Dive into the Strawberry Gene Pool: It's getting deeper!

The cultivated strawberry originated from an accidental cross between a white-fruited type brought to France from Chile in 1714 and a red-fruited species brought from the Virginia Colony to Europe in the 1600s. By the early 1800's a number of plantsmen on both sides of the Atlantic realized that larger, sweeter strawberries could be made by breeding, growing out seedlings, and selecting the offspring for improved traits. Since that time strawberry breeders have worked together and developed the tasty fruit that graces our markets today.

Breeders have tended to share their good quality fruit selections with others in a concerted breeding effort in the 19th and 20th centuries. One unfortunate result was, as scientists call it, the development of "a narrow germplasm base," i.e., a shallow gene pool. Cultivars introduced from North American breeding programs from 1960 to 1990 are descended from 53 founding clones with only 17 cytoplasm sources (Dale and Sjulin, 1990). This approach, if continued, could cause deleterious effects of inbreeding and genetic vulnerability to diseases, pests, and environmental stresses.

The Corvallis Repository, which has the strawberry genebank for the US National Plant Germplasm System, is cooperating with many scientists around the world to increase the availability of wild strawberry species for crop improvement. Under the sponsorship of USDA Plant Exploration, in cooperation with the Instututo de Investigaciones Agropecuarias Estacion Experimental La Platina, Santiago, Chile, Dr. J. Scott Cameron, Washington State University collected a number of samples throughout Chile in 1990 and 1992. These samples are now available for distribution from the Corvallis Repository.

For example, on the Island of Lemuy, Dr. Cameron found a sample of Fragaria chiloensis subsp. chiloensis f. chiloensis Staudt. This species has large white fruits similar to those described by Antoine Duchesne for the original type brought to Europe in 1714. This clonal sample (FRA 742.001) is now available from the Repository.

The small red fruited F. chiloensis subsp. patagonica Staudt (FRA 713.001) was also collected.

Another unusual clone growing at Purranque, Chile, was observed. This clone, (FRA 792.001) , was found growing wild. The fruit suggest, however, that an introgression with a cultivated sort must have occurred.

Presently, the Corvallis Repository has more than 120 new accessions of Chilean strawberries available for evaluation and screening tests by researchers and breeders. Any interested cooperators are encouraged to contact Kim Hummer, the Curator, to request some material.

In 1996, the USDA and the Corvallis Repository are sponsoring collecting expeditions to Alaska and to northeast China to obtain additional diverse strawberry species. The strawberry gene pool is getting deeper!

K. Hummer, 1 May 1996