37. Frizzy panicle, an EMS-induced mutant in the Japonica cultivar M-201

1) USDA-ARS, Dept. of Agronomy and Range Science, University of California, Davis, CA 95616, U.S.A.

2) USDA-ARS, Texas A & M Experiment Station, Route 7 Box 999, Beaumont, TX 77713, U.S.A.

3) USDA-ARS, Jamie Whitten Delta States Research Center, P.O. Box 225, Stoneville, MS 38776-0225, U.S.A.

The completely sterile, induced-mutant, "frizzy panicle", was isolated from a population of the California cultivar M-201. M-201 seeds were treated with 1% EMS solution, and M2 plants were grown in the field at Davis, California in 1984. Plants with shriveled spikelets were noted in one subsequent M3 row and

Fig. 1. Frizzy panilce mutant, fzp, and a normal panicle (right) from the same segregating population.

Fig. 3. Closeup photograph of a frizzy panicle. "Inflorescense-like" structures form at the tips of the panicle branches.

fertile plants were harvested. In 1991, Six M6 fertile plants were individually harvested from rows segregating for frizzy panicle. The progeny were space-planted in the field at Davis in 1992. Progeny from four of the six plants segregated for frizzy panicle. Of a total of 1,438 plants grown, 353 were frizzy, showing a good fit to a 1:3 ratio (X²=0.16, 0.50<P<0.75). This trait is therefore inherited as a single recessive gene.

Frizzy plants produce no seed (Fig. 1), and can only be propagated as heterozygotes. Development of the rachis branches appears to be normal, but small branches continue to form instead of spikelets (Fig. 2, 3). These branches appear to produce multiple rachillas. The list of gene symbols (RGN 8:4-25) does not contain any previous report of a mutant with this description. We therefore propose the gene symbol fzp for this recessive mutant.