Vitamin A deficiency (VAD) is a problem in many developing countries in Africa where maize (Zea mays L.) is a staple food (http://www.harvestplus.org/content/vitamin-maize).
Maize grain with white endosperm is preferred for human consumption and contains little or no carotenoid compounds, including the vitamin A precursors β-carotene and β-cryptoxanthin. Maize grain with orange endosperm, which does contain pro-vitamin A compounds, could help alleviate this problem, but is uncommon in Africa. When combined with education, color has implications for acceptance because consumers can associate orange grain color, which African consumers appear to accept, with provitamin A (Stevens and Winter-Nelson, 2008; Meenakshi, 2010).
A QTL mapping study was undertaken to determine the genetic basis of visually scored orange endosperm color in maize. Linkage analysis conducted across and within ten of the nested association mapping families identified five common quantitative trait loci (QTL), and six rare QTL related to the relative intensity of orange grain color.
Of the identified QTL, most coincide with carotenoid biosynthetic pathway genes previously identified, including phytoene synthase (y1/psy1), ζ-carotene desaturase 1 (zds1), lycopene epsilon cyclase (lcyε), and β-carotene hydroxylase 1 (crtRB1), suggesting that selection for orange color will successfully increase total carotenoid levels in the grain (Chandler K., 2011; Buckner et al., 1996; Wong et al., 2004; Harjes et al., 2008, Yan et al., 2010).
Grain color phenotyping methods could be integrated in a cost effective manner with marker-assisted selection to improve the efficiency of breeding for improved provitamin A in maize grain.
Color variation in Hi27 x A272 population.
This spectrometer is used to quantify the amount of carotenoids in a maize sample.
Funding for this project is provided in part by HarvestPlus (Gates/USAID) and the National Science Foundation.