GrainGenes

II. 10. Shrunken endosperm mutant seg8.

R. T. Ramage and Chere L. Crandall. Department of Plant Sciences, University of Arizona, Tucson, Arizona 85721, U.S.A. "R"

In 1972, the line 60-Ab-1810-53 was increased at Aberdeen, Idaho by Darrell Wesenberg. This line was later released as the cultivar 'Klages', C.I. 15478. In the increase field, a very low frequency of partially sterile plants was observed. We collected some of these plants to serve as a source of trisomics in the cultivar Klages. During the collection, we found several other types of mutant plants, including one with shrunken endosperm. Seed produced on the plant with shrunken endosperm weighed 21 percent of the seed produced on normal neighboring plants.

Seed produced by the mutant shrunken endosperm plant were sown in the greenhouse in Arizona. The resulting plants were examined cytologically and found to have seven pairs of chromosomes and normal pollen mother cell meiosis. Pollen and ovule fertility were normal. All of the plants had shrunken seed which weighed 27 percent of normal seed of Klages.

Mutant plants were crossed with normal Klages. The resulting F1 plants produced spikes containing all normal, plump seed. The F2 segregated about 3 plump-seeded : 1 shrunken-seeded plants. The mutant was then assigned the symbol, seg,,k.

Seed weights of mutant seg,,k plants have been compared with normal Klages when produced in the field in Arizona and in Montana. In Arizona, mutant plants produced seed that weighed 24 percent of normal Klages and in Montana, seed produced on mutant plants weighed 23 percent of normal Klages seed. We conclude that different environments do not significantly affect the seed weight of the seg,,k mutant.

Over several seasons, we have grown the seg,,k mutant in the greenhouse in Arizona, in the field in Arizona and in the field in Montana. No difficulties have ever been encountered in establishing stands of the mutant.

The mutant seg,,k was crossed with the shrunken endosperm mutants segl, seg2, seg3, seg4, seg5, seg6 and seg7. All of the F1 plants from all crosses produced plump seed. F2's were grown from all of the allele crosses and all segregated in an approximate 9 plump-seeded : 7 shrunken-seeded ratio. The Fl's and F2's of the allele crosses indicate that seg,,k is non-allelic to the other seg mutants that have been assigned to loci. We are designating the seg,,k mutant as seg8.

Linkage tests are now in progress to determine the chromosomal location of seg8.

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