Reduced pigment gene of carrot and its use

Details Reduced pigment gene of carrot and its use Reduced pigment gene of carrot and its use

1998-08-20

2002-08-20

Nelson, Amy J. (Department: 1638)

Multicellular living organisms and unmodified parts thereof and

Plant, seedling, plant seed, or plant part, per se

Higher plant, seedling, plant seed, or plant part

C800S266000, C800S260000, C800S268000, C435S410000

Reexamination Certificate

active

06437222

ABSTRACT:

The present invention relates to a
Daucus carota
reduced pigment gene, a carrot seed, a carrot plant, a carrot inbred and a method of producing carrot hybrids. The reduced pigment gene of the present invention can be incorporated into various Daucus genetic backgrounds. The present invention also relates to a carrot root having an increased level of &agr;-tocopherol.
BACKGROUND OF THE INVENTION
Carrot (
Daucus carota
L.) is a biennial plant that belongs to the parsley family. Carrot roots are commonly-known as a good source of Vitamin A. In particular, it has been estimated that carrots contribute approximately 14% of the total Vitamin A to the human diet in the United States (Senti, F. R., and R. L. Rizek, 1975, Nutrient Levels in Horticultural Crops. Hort.Science. 10:243-246). Vitamin A content is related to the pigmentation in the carrot roots. In particular, carrot roots contain &bgr;-carotene which animals convert into provitamin A. Beta carotene is also responsible for the orange color of carrot roots. Carrot pigmentation is present in carrots in many different forms. Carrot roots can exhibit several colors including white, yellow, orange, red and purple (Banga, 0., 1964, Origin and Distribution of the Western Cultivated Carrot.
Genetica Agrafia
. 17:357-370). Of these colors, purple pigmentation is due to the presence of anthocyanins whereas yellow, orange and red pigmentation are due to carotenoids. The primary carotenoids in orange carrot tissue are &agr; and &bgr;-carotene (Laferriere, L., and W. H. Gabelman, 1968, Inheritance of Color, Total Carotenoids, Alpha-carotene, and Beta-carotene in Carrots,
Daucus carota
L., Proc. Amer. Soc. Hort. Sci. 93:408-418).
Carrot cultivars are often separated into several categories for market use. These include 1) fresh market, 2) cut and peel, and 3) processing. Fresh market carrots are typically known as Imperator types and have long, straight, thin roots. They are also known as cello or bunching carrots because they are sold bunched in cello bags in the market. Cut and peel carrots refer to the “baby” carrot now seen in markets throughout the world. These carrots have roots that are similar in type to the fresh market carrot, however, they have been cut into small sections for market. Processing carrots are large, often tapered, bulky roots used for canning, freezing, and other processed carrot products. Cultivars of processed carrot and fresh market carrot are developed and maintained in separate breeding programs.
Although the beta-carotene present in commonly-known carrots may be converted into Vitamin A in the body, sufficient levels of other nutrients must be obtained from sources other than carrots. For example, the presence of &agr;-tocopherol has not been recorded in any carrot inbred, hybrid, or openpollinated cultivar. Furthermore, because &agr;-tocopherol is usually associated with the oil fraction of plant extracts, (while carrots are consumed for their high moisture content and high fiber root) carrot inbred lines, hybrids, or open-pollinated cultivars have not been associated with this vitamin. Alpha tocopherol (Vitamin E) cannot be synthesized by the body. Alpha tocopherol is important in the body as a vitamin. Beyond its importance as a vitamin, &agr;-tocopherol also possesses antioxidant activity. More specifically, &agr; tocopherol along with other members of the Vitamin E family, namely, &bgr;, &ggr;, and &dgr; tocopherol and their corresponding unsaturated derivatives &agr;, &bgr;, &ggr; and &dgr; tocotrienol, are primarily used by the body as antioxidants. Nevertheless, the average U.S. citizen consumes less than the U.S. Recommended Daily Allowance of 30 International Units of Vitamin E. Biosynthetic pathway for carotenoids (left column) and tocopherols (right column) are shown in Table 1 below:
