Characterization of a flint maize (Zea mays var. indurata) Italian landrace: II. Genetic diversity and relatedness assessed by PCR-based markers.

A comparative characterization of 10 field populations of the maize (Zea mays var. indurata) landrace \u2018\u2018Nostrano di Storo\u2019\u2019 was carried out using different types of PCR-based markers. The inbred line B73 and three synthetics (VA143, VA154 and VA157) selected from as many landraces were also used. Genetic diversity and relatedness were evaluated over 84 SSR and 53 I-SSR marker alleles using a total of 253 individual DNAs. Up to 23 alleles per SSR locus were scored while the average effective number of alleles per population was 6.99. Nei\u2019s total genetic diversity as assessed with SSR markers was HT 5 0.851 while the average diversity within populations was HS 5 0.795. The overall Wright\u2019s fixation index FST was as low as 0.066. Thus, more than 93% of the total variation was within population. Unique alleles over all SSR loci were found for six populations. An average of 17.7 marker alleles per I-SSR primer were scored with an effective number of marker alleles per locus of 1.34. The Shannon\u2019s diversity information index over all populations and I-SSR loci was 0.332, varying from 0.286 to 0.391. The extent of differentiation between populations was as low as GST 5 0.091. Dice\u2019s genetic similarity matrices were estimated for both SSR and I-SSR markers. The mean genetic similarity coefficients within and between populations were respectively 0.269 and 0.217, for SSR markers, and 0.591 and 0.564, for I-SSR markers. UPGMA dendrograms displayed all field populations but one clustered into a distinct group, in which the synthetic VA154, selected from the \u2018\u2018Marano Vicentino\u2019\u2019 landrace, was also included. One field population and the other two synthetics were clustered separately as well B73. The matrix correlation assayed by the Mantel\u2019s correspondence test was as high as 0.908. Findings suggest that, although a high variability can be found among plants, most plant genotypes belong to the same landrace called \u2018\u2018Nostrano di Storo\u2019\u2019. Although gene flow from commercial hybrids might have occurred, the large number of polymorphisms and the presence of both unique alleles and alleles unshared with B73 and synthetics are the main factors underlying the value of this flint maize landrace as a source of genetic variation and peculiar germplasm traits. Because of its exclusive utilization for human consumption, such a molecular marker characterization will be a key step for obtaining the IGP mark and so promote the in situ conservation and protection of the landrace \u2018\u2018Nostrano di Storo\u2019\u2019