|MadSci Network: Molecular Biology|
I previously wrote a discussion of comparison of plant and animal genomes in another MadSci post, as you've mentioned. In that one I suggested using the NCBI homologene tool to make this comparison. This tool does overall comparisons of predicted proteins from two species, but it only gives a limited set of choices for those species, and the only plant available is Arabidopsis . The rice genome has been compared in various places with the Arabidopsis genome, notably by the workers who released the rice genome themselves. In the paper describing the first draft sequence of the rice genome, Yu et al. (Science. 2002 Apr 5;296(5565):79-92) point out that, while the vast majority of Arabadopsis genes are found in the rice genome, there are many more genes in the rice genome that don't appear in Arabidopsis. I can't find any direct full comparison of rice and human genomes. A powerpoint on "alignment" from the Natural History Museum of Britain contains a table that shows a distance matrix that includes a distance value of 122.6 for the human and rice genomes (compared to a distance of 3.3 for human and monkey), so you can see we're not all that close. Still, you're asking whether the rice genome sheds any new light on the human/plant evolutionary distance. I'd guess that the rice/human distance is rather similar to the Arabidopsis/human distance. My reasoning is this: Most of the Arabidopsis genes are found in rice. Second, the additional genes in rice are probably the result of gene duplications (see Yu et al. 2002), so they're unlikely to be any more similar to human genes than the rest of the genome is.
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