Patent Description:
Spinach or Spinacia oleracea is an edible plant originating from Western and Central Asia. It belongs to the family Amaranthaceae. Formerly it was denoted as member of the Chenopodiaceae; this family however was merged in the Amaranthaceae around <NUM>, and now is the subfamily Chenopodioideae. It has been cultivated in Europe since around the year <NUM>.

Hybrids of spinach can readily be produced making use of plants which have a female flowering and plants which have a male flowering phase as pollinated plants. Before the female plants develop male flowers, all female flowers are fertilized by the male.

Three basic types of spinach are on the market:.

Breeding resulted in spinach plants which are rapid growing without premature flowering. Older varieties tend to have narrower leaves and have a stronger, somewhat bitter taste; newer varieties have broader leaves and a milder taste. Also, recent types have little tendency for bolting in warm conditions and therefore will not prematurely flower and produce seeds.

Regarding nutritional value, providing only a small amount of calories (only <NUM> for <NUM> grams of cooked spinach), spinach is a rich source of vitamins A, B2 (or folate), B6, C, E and K; magnesium, manganese, calcium, potassium, iron and dietary fibre.

Spinacia oleracea is an annual or biennial plant with smooth glossy leaves without trichomes. Initially leaves grow as a rosette; the stem grows erect and are mostly unbranched; the alternate leaves consist each of a petiole and a simple blade; this blade is triangular (or even arrow shaped) to ovular, sometimes with elongated lobes; with an entire or dentate margin and an acute apex. Sometimes red midveins are present in the leaves. In general plants are dioecious, also monoecious plants occur.

The male flowers are arranged in glomeruli forming interrupted terminal spike-like panicles. They each consist of <NUM>-<NUM> oblong perianth segments and <NUM>-<NUM> stamens. Female flowers are in glomeruli positioned in the leaf axils. Enclosed by two united bracteoles, without perianth, they consist of an ovary with <NUM>-<NUM> filiform stigmas. The chromosome base number is x = <NUM>, which is unusual for Chenopodioideae, more common in this family is x = <NUM> or a multitude thereof. During seed set, bracteoles become enlarged and hardened and may have dentate margins, sometimes several flowers become united. The membranous pericarp adheres to the vertically orientated seed. The dark seed coat is spiny or smooth. The embryo is annular or ring shaped, surrounding the copious, grainy perisperm.

The pericarp is an outer layer of material surrounding the seed (with embryo, endosperm and seed coat); it is comprised of (from the outside to the inside) the exocarp; the mesocarp and the endocarp. With respect to seeds of Spinacia oleracea, the pericarp is forming a dry wall around the true seed. The presence of the pericarp around spinach seeds poses a number of practical problems in the art.

First, since the pericarp is relatively voluminous, the presence of the pericarp results in a vast increase of the volume of a seed lot. Both during transportation as well during storage, this is a serious problem. As a rule of thumb volume of pericarp hulled seeds is increased by a factor <NUM> and weight by a factor <NUM>. Further, the presence of pericarp hampers gas exchange by and imbibition and germination of the seed; during germination the embryo has to break through this relatively strong layer of tissue. Further, the pericarp causes a strong dormancy effect in certain species; sometimes resulting in around <NUM> % dormant seeds. The disadvantages of pericarp surrounding the spinach seeds can be summarized as follows:.

In the past methods were developed to physically remove pericarp from seeds. Mechanical removal of the pericarp from Hedysarum scoparium resulted in improvement of the germination from <NUM>% to <NUM>% (<NPL>). In patent application <CIT>; "Seed coat equipped seed and its production method"') a method is described to break a part of the seed coat by mechanical impact. First seeds are frozen to a temperature between -<NUM> to -<NUM>, subsequently, at a temperature <= -<NUM> seeds are mechanically treated to break the seed coat. In contrast to the prior art methods, studies performed to remove the pericarp from the seed by mechanical means were shown to result in a large portion of damaged seeds. Remaining seeds after these treatments had lower germination of the resulting seed lot, but germination of these remaining seeds was faster which also resulted in a higher yield per plant at harvest.

Another physical solution of the problem is found in patent application <CIT>; "Method for improving germination of hard seed by laser beam irradiation and germination improved seed") disclosing a method of treating hard seeds of several species by laser beams to enhance germination. This treatment resulted in seeds which are perforated, enabling a better supply of oxygen and water to the embryo and/or an easier appearance of the embryo through the perforated pericarp or testa. The prior art methods require a lot of handling of the seeds and precise adjustment of equipment used and lead to seed losses due to damaging seeds.

It is an object of the present invention, amongst other objects, to at least partially, if not completely, solve the above problems of the prior art.

This object of the present invention, amongst other objects, is met providing seeds, methods and plants as outlined in the appended claims.

