DNA extraction.

Hiranya Roychowdhury hroychow at NMSU.EDU
Fri Jul 31 15:20:30 EST 1998

At 02:46 PM 7/30/98 -0700, Deepali Mitra wrote:
>I have tried to extract DNA from tissue cultured tobacco leaves that
>were soaking in 70-95 % ethanol in order to get rid of all the
>chlorophyll.I have tried the CTAB,Qiagen mini kit,DNAzol and the
>Dellaporta methods.I have got good yields from control tissues but not
>much DNA from the ethanol soaked tissues.I would like to know if and how
>DNA can be extracted from ethanol soaked plant material.

I wont ask why it is necessary to remove the chlorophyll from the leaves.
However, I should add that chlorophyll (and other phenolics) does not
normally pose a problem in DNA extraction in our hands. 
        Alcohol will dehydrate the tissue severely to render it refractory
to various extraction procedure. You may have better luck with such tissues
after rehydrating for a prolonged period (say 12h or overnight). By the way,
does alcohol really get rid of the chl or is it just a "bleaching" effect
that you are obvserving? Normally, CHCl3 or acetone would be used to extract
the Chl from plant tissues.
        These days we are routinely using benzyl chloride to extract plant
DNA from mg to g quanitities of tissues. I have not used any of the kits
(Qiagen or DNazol etc.) so I can't comment on those.

Dr. Hiranya Sankar Roychowdhury
Plant Genetic Engineering Lab.
New Mexico State University
Las Cruces, NM 88003
Ph. (505) 646-5785
hroychow at nmsu.edu

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