Econ. Botany 70, 37–48 (2016)

Germplasm conservation studies tend to focus on managing diversity within centres of origin or ex situ in seed banks. A new study by Joanne Heraty and Norman Ellstrand of the University of California, USA, examines the genetic diversity of maize (Zea mays spp. mays) varieties in home and community gardens planted by immigrant Mexican farmers in southern California.

Heraty and Ellstrand compared the genetic diversity of commercial varieties available in California with that of the varieties actually being grown by the migrants. They saw that the genetic diversity of the ‘migrant’ maize was similar to that seen in Mesoamerican landraces. This could be the result of multiple introductions, selective breeding and cross-pollination among the several introduced varieties. These introductions may represent seeds that the farmers brought with them, or from planting of corn imported from Mexico intended as food.

Given that genetic diversity of maize in Mexico is known to be eroding, the researchers suggest that the small-scale cultivation of the multiple maize varieties Mexican farmers bring to California is an important way of maintaining genetic diversity. They argue that current research into maize biodiversity ignores the importance of human migration and the accompanying food species. Instead, they suggest, we should celebrate the migrant farmers who are conserving maize diversity in new places.