Planta 209: 195-201 (1999)

Distinct ethylene- and tissue-specific regulation of ß-1,3-glucanases and chitinases during pea seed germination

Luciana Petruzzelli (1), Christian Kunz, Rosa Waldvogel, Frederick Meins Jr., Gerhard Leubner-Metzger

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

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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