Tomatoville® Gardening Forums - View Single Post - Breeding for improved beta-carotene

joseph · July 15, 2013

I prefer the taste of high carotene foods to low carotene versions of the same food.

Genes crossover between the paired chromosomes, so it's possible to break the linkage between two genes on the same chromosome. How frequently that happens depends on how close together the genes are located on the chromosome. If they are on opposite ends of the chromosome it's like they are not linked at all. If they are side by side then it would be much less likely to break the linkage. If you can find a gene-map containing both genes, and it has a centimorgan scale on it, then that is a measures the likelihood of the linkage being broken in a cross. 1 centimorgan = 1% chance. So if they are tightly linked you just have to grow more plants to break the linkage.

Here's an example of a gene map. In this particular cross, chromosomes 3 and 8 contain a QTL for carotene content. The B gene is located on Chromosome 6. So there are lots of opportunities for increased carotene content.

July 15, 2013	#19
joseph Tomatovillian™ Join Date: May 2013 Location: Cache Valley, N/E of The Great Salt Lake Posts: 1,244	I prefer the taste of high carotene foods to low carotene versions of the same food. Genes crossover between the paired chromosomes, so it's possible to break the linkage between two genes on the same chromosome. How frequently that happens depends on how close together the genes are located on the chromosome. If they are on opposite ends of the chromosome it's like they are not linked at all. If they are side by side then it would be much less likely to break the linkage. If you can find a gene-map containing both genes, and it has a centimorgan scale on it, then that is a measures the likelihood of the linkage being broken in a cross. 1 centimorgan = 1% chance. So if they are tightly linked you just have to grow more plants to break the linkage. Here's an example of a gene map. In this particular cross, chromosomes 3 and 8 contain a QTL for carotene content. The B gene is located on Chromosome 6. So there are lots of opportunities for increased carotene content. Last edited by joseph; July 15, 2013 at 12:58 PM.