GENETIC FINGERPRINTING: A PRACTICAL, INEXPENSIVE, AND INDISPENSABLE TOOL IN NATIVE GRASS
VARIETY IDENTIFICATION.

Craig C. Dremann, co-owner, The Reveg Edge, Box 609, Redwood City, CA. 94064.

Phone (650) 325-7333 - FAX (650) 325-4056 - Email

Ecological restoration is the replanting of species indigenous to a particular natural ecosystem, with the purpose of recreating a self-sustaining plant community structure, that can thrive and reproduce without human input over time. A principle ingredient of success is the use of not only correct species of plants, but the proper locally-adapted ecotypes as well.

Ecotypes are forms of wild plant species that, over time, have become adapted to a particular environment, and are genetically fixed with particular adaptive traits. They are therefore suited to grow, thrive and reproduce best at sites with a particular combination of elevation, annual precipitation, soil type, biome, other environmental factors.

One way to detect ecotypes is by growing several different populations together in what is called a "common garden." In a common garden, the environmental factors such as light, water, fertilization and soil conditions are uniform. By holding environmental variables constant, an investigator can detect the genetically-based ecotypic variations such as variations in flowering dates. While common gardens are very valuable in highlighting environmentally adaptive traits, they only provide a means to identify ecotypes through their morphological characteristics. What is needed is a test which can match seed samples without having to wait for the results of a year-long common garden.

Genetic analysis using isoelectric focusing gels provides a quick and important tool in identifying ecotypes. Using proteins extracted directly from native grass seeds, along with the esterase enzyme, the gel creates a "fingerprint" of the different ecotypes. Cereal crop breeders have been using the genetic gel process for some time and a review of this well established technique was published by Cooke (1995). We first began adapting this process to wild native grass populations in 1993, primarily as a means of tracking the integrity of native populations through the commercial production process. Since then, I have identified at least five areas in which the genetic gel process provides valuable new tools.
Example of a gel of Great Basin Wild Rye populations.

You can see more gels -- Canadian native grass populations:
--- Festuca, Koeleria, Poa and Trisetum.

--- Agropyron and Festuca saximontana.

IDENTIFICATION. Gels give each ecotype a "bar-code" that is consistent year-to-year within certain tolerances, and can be used to identify a particular population. This is especially useful for tracking a wild population through commercial reproduction and back; it is the only guarantee of receiving back the same genetic material that is sent in. The beauty of utilizing this method of gels is that you don't need viable seeds to produce a gel, and the seed proteins do not degrade. The gels can producing a consistent banding pattern for decades, with our current record, a herbarium seed collection from 1895! This method has already identified three mistakes by growers who mislabeled native grass seeds. Furthermore, a gel costs about half the price of a seed germination test, only $20-25 per population.

TAXONOMIC IDENTIFICATION OF SPECIES. There are at least 300 native grass species in California alone. Many look alike and some even cross pollinate. A recent collection we received from California, included Achnatherum hymenoides, A. occidentalis, A. pinetorum, A. speciosum, A thurberianum, A. webberi, Elymus elymoides, Hesperostipa comata, and Leymus cinereus. Achnatherum occidentalis and A. thurberianum seed look nearly identical. There are three botanical subspecies of A. occidentalis and three subspecies of Elymus elymoides. In cases where field identification of look-alike species may be difficult, gels provide a means to double check initial assessments.

DETERMINING RELATIONSHIPS BETWEEN POPULATIONS ON A GEOGRAPHIC BASIS. Genetic gels may also show broad environmental or geographic relationships between populations. Elevational relationships are the most commonly encountered, and relationships to specific soil types, and other environmental factors do show up. The gels can help group populations into broadly related groups called "geo-vars," or geographically related ecotypic varieties. This means that ecotypes in one geo-var group are like brothers, sisters, and cousins, whereas a separate geo-var group is like another family. Like separating the Smiths and the Joneses, you can give your populations a "geo-var" family name, and then each individual population, with its own genetic gel, has its own personal name or bar-code.

SEED CERTIFICATION. Crop Improvement Associations around the country, including California's, are writing rules for the certification of ecotypes and/or the tracking of commercial reproduction of wild grass populations. The gels process would be useful to track material from the wild through each year of cultivation. The gels could check each year's cultivated material and see that it matches the original wild collected material. Customers wanting to check the identity of purchased material could also run a gel and see that it matches the certified reference seed.

Other relationships are likely to be found between the populations and the environments that created them, as more samples of native grass populations are systematically run through the gel process. We may be able to identify, for example, populations which have greater potential tolerance for restoring disturbed areas like mines or roadsides. Efforts to certify native grass seeds might consider this technique a quick and easy check for the commercial reproduction of wild material.

NATIONAL NATIVE GRASS ECOTYPE MAP. Utilizing the data from our studies, we have been able to produce a map of the whole United States and southern Canada which shows the ecotype zones for native grasses for commercial seed reproduction. This map is available under a licensing program for governement agency use.

REFERENCE: Cooke, Robert J. 1995. Review: Gel electrophoresis for the identification of plant varieties. JOURNAL OF CHROMATOGRAPHY A. 698: 281-299.

Update November 18, 2010 .