TABLE 1
Biosynthesis of carotenoids and tocopherols is connected through the common intermediate geranylgeranyl pyrophosphate (GGPP), Norris et al., 1995, Plant Cell, 7:2139-2149.
Although some vegetables synthesize both &agr;-tocopherol and &bgr;-carotene, these vegetables are primarily seed-producing plants such as maize and some seed oil plants. It would be desirable to have a new carrot that synthesizes &agr; tocopherol (Vitamin E). Moreover, it would be desirable to have a carrot inbred line with &agr; tocopherol synthesis in its root.
SUMMARY OF THE INVENTION
The present invention relates to a Daucus seed, a Daucus plant, a Daucus variety, a Daucus hybrid and a method for producing a Daucus plant.
More specifically, the invention relates to a carrot root having a mutant reduced pigment gene designed rp. The present invention is directed to a carrot root with a total &agr;-tocopherol content between about 0.01 mg per 100 grams of fresh weight of the carrot root and about 0.40 mg per 100 grams of fresh weight of the carrot root. The present invention is also directed to an F
1
hybrid carrot plant having a total &agr;-tocopherol content greater than about 0.01 mg per 100 grams of fresh weight of the carrot root. The present invention further relates to a method of producing the disclosed carrot plants and seeds by crossing a reduced pigment plant of the instant invention with another carrot plant. The invention also relates to the transfer of the genetic reduced pigment into other genetic backgrounds.
It is an object of this invention to provide a carrot that synthesizes &agr;-tocopherol in its root. Generally, the carrot inbred line of the present invention provides for &agr;-tocopherol biosynthesis in the root. The carrot seed of the present invention contains a recessive gene, designated rp, for a reduced pigment phenotype. The present invention is also directed to a reduced pigment carrot plant produced from growing the carrot seed. The carrot plant has an increased level of &agr;-tocopherol. The &agr;-tocopherol level of the carrot plant is at least 0.01 mg per 100 grams of fresh weight of the carrot. In general, a method of the present invention is for producing F
1
hybrid carrots. This method includes crossing a first parent carrot plant with a second parent carrot plant. The resultant F
1
hybrid carrot root is harvested. Either the first or second parent carrot plant is the reduced pigment carrot plant produced by growing the seed which contains the gene (allelic DNA genetic factor) for reduced pigment phenotype of the present invention. A first generation (F
1
) hybrid carrot plant is produced by growing the hybrid carrot root produced by the method of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
In order to provide an understanding of some of the terms used in the specification and claims, the following definitions are provided:
&agr;-tocopherol—as used herein, the term alpha(&agr;)-tocopherol is synonymous with Vitamin E.
Daucus carota
—as used herein, the term
Daucus carota
is synonymous with carrot.
Although trace levels have been speculated, no detected levels of &agr;-tocopherol have been confirmed in
Daucus carota
until the present invention. Additionally, there are no known reports of &agr;-tocopherol biosynthesis in any
Daucus carota
species, cultivar, in the wild or commercially available. The novel &agr;-tocopherol biosynthesis of the present invention arose from breeding and research efforts which were conducted beginning in 1996.
The instant invention is the genetic expression of a mutant reduced pigment gene. This reduced pigment gene is associated with increased &agr;-tocopherol biosynthesis. The genetic basis for &agr;-tocopherol production in
Daucus carota
involves a single recessive allele. When the reduced pigment gene is incorporated into different genetic backgrounds of
Daucus carota
in the homozygous recessive condition, the &agr;-tocopherol characteristic is transferred into these genetic backgrounds.
The seeds from the developed true-breeding reduced pigment lines can also be marketed. Reduced pigment lines can also be used as one of the parents in F
1
hybrid seed production resulting in an F
1
hybrid.
The reduced pigment gene has been design

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