Using molecular markers to identify two major loci controlling carotenoid contents in maize grain

National Maize Improvement Center of China, China Agricultural University, Yuanmingyuan West Road, Haidian, 100094 Beijing, People's Republic of China.
Theoretical and Applied Genetics (Impact Factor: 3.79). 02/2008; 116(2):223-33. DOI: 10.1007/s00122-007-0661-7
Source: PubMed


Maize is an important source of pro-vitamin A; beta-carotene, alpha-carotene and beta-cryptoxanthin, and the non-pro-vitamin A carotenoids including lutein and zeaxanthin. In the present study, a recombinant inbred (RI) population with 233 RI lines derived from a cross between By804 and B73 was employed to detect QTL for these nutritionally important components in maize grain. High Performance Liquid Chromatography was used to measure amounts of individual carotenoids over 2 years. A genetic linkage map was constructed with 201 molecular markers. In all, 31 putative QTL including 23 for individual and 8 for total carotenoids were detected on chromosome(s) 1, 3, 5, 6, 7, 8 and 10. The notable aspect of this study was that much of the phenotypic variation in contents of carotenoids could be explained by two loci (y1 and y9), and the QTL for carotenoids elucidated the interrelationships among these compounds at the molecular level. A gene targeted marker (Y1ssr) in the candidate gene phytoene synthase 1 (psy1) tightly linked to a major QTL explaining 6.6-27.2% phenotypic variation for levels of carotenoids was identified, which may prove useful to expedite breeding for higher level of carotenoids in maize grain. This functionally characterized gene (psy1) could also be exploited for further development of functional marker for carotenoids in maize. The QTL cluster located at y9 locus may also be used for pyramiding favorable alleles controlling contents of carotenoids from diverse maize germplasm.

