Genetic Analysis of Carotenoid Content in Expired Plant Variety Protected Maize (Zea Mays L.) Inbreds

Lutein and zeaxanthin are the only carotenoids preferentially accumulated in the macular region of the eye. Studies have associated reduced risk of age-related macular degeneration with accumulation of lutein and zeaxanthin. Both lutein and zeaxanthin carotenoids can not be synthesized de-novo by humans and must be obtained from dietary sources. In adults over the age of 65 within the developed world, age-related macular degeneration is the leading cause of blindness. Given the prevalence of age-related macular degeneration in developed regions of the world such as the United States, and the expected increase in the human population over 65 years of age, better dietary sources of lutein and zeaxanthin are desired. The two predominant carotenoids found in maize grain (Zea mays subsp. mays) are lutein and zeaxanthin. The wide-spread consumption of maize in the United States makes it a logical platform to deliver higher amounts of lutein and zeaxanthin. Current levels of lutein and zeaxanthin in maize grain are much lower than what maybe needed to reduce the likelihood of age-related macular degeneration. Maize has a germplasm base with considerable phenotypic diversity for lutein, zeaxanthin and other closely related carotenoids, making successful selection for higher levels of lutein and zeaxanthin very possible. The study examines 350 maize inbreds with expired plant variety protection certificates and 64 public inbreds which together are the main genetic contributors to current commercial North American inbreds and hybrids. I present the current levels of carotenoids in expired plant variety protection inbreds based on high performance liquid chromatography analysis. The results show great potential to select for higher carotenoid levels in this germplasm. Given the labor and expense of HPLC per sample, I also propose a model based on a nondestructive quantitative color scale to quickly and cheaply estimate carotenoid levels. A Genome Wide Association Study was performed using HPLC obtained carotenoid values on the same 414 lines. The purpose was to assess the genetic architecture of carotenoids in these lines, and provide significant SNP association information that may be relevant to the potential for the selection of current lower carotenoid lines into higher producing ones