Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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IMPROVEMENTS IN THE FORMATION OF BRASSICA NAPUS Fl
HYBRID SEEDS WITH HIGH OLEIC ACID CONTENT AND
A REDUCED LINOLENIC ACID CONTENT
Background of the Invention
Canola oil presently is commercially available which consists of approximately
6
percent saturated fatty acids primarily in the form of stearic acid (C18:0)
and palmitic
acid (C 16:0), approximately 62 percent by weight oleic acid (C 18:1 ) which
contains a
single double bond per molecule, approximately 22 percent by weight linoleic
acid
(C18:2) which contains two double bonds per molecule, approximately 10 percent
by
weight linolenic acid (C18:3) which contains three double bonds per molecule,
and less
than one percent by weight erucic acid (C22:1) which contains a single double
bond per
molecule.
Over the years scientists have worked to improve the fatty acid profile for
rapeseed oil. Initially the erucic acid (C22:1) composition of rapeseed oil
was reduced
to produce what is often termed to be "canola" oil. The oxidative stability of
the
vegetable oil is related to the number of double bonds in its ,fatty acids.
Molecules with
several double bonds are recognized to be less stable. Thus, scientists also
have worked
to reduce the content of linolenic acid (C18:3) in order to improve shelf life
and
oxidative stability, particularly upon exposure to heat. This has not proved
to be
possible through the use of naturally occurring germplasm and the reported
values for
linolenic acid (C18:3) for such germplasm have been greater than 6 percent by
weight
(g,,g,,., greater than 6 up to approximately 12 percent by weight). As
reported by
Gerhard Robbelen in Chapter 10 entitled "Changes and Limitations of Breeding
for
Improved Polyenic Fatty Acids Content in Rapeseed" from "Biotechnology for the
Oils
and Fats Industry" edited by Colin Ratledge, Peter Dawson, and James Rattray,
American Oil Chemists' Society (1984), a mutagenesis experiment was able to
achieve
lines with less than approximately 3.5 percent by weight of linolenic acid
(C18:3) based
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upon the total fatty acid content. The profiles of these lines indicated that
nearly all of
the linolenic acid was being directed to linoleic acid (C18:2) and that the
levels of oleic
acid (C18:1) increased only one or two percent. Nevertheless the oil appeared
to offer
some advantages over normal canola oil. For instance, the refining process
required
less hydrogenation than normal canola oil and it exhibited a superior fry
life.
Studies have established the value of monounsaturated fatty acids as a dietary
constituent. This has led to the popularization of the "Mediterranean Diet,"
with its
emphasis on olive oil, a naturally occurring high source of oleic acid
(C18:1). Such a
diet is thought to avoid the problem of arteriosclerosis that results from the
consumption
of saturated fatty acids. However, even in this diet olive oil is thought to
be less than
ideal, due to its level of saturates. Canola oil is potentially a superior
dietary oil, since
it contains approximately one-half the saturated fat content of olive oil.
Mutagenesis techniques have been disclosed in the technical literature for
increasing the oleic acid (C18:1) content of endogenously formed canola oil
over that
typically encountered. See in this regard the teachings of United States
Patent Nos.
5,625,130 and 5,638,637; European Patent No. 0323753; and International
Publication
Nos. W090/10380 and W092/03919.
Also, approaches involving genetic engineering have been utilized to modify
the
fatty acid profile of the oil that is endogenously formed in rapeseeds. See,
for instance,
International Publication No. WO 93/11245, and the Hitz et al. article
appearing in the
Proceedings of the Ninth International Rapeseed Congress, Cambridge, UK, Vol.
2,
Pages 470 to 472 (1995).
Heretofore, it commonly has been observed that when a rape plant is provided
that endogenously forms a vegetable oil having an oleic acid content (C18:1)
of at least
80 percent by weight that such plant also exhibits less than optimum agronomic
performance. Such reduced agronomic performance often is manifest by reduced
plant
vigor, a later flowering propensity, a lesser number of seed pods per plant, a
lesser
number of seeds per pod, a lesser overall plant yield, a smaller number of
leaves per
plant, a lesser total leaf area per plant, a lesser plant height, and a
requirement for more
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time for the plant to reach full maturity. This reduced agronomic performance
must be
weighed against the improved character of the endogenously formed vegetable
oil with
respect to oleic acid production that is made possible by such plants.
