Hello all,
Recently I ran a lab for a plant physiology course that involved the
reduction of DCPIP by isolated chloroplasts from store bought
spinach. This seems like a fairly robust lab and the two basic
treatments work quite well. Light resulted in the reduction of DCPIP by
chloroplasts. DCMU completely inhibited this activity, as does boiling
the chloroplasts.
Another of the treatments I included was KCN. My thoughts on this were
that mitochondrial activity in the chloroplast prep may also reduce
DCPIP, therefore inclusion of KCN would stop mitochondiral electron
transport, and DCPIP reduction, if occurring. Therefore either no
effect of the KCN on rate of reduction or a slight decrease in rate of
reduction would be expected. Much to my surprise however the KCN
treatments actually had an accelerated rate of DCPIP reduction. To
them, it appeared that KCN accelerates photosynthetic activity. I was
at a loss to explain this to my students. Any ideas on what is
happening here?
Many thanks for any replies,
Douglas Bielenberg
Department of Horticulture
Clemson University
