Microsatellite marker development, mapping and applications in rice genetics and breeding

Area of Science:

• Genomics
• Molecular Biology
• Plant Genetics

Background:

• Microsatellites are tandemly repeated DNA sequences valuable as genetic markers.
• They are co-dominant, exhibit high allelic diversity, and are efficiently analyzed using polymerase chain reaction (PCR).
• Rice (Oryza sativa) possesses a significant number of microsatellites, crucial for genetic studies.

Purpose of the Study:

• To estimate the number and distribution of microsatellites in the rice genome.
• To assess the utility of microsatellite markers for various genetic applications in rice.
• To evaluate allelic diversity within cultivated rice and its wild relatives.

Main Methods:

• Screening of a rice genomic library to identify microsatellites.
• Development and mapping of 120 microsatellite markers across rice chromosomes.
• Identification of multiple copy primer sequences for independent chromosomal mapping.
• Analysis of allelic diversity in rice germplasm and wild relatives.

Main Results:

• An estimated 5,700–10,000 microsatellites were found in the rice genome.
• Microsatellite frequency decreases as repeat motif size increases.
• 120 microsatellite markers are well-distributed across all 12 rice chromosomes.
• Up to 25 alleles per locus were observed in cultivated rice, with reliable amplification in wild relatives.

Conclusions:

• Rice microsatellites (SSLPs) are abundant and well-distributed, providing valuable genetic markers.
• Current SSLP marker density is sufficient for genotype identification, gene/QTL analysis, and marker-assisted selection.
• Increasing numbers of mapped SSLP markers will enhance rice genome analysis, complementing existing RFLP and AFLP maps.