University of Massachusetts
Reverse maize breeding for high density populations
--Galinat, WC

After having repeatedly taken maize apart by isolating its key traits in a teosinte background and then hybridizing the derivatives to reconstruct maize by recombination of the key genes--and all the time fighting a battle with weeds, birds, squirrels and the irrigation system, all after 60 years of corn experience, I have concluded that maybe the Europeans have the right idea with their high density monoculture of cereals. They have: no weeds, no herbicides, no irrigation, no soil erosion and almost no problems.

The wheat breeders and corn breeders developed their cereal plants and agriculture in complete isolation from each other in two different Worlds separated for thousands of years by the Atlantic Ocean until the time of Columbus. During this period they evolved different breeding procedures because their available grasses were very different after isolation along different evolutionary pathways for millions of years. They had different forms of reproduction and inheritance. The farmer-breeders on the European side of the Ocean happened to work out a system that is more environmentally friendly and better adapted to mass-production industrial agriculture than that represented by present-day maize starting on the western side of the Atlantic. However, some modern corn-breeders have been now considering reverse breeding for adaptation to high density populations, e.g. wheat, that would be both environmentally safe and make use of the huge harvesting combines designed for wheat. They would have to retrogress maize back some 5000 years to reach the same level as present-day wheat. They have already started maize in this direction by breeding for adaptation to increases in stand density. (See my item "Canopy and yield enhancement per acre with dense populations". MNL70:67, 1996.)

The reverse breeding of the new high density maize combines certain primitive plant habit traits from teosinte with other highly evolved traits of maize--its tassels, ears and kernels that adapt to hybrid seed production and economic uses. The high density maize would still carry its C4 type of photosynthesis yielding greater productivity than wheat and still carry the yellow endosperm gene from maize for the high carotene so tragically absent in all other cereals. From wheat we might transfer the gene(s) for gluten endosperm into maize to give it the elastic cohesiveness necessary for leavened dough to rise as it captures the CO2 gas. This increases the quality and lightness of baked bread. This transfer of the gluten endosperm to maize is technologically possible by the gene gun techniques. This would create the new maize as a superior daily bread that becomes the hope for survival and glory of humankind.

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