تعيين روابط ژنتيكي در اينبردلاين هاي ذرت با استفاده از نشانگر ريزماهواره

Utilization of Microsatellite Markers for Determining Genetic Relationships in Maize Inbred Lines

Simple sequence repeats (SSRs) are a relatively new class of DNA markers consisting of short runs of tandemly repeated sequence motifs, 2 to 6 base pair, evenly distributed throughout eukaryotic genomes. Among maize (Zea mays L.) breeders, there is a heightened awareness of the necessity for maintaining both genetic diversity for crop improvement as well as improving the quality of genetic resource management. In this study, genetic similarities and relationships among 46 maize inbred lines were estimated based on the allelic variability detected. DNA was extracted from young leaf tissues according to the procedure of Dellaporta et al. (1983). One SSR primer was chosen from each corn chromosome and totally ten primers were assayed using the sample of 46 inbreds. The amplified products were separated using 6% polyacrylamide gel with 7 M urea under denaturing conditions and visualized by staining with silver nitrate. Gels were then scored based on either the presence or absence of bands. Polymorphism information content (PIC) for each SSR marker was determined with 1-sf12 where f, is the frequency of the ith allele. The number of alleles per locus ranged from 3 to 14. The 69 alleles identified served as raw data for estimating genetic similarities among these lines using the NTSYS program. Ten primers revealed 73% polymorphism rate. The 46 inbreds were clustered based on the matrix of genetic similarity jaccard using the complete clustering algorithm. Cluster analysis placed the inbred lines in three clusters with elite inbreds B73 and MO17 from two opposite heterotic groups as well as endosperm types helping to interpret them. The results showed that the microsatellite marker has a high degree of polymorphism that allows efficient identification of maize genotypes which could be used in determining heterotic groups as well as in estimation of heterosis in hybrid production.