Dominguez, P. G. | bioRxiv Science

bioRxiv2026

Southern South American Maize Landraces: A Source of Phenotypic Diversity

Maize (Zea mays L.) is a globally important crop for food, feed, and industrial uses. Modern breeding increasingly targets traits beyond yield, including stress tolerance, nutritional quality, and pest resistance. Progress toward these goals is constrained by the narrow genetic diversity of commercial varieties, a consequence of the repeated use of a limited number of inbred lines. Maize landraces therefore represent valuable reservoirs of genetic and phenotypic diversity. Northern Argentina is one of the southernmost regions of maize landrace cultivation and comprises two main centers of diversity: Northeastern Argentina (NEA; <2000 m.a.s.l.) and Northwestern Argentina (NWA; >2000 m.a.s.l.). Despite their potential relevance, phenotypic characterization of these landraces remains limited, particularly for biochemical traits, which, although less visible, play key roles in biomass accumulation, defense against pathogens and herbivores, tolerance to environmental stress, and quality attributes such as flavor. Here, we evaluated 17 phenotypic traits, including morphological traits, leaf biochemical compounds (such as pigments, carbohydrates, and phenolics), and salt stress tolerance, in 19 maize landrace accessions from Northern Argentina. Substantial variation was detected across all traits, both within and among accessions, indicating that each accession harbors a distinct phenotypic profile. While no significant differences were observed between regions, redundancy analysis revealed associations between phenotypic variation and collection-site altitude. These findings highlight the value of Argentine maize landraces as sources of biochemical and stress-related traits and support their conservation and use in breeding programs aimed at broadening the genetic base of cultivated maize. Main ConclusionMaize landraces from Southern South America show high within and between accession phenotypic variability, while differences between regions of origin are associated with altitude.

plant biology↗

bioRxiv2024

Genome-wide diversity in lowland and highland maize landraces from southern South America: population genetics insights to assist conservation

Maize (Zea mays ssp. mays L.) landraces are traditional American crops with high genetic variability that conform a source of original alleles for conventional maize breeding. Northern Argentina, one the southernmost regions of traditional maize cultivation in the Americas, harbours around 57 races traditionally grown in two regions with contrasting environmental conditions, namely the Andean mountains in the Northwest and the tropical grasslands and Atlantic Forest in the Northeast. These races encounter diverse threats to their genetic diversity and persistence in their regions of origin, with climate change standing out as one of the major challenges. In this work, we use genome-wide SNPs derived from ddRADseq to study the genetic diversity of individuals representing the five groups previously described for this area. This allowed us to distinguish two clearly differentiated gene pools, the Highland Northwestern maize (HNWA) and the Floury Northeastern maize (FNEA). Subsequently, we employed Essential Biodiversity Variables at the genetic level, as proposed by the Group on Earth Observations Biodiversity Observation Network (GEO BON), to evaluate the conservation status of these two groups. This assessment encompassed genetic diversity (Pi), inbreeding coefficient (F), and effective population size (Ne). FNEA showed low Ne values and high F values, while HNWA showed low Ne values and low Pi values, indicating that further genetic erosion is imminent for these landraces. Outlier detection methods allowed identification of putative adaptive genomic regions, consistent with previously reported flowering-time loci and chromosomal regions displaying introgression from the teosinte Zea mays ssp. mexicana. Finally, species distribution models were obtained for two future climate scenarios, showing a notable reduction in the potential planting area of HNWA and a shift in the cultivation areas of FNEA. Taken together, these results suggest that maize landraces from Northern Argentina may not be able to cope with climate change. Therefore, active conservation policies are advisable.

genomics↗