Plant, Cell and Environment 26: 661-671 (2003)


Calcium requirement for ethylene-dependent responses involving 1-aminocyclopropane-1-carboxylic acid oxidase in radicle tissues of germinated pea seeds

Luciana Petruzzelli (1), Monica Sturaro (1), Davide Mainieri (1), Gerhard Leubner-Metzger (2)

(1) Istituto Biosintesi Vegetali, C.N.R., via Bassini 15, I-20133 Milano, Italy
(2) Institut für Biologie II, Botanik, Albert-Ludwigs-Universität, Schänzlestr. 1, D-79104 Freiburg i. Br., Germany

Received: 12 July 2002 / Accepted: 30 October 2002

cover pea Cover photograph of the May 2003 issue of Plant, Cell & Environment related to
this publication showing the effect of ethylene treatment on pea radicle growth

View a larger image of the cover photograph in a new window (16 KB)

Abstract. The Ca2+ requirements of ethylene-dependent responses were investigated in germinating seeds of Pisum sativum L. using 1-aminocyclopropane-1-carboxylic acid (ACC) oxidase (Ps-ACO1), ACC synthase (Ps-ACS2) and class I ß-1,3-glucanase as molecular markers. Ethylene biosynthesis and responsiveness are localized to the elongation and differentiation zones of the pea radicle. Ethylene treatment induced ectopic root hair formation in the cell elongation zone and promoted root hair elongation growth in the radicles of germinated seeds. Characterized Ca2+ antagonists, including EGTA, lanthanum, verapamil, ruthenium red, W-7, lithium and neomycin, were used to test for the involvement of the apoplastic and the intracellular Ca2+-pool, the Ca2+/calmodulin complex and the phoshoinositide (PI) cycle in the ethylene responses. Ca2+ release from internal pools, but not appreciably apoplastic Ca2+, is involved in the transcriptional induction by ethylene of Ps-ACO1 and in ectopic root hair formation in the radicle elongation zone of germinated pea seeds. Furthermore, the Ca2+/calmodulin complex and the PI cycle seem to be involved in these ethylene responses. In contrast, both the intracellular and the apoplastic Ca2+-pools are required for the negative and positive ethylene-responses on the gene expression of PS-ACS2 and class I ß-1,3-glucanase, respectively; and, apoplastic Ca2+ also promotes root hair elongation growth. Tissues from adult plants and germinating seeds exhibit temporal and spatial differences in the signal/response coupling by Ca2+ of ethylene-regulated processes.

Key words: 1-Aminocyclopropane-1-carboxylic acid oxidase - Calcium signaling - Ethylene signaling - Embryonic root - Pisum - Root hair development

Links to other publications on ethylene and pea seed germination:
Petruzzelli et al. 2000
Petruzzelli et al. 1999
Article in PDF format (332 KB)
Abstract          Fig. 1          Fig. 2          Fig. 3          Fig. 4          Fig. 5          ßGlu expression
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