Inheritance of Kernel Color in Corn: Explanations & Investigations
The American history teacher
V ARIATIONS 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
... cs 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 F 2 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. Four Kernel Colors, Four Genes Three of the four kernel colors-yellow, red and purple-are produced by pigments synthesized from one of two metabolic pathways, the carotenoid (yellow pigments) or the anthocyanin (red and purple pigments) pathway. White, the fourth color, results from the lack of pigments produced from either pathway.