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Old February 12, 2012   #7
bower
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Location: Newfoundland, Canada
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Originally Posted by loeb View Post
So, if i want to work with tomatoes like lutescent or variegated or tigerette cherry, I should use them as a maternal parent?
If you are concerned about the colour, I think maternal parent would only have an effect in a few cases where the colour effect is specifically produced by nuclear DNA acting upon the 'plastome' DNA in the chloroplast, which is also the chromoplast in the ripe fruit.

The rin gene study which Tom linked is a good example of this, and I also found another while reading today: the hp or 'high pigment' genes - which are in the nuclear genome and equally distributed by the male or female parent - produce their effects, at least in part, by affecting the gene expression of the chloroplast DNA inherited from the mother. So presumably some differences in that maternal DNA could contribute to the final phenotype result.
This study found that the number of copies of chloroplast DNA was increased by the HP gene. So when HP high pigment is expressed, the larger number of chloroplasts (becoming chromoplasts) in the fruit would cause more intense colour in the fruit.
http://www.springerlink.com/content/p8f77vyhf1jenbq9/
A second study involving a hp-2 allele also found increased chloroplast size and number was present from early stage of fruit development.
http://www.plantphysiol.org/content/145/2/389.full

Other than the 'pigment container' chromoplast expression effects, there seems a relatively small potential for fruit colour to be affected by maternal cDNA. Most of the chloroplast DNA is strongly downregulated in ripening fruit, except for one gene (accD) which is involved in fatty acid biosynthesis for the membranes of the chromoplasts which will contain the pigments, according to this article: http://www.plantcell.org/content/20/4/856.full.

On the other hand, the majority of colour related genes are in the nuclear genome. There's a good section on colour genetics and pigment chemistry in tomatoes and peppers in this article, which is nicely written in fairly plain english.
http://jxb.oxfordjournals.org/content/58/14/3841.full
Another overview of the major colour genes in tomato nuclear genome is found here: www.oardc.ohio-state.edu/tomato/jashs1098.pdf

Red/yellow fruit colour is not affected by maternal DNA, according to reciprocal cross results: http://www.scielo.br/scielo.php?pid=...pt=sci_arttext

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