plant rna extraction : purity problems

[Sam Lievens]

hi all,

i'm having serious problems getting pure rna out of the roots of our
plant. it's a tropical legume. getting rna from the aerial parts is no
problem (od 260/280 of 2.0 and 260/230 of about 2.3), pure enough to
prepare cdna of.
but using the same protocol (licl based method) on roots gives me dirty
rna (od 260/280 still around 1.8 but 260/230 of only 1-1.5 so i guess
caused by polysaccharide contamination). i tried other methods (trizol,
quiagen rneasy columns) but it doesn't help.
so two questions: how can i get pure rna and how can i further purify
the dirty rna i already have (i already precipitated it again with licl,
doesn't help; i did 2 fenol/chloroform extractions and ethanol
precipitation, doesn't help neither).

sam

--
===========================================================
Sam Lievens

DEPARTMENT OF GENETICS       -       UNIVERSITY OF GENT/VIB
K.L. Ledeganckstraat 35    -    9000 Gent    -      Belgium
tel: +32(0)92645183                     fax: +32(0)92645349
salie at gengenp.rug.ac.be  http://www.plantgenetics.rug.ac.be
===========================================================