Research PaperGenetic diversity and intra-racial structure of Chilean Choclero corn (Zea mays L.) germplasm revealed by simple sequence repeat markers (SSRs)

- Representative Chilean Choclero corn landraces and inbred lines were genotyped with SSRs.
- Population structure and ample genetic diversity was observed.
- Molecular and historical data allowed the understanding of germplasm conformation.
- A reconsideration of the biological status of some accessions is proposed.

Choclero is a Chilean pre-Columbian floury corn with great economic value. The genebanks network of the Instituto de Investigaciones Agropecuarias (INIA) have preserved the largest Choclero corn collection, which is underutilized despite the existence of several Choclero breeding programs. This germplasm could serve as a valuable resource in breeding for green corn yield and cooking/eating quality. To use such materials, however, breeders need information about extent and distribution of genetic diversity present within the collection. Ten simple sequence repeats (SSRs) markers were used for population genetic analysis of 34 Choclero corn landraces collected from different places of Chile and 22 inbred lines developed by the INIA corn breeding program, of two sources: Choclero landraces and commercial hybrid S1 segregant populations. Number of alleles, gene diversity per locus, unique alleles per locus and population structure all differ between the two germplasm groups. In the landraces group, two genetic subgroups were identified. Several landraces accessions were considered as mixed. Linking genetic diversity information with vernacular name and historical events allowed us to understand the origin of this admixed group. Our results suggest that this group are open pollinated Choclero varieties released by INIA in the 1970s. A reclassification based on the original biological status is proposed. The results highlight the importance of intra-racial studies for understanding diversification and origin of local corn accessions. Data also suggests that there is scope for exploiting the genetic diversity of Choclero germplasm for Choclero corn improvement.