Nucellain, a Barley Homolog of the Dicot Vacuolar-Processing Protease, Is Localized in Nucellar Cell Walls1
The nucellus is a complex maternal grain tissue that embeds and feeds the developing cereal endosperm and embryo. Differential screening of a barley ( Hordeum vulgare ) cDNA library from 5-d-old ovaries resulted in the isolation of two cDNA clones encoding nucellus-specific homologs of the vacuolar-...
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Published in | Plant physiology (Bethesda) Vol. 118; no. 4; pp. 1169 - 1180 |
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Main Authors | , , , , , , |
Format | Journal Article |
Language | English |
Published |
American Society of Plant Physiologists
01.12.1998
|
Online Access | Get full text |
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Summary: | The nucellus is a complex maternal
grain tissue that embeds and feeds the developing cereal endosperm and
embryo. Differential screening of a barley (
Hordeum
vulgare
) cDNA library from 5-d-old ovaries resulted in the
isolation of two cDNA clones encoding nucellus-specific homologs of the
vacuolar-processing enzyme of castor bean (
Ricinus
communis
). Based on the sequence of these barley clones, which
are called nucellains, a homolog from developing corn (
Zea
mays
) grains was also identified. In dicots the
vacuolar-processing enzyme is believed to be involved in the processing
of vacuolar storage proteins. RNA-blot and in situ-hybridization
analyses detected nucellain transcripts in autolysing nucellus
parenchyma cells, in the nucellar projection, and in the nucellar
epidermis. No nucellain transcripts were detected in the highly
vacuolate endosperm or in the other maternal tissues of developing
grains such as the testa or the pericarp. Using an antibody raised
against castor bean vacuolar-processing protease, a single polypeptide
was recognized in protein extracts from barley grains.
Immunogold-labeling experiments with this antibody localized the
nucellain epitope not in the vacuoles, but in the cell walls of all
nucellar cell types. We propose that nucellain plays a role in
processing and/or turnover of cell wall proteins in developing cereal
grains. |
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Bibliography: | Corresponding author; e-mail odd-arne.olsen@ibf.nlh.no; fax 47–64941465. |
ISSN: | 0032-0889 1532-2548 |