It is an object of the present invention to provide an improved plant breeding
process for forming ~rassica Fl hybrid seed having an enhanced commercial
value attributable to a combination of (1) the atypical fatty acid profile of
the
endogenously formed seeds, and (2) the seed yield.
It is an object of the present invention to provide an improved plant breeding
process for forming rassica nanus Fl hybrid seed which exhibits a highly
elevated
oleic acid (C18:1) content.
It is a further object of the present invention to provide an improved process
for
forming ~~ Fi hybrid seeds which exhibit a highly elevated oleic acid
(C18:1) content and when planted can be grown to form rape plants associated
with
high oleic acid production which are free from the agronomic shortcomings
commonly
encountered in the prior art with rape plants that yield such an elevated
oleic acid
content.
These and other objects and advantages as well as the scope, nature, and
utilization of the claimed invention will be apparent to those skilled in the
art from the
following detailed description and appended claims.
Summary~f thg Invention
It has been found that an improved process for producing seeds capable of
forming F1 hybrid Brassier plants comprises:
(a) planting in pollinating proximity in a planting area parent plants (i) and
(ii),
wherein parent (i) is a ~irassica plant possessing solely in either the A-
genome or
the C-genome a homozygous modified FAD-2 (1,~" oleate desaturase) gene pair
that
causes expression of an elevated oleic acid concentration in the endogenously
formed oil
of the seeds formed thereon, and further possesses at least one homozygous
modified
FAD-3 (j~,., linolate desaturase) gene pair that causes the expression of a
reduced
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linolenic acid concentration in the endogenously formed oil of the seeds, and
wherein parent (ii) is a Brassica napus plant possessing in each of the A-
genome and the C-genome a homozygous modified FAD-2 gene pair that
causes the expression of an elevated oleic acid concentration in the
endogenously formed oil of the seeds formed thereon whereby oleic acid is
formed in the endogenously formed oil of the seeds in a greater concentration
than in the seeds of parent (i) under the same growing conditions, and further
possesses at least one homozygous modified FAD-3 gene pair that results in a
reduced linolenic acid concentration in the endogenously formed oil of the
seeds formed thereon;
(b) growing Brassica napus plants resulting from the planting of step
(a);
(c) preventing self pollination of the plants of patent (i);
(d) transferring pollen between parent (ii) and parent (i); and
(e) harvesting F~ hybrid seeds produced on plants of parent (i) that
are capable of forming Brassica napes plants that upon self pollination form
seeds possessing an endogenously formed vegetable oil having an oleic acid
concentration of at least 80 percent by weight and which exceeds that of
parent
(i), a linolenic acid concentration of no more than 3 percent by weight, and
wherein the resulting F~ hybrid seeds when planted are capable of producing a
crop in a yield that exceeds that of parent (i) and parent (ii) when each
parent is
pollinated by a pollen source possessing a genotype substantially the same as
that of each parent plant and is grown under the same conditions.
