Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/19/2007
Publication Date: 1/16/2008
Citation: Lorenz, A., Scott, M.P., Lamkey, K.R. 2008. Genetic variance and breeding potential of phytate and inorganic phosphorus in a maize population. Crop Science. 48:79-84. Interpretive Summary: Phosphorous from animal waste is harmful to the environment because of it's detrimental effect on water quality. The problem is most promounced when livestock and poultry are produced in high-density systems. Phosphorous in animal waste can be reduced by reducing the level of phytic acid in the maize grain that is the main component of animal feed. One approach to doing this is by breeding with selection for reduced grain phytic acid levels. In this study, we evaluated a maize breeding population and determined that it should be possible to produce varieties with reduced phytic acid content through breeding, although progress will be slow if desirable agronomic characteristics are to be maintained. The information in this study will be valuable to researchers and breeders in the seed industry who are interested in grain with reduced phytic acid content because it provides information required to design breeding programs to produce low phytic acid maize. This is a new approach to producing grain that is better for the environment and is complementary to work with the same objective that is being carried out with mutations and transgenes. This work will be of particular benefit to people living in areas where high intensity livestock and poultry production are used.
Technical Abstract: Seed phosphorus (P) is predominantly bound in the organic compound phytate making the bioavailability of P in maize-based diets poor. Decreasing phytate and increasing inorganic P (Pi; an available form of P) concentrations in maize grain would be desirable to help solve associated environmental and nutritional problems. Our objective was to investigate the potential of improving the P profile of maize grain through breeding and selection. Ninety S1 families were evaluated at two locations for phytate, Pi, and other grain quality and agronomic traits. Phytate concentrations ranged from 1.98 to 2.46 g kg-1 and the broad-sense heritability (H2) was relatively low (0.60). Genetic variance was much greater for Pi, which resulted in a H2 of 0.84 and a three-fold difference between high and low families. The family by location interaction was nonsignificant for both phytate and Pi. As reported previously, a reduction in protein and increase in starch is expected when breeding for low phytate. Lack of any unfavorable correlations as well as selection differentials of multiple trait indices indicate that the P profile of maize grain can be improved along with important agronomic traits such as yield and moisture. However, many cycles of selection will be needed to reach desirable phytate and Pi concentrations, especially when selecting for multiple traits. Regardless, our results are encouraging given that the families evaluated were related, S1 families and the number of families was relatively small.