engleski

Changes of genetic diversity of maize inbred lines over four decades of hybrid breeding in the Bc Institute Zagreb revealed by SSR markers

Knowledge on genetic diversity among maize inbred lines is of great importance for the development of new inbred lines, their assignment to heterotic groups and the choice of testers for estimation of their hybrid performance. In determining genetic diversity, molecular markers can be helpful to a large degree. Microsatellites or simple sequence repeats (SSRs) offer advantages in high reproducibility, highly polymorphic nature, codominant inheritance and cost effectiveness over other marker types and have been extensively used for studying maize germplasm. The objective of this study was to investigate genetic diversity among Bc inbred lines used as parents in hybrids released during four decades (1970s, 1980s, 1990s and 2000s) using 28 SSR markers. All 28 SSR loci analysed were polymorphic in the set of 40 inbred lines with a total of 123 alleles detected. The number of alleles per SSR locus varied from 2 to 12, with an average of 4.2 for the whole set of lines. The number of alleles per SSR locus was 3.1, 3.4, 3.1 and 3.3 for lines from 1970s, 1980s, 1990s and 2000s, whereas the number of unique alleles for the same four decades was 4, 8, 0 and 5, respectively. Cluster analysis clearly separated all inbred lines from each other assigning them into clusters, which largely corresponded to their pedigree. Analysis of molecular variance revealed significant variation among decades as well as within decades. Percent of variation among decades contributed with 5.25 % in total variation. The FST values were 0.038, 0.041 and 0.001 between 1970s - 1980s, 1980s - 1990s and 1990s - 2000s, respectively. The largest FST value (0.108) was observed between 1980s and 2000s. Based on the results of the present study it can be concluded that genetic diversity among Bc inbred lines have been preserved during the four decades of hybrid breeding.

maize; breeding; SSR markers

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