According to another aspect of the present invention there is provided an
improved
process for producing seeds capable of forming F~ hybrid Brassica napes plants
comprising:
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(a) planting in pollinating proximity parent plants (i) and (ii), wherein
parent (i) is a ra 'ca ~an_u~ plant possessing solely in either the A-genome
or the
C-genome a homozygous modified FAD-2 gene pair that results in an elevated
oleic
acid production in the endogenously formed oil of the seeds formed thereon
which
exceeds that of the Profit'variety which possesses an unmodified FAD-2 gene
pair by at
least 14 percent by weight based upon the total fatty acid content under the
same
growing conditions, and at least one homozygous modified FAD-3 gene pair that
results
in a reduced linolenic acid production in the endogenously formed oil of the
seeds
formed thereon of no more than 3 percent by weight based upon the total fatty
acid
content, and wherein parent (ii) is a Brassica plant possessing in each of the
A-genorne and the C-genome a homozygous modified FAD-2 gene pair that results
in
an elevated oleic acid production in the endogenously formed oil of the seeds
formed
'TM
thereon which exceeds that of the Profit variety which possesses an unmodified
FAD-2
gene pair by at least 20 percent by weight based upon the total fatty acid
content and
forms oleic acid in the endogenously formed oil of said seeds in a greater
concentration
than parent (i) under the same growing conditions, and a homozygous modified
FAD-3
gene pair that results in a reduced linolenic acid content in the endogenously
formed oil
of the seeds formed thereon of no more than 3 percent by weight based upon the
total
fatty acid content;
(b) growing a ica a a plants resulting from said planting of step
(a);
(c) preventing self pollination of the plants of parent (i);
(d) transferring pollen between said parent (ii) and said parent (i); and
(e) harvesting F~ hybrid seeds produced on plants of parent (i) that are
capable of foaming ~r ssica us plants that upon self pollination form seeds
possessing an endogenously formed vegetable oil having an oleic acid
concentration of
at least 80 percent by weight and which exceeds that of parent (i), and a
linolenic acid
concentration of no more than 3 percent by weight, and wherein said resulting
Fl
hybrid seeds when planted are capable of producing a crop in a yield that
exceeds that
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of parent (i) and parent (ii) when each is pollinated by a pollen source
possessing a genotype substantially the same as that of each parent plant and
is
grown under the same conditions.
Description of Preferred Embodiment
The fatty acid concentrations discussed herein are determined in
accordance with a standard procedure wherein the oil is removed from the
Brassica napus oilseeds by crushing and is extracted as fatty acid methyl
esters
following reaction with methanol and sodium methoxide. Next the resulting
ester is analyzed for fatty acid content by gas liquid chromatography using a
capillary column which allows separation on the basis of the degree of
unsaturation and chain length. This analysis procedure is described in the
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work of J.K. Daun et al, J. AmerL9j~ ~h~oc., 60:1751-1754 (1983).
1t is recognized that Brassica na~u~ is a dibasic allotetraploid formed of
t'wo
genomes i.e., the A-genome and C-genome) and has a total of 38 chromosomes.
The
A-genome component is derived from a i a campestris and consists of 20
chromosomes. The C-genome component is derived from a ica oleracea and
consists of 18 chromosomes..
When carrying out the process of the present invention, two parent plants
described herein are planted in a planting area and are grown in pollinating
proximity,
~ self pollination of the female parent plants (a_g:., seed parent plants) is
prevented, pollen
is transferred from the male parent plants to the female parent plants to
achieve
fertilization, and Fl hybrid seeds are formed thereon in.a yield that exceeds
that of both
parent plants having an elevated oleic acid (C18:1) content of at least 80
percent by
weight based upon the total fatty acid content in the endogenously formed
vegetable oil
of the seeds. "Pollinating proximity" is used herein to specify that the
parent plants are
grown in su~cient closeness to make possible the transfer of pollen while
maintaining
the viability of such pollen. The high oleic acid concentration of the
vegetable oil is
achieved through the concept of the present invention without sacrifice in
agronomic
properties.
The improved plant breeding process of the present invention involves the
selection and utilization of specifically-defined Brassy na~us parent plants.