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Available from: Xiaohong Yang, Nov 19, 2014
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    • "This could be due to the effects of modifier loci present in the genetic background. Many such loci for accumulation of βcarotene and other kernel carotenoids have been reported earlier in maize (Wong et al. 2004; Chander et al. 2008). "
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    ABSTRACT: Vitamin A deficiency caused by insufficient intake of β-carotene has emerged as one of the most important problems afflicting people worldwide. Traditional yellow maize is predominated by lutein and zeaxanthin; but contains low β-carotene par below the daily requirement for humans. A natural variant of crtRB1 allele increases β-carotene in kernel by blocking its conversion to zeaxanthin. In the present study, genetic diversity analyses were carried out among 24 diverse maize inbreds possessing rare allele of crtRB1. The mean β-carotene among the inbreds was 9.3 μg/g, with 14 inbreds having 9.1-18.8 μg/g. Among the inbreds of exotic origin, HP704-23, HP704-22, HP467-15, HP465-41 and HP467-20 were promising with high β-carotene. In case of inbreds developed in India, VQL-2-PV, VQL1-PV, V345-PV, V335-PV, HKI161-PV, MGU-PV-2, HKI1105-PV, HKI323-PV and MGU-PV-3 were identified to possess high kernel β-carotene. These inbreds with rare allele of crtRB1 are unique germplasm and therefore holds immense promise in the biofortification programme worldwide. Molecular profiling of these inbreds using 65 SSRs distributed throughout the genome generated 268 alleles with a mean of 4.12 alleles per locus. The polymorphism information content varied from 0.21 to 0.82 with a mean of 0.58. The study detected 12 each of unique and rare alleles. Genetic dissimilarity ranged from 0.40 to 0.94 with an average of 0.79. Cluster analyses grouped 24 genotypes into four major clusters, and principal coordinate analysis depicted the diverse nature of the genotypes consistent with their pedigree. The study identified potential hybrid combinations for higher β-carotene that can be directly utilized in the biofortification programme.
    Journal of Plant Biochemistry and Biotechnology 02/2015; DOI:10.1007/s13562-015-0300-3 · 1.09 Impact Factor
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    • "While the grain of most yellow maize lines worldwide contains <2 mg/g of the provitamin A compound b-carotene, considerable variation has been found for this and a number of other non-provitamin A carotenoids with health benefits in diversity panels—including b-carotene content nearing the 15 mg/g fresh weight (17 mg/g dry weight) provitamin A breeding target established by HarvestPlus (Bouis and Welch, 2010; Harjes et al., 2008). This extensive genetic diversity, characteristic of maize, is being dissected and leveraged to identify alleles at quantitative trait loci (QTL) favorable for high provitamin A content in grain at harvest (Chander et al., 2008; Fu et al., 2013; Harjes et al., 2008; Owens et al., 2014; Wong et al., 2004; Yan et al., 2010; Zhou et al., 2012). Some of these alleles are being backcrossed into varieties already adapted to HarvestPlus target regions in Zambia, Nigeria, and Ghana to maintain competitive grain yield and disease resistance. "
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    ABSTRACT: Improvement of crop nutritional quality through breeding, termed biofortification, is a strategy being used to address micronutrient deficiencies worldwide. These efforts stand to benefit tremendously from recent advances across the plant sciences, from flourishing germplasm and genomic resources and phenotyping tools to improved characterization at the levels of physiology, cell biology, and gene expression. Next steps in crop biofortification in this decade and beyond include adapting high-throughput phenotyping platforms for measurement of nutritional quality traits, testing genome-wide and other DNA marker-based selection strategies that can mine parsimonious answers from large data sets, and further characterizing genotype × environment interactions and post-harvest effects on end nutrition. Also necessary are accompanying considerations of yield and other agronomic traits—in particular, the non-uniform responses of both these and quality traits to climate change across crops, environments, and farming management systems. These integrative analyses from genotype to phenotype and planting to consumption can minimize trade-offs between yield and nutrition and maximize the range, magnitude, and longevity of the benefits of biofortified varieties to human health and nutrition.
    Crop Science 01/2015; 55:1-12. DOI:10.2135/cropsci2014.08.0555 · 1.58 Impact Factor
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    • "To date, efforts have focused on engineering or selecting natural variants of specific carotenoid biosynthetic enzymes for a desired outcome (Shewmaker et al., 1999; Ye et al., 2000; Paine et al., 2005; Fitzpatrick et al., 2012). However, the majority of QTL intervals affecting seed carotenoid traits in several crops do not contain carotenoid biosynthetic genes, suggesting that novel genes make substantial contributions to observed natural variation in carotenoid traits (Wong et al., 2004; Pozniak et al., 2007; Chander et al., 2008, 2013; Fernandez et al., 2008). This is also true in model plants like Arabidopsis, where ;80% of the QTL intervals in the Col-0/ Ler and Cvi/Ler RIL populations lack carotenoid biosynthetic genes (see Supplemental Table 1 online). "
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    ABSTRACT: Experimental approaches targeting carotenoid biosynthetic enzymes have successfully increased the seed β-carotene content of crops. However, linkage analysis of seed carotenoids in Arabidopsis thaliana recombinant inbred populations showed that only 21% of quantitative trait loci, including those for β-carotene, encode carotenoid biosynthetic enzymes in their intervals. Thus, numerous loci remain uncharacterized and underutilized in biofortification approaches. Linkage mapping and genome-wide association studies of Arabidopsis seed carotenoids identified CAROTENOID CLEAVAGE DIOXYGENASE4 (CCD4) as a major negative regulator of seed carotenoid content, especially β-carotene. Loss of CCD4 function did not affect carotenoid homeostasis during seed development but greatly reduced carotenoid degradation during seed desiccation, increasing β-carotene content 8.4-fold relative to the wild type. Allelic complementation of a ccd4 null mutant demonstrated that single-nucleotide polymorphisms and insertions and deletions at the locus affect dry seed carotenoid content, due at least partly to differences in CCD4 expression. CCD4 also plays a major role in carotenoid turnover during dark-induced leaf senescence, with β-carotene accumulation again most strongly affected in the ccd4 mutant. These results demonstrate that CCD4 plays a major role in β-carotene degradation in drying seeds and senescing leaves and suggest that CCD4 orthologs would be promising targets for stabilizing and increasing the level of provitamin A carotenoids in seeds of major food crops.
    The Plant Cell 12/2013; DOI:10.1105/tpc.113.119677 · 9.34 Impact Factor
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