Originality of M3S maize population and changes in allele frequencies revealed by SSR markers after two cycles of selfed progeny recurrent selection

Abstract

Maksimir 3 Synthetic (M3S) maize population was developed at the Faculty of Agriculture University of Zagreb by intercrossing inbred lines, whose origins trace back to several open-pollinated varieties and local populations from different regions of the former Yugoslavia. The population was subjected to two cycles of selfed progeny recurrent selection for grain yield. The objectives of this study were: (i) to determine genetic distances among the parental inbred lines of the M3S population (M3S progenitors), the M3S population before and after two cycles of recurrent selection, and elite inbred lines representing the BSSS and Lancaster heterotic group; and (ii) to examine the effect of two cycles of recurrent selection on allele frequency changes in the population. Nine M3S progenitors, three BSSS lines, and three Lancaster lines were genotyped at 24 SSR loci, out of which nine randomly chosen loci were used for genotyping 96 individuals from both C0 (the M3S population before selection) and from C2 (M3S population after two cycles of selection). A total of 101 alleles were detected across 24 loci in the 15 lines, whereas 83 alleles were found in the nine M3S progenitors. Among the latter 83 alleles 31 were unique, i.e. found only in one of the progenitors. Mean genetic distance among nine M3S progenitors was 0.61 indicating a broad genetic base of the M3S population. High mean genetic distance was found between M3S progenitors and BSSS lines (0.69) and M3S progenitors and Lancaster lines (0.71). This indicates that the M3S population represents a germplasm source unrelated to both the BSSS and Lancaster germplasm. Mean genetic distance between the M3S population and BSSS as well as Lancaster lines decreased slightly after two cycles of recurrent selection suggesting the need to introduce testers from both groups in future selection in the M3S population in order to maintain heterotic complementarity of the M3S population to these groups. A test of selective neutrality identified several non-neutral loci in the population whose allele frequency changes from the C0 to the C2 cannot be explained by genetic drift. The majority of nonneutral alleles, whose frequency increased after two cycles of selection, were present in at least one line from the BSSS or Lancaster heterotic group.

<b>Population structure and impact of recurrent selection on popcorn using EST-SSR markers

“…Genetic variability is used to refer to the diversity of existing alleles at genetic loci (Solomon, Martin, & Zeppa, 2010). To understand the genetic variation during selection cycles, estimating the proportion of heterozygotes in the populations is important to ensure the progress of the selection of traits of interest for the crop, as alterations in allele frequencies due to selection may lead to biased estimates and reduce the degree of polymorphism and expected heterozygosis (Choudhary et al, 2012;Sarcevic, Pejic, Baric, & Kozumplik, 2007). Therefore, knowing the variability and genetic structure of a population can contribute to the long-term success of breeding programs.…”

Genetic Diversity and Population Structure Among 98 Maize Inbred Lines Investigated With SSR Markers

“…SSR markers, due to their abundance, co-dominance, and locus specificity, have been extensively used to assess genetic diversity in maize genotypes (Šarčević et al, 2008;Inghelandt et al, 2010).…”

“…The introduction of exotic germplasm, using its abundant genetic variation and good agronomic traits, is therefore essential to solve the narrow genetic base for maize improvement in China (Wen et al, 2012 ). However, it is necessary to make a comprehensive evaluation on the genetic diversity and population structure of exotic germplasm (Tarter et al, 2004;Šarčević et al, 2008;Živanović et al, 2012). Molecular markers can be employed to investigate levels of genetic diversity and population structure among maize inbred lines and breeding materials.…”

Proceedings of the 9th Alps-Adria Scientific Workshop, 12–17 April 2010, Špičak, Czech Republic – PLANT RELATIONS

“…M3S (Maksimir 3 Synthetic) maize population was developed at the Faculty of Agriculture University of Zagreb by intercrossing 12 inbred lines, whose origins trace back to several open-pollinated varieties and local populations from different regions of the former Yugoslavia. The population was subjected to several cycles of selfed (S1) and full-sib (FS) progeny recurrent selection for grain yield and disease resistance (Šarčević at al., 2004;Šarčević, 2006;Sabljo et al, 2008).…”