Such
parent plants have been found through empirical research to be capable of
yielding the
advantageous results with respect to highly elevated oleic acid content and
reduced
linolenic acid content in the endogenously formed vegetable oil of the seeds
combined
with good agronomic performance which cornrnonly was lacking in the prior art_
The ra i a ~a~u_s female parent (use , the seed parent) selected for use in
the
hybridization process of the present invention possesses solely in either the
A-genome
or the C-genome a homozygous modified FAD-2 (~.e., oleate desaturase) gene
pair that
causes the expression of an elevated oleic acid (C18:1) concentration in the
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endogenously formed oil of the seeds combined with at least one homozygous
modified
FAD-3 ('~P., linolate desaturase) gene. pair that causes the expression of a
reduced
linolenic acid (C18:3) concentration in the endogenously formed oil of the
seeds. Such
female parent commonly is selected that forms an oleic acid content of
approximately 77
to ~79 percent by weight based upon the total fatty acid content in the
endogenously
formed vegetable oil of the seeds. The vegetable oil oleic acid content of the
female
parent commonly will exceed that of the well-known Profit variety which
possesses an
- unmodified FAD-2 gene pair by at least 14 percent (e g." by 14 to 17
percent) by
weight under the same growing conditions., The reference Profit variety was
introduced
by Agriculture Canada during 1989 and is known and publicly available. Seeds
of the
Profit variety can be obtained from Agriculture and Agri-Food Canada,
Sakatoon,
Saskatchewan, Canada. It has been found to be essential that the modified FAD-
2 gene
pair be present solely in either the A-genome or the C-genome so as to avoid
the
impairment of agrononvc qualities that otherwise are observed if such
modification
were present in both genomes. The presence of the modified FAD-2 gene pair in
both
genomes (i,~, in the A-genome as well as in the C-genome) which leads to an
even
more highly elevated 'oleic acid production in the endogenously formed
vegetable oil of
the seeds commonly has been found to concomitantly impact adversely upon lipid
loading throughout the plant including the cell membranes and to result in
reduced
agronomic performance as previously discussed. The presence of a' modified FAD-
2
gene pair solely in one genome can be confirmed by a oleic acid (C18:1) in the
endogenously formed vegetable oil of the seeds of approximately 76 to 79
percent by
weight based upon the total fatty acid content.
The a 'ca nanus male parent (,~g_, the pollen parent) selected for use in the
hybridization process of the present invention possesses in each of the A-
genome and in
the C-genome a homozygous modified FAD-2 gene pair that causes the expression
of an
elevated oleic -acid concentration in the endogenously formed oil of the seeds
in a
greater concentration than in the seeds of the female parent. Such male parent
commonly is selected that forms an oleic acid content of approximately 85 to
89 percent
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by weight based upon the total fatty acid content in the endogenously formed
vegetable
oil of the seeds. The vegetable oil oleic acid content of the male parent
commonly will
exceed that of the well-known Profit variety by at least 20 percent (fig," by
20 to 25
percent) by weight under the same growing conditions. In view of the presence
of the
modified FAD-2 gene pair in both the A-genome and the C-genome, the overall
agronomic qualities of the male parent are lesser than those of the female
parent.
Parent plants possessing the modified genomes as discussed above can be formed
by genetic engineering or the mutagenesis of conventional ~,S,~ica nab
germplasm
(~,g,., existing canola varieties), or can be selected from previously
available sources
that already incorporate the requisite modified genomes .as discussed herein.
Once on
hand, the requisite genes can be readily transferred by conventional plant
breeding into
other ~rassica germplasms.
In a preferred embodiment when carrying out mutagenesis, one selects plant
cells capable of regeneration (e,,g." seeds, microspores, ovules, pollen,
vegetative parts)
from any of the oilseed Brassier opus varieties (fig," canola) which are
recognized to
have superior agronomic characteristics. The J rassi~ nab plants may be of
either the
summer or winter types. The oilseed ~L~Si~ n~us plant cells are subjected in
at least
one generation to mutagenesis, and an oilseed Brassy napus plant is
regenerated from
the cells to produce an oilseed plant and to form an oilseed in at least one
subsequent
generation that possesses the ability to form the atypical modified FAD-2 gene
pair in
the female parent and the atypical modified FAD-2 gene pairs in the male
parent.
Parent oilseed rassica n , us plants possessing the requisite FAD-2 gene
pairs) may be
produced following mutagenesis via self pollination for a sufficient number of
generations (~.g,., 2 to 8 generations) to achieve substantial genetic
homogeneity.
Alternatively, the desired characteristics can be fixed through the formation
of a new
plant from a haploid microspore cell, causing the haploid to double, and
producing a
homozygous diploid plant in accordance with known techniques.
The mutagenesis preferably is accomplished by subjecting the plant cells
(~,,g"
an oilseed) to a technique selected from the group consisting of contact with
a chemical
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mutagen, gamma irradiation, and a combination of the foregoing, for a
sufficient
duration to accomplish the desired genetic modification but insu~cient to
completely
destroy the viability of the cells and their ability to be regenerated into a
plant. The
rass'c plus oilset:d preferably possesses a moisture content of approximately
5 to 6
percent by weight at the time of such mutagenesis. The mutagenesis may be
accomplished by use of chemical means, such as by contact with
ethylmethylsulfonate,
ethylnitrosourea, etc., and by the use of physical means, such as x-rays, etc.
