Identification of a CYP84 Family of Cytochrome P450-Dependent Mono-Oxygenase Genes in Brassica napus and Perturbation of Their Expression for Engineering Sinapine Reduction in the Seeds1
CYP84 is a recently identified family of cytochrome P450-dependent mono-oxygenases defined by a putative ferulate-5-hydroxylase (F5H) from Arabidopsis. Until recently F5H has been thought to catalyze the hydroxylation of ferulate to 5-OH ferulate en route to sinapic acid. Sinapine, a sinapate-derive...
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Published in | Plant physiology (Bethesda) Vol. 123; no. 4; pp. 1623 - 1634 |
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Main Authors | , , , , , , , |
Format | Journal Article |
Language | English |
Published |
American Society of Plant Physiologists
01.08.2000
|
Online Access | Get full text |
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Summary: | CYP84 is a recently identified family of cytochrome P450-dependent mono-oxygenases defined by a putative ferulate-5-hydroxylase (F5H) from Arabidopsis. Until recently F5H has been thought to catalyze the hydroxylation of ferulate to 5-OH ferulate en route to sinapic acid. Sinapine, a sinapate-derived ester in the seeds, is antinutritional and a target for elimination in canola meal. We have isolated three
F5H
-like genes (
BNF5H1-3
) from a cultivated
Brassica napus
, whose amphidiploid progenitor is considered to have arisen from a fusion of the diploids
Brassica rapa
and
Brassica oleracea
.
Two cultivated varieties of the diploids were also found to contain
BNF5H3
and additionally either
BNF5H1
or
BNF5H2
, respectively. Whereas all three are >90% identical in their coding sequence,
BNF5H1
and
BNF5H2
are closer to each other than to
BNF5H3
. This and additional data suggest that the two groups of genes have diverged in an ancestor of the diploids.
B. napus
showed maximal
F5H
expression in the stems, least in the seeds, and subtle differences among the expression profiles of the three genes elsewhere. Transgenic
B. napus
with cauliflower mosaic virus 35S-antisense
BNF5H
contained up to 40% less sinapine, from 9.0 ± 0.3 mg in the controls to 5.3 ± 0.3 mg g
−1
seed. F5H from Arabidopsis and a similar enzyme from sweetgum (
Liquidamber styraciflua
) has recently been shown to have coniferaldehyde hydroxylase activity instead of F5H activity. Thus the supply of 5-OH coniferaldehyde or 5-OH ferulate has a bearing on sinapine accumulation in canola seeds. |
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Bibliography: | Corresponding author; e-mail gopalan.selvaraj@nrc.ca; fax 306–975–4839. Present address: Aventis Crop Science, 203–407 Downey Road, Saskatoon, SK, Canada, S7N 4L8. Present address: WestCan Malting, P.O. Box 113, Alix, AB, Canada, T0C 0B0. |
ISSN: | 0032-0889 1532-2548 |