Institute for Integrative Genome Biology

Studying Genetic Diversity in Corn for Crop Improvement

IIGB professor of genetics Norman Ellstrand, has discovered that the genetic diversity of corn in some home and community gardens in Southern California far exceeds levels found in commercially available seeds.The research addresses the importance of maintaining a diverse range of genetic resources for future crop improvement.

Norman Ellstrand co-authored the paper, “Maize Germplasm Conservation in Southern California’s Urban Gardens: Introduced Diversity Beyond ex situ and in situ Management,” with Joanne Heraty, a former UC Davis graduate student who Ellstrand supervised, which was published online in the journal Economic Botany. Ellstrand, who is also interim director of the university’s new “broad-sense” agriculture institute, CAFÉ (California Agriculture and Food Enterprise), cautioned that this is a preliminary study with a small sample size.

Future research would expand to include a greater number of gardens, and focus on characteristics of the corn, such as tolerance to drought, difference in cob size and flowering time. A broad mix of genetic material is useful for breeding modern improved lines, minimizing the vulnerability of inbred crops to pathogens and pests, improving performance and incorporating unique traits.

Yet, crop genetic diversity is threatened in developing and developed countries as policies and program encourage the use of relatively homogeneous modern cultivars and as people migrate from farms to cities, often abandoning farming altogether.

Southern California is an ideal location to study joint human and plant migration because immigrants from Mexico and Central America frequently maintain plots of crops from their homelands in home gardens and community gardens.

Past research has shown that corn genetic diversity is being eroded, particularly in Mexico and conservation strategies tend to fall into two categories: ex situ and in situ. Ex situ refers to using a controlled environment, such as a gene bank or botanical garden, to maintain genetic resources. In situ refers to a farmer-based approach via traditional agricultural practices like seed saving and selective breeding.

Ellstrand and Heraty describe home and community gardens in Southern California as providing a third method, which combines ex situ and in situ methods of conservation and is aided by human migration.

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