The
mutagenesis also may be carried out by gamma radiation, such as that supplied
by a
Cesium 137 source. The gamma radiation preferably is supplied to the plant
cells (e_::g."
an oilseed) in a dosage of approximately 60 to 200 Krad., and most preferably
in a
dosage of approximately 60 to 90 Kxad. It should be understood that even when
operating at radiation dosages within the ranges specified, some plant cells
(e g.,,
oilseeds) may completely lose their viability and must be discarded. See
commonly
assigned United States Patent Nos. 5,625,130 and 5,638,637
for a further discussion of the mutagenesis treatment.
When a mature a 'ca balfseed is found to possess a desired
mutation(s), the other halfseed, which will be genetically the same as the
balfseed which
was subjected 'to halfseed analysis, can next be caused to germinate and an
oilseed
a sic napes plant is formed from the same and is allowed to undergo self
pollination.
Such planting of the halfseed preferably also is carried out in a greenhouse
in which the
pollination is carefully controlled and is monitored. The resulting oilseeds
formed on a
plant resulting from the halfseed are harvested, planted, and are self
pollinated for a
su~cient number of generations to achieve substantial genetic homogeneity. The
genetic stabilization of the oilseed ~r_a_s,~ica plant material enables the
creation of
plants having a reasonably predictable genotype which can be used as breeding
or
source material.
In accordance with the concept of the present invention, it additionally is
essential that each of the female and male parent plants possesses at least
one
homozygous modified FAD-3 i.e., linolate desaturase) gene pair that causes the
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expression of a reduced linolenic acid (~,~" alpha-linolenic acid)
concentration in the
endogenously formed oil of the seeds.
Such modified FAD-3 gene pair can be obtained by genetic engineering or the
mutagenesis of conventional Brassica germplasm (~,.g" existing canola
varieties)
or can be selected from previously available sources that already incorporate
the
requisite FAD-3 gene modification. The modified FAD-3 gene pair can be present
in
either the A-genome or in the C-genome, and preferably is present in each of
the these
genomes. The modified FAD-3 gene pair likewise preferably is obtainable by
mutagenesis. A reduced linolenic acid content of no more than 3 percent by
weight
based upon the total fatty acid content preferably is exhibited by each of the
parent
plants in the endogenously fornned vegetable oil of the seeds. In a preferred
embodiment, both the female parent and the male parent exhibit a linolenic
acid (C18:3)
content of approximately 1 to 3 percent by weight (fig" 1 to 2 percent by
weight) based
upon the total fatty acid content.
Oilseed Brassica germplasm containing the requisite homozygous
modified FAD-3 gene pairs) that causes a reduced linolenic acid concentration
in the
endogenously formed oil of the seeds is known and is publicly available. For
instance,
rape germplasm possessing this trait has been available in Germany from the
mid-
1970's, and in North American since 1983. Representative commercially
available rape
varieties that include the genetic means for the expression of this low
linolenic acid trait
include STELLAR, and APOLLO. A particularly preferred source for the requisite
FAD-3 gene pair for the expression of enhanced linoleriic acid in the stated
concentration is the STELLAR variety that was developed at the University of
Manitoba, Manitoba, Canada, during 1987, following receipt of support from the
Western Canola and Rapeseed Recommending Committee. Also, a particularly
preferred source for the requisite FAD-3 gene pair for the expression of
enhanced
linolenic acid in the stated concentration is the APOLLO variety that was
developed at
the University of Manitoba, and was registered in Canada as No. 3,694 during
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February, 1992, following the receipt of support from the Western Canola and
Rapeseed Recommending Committee.
Brassica nab seeds designated NS1973 and NS2037 and possessing the
requisite modified FAD-2 gene pair solely in one genome as well as the
modified FAD-
3 gene pair suitable for use as the female parent in the process of the
present invention
were deposited at the American Type Culture Collection, 10801 University
Boulevard,
Mantissas, Virginia, U.S.A. 20110-2209, on June 25, 1998. A 2,500 seed deposit
of
NS1973 has been assigned ATCC Accession No. 209997, A 2,500 seed deposit of
NS2037 has been assigned ATCC Accession No. 209994.
