Subject: Re: HELP: chlorophyll in mosses
From: [email-masked] (Sam Beale)
Date: 13 Jul 1994 18:25:59 GMT
Newsgroups: bionet.photosynthesis

In article <[email-masked]>, [email-masked] (j.kerslake)
wrote:

> HI...
> 
> Could anyone please help with the following question:
> 
> Is biosynthesis of chlorophylls and carotenoids light - dependent in 
> bryophytes (particularly mosses) in the same way as it is in angiosperms?
> 
> If so, which wavelengths are required?
> 
> Any references?
> 
> (this is for a friend who is studying mosses under snowbeds)
> 
> Thanks for any help.....
> 
> Jim (for Clare).
> 
> [email-masked]

Chlorophyll synthesis in mosses is not dependent on light.  This subject
has not been studied in mosses for a very long time.  It has been known
for well over a century that gymnosperms can form chlorophyll in the
absence of light.  There are also several inderect references to
light-independent chlorophyll synthesis in other "nonflowering plants". 
As for mosses in particular, the earliest reference that I could find for
light-independent chlorophyll synthesis is Schimper, A. F. W. (1885)
Untersuchungen u(e)ber die Chlorophyllko(e)per und die inhen homologen
Gebilde.  Jahrbuch fu(e)r wissenshaften Botanik XVI, 1-247.  The mention
of mosses occurs on pp 159-161 of this lengthy article.

To bring things up to date, light-independent chlorophyll synthesis is now
known to be associated with several nuclear genes as well as with three
chloroplast genes, chlB, chlL, and chlN.  These chloroplast genes (or
homologs thereof) are present in cyanobacteria, photosynthetic bacteria,
green algae, "lower" plants including the liverwart Marchantia polymorpha,
and gymnosperms, but not in the plastids of any of the angiosperms whose
chloroplast genomes have been completely sequrenced.  I don't believe
mosses have been examined for the presence of these genes.  I would be
inclined to conclude that angiosperms can not synthesize chlorophyll in
the dark, notwithstanding occasional reports to the contrary.  For a
fairly recent paper on these chl genes, see Li, J., Goldschmidt-Clermont,
M., and Timko, M. P. (1993) Chloroplast-encoded chlB is required for
light-independent protochlorophyllide reductase activity in Chlamydomonas
reinhardtii.  The Plant Cell 5, 1817-1829.

I hope this helps.