Crinkly-4 (cr4): a new crinkly-leaf/aleurone mosaic mutant on 10S

--Philip S. Stinard

A new recessive mutant conditioning aleurone mosaicism was found segregating on the selfed ear of a bz-mum8 plant, 84-6143-8 selfed. When planted in the field, mosaic kernels give rise to crinkly-leafed seedlings, which in turn mature to become short, crinkly-leafed plants. The crinkling of mature mutant plant leaves is much more extreme than that of cr1, and the leaves are rough, with a dull luster. The tassels of mutant plants are club-shaped, and are poor shedders. The aleurone mosaicism of mutant kernels shows incomplete penetrance. This mutant, originally designated dap*-6143 (MNL 61:9), was propagated and placed in our 1989 TB block. Two crosses by TB-10Sc uncovered mosaicism in the aleurone. When wildtype kernels from the TB cross were planted in the sandbench, only wildtype seedlings resulted. However, a close inspection of the wildtype kernels from the TB cross ears revealed that some of them were germless. Perhaps these germless kernels represent the hyperploid endosperm/hypoploid mutant embryo condition. If this is the case, then hemizygosity for the mutant allele has a deleterious effect on embryo development that is not observed in diploid mutant embryos.

In order to confirm the placement of this mutant to chromosome, ten mosaic kernels from the TB-10Sc cross, presumably representing the hypoploid mutant endosperm/hyperploid embryo condition, were planted in our 1990 summer nursery, and the resulting plants selfed and outcrossed to both oy and y9 testers. None of the selfed ears segregated for y9, but they did segregate for a low frequency of mosaic kernels. The outcrosses to y9 all segregated for pale yellow kernels. The crosses to oy, when seedling tested, segregated for oil yellow seedlings. Thus, all ten plants grown from mosaic kernels were hyperploids, confirming that this mutant is located on 10S.

Since the expression of the crinkly mutant phenotype is good, but the expression of aleurone mosaicism is not always consistent, we have given this mutant the name crinkly-4 (cr4) (mutants given the names cr2 and cr3 have been reported, but are lost). Three-point linkage studies of cr4 utilizing the chromosome 10 linkage stocks oy y9 and oy bf2 are in progress.

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