A New Methodological Approach to Detect Microcenters and Regions of Maize Genetic Diversity in Different Areas of Lowland South America

Microcenters of diversity of crop plants are small geographic areas, while regions of diversity are large and relatively diffuse areas that conserve high or moderate genetic diversity, respectively. This study aimed to identify microcenters and regions of maize diversity in different areas of lowland South America, in Brazil and Uruguay, proposing a new methodological approach based on ethnobotanical, morphological, and molecular indicators and genetic diversity indices. The collection areas considered microcenters were surrounded by a buffer of 50 km (area: 7,850 km 2 ) and the regions by buffers of 150 km (area: 70,650 km 2 ) to 300 km (area: 282,600 km 2 ). The study was carried out in parts of the biomes of Amazonia, Caatinga, Cerrado, Atlantic Forest, and Pampa. A total of 261 farmers participated, of whom 129 were interviewed. Four microcenters and four regions of maize diversity were identified, showing: (i) richness and genetic diversity of landraces (mostly unique to each region) and richness of maize races; (ii) the presence of landraces under diversification by current human action as diagnosed by sociocultural aspects and diversity of uses attributed to landraces; and, (iii) maize germplasm conservation areas, on microregional and regional geographic scales. Indicators of strengths , weaknesses , opportunities , and threats were identified in the areas involved in the study.