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Snp single nucleotide polymorphism marker snps need

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Unformatted text preview: e desired crop variety – Marker assisted selection • Fortify food with Vitamin A precursors • Case study: Maize and Vitamin A – Lower Vitamin A deficiency related diseases 29 30 5 04/03/2013 Visually scoring key precursors is difficult Marker Assisted Selection • SNP markers that co segregate with the trait … …candidates for linkage to the genes for the trait. – SNP = single nucleotide polymorphism – Marker SNPs need not be causal • SNPs correlated with B carotene production: • Goal: – 2 5 fold higher production – Maximize carotenoids and B carotenes • But: • Incorporating these genomic regions into maize varieties could help reduce Vitamin A deficiencies – Color phenotype alone is unreliable – Difficult to quantify precursors in high throughput – If adopted by local growers • Therefore: Use genotype instead of phenotype! 31 Harjes et al. 2008, Science 319: 330 333 32 -Breeding the yellowest kernels isn't going to work to m aximize B-carotenes -However, colour is an unreliable phenotype -Incorporating the SNPs that co-segregate with the trait of Vitamin A production will reduce Vitamin A deficiencies Why do we care about genetic variation in crops? Irish Potato Famine (1845 1852) • 750,000 1 million Irish died during the famine 1. Clues to past artificial selection – 1 2 million more emigrated – On what traits did our ancestors select? • Population of Ireland fell by ~25% 2. Future improvement of crops – Is it possible to keep breeding better crops without genetic engineering? – Or is there insufficient genetic variation? • Many emigrants settled in Britain, USA & Canada – Started cultural ties that last to this day – Irish immigrants comprised ~25% of many major cities 3. Pest and pathogen management • Boston, Baltimore, Philadelphia, Toronto – Single largest ethnic group in Toronto in early 1850’s – Can we reduce crop loss to pests? 33 34 What happened? • Potatoes do not grow easily from seed • They sprout easily from the underground tuber (potato) • Leads to clonal propagation • This happens in your house if you forget about potatoes in a cabinet for too long ! • Social, economic, and religious discrimination, and colo...
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