engleski

Genetic diversity of Croatian wheat cultivars

Knowledge about genetic diversity pattern in existing wheat germplasm is essentially important for further sustainable genetic improvement and successfulness of breeding programs. Genetic diversity analysis can provide better understanding of plant breeding influence on crop genetic diversity and more efficient utilization, management and conservation of germplasm resources. Owing to their high level of polymorphisms, microsatellite markers (simple sequence repeats ; SSR) representing important tool for genetic diversity analysis and have been successfully applied for numerous assessments of genetic relationships in different plant species. Consequently, the objective of this study was to estimate genetic diversity of 98 Croatian wheat cultivars released since 1905 to 2008 year and 24 foreign wheat cultivars. Foreign cultivars were included in this research regarding to their pre-ancestral and ancestral role in Croatian cultivars, as well as important widely grown cultivars and as a control. A total of 122 cultivars were screened by 45 wheat microsatellite markers, 1 to 3 from each wheat chromosome. Within group of 122 cultivars a total of 413 polymorphic alleles were amplified. Within group of Croatian cultivars (n=98) were amplified 354 alleles, while within group of cultivars created on Agricultural Institute Osijek (n=74) were found 303 alleles. Allele number per locus (Na) was varied from 3 to 20 with an average of 9.18, 7.87 and 6.73 alleles within group of n=122, n=98 and n=74 cultivars, respectively. Average value of gene diversity (HE) and polymorphic information content (PIC) were ranged from HE=0.69 and PIC=0.65 (n=122) to HE=0.63 and PIC=0.58 (n=74). Allelic richness (Nar) as the measure of the number of alleles per locus independent of sample size showed decreasing trend from 8.78 within group of n=122 to 6.73 within group of n=74 cultivars. Overall observed gene diversity and polymorphic information content per marker were varied from HE=0.34 and PIC=0.32 (marker gwm493) to HE=0.86 and PIC=0.85 (marker wmc634). Genetic distances among pairs of cultivars based on proportion of shared alleles distance matrix (DPSAM) were ranged from 0.02 to 0.96 with higher average value among all (0.69), then among Croatian (0.66) and Agricultural Institute Osijek cultivars (0.63). The cultivars were grouped by cluster analysis using the unweighted pair- group method with arithmetic averages (UPGMA). At the constructed UPGMA tree was possible to successfully differentiate all investigated cultivars. However, no clear clustering of cultivars by breeding program or year of release was observed. Cultivars that belong to the same group generally share the concerned proportion of common pre-ancestral or ancestral genetic basis. Results of this research are providing better insight in genetic diversity of Croatian cultivars at DNA level. Estimated genetic distances (DPSAM) among cultivars can be helpful for more accurate parent assortment for hybridization and creation of new wheat breeding populations with respect to genetic diversity preservation. This research is one of the prerequisites for adoption of marker assisted selection (MAS) and molecular breeding in Agricultural Institute Osijek wheat breeding program as complement to the classical breeding methods.

genetic diversity ; wheat ; microsatellites ; UPGMA

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