Understanding heirlooms, hybrids and GMOs

By Bill Snyder

OSU Extension master gardener volunteer

In light of pending purchases for spring planting, it is important to understand the confusing terms associated with the vast selection of vegetable seeds and plants. Specifically, what’s the difference between heirlooms, hybrids and genetically modified organisms (GMOs) or GM plants? At the core, heirlooms and hybrids are the results of plant sexual reproduction, while GMOs are produced through techniques of genetic manipulation.

The term heirloom describes vegetable plants from which seeds have been collected for many years and passed down, usually through generations. Each year, the collected seeds from an heirloom tomato, for example, will generate plants that produce the exact same tomatoes the following season. In order to achieve this predictability, the plants must be open-pollinated. That means that they produce seeds that germinate into seedlings that are just like the parent plants.

In contrast, a hybrid plant is the result of a cross-pollination, the product of sexual reproduction between compatible but different varieties. They can be produced through natural pollination involving wind or insects dispersing the pollen or in a laboratory setting where humans select the parents and carry out the pollen transfer. The process is far from a modern occurrence since farmers have been using these techniques for thousands of years. The idea is to cross two plants, each with different desirable characteristics to produce offspring (hybrids) with the sought-after traits of both parents.

Using hybrid technology, it is possible to cross a very flavorful, large fruit tomato with one that matures quickly and is disease-resistant. It is likely that the hybrid produced will have all of the desired properties from the parents. However, the seeds produced by these hybrid super tomatoes will tend to produce plants that are more like the original parents and not like the hybrids. Therefore, while the first generation hybrids will have properties of both parents, their next generation seeds will probably be unpredictable and show many undesirable properties.

Hybrids should never be confused with genetically modified organisms (GMO), which have acquired one or more genes from another species or a different variety of the same species by artificial means. Instead of obtaining genes through pollination, these transgenic plants have genes artificially inserted using modern techniques of molecular genetics.

For example, soybean plants are normally killed (as are all plants) by the herbicide glyphosate (Roundup being the most well known brand). The process involves inhibiting a crucial enzyme needed for the growth of all plants. However, if a gene from a bacterial source is inserted into the plant, the resulting GM plant can produce the bacterial version of the same enzyme that is not inhibited by glyphosate. The resulting soybean plants are glyphosate-resistant, making it easy to eliminate competing weeds in the fields.

Although GMOs are widely used in U.S. agriculture (e.g. corn, soybeans, cotton and canola), the home gardener will not find access to GM plants and seeds, and therefore, their choices will be limited to traditional heirloom and hybrid varieties.

To review proper seed-saving techniques: visit http://go.osu.edu/saving. To understand the difference between heirlooms, hybrids and GMOs: http://go.osu.edu/organictogmo.