|Authors: ||A. Reolon-Costa, M.F. Grando, V.P. Cravero, E.A. Martin|
|Keywords: ||Cynara cardunculus [var. scolymus (L.) Fiori], allele frequencies, genetic variability|
The objective of the present study was to evaluate the impact of selection on allele frequencies and genetic variability during two cycles of phenotypic recurrent selection in artichokes using two types of DNA molecular markers.
Genomic DNA was extracted from young leaves collected randomly from 30 plants in each generation (C0, C1 and C2). DNA quantification was performed using 1% agarose gel electrophoresis.
Fifteen microsatellites (SSRs) and seven combinations of Sequence-Related Amplified Polymorphisms (SRAPs) were used.
The amplification products were visualized using 6% polyacrylamide gel electrophoresis stained with silver nitrate.
The percentage of polymorphic loci, allele frequencies, number of alleles, number of effective alleles, observed heterozygosis, expected heterozygosis, inbreeding coefficients (FIS, FIT, and FST), index of genetic identity, and molecular variance (AMOVA) were estimated.
Of the 15 microsatellites, four were amplified with polymorphisms for four loci (100%) in all cycles.
From the seven combinations of SRAPs tested, three detected 61 loci, while four have no amplification.
The polymorphic loci variation was determined between selection cycles.
Random amendment of allele frequencies was observed with the two kinds of markers.
Heterozygosis detected by SSRs indicated that there was no reduction of genetic variability, it was evidenced by the negative FIS and FIT values.
For SRAP markers of the expected heterozygosis values were lower than those found with SSR. The molecular variance showed greater variation within each cycle and lower between cycles for both markers.
There were alterations in allele frequencies throughout the three generations of recurrent selection and there was no reduction in genetic variability throughout the selection process due to the selection pressure applied.
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