The pleiotropic mutation dek*-Mu1364 maps to chromosome arm 9L
--Mike Scanlon, Mi Chang and Michael Freeling

The recessive mutation dek*-Mu1364 was generated from Mutator stocks and causes numerous developmental aberrations: small endosperm, small embryo, 50% germination rate among homozygous kernels, brachytic plants, drooping leaves exhibiting ligule disruption over the midrib, and male sterility (Scanlon et al., Genetics, in press).

Subsequent analyses indicated the presence of both ectopic ligule and displaced ligule along the midrib of all leaves in dek*-Mu1364 homozygous plants. Transverse sections of leaves were treated with phloroglucinol (stains lignin) to demonstrate that the ligular region of dek*-Mu1364 homozygotes is markedly delignified as compared to wild type siblings. The reduction in lignin accumulation in leaves of dek*-Mu1364 homozygotes explains the drooping leaf phenotype observed in these plants. Histological analyses of the vegetative shoot apex of 14 day-old mutant seedlings have revealed that the meristem of dek*-Mu1364 homozygotes is abnormally short and flattened.

Plants heterozygous for the dek*-Mu1364 mutation were crossed to TB-9Lc and several ears were identified which segregated kernels with small endosperm and large embryos, and plump endosperm and small embryos. The discordant kernel classes were planted in the greenhouse and those with small endosperm and large embryos (putative hyperploid embryos) produced normal seedlings whereas the kernels with plump endosperm and small embryos (putative hypoploid embryos) yielded small brachytic plants with ligule disruption. These data indicate that dek*-Mu1364 is located on the long arm of chromosome 9. 

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