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plant DNA extraction - (May/12/2005 )


There are some questions related to plant DNA extraction:

1. why the conc. of protein is differe from plant to plant? this is observe when i quantify the DNA by spectrophotometer.

2. why some plant contain polyssacaride and polyphenols than others.

3. when im doing the extraction to the same species ( one of them as replicate) , same procedure and at the same time i will find that the ratio, DNA conc., and purity are differrent although they are same . this is may be during the grinding that im grind one to fine powder which my DNA degraded by nucleases activity.


Hi Nona

The quantity of protein is different from plant to plant, depending on the size of the cells (and thus which tissues) you are extracting from for example if you are extracting from leaves you might get a relatively high protein content, compared to extracting from roots. However, you shouldn't get much protein in your DNA after the extraction proceedure, no matter what tissue you are extracting from.

The level of polysaccharide and polyphenols in plants varies widely, I used to work on Pittosporum which are full of polyphenolics, and really hard to get clean DNA from. It is thought that these compounds are sued as defence against bacterial and funagl attack as well a protection against insects and other browsers, by making the plants taste bad, or indigestible.

You will find that any two extractions from replicate samples will be different, this is because you will have used slightly different amounts of tissue and reagents in each individual reaction. Still replicates if all conditions are the same, should have reasonably close purity, concentration etc. When grinding tissue, it may help to use liquid nitrogen or dry ice so that you inhibit nucleases (and it is easier to grind when frozen).

Anyway, Hope this has helped,



thanks bob

im extract DNA from plant leave tissue, also i want to know why the conc. of protein and DNA are not unique in all plant although im using the same tissue (leave) and same weight (2g) in all plant.