1.asp)
and on CDs from V.Mahalakshmi@cgiar.org.
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