chapter  7
8 Pages

Nuclear DNA and Plant Evolution

WithArchana Sharma, Sumithra Sen

The nuclear DNA content of plant has direct relation with generation time, which affects the rate of plant development, that is, period of cell cycle, meiotic duration, pollen maturation time, and such other features. In species where there is no phylogenetic increase either through polyploidy or high amount of repeats, the organisms develop an evolutionary strategy of ontogenetic increase in nuclear DNA through endomitotic replication. The values of nuclear DNA often vary widely among different groups. In general, tree species exhibit low DNA value in chromosomes. In general, polyploidy and repetitive sequences are considered to be mechanisms of phylogenetic increase of nuclear DNA. As far as evolutionary rate is concerned, highly evolved species with low DNA content may represent a blind lane in evolution as compared to less advanced species with more DNA content. In plants higher in the evolutionary scale, a balance between phylogenetic and ontogenetic increase in DNA has been one of the principal features in evolution.