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Home >> Plant Biotechnology and Genomics >>Construction of Molecular Maps and Synteny (Collinearity) >>Genomics for Evolutionary Studies

Genomics for Evolutionary Studies
DNA sequences have also been utilized for evolutionary studies, where phylogenetic trees could be prepared on the basis of similarities between sequences of individual genes like 5S rRNA genes, 18S rDNA genes, rbcL and several other genes. Already by 1980s, large sequence data and sophisticated computer based analytical tools had become available for this purpose for redrawing the phylogenetic tree of life. However, in most of these earlier studies, sequences of one or two genes were utilized at a time, and the sequences of individual genes like 185 rDNA and rbcLgene did not find the most parsimonious trees.

Therefore, in a study conducted in 1999, DNA sequences of plastid genes rbcLand atpB and the nuclear gene for 18S rRNA of 560 species of angiosperms and seven non-flowering plants were utilized together for preparing a well-resolved phylogenetic tree. Similarly, a study of DNA sequences of five mitochondrial, plastid and nuclear genes (atpl, matR, atpB rbcL, 18S rDNA) of 105 species belonging to 103 genera and 63 families suggested that Amborella,Nymphaeales and illicales- Trimeniaceae- Austrobaileyarepresent the first stage of Angiosperm evolution, with Amborellabeing sister to all other angiosperms. Almost the same conclusions were also drawn through a study of duplicate phytochrome genes, PHYA and PHYC.

 

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