PLANT PHYSIOLOGY , Vol 105, Issue 4 1375-1383, Copyright © 1994 by American Society of Plant Biologists
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DEVELOPMENT AND GROWTH REGULATION |
Catalase Is Differentially Expressed in Dividing and Nondividing Protoplasts
C. I. Siminis, A. K. Kanellis and K. A. Roubelakis-Angelakis
Department of Biology, University of Crete, P.O. Box 1470, 71110 Heraklio, Crete, Greece (C.I.S., K.A.R.-A)
Based on our previous results that peroxidase is induced in dividing
tobacco protoplasts but it is not expressed in the nondividing grapevine
(Vitis vinifera L.) protoplasts during culture (C.I. Siminis, A.K.
Kanellis, K.A. Roubelakis-Angelakis [1993] Physiol Plant 87: 263-270), we
further tested the hypothesis that oxidative stress may be implicated in
the recalcitrance of plant protoplasts. The expression of catalase, a major
defense enzyme against cell oxidation, was studied during isolation and
culture of mesophyll protoplasts from the recalcitrant grapevine and
regenerating tobacco (Nicotiana tabacum L.). Incubation of tobacco leaf
strips with cell wall-degrading enzymes resulted in a burst of catalase
activity and an increase in its immunoreactive protein; in contrast, no
such increases were found in grapevine. The cathodic and anodic catalase
isoforms consisted exclusively of subunits [alpha] and [beta],
respectively, in tobacco, and of subunits [beta] and [alpha], respectively,
in grapevine. The catalase specific activity increased only in grapevine
protoplasts during culture. The ratio of the enzymatic activities to the
catalase immunoreactive protein declined in dividing tobacco protoplasts
and remained fairly constant in nondividing tobacco and grapevine
protoplasts during culture. Also, in dividing tobacco protoplasts the de
novo accumulation of the catalase [beta] subunit gave rise to the acidic
isoenzymes, whereas in nondividing tobacco and grapevine protoplasts, after
8 d in culture, only the basic isoenzymes remained due to de novo
accumulation of the [alpha] subunit. The pattern of catalase expression in
proliferating tobacco leaf cells during callogenesis was similar to that in
dividing protoplasts. The different responses of catalase expression in
dividing and nondividing tobacco and grapevine mesophyll protoplasts may
indicate a specificity of catalase related to induction of totipotency.
