Planta 209: 195-201 (1999)
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Distinct ethylene- and tissue-specific regulation of ß-1,3-glucanases
and chitinases during pea seed germination
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Luciana Petruzzelli (1), Christian Kunz, Rosa Waldvogel, Frederick
Meins Jr., Gerhard Leubner-Metzger
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Friedrich Miescher Institute, Maulbeerstr. 66, CH-4058 Basel, Switzerland
(1) Istituto Biosintesi Vegetali, C.N.R., Via Bassini 15, I-20133 Milano,
Italy
Received: 12 January 1999 / Accepted: 22 March 1999
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Abstract. We investigated the expression of ß-1,3-glucanase
(ßGlu) and chitinase (Chn) in the testa, cotyledons, and embryonic
axis of germinating Pisum sativum L. cv. 'Espresso generoso' seeds.
High concentrations of ßGlu and Chn activity were found in the embryonic
axis. Treatment with ethylene or in combination with the inhibitor of ethylene
action 2,5-norbornadiene (NBD) showed that an early, 4-fold induction of
ßGlu activity in the embryonic axis during the first 20 h after the
start of imbibition is ethylene-independent. This initial increase was followed
by a later 4-fold ethylene-dependent induction in the embryonic axis starting
at 50 h, which is after the onset of ethylene evolution and after completion
of radicle emergence. The ßGlu activity in cotyledons increased gradually
throughout germination and was ethylene-independent. In contrast, Chn activity,
which was ethylene-independent, increased slightly after the onset of radical
emergence in the embryonic axis and remained at a constant, low level in
cotyledons. Immunoinactivation assays and immunoblot analyses suggest that
early ßGlu activity in the embryonic axis is due to a 54 kDa antigen,
whereas, late induction is due to a 34.5 kDa antigen, which is likely to
be the ethylene-inducible class I ßGlu G2 described for immature pea
pods. Increases in Chn in the embryonic axis were correlated with a 26 kDa
antigen, whereas the additional 32 and 20 kDa antigens remained roughly
constant. Thus, ethylene-dependent and ethylene-independent pathways regulate
ßGlu and Chn during pea seed germination. The pattern of regulation
differs from that of leaves and immature pods and from that described for
germinating tobacco seeds. The functional significance of this regulation
and its underlying mechanisms are discussed.
Key words: Seed germination, Pisum, Chitinase, ß-1,3-Glucanase, Ethylene,
Signaling
Links to other publications on ethylene and pea seed germination:
Petruzzelli et al. 2000
Petruzzelli et al. 2003
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