Inheritance of Kernel Color in Corn: Explanations & Investigations

Abstract

VARIATIONS in the color of corn kernels (Zea mays L.) have attracted geneticists since the early 1900s when studies on the inheritance patterns of kernel color helped validate classical genetics. Even now, research scientists investigate the molecular genetics of these characteristics, and students in introductory biology and genetics courses learn more about monohybrid and dihybrid crosses by studying the inheritance of kernel colors. The reasons for introducing corn genetics in the classroom are obvious—a single ear holds a large number of progeny and a variety of ears are available that represent basic inheritance patterns, such as the monohybrid cross (3:1), the dihybrid cross (9:3:3:1), and more complex genetic patterns illustrating gene interactions (12:3:1; 9:3:4, 13:3; 9:7, etc.). In addition, these ears are obtained readily from several biological supply houses and are relatively inexpensive, especially since students can use them for several years. Students usually confirm different phenotypic ratios of the F2 generation by first counting kernels, then performing chi-square analyses to test their data. However, their experience can be enriched by introducing explanations about the nature of each gene and its mutations, the related metabolic pathways, and their locations within the kernel. I have included information in this review that would be appropriate at different levels—from high school biology to introductory genetics at the college level. The purpose is the same. By exploring these areas, students more fully understand how these simple phenotypic ratios and variations are derived.