~ nanus seeds designated 95SN-56605 and 95SN-56634 and possessing
the requisite modified FAD-2 gene pair in both the A-genome and the C-genome
as well
as modified FAD-3 gene pair suitable for use as the male parent in the process
of the
present invention additionally were deposited at the American Type Culture
Collection
on June 25, 1998. A 2,500 seed deposit of 95SN-56605 has been assigned ATCC
Accession No. 209995. A 2,500 seed deposit of 95SN-56634 has been assigned
ATCC
Accession No. 209996.
When the parent plants are grown within pollinating proximity of each other in
accordance with the process of the present invention, it is essential that
self pollination
of the female parent plants be precluded. This can be done through the
emasculation of
the flowers at an early stage of flower development. Such impediment to self
pollination preferably is accomplished through the prevention of pollen
formation on the
female parent plants through any one of a variety of techniques that is
inherent within
the plant. Such female parent plants can incorporate some form of male
sterility. For
instance, male sterility can be cytoplasmic male sterility (ag" genic-
cytoplasmic),
nuclear male sterility, molecular male sterility wherein a transgene inhibits
microsporogenesis and/or pollen formation, or be produced by self
incompatability. In
a particularly preferred embodiment the female parent plants possess
cytoplasmic male
sterility of the ogura (OGU) type and the male parent plants include a
fertility restorer
as available from Institut National de Recherche Agricole (INRA) of Rennes,
France.
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CA 02391612 2002-08-O1
See also in this regard the technology of International Publication Nos.
W092/05251
and W098/027806.
The improved process of the present invention can be used to advantage to~for~
single-cross $~,panus Fl hybrids. During such single-cross embodiment the
parent plants can be grown as substantially homogeneous adjoining populations
so as to
well facilitate natural cross-pollination from the male parent plants to the
female parent
plants. The Fl seed formed on the female parent plants next is selectively
harvested by
conventional means. One also has the option of growing the two parent plants
during
the formation of a single-cross hybrid in bulk and harvesting a composite seed
blend of
high oleic acid content consisting of F~ hybrid seed, formed on the female
parent and
_.. seed formed upon the male parent as the result of self pollination.
Alternatively, three-
way crosses can be carried out wherein a single-cross F~ hybrid is used as a
female
parent and is crossed with a different male parent that satisfies the fatty
acid parameters
for the female parent of the first cross. Here, assunvng a bulk planting, the
overall
oleic acid content of the vegetable oil will be reduced over that of a simple
single-cross
hybrid; however; the seed yield will be further enhanced in view of the good
agronomic
performance of both parents when making the second croSS. Also, the formation
of
double-cross hybrids can be carried out wherein the products of two different
single-
crosses are combined. Self incompatibility can be used to particular advantage
to
prevent self pollination of female parents when forming a double-cross hybrid.
Here
the final seed product will be a composite of more than one genotype wherein
the
overall oleic acid content is at least 80 percent by weight based upon the
total fatty acid
content.
The F, hybrid seeds made possible by the use of the technology of the present
invention commonly exhibit an oleic acid concentration of approximately 80 to
86
percem by weight and a linolenic acid content of approximately 1 to 3 percent
by weight
based upon the total fatty acid content, and are capable of forming plants
which
following self pollination and seed set yield a seed harvest bearing a
vegetable oil
having average oleic acid and linolenic acid concentrations within the
specified ranges.
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The improved process of the present invention makes possible the formation of
rassica rFl hybrid seeds which when planted are capable of producing a crop in
a
yield that exceeds that of each parent used in the formation of the Fl hybrid
when each
parent is pollinated by a pollen source possessing a genotype substantially
the same as
that of each parent and is grown under the same conditions. Additive gene
action with
respect to oleic acid production is achieved without sacrifice of agronomic
characteristics. This good yield is made possible while making possible an
oleic acid
content in the vegetable oil of at least 80 percent (g.,,g" 80 to 86 percent)
by weight
based upon the total fatty acid content. Commonly, seed yields of equal to or
greater
than those of widely grown canola varieties which lack the modified fatty
acid, profile
are made possible. In a preferred embodiment the yield exceeds that of the
well-known
Legend variety under the same growing conditions. The reference Legend variety
was
introduced by Svalof AB during 1988 and is known and publicly available. Seeds
of the
Legend variety can be obtained from Svalof Weibull Canada Ltd., of Lindsay,
Ontario,
Canada.
