Multi-layered expression of aleurone-specific genes --Walton C. Galinat In the process of recombining the two-celled pericarp from teosinte with the multiple layered aleurone from Coroico in a sweet corn background, a faint blue color was detected. In addition to the prime components of selection, the blue color was held onto in the hope that it would be an easy tool to identify the multiple-layered segregants. In fact, this has proven to be the case. As the number of aleurone layers increased, there was a dosage effect on increases in the intensity of blueness. Freehand sections through the kernels showed the blue was present in all layers. It may be expected that other aleurone-specific genes will have dosage effects in the multi-layered aleurone and, thereby, increase the total output of their special phenotype. This dosage effect with increased layering appears also to be manifest with genes for the bronze or orange colored aleurone that is common in Coroico. The most primitive kernels from Tehuacan had this same bronze-orange aleurone; identified as the race Nal Tel, it may have been the distant ancestor of Coroico. The Tehuacan kernels were not sectioned and Nal Tel is not known at present to have multiple aleurone. It seems probable that the multi-layered condition evolved under the eye and mind of the Guarany Indians. The aesthetic beauty of these intensely orange ears with multi-layered aleurone was probably the direct reason for their selection by the Guarany Indians. But the multiple aleurone may also have other benefits not initially intended such as increased protein in an opaque-2 background (Nelson and Chang, Crop Sci. 14:374, 1974) and a potential to cope with increased kernel size.

It is hoped that this stock with thin pericarp and thick aleurone will not only result in new high quality sweet corn but that it will also be useful in studies of gene action in the aleurone and of the chemical improvement of the nutritive value of this digestible layer or layers.

Seed of my blue multi-aleurone, thin pericarp stock has already been supplied for research purposes to Dr. Prem Chourey (Univ. of Fla., Gainesville) for studies of gene action and to Dr. Victor Raboy (Montana State Univ., Bozeman) for studies of phytic acid.

The sweet corn inbred Illinois 677a is reported by Dusty Rhodes to contain some Coroico germplasm. The inbred has been important as a source of the se (sugary enhancer) gene. It has only a single aleurone layer, unlike Coroico.

The combination of Ma and Tpe such as occurs in Coroico with sh2 (shrunken) endosperm is a better means to cope with the sh2 germination problems than the currently used thick pericarp which gives poor eating quality.

Please Note: Notes submitted to the Maize Genetics Cooperation Newsletter may be cited only with consent of the authors

Return to the MNL 64 On-Line Index
Return to the Maize Newsletter Index
Return to the Maize Genome Database Page