Improving plants for tolerance to iron deficiency and other mineral nutrition problems: Breeding and genetic points of view

Abstract

From the breeding and genetic points of view, improving plants for mineral metabolism, such as reducing iron‐deficient chlorosis, differs little in principle from improving them for agronomic and quality traits or pest resistance. As with these latter categories, mineral‐nutrition traits may range from simple to complex in their inheritance. Moreover, a given trait, such as iron‐deficient chlorosis, may be relatively simply inherited in one crop, e.g., in dry bean (Phaseolus vulgaris L.), or more complexly inherited in another, e.g., in soybean [Glycine max (L.) Merr.]. The complexity of inheritance and the mode of reproduction of the plant determine the breeding methodologies to employ. In some instances, pedigree breeding, including backcrossing, is adequate. In other instances, population improvement may be necessary before extracting lines or cultivars.

When quantitative genetic approaches are used, consideration must be given to experimental designs and biometrical procedures so that reliable estimates of parameters are obtained. Tissue culture, cell culture, protoplast culture and fusion, and recombinant DNA methodologies also hold interesting possibilities for improving various plant characters, which could include tolerance to iron‐deficient chlorosis. If successful, these techniques will uniquely complement and supplement conventional plant breeding methods. Exotic germplasm and plant introductions would then become a more tangible source of useful genes.

Key words:

• Breeding methodology
• Genetic engineering
• Inheritance
• Mode of reproduction
• Statistics and biometrics

Notes

Published as Paper no. 7847, Journal Series, Agricultural Research Division, Institute of Agriculture and Natural Resources, Lincoln, NE 68583.

Research geneticist (retired), U.S. Department of Agriculture, Agricultural Research Service.