The following Examples are presented as specific illustrations of the claimed
invention. It should be understood, however, that the invention is not limited
to the
specific details set forth in the Examples.
FXt~MpLE I
A Brassica line designated NS1973 was selected for use as the female
parent. Such line was derived through crossing and pedigree selection in
progeny
generations from FA677M5-132 (ATCC Accession No. 40523). In the endogenously
formed vegetable oil of NS1973 there was exhibited an average oleic acid
(C18:1)
content of 79.02 percent by weight and an average linolenic acid (C18:3)
content of
1.65 percent by weight based upon the total fatty acid content. In this female
parent the
elevated oleic acid content was created through the presence of a homozygous
modified
FAD-2 gene pair solely in one genome that was formed through mutagenesis and
the
reduced linolenic acid content was created through the presence of at least
one
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CA 02391612 2002-08-O1
homozygous modified FAD-3 gene pair that was formed through mutagenesis. Seeds
of
NS 1973 bear ATCC Accession No. 209997 as earlier discussed.
A 1~~:~assica line designated 95SN56605 was selected for use as the male
parent. Such line was derived through crossing and pedigree selection in
progeny
generations from FA677M5-132 {ATCC Accession No. 40523). In the endogenously
formed vegetable oil of 95SN56605 there was exhibited an average oleic acid
{C18:1)
content of 87.09 percent by weight and an average linolenic acid (C18:3)
content of
1.64 percent by weight based upon the total fatty acid content. In this male
parent the
highly elevated oleic acid content was created through the presence of a
homozygous
modified FAD-2 gene pair in both the A-genome and the C-genome that was formed
through mutagenesis and the reduced linolenic acid content was created through
the
presence of at least one homozygous modified FAD-3 gene pair that was formed
through mutagenesis. Seeds of 95SN56605 bear ATCC Accession No. 209995 as
previously discussed.
In order to determine parent yield potential, the parent lines were grown as a
plot of twenty plants each in a replicated yield trial at Acton, Ontario,
'Canada, and
were bagged to ensure self pollination. The bags were removed at the end of
flowering
so that the fatty acid composition of the selfed seed would not be affected by
an
artificial bagged environment during the final portion of the seed filling
when most of
the lipid accumulation takes place. At maturity the selfed plants were
harvested
individually. Fatty acid and yield determinations were made. When determining
yield
the total weight of harvested seed was adjusted to 8.5 percent moisture. A
value of 100
was assigned to the seed yield of the NS1973 female parent. On this scale, a
seed yield
of only 43 percent that of the female parent was found to form on the
95SN56605 male
parent.
Fl hybrid seeds and F2 seeds- were produced in a common filed environment at
the same location and were evaluated for yield and fatty acid composition.
More
specifically, the flowers of the NS 1973 female parent were hand emasculated
at an early
stage of flower development according to the procedure described in Chapter 35
entitled
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CA 02391612 2002-08-O1
"Rapeseed and Mustard° by R.K. Downey et al appearing at Pages 495 to
509 of
"Hybridization of Crop Plantsn edited by Walter R. Fehr and Henry H. Hadley
(1980)
in order to prevent the self pollination of the female parent plants. At the
appropriate
stage in flower maturity, pollen was transferred by hand from the 95SN56605
male
parent plants to the NS1973 female parent plants to accomplish fertilization.
Fl hybrid
seeds were next produced on the fertilized NS1973 female parent plants which
were
selectively harvested and were analyzed for the fatty acid composition of the
endogenously formed vegetable oil of the seeds.
The resulting F, hybrid seeds were found to exhibit an average elevated oleic
acid content of 82.36 percent by weight and a reduced linolenic acid content
of 1.59
percent by weight based upon the total fatty acid content. Also, the F~ hybrid
seed yield
was found to be 127 percent of the female parent and exceeded that of each of
the
parent plants. Also, .when the Fl hybrid seeds were planted, they were found
to exhibit
good agronomic characteristics unlike the male parent plants.
