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Home >>Molecular Maps of Plant Genome >>Study of Phylogenetic Relationship Using RFLPs
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Study of Phylogenetic Relationship Using RFLPs -In recent years, the techniques of molecular biology have been extensively utilized for revealing phylogenetic relationships. For instances sequences of small DNA segments (e.g. 5S rRNA genes) have been used for suggesting phylogenetic relationships in Angiosperms.
Similarly, nuclear RFLPs (not so much those for mitochondrial or chloroplast DNA) have proved useful for the study of phylogenetic relationships in several groups of plant species including the genera Brassica, Lens (lentils) and Solanum.
In the genus Solanum, phenetic trees were obtained using wild and cultivated species and it was demonstrated that these trees do not change, when different computational methods or different genotypes of the same species or different sets of RFLPs were used.

In order to establish phylogenetic, relationship among different species of a genus, data on restriction fragment patterns of these species using a large number (sometimes upto one hundred) of probe/enzyme combinations (several enzymes per probe) are first collected. Fragments on Southern blots are numbered 1 to n and a distance matrix is computed using presence or absence of these fragments in different species.
It will be seen that in four genotypes, not all fragments are informative. In two genotypes of a pair, number of fragments for which two genotypes differ are worked out (Bjj) and divided by the total number of fragments present in at least one of the two genotypes (Mjj).
From these estimates, distance (Djj) between the two genotypes is calculated as follows: Djj = Bjj / Mij . This gives a distance matrix.This information is then used for computer analysis of the data and phylogenetic trees depicting phylogenetic relationships can be prepared.

 

  

 
 

 

 
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