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Project Leader and Principal UC Investigators

David J. Mackill, research geneticist, USDA-ARS, Dept. of Agronomy & Range Science, UC Davis

Teresa Erickson, biological technician, USDA-ARS, Dept. of Agronomy & Range Science, UC Davis

Xiamoto Lei, staff research associate, Dept. of Agronomy & Range Science, UC Davis

Edilbeto Redona, graduate student, Dept. of Agronomy & Range Science, UC Davis

Satoshi Masaki, visiting scientist, Dept. of Agronomy & Range Science, UC Davis


Rice research is taking another big step into the future with the new techniques being developed in molecular genetics. Scientists are more effectively exploring a set of diverse rice varieties and wild species with the aim of introducing useful new germplasm and agronomically important traits into California varieties

Molecular markers

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Recent upgrades in the genetics laboratory at UC Davis include an ultra-low temperature freezer, a refrigerated table top centrifuge and a DNA thermocycler. These new tools will enable scientists to take advantage of emerging techniques in molecular biology to understand the genetic make-up of rice.

Facilitated by a recently renovated laboratory at UC Davis, geneticists began experimenting with ,"molecular markers" to help them select desirable traits in rice breeding. Laboratory procedures using DNA "probes" are being finetuned to help researchers map genes of importance to California conditions.

The gene pool

Scientists are also at work setting up the gene pool for breeding and genetic studies. Of the 378 rice accessions acquired last year from the International Rice Research Institute in the Philippines, 76 were grown for seed in quarantine at Davis. Seed from another 135 accessions were obtained from a USDA quarantine facility in Maryland. Additionally, more than 600 varieties from the local collection were grown out at Davis.

Researchers selected 140 of these various rice varieties to assess genetic variability with the molecular marker technique. Their objective is to determine the genetic diversity of California varieties in relation to japonica varieties from other countries and to the species as a whole. Most rice researchers feel that japonica varieties are less diverse than indica varieties. California varieties in particular have a narrow germplasm base.

Molecular markers provide an objective method of determining genetic diversity. The results of the geneticists' work will have important implications for California rice breeding since genetic diversity may provide some measure of protection against biological pests. Genetic diversity will also be necessary to exploit hybrid vigor should hybrid rice become a reality.

Useful genes tracked

Using molecular markers, researchers are also mapping useful genes - such as those that confer cold tolerance, seedling vigor and resistance to stem rot and water weevil - in a number of populations.

Researchers report progress in developing the genetic mechanisms for commercial hybrid rice. Part of that process will involve key hybrid rice genes. Researcher successful transferred some of these genes during 1992, including cytoplasmic male sterility, restoring ability, compatibility and EUI (elongated uppermost internode) genes.

One mutant line from Calrose 76 is potentially very useful because it is fertile when grown in the southern U.S. but sterile when grown under California conditions. With this mutant, the sterile lines can be maintained by increasing the seed in the southern U.S. where the plants are fertile.

Whether these mechanisms prove viable in California will depend upon the cost of seed production and the availability of a hybrid with sufficient yield advantage and acceptable grain quality. Efforts to develop this yield advantage are concentrating on crosses between japonica cultivars and indica cultivars since previous japonica-japonica crosses did not yield well.

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