Example I was repeated with the exception that Brassj,~ 95SN56634
(ATCC Accession No. 209996) was substituted for male parent 95SN56605. Such
95SN56634 line was derived through crossing and pedigree selection in progeny
generations from FA677M5-132 (ATCC Accession No. 40523). In the endogenously .
formed vegetable oil of 95SN56634 there was exhibited an average oleic acid
(C18:1)
content of 86.57 percent by weight and an average linolenic acid (C18:3)
content of
1.42 percent by weight based upon the total fatty acid content. The seed yield
of the
95SN56634 male parent was found to be only 50 percent that of the female
parent: The
highly elevated average oleic acid content of the male parent was created
through the
presence of a homozygous modified FAD-2 gene pair in both the A-genome and the
C-genome that was formed through mutagenesis and the reduced linolenic acid
content
was created through the presence of at least one homozygous modified FAD-3
gene pair
that was formed through mutagenesis. The resulting Fl hybrid seeds were found
to
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CA 02391612 2002-08-O1
exhibit an average elevated oleic acid content of 82.6 percent by weight and
an average
reduced linolenic acid content of 1.69 percent by weight based upon the total
fatty acid
content. Also, the Fl hybrid seed yield was found to be 108 percent that of
the female
parent. When the F; hybrid seeds were planted, the resulting plants were found
to
exhibit good agronomic characteristics unlike the male parent plants.
Example I was repeated with the exception that Brassica nanus line NS2037
(ATCC Accession No. 209994) was substituted for female parent line NS1973 and
~~ line 95SN56634 was substituted for male parent line 95SN56605. Such
NS2037 line was derived through crossing and pedigree selection in progeny .
generations from FA677M5-132 (ATCC Accession No. 40523). In the endogenously
formed vegetable oil of NS2037 there was exhibited an average oleic acid
(C18:1)
content of 78.64 percent by weight and an average linolenic acid (C18:3)
content of
1.52 percent by weight based upon the total fatty acid content. In such female
parent
the elevated oleic acid content was created through the presence of a
homozygous
modified FAD-2 gene pair solely in one genome that was formed through
mutagenesis
and. the reduced linolenic acid content was created through the presence of at
least one
homozygous modified FAD-3 gene pair that was formed through mutagenesis. The
Fl
hybrid seed was found to exhibit an average elevated oleic acid content of
82.3 percent
by weight and an average reduced linolenic acid content of 1.51 percent by
weight
based upon the total fatty acid content. Also, the Fl hybrid seed yield was
found to be
150 percent that of the female parent and exceeded that of each of the parent
plants.
Also, when the Fl hybrid plants were planted, the resulting plants were found
to exhibit
good agronomic characteristics unlike the male parent plants.
Example I was repeated with the exception that rassica pline
NS2037(ATCC Accession No. 20994) utilized in Example III was substituted for
female
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CA 02391612 2002-08-O1
parent line NS1973. The Fl hybrid seed was found to exhibit an average
elevated oleic
acid (C18:1) content of 82.69 percent by weight and an average reduced
linolenic acid
(C18:3) content of 1.46 percent by weight based upon the total fatty acid
content. Also,
the Fl hybrid seed yield was found to be 119 percent that of the female
parent. When
Fl hybrid plants were planted, the resulting plants were found to exhibit good
agronomic characteristics unlike the male parent plants.
The homozygous modified FAD-2 and FAD-3 gene pairs present in the Bras jca
parent plants of all Examples can be readily transferred by conventional plant
breeding to other Brassier napes germplasms which can likewise be used to
carry out
the process of the present invention. Also, the prevention of the self
pollination of the
female parent plants when carrying out the process of the present invention
can be
expeditiously carried out on a larger scale by the use of various types of
male sterility,
etc., as previously discussed. Such techniques to preclude self pollination of
the female
parent plants are already known and available to those skilled in plant
breeding.
Although the invention has been described with preferred embodiments, it is to
be understood that variations and modifications may be resorted to as will be
apparent
to those skilled in the art. Such variations and modifications are to be
considered within
the purview and scope of the claims appended hereto.
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