brown stuff secreted by plants??
ajt at rri.sari.ac.uk
Thu Mar 28 14:02:02 EST 1996
Chris Skory wrote:
> This question will probably reveal my ignorance in plant physiology,
> but, I was curious what general types of compounds do plants secrete
> from their roots. I ask this because I saw some plants (eg lettuce,
> carrots, etc) growing in sterile medium the other day. The medium
> became increasingly more turbid and brown as the culture grew. Is
> this protein, alkaloids or some other secondary metabolite. Any
> help would be appreciated.
Plant roots are adapted for the uptake of water and minerals. They do
not normally 'secrete' anything as such but the root 'cap' is sloughed
off as the root penetrates the soil or other medium it is growing
This has important consequences for interaction between the plant and
soil microorganisms, but it may also release soluble phenolic compounds
amongst other things into a sterile medium. These phenolic compounds
would turn brown and be insoluble when oxidised.
Of course, if the roots are growing in a sterile _solution_ then no
sloughing of the root cap will occur. The cells in the root cap will
simply degenerate and lose their contents into the medium. However, if
the sterile medium is exposed to light then you may just be seeing the
growth of algae - if it's not sterile any more ...
Dr. A.J.Travis, | mailto:ajt at rri.sari.ac.uk
Rowett Research Institute, | http://www.rri.sari.ac.uk/~ajt
Greenburn Road, Bucksburn, | phone:+44 (0)1224 712751
Aberdeen AB2 9SB, Scotland, UK. | fax:+44 (0)1224 716687
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