We have not made any root cDNA libraries, but . . .
Collecting Arabidopsis root material need not be a horrendous
task. Arabidopsis plants can be grown shaking in sterile liquid
medium (We heard about this originally from Elliot Meyerowitz, but
several groups apparently do this). In our lab we sow 5
surface-sterilized seeds into a 350 ml capacity flask containing
75 ml Murashige & Skoog medium with 2% sucrose. After 21 to 25 days
shaking at 25 degrees C we replace the medium and then harvest 7 to
10 days later. This generally yields about 3.5 g of tissue. We
have never specifically measured, but eyeballing it I would guess
that root tissue exceeds leaf tissue considerably.
Mitsui Plant Biotechnology Research Institute