QTL and candidate genes phytoene synthase and ζ-carotene desaturase associated with the accumulation of carotenoids in maize

Abstract

Carotenoids are a class of fat-soluble antioxidant vitamin compounds present in maize ( Zea mays L.) that may provide health benefits to animals or humans. Four carotenoid compounds are predominant in maize grain: beta-carotene, beta-cryptoxanthin, zeaxanthin, and lutein. Although beta-carotene has the highest pro-vitamin A activity, it is present in a relatively low concentration in maize kernels. We set out to identify quantitative trait loci (QTL) affecting carotenoid accumulation in maize kernels. Two sets of segregating families were evaluated-a set of F2:3 lines derived from a cross of W64a x A632, and their testcross progeny with AE335. Molecular markers were evaluated on the F2:3 lines and a genetic linkage map created. High-performance liquid chromatography was performed to measure beta-carotene, beta-cryptoxanthin, zeaxanthin, and lutein on both sets of materials. Composite interval mapping identified chromosome regions with QTL for one or more individual carotenoids in the per se and testcross progenies. Notably QTL in the per se population map to regions with candidate genes, yellow 1 and viviparous 9, which may be responsible for quantitative variation in carotenoids. The yellow 1 gene maps to chromosome six and is associated with phytoene synthase, the enzyme catalyzing the first dedicated step in the carotenoid biosynthetic pathway. The viviparous 9 gene maps to chromosome seven and is associated with zeta-carotene desaturase, an enzyme catalyzing an early step in the carotenoid biosynthetic pathway. If the QTL identified in this study are confirmed, particularly those associated with candidates genes, they could be used in an efficient marker-assisted selection program to facilitate increasing levels of carotenoids in maize grain.

The colours of durum wheat: a review

“…This is in agreement with significant positive correlations among the individual carotenoids, and between the individual carotenoids and the total carotenoids and the YI within the segregating population. The QTLs have been found that explain the accumulation of more than one of these compounds, as previously shown for maize (Wong et al 2004;Chander et al 2008), chickpea (Abbo et al 2005) and carrot (Just et al 2009). Since the examined carotenoid traits represent compounds that are synthesised at different steps in the same biochemical pathway in several plant species (Just et al 2009), the clustering of several QTLs for various carotenoid traits may be due to pleiotropy.…”

“…Such HPLC techniques provide selective methods for the identification and quantification of novel genetic sources aimed at increasing b-carotene levels. These techniques are also useful to distinguish the two provitamin A components, a-carotene and b-cryptoxanthin, attributable to a single provitamin A structure (Wong et al 2004;Blanco et al 2011).…”

Mapping QTL, epistasis and genotype × environment interaction of antioxidant activity, chlorophyll content and head formation in domesticated lettuce (Lactuca sativa)

“…However, because of its high per capita consumption, lettuce is the fourth highest contributor of antioxidants of all vegetables consumed in the USA (Song et al 2010). Quantitative trait loci (QTL) have been associated with increased antioxidants in carrot (Santos and Simon 2002), tomato (Rousseaux et al 2005), rapeseed (Marwede et al 2005), chickpea (Abbo et al 2005), apple (Davey et al 2006), maize (Chander et al 2008;Wong et al 2003Wong et al , 2004, durum wheat (Patil et al 2008), and oat (Jackson et al 2008). Significant genotype 9 environment interaction (GEI) was reported for antioxidant content in tomatoes (Rousseaux et al 2005), tocopherol in oat (Jackson et al 2008) and rapeseed (Marwede et al 2005), and carotenoids in durum wheat (Patil et al 2008).…”

Probability of success of breeding strategies for improving pro-vitamin A content in maize

“…Two traits were deWned, one for pVAC in maize grain, and the other for Weld adaptation. Based on previous genetic studies (Wong et al 2004;Chander et al 2008a;Harjes et al 2008;Yan et al 2010), four additive genes, distributed on four chromosomes, were assumed to control pVAC (Table 1). The total additive eVect of these genes was 7.5 g/g and the mid-parent value of pVAC was 7.5 g/g.…”

“…Progress in developing saturated genetic maps and quantitative trait loci (QTL) mapping methods (Bernardo 2002;Li et al 2007a) has led to the intensive use of QTL mapping in various segregating populations to study the genetic control of carotenoids in maize grain (Wong et al 2004;Chander et al 2008a). Major genes with large genetic eVects (i.e., crtRB1 and LcyE), have been identiWed and conWrmed across diVerent populations (Harjes et al 2008;Yan et al 2010).…”