Specifically, according to a first aspect, this object of the present invention, amongst other objects, is met by providing Spinacia oleracea seeds wherein substantially all seeds are free of pericarp and wherein the seeds are obtainable by crossing a female Spinacia oleracea parent plant with a male Spinacia oleracea parent plant resulting in seed production by the female Spinacia oleracea parent plant. The female Spinacia oleracea parent homozygously comprises in its genome a recessive trait substantially preventing pericarp formation surrounding seeds produced.

According to the present invention, considering that pericarp is formed by the female parent and not by the progeny itself, substantially, or completely, seeds without pericarp can readily be obtained in any genetic background using a female parent line wherein the trait is functionally (homozygously recessive) present. Seed production with these female parent lines results essentially in <NUM> % pericarp free Fl seeds. The spinach plants, grown from these seeds, are likely to bear wild type, pericarp covered seeds since the genetic trait is heterozygous in this generation.

Seed technological research on these pericarp free seeds revealed that they are less infected by pathogens and can easily be processed and treated by e.g. warm water for disinfection. Also the application of seed pelleting, encrusting or coating can be performed very well. In summary the advantages of the pericarp free seeds are:.

According to a preferred aspect of the present invention, the present Spinacia oleracea seeds are hybrid seeds obtained by crossing the female Spinacia oleracea parent plant carrying the pericarp free trait with a male Spinacia oleracea plant being a different variety than said female Spinacia oleracea parent plant thereby readily producing hybrid seeds.

According to another preferred aspect of the present invention, the present Spinacia oleracea seeds can be grown into Spinacia oleracea plants being sterile, preferably male sterile.

According to an especially preferred embodiment, the present pericarp less trait, or the recessive trait substantially preventing pericarp formation, is obtainable, obtained or is from a Spinacia oleracea plant deposited at NCIMB under deposit number NCIMB <NUM> on February <NUM>, <NUM> (NCIMB Limited; Ferguson Building; Craibstone Estate; Bucksburn Aberdeen; Scotland, AB21 9YA, United Kingdom. ) It is noted that the present trait is heterozygous present in the deposit and thus the deposit itself produces normal seeds (seeds surrounded by pericarp). Using well known Mendelian inheritance, the present trait can be readily obtained in a homozygous recessive form. Spinach plants carrying the homozygous recessive form of the present trait can be readily identified by their pericarp free seeds.

According to another aspect, the present invention relates to methods for producing Spinacia oleracea seeds free of pericarp, the methods comprise the step of:.

According to a preferred embodiment of the present method, the female Spinacia oleracea parent plant is crossed with a male Spinacia oleracea plant being a different variety than said female Spinacia oleracea parent plant thereby producing hybrid Spinacia oleracea seeds, preferably sterile hybrid Spinacia oleracea seeds, more preferably male sterile hybrid Spinacia oleracea seeds.

According to an especially preferred embodiment of the present method, the present substantially preventing pericarp formation trait is obtainable, obtained, or is from a Spinacia oleracea plant deposited at NCIMB under deposit number NCIMB <NUM> on February <NUM>, <NUM>.

According to yet another aspect, the present invention relates to Spinacia oleracea plants capable of producing seeds substantially free of pericarp wherein the Spinacia oleracea plant homozygously comprises in its genome a recessive trait substantially preventing pericarp formation on produced seeds. The present plants are preferably male sterile female plants.

According to an especially preferred embodiment, the present Spinacia oleracea plants comprise a recessive trait substantially preventing pericarp formation obtainable, obtained or being from a Spinacia oleracea plant deposited at NCIMB under deposit number NCIMB <NUM> on February <NUM>, <NUM>.

According to still another aspect, the present invention relates to the use of a recessive trait capable of substantially preventing pericarp formation on seeds produced wherein the trait substantially preventing pericarp formation is obtainable, obtained, or is from a Spinacia oleracea plant deposited at NCIMB under deposit number NCIMB <NUM> on February <NUM>, <NUM> for the production of substantially pericarp free Spinacia oleracea seeds.

The present invention will be further detailed in the example below. In the example, reference is made to figures wherein:.

Female Spinacia oleracea parent lines homozygously carrying the present trait were crossed with several male Spinacia oleracea parent lines with a different genetic backgrounds not carrying the present trait. Subsequently, substantially <NUM>% seeds without pericarp were produced and collected. The collected seeds were subjected to standard viability, yield and disease tests. The results thereof are summarised in <FIG>.

As can be clearly seen in <FIG>, as compared to traditional Spinach seeds, weight/volume (<FIG>); viability (<FIG>); yield (<FIG>) and disease resistance (<FIG>) were significantly improved in the present seeds.

With respect to the physical properties of the present seeds (<FIG>), weight of <NUM> seeds (TGW, thousand grain weight) of both conventional as pericarp free seeds was determined. The average TGW of pericarp free seeds is <NUM> - <NUM> gram; of conventional seeds <NUM> - <NUM> gram. Another parameter determined is the average diameter of seeds; two different lots of pericarp free seeds and related conventional seeds were used to determine the diameter. In one fraction of seeds the conventional seeds had a diameter of <NUM> and pericarp free seeds of <NUM>; in a second seed