Seed Science Research 13: 139-153 (2003)
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Distinct expression patterns of ß-1,3-glucanases and
chitinases during the germination of Solanaceous seeds
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Luciana Petruzzelli (1), Kerstin Müller (2), Katrin Hermann
(2), Gerhard Leubner-Metzger (2)
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(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: 10 July 2002 / Accepted after revision: 8 January 2003
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Abstract. The expression patterns of ß-1,3-glucanases
(ßGlu) and chitinases (Chn) were investigated during the seed germination
of type members of the Cestroideae (three Nicotiana species,
Petunia hybrida) and the Solanoideae (Capsicum annuum,
Physalis peruviana) subgroup of Solanaceous species. Rupture of the
micropylar testa (seed coat) and rupture of the micropylar endosperm, i.e.
radicle emergence, were distinct and temporally separate events during the
germination of Cestroideae-type seeds. ßGlu accumulation in
imbibed Cestroideae-type seeds occurred after testa rupture, but
prior to endosperm rupture, was inhibited by abscisic acid (ABA) and promoted
by gibberellins (GA) and light in strict association with germination, and
appeared to be caused by transcriptional regulation of the class I ßGlu
genes. The micropylar cap of Solanoideae-type seeds does not allow
a distinction between testa and endosperm rupture, but ßGlu accumulation
occurred prior to radicle emergence of pepper and P. peruviana seeds. ABA
inhibited endosperm rupture and ßGlu accumulation in the micropylar
cap of pepper seeds. In contrast to tomato, ßGlu accumulation in pepper
seeds was not only confined to the micropylar cap, was due to distinct,
tissue-specific ßGlu isoforms, and was not accompanied by Chn accumulation.
In conclusion, ABA inhibition of germination and ßGlu accumulation
in the micropylar endosperm appears to be a widespread event during the
seed germination of Solanaceous species. In contrast, accumulation of Chn
and of distinct ßGlu isoforms in the embryo prior to germination appears
to be a species-specific phenomenon within the Solanaceae. In addition,
a post-germination co-induction of ßGlu and Chn in the root of the
emerged seedling was found in endospermic and non-endospermic species and
could represent an evolutionary conserved event during dicot seedling development.
Key words: abscisic acid - Capsicum - chitinase - gibberellin
- ß-1,3-glucanase - Nicotiana - seed germination - Solanaceae
family
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