Nature of Fo'

Jonathan B. Marder MARDER at
Mon Sep 30 11:04:39 EST 1996

In article <526gl3$3dm at>,
   Mark.Hovenden at (Mark Hovenden) wrote:
>Does anyone out there know where I might find the first records of
>minimal fluorescence in light adapted samples, Fo'?  Also, can some
>learned person begin a discussion on the nature Fo'?

I think that there is even a problem with Fo (Fo is for dark-adapted
leaves, Fo' for light-adapted). We have shown by fluorescence
lifetime that for healthy leaves, the vast majority of Fo appears to
come from PSII. However, in other cases (e.g. stress), this is no longer
the case. We therefore suggested the resolution of Fo into 2 components,
the active portion (due to open PSII) and the inactive portion (Fn in
our publications) which is "dead" fluorescence which stays constant
during PSII closure. Take a look at our paper in the last Photosynthesis
Congress proceedings:
  Marder JB, Caspi V & Raskin VI (1995) Free chlorophyll effects on
  variable fluorescence. In: Photosynthesis: from Light to Biosphere
  (P. Mathis, Ed.), Vol. III, pp. 345-348, Kuwer Academic Publishers.

I expect that for Fo', the fluorescence lifetime and yield of (open)
PSII would be smaller, thus the contribution of dead fluorescence would
be proportionately larger.

Jonathan B. Marder             ,      Department of Agricultural Botany
E-mail: MARDER at |      The Hebrew University of Jerusalem
Phone: (08 or +9728) 9481918   | /\/  Faculty of Agriculture
Fax:   (08 or +9728) 9467763   |/  \  P.O.Box 12, Rehovot 76100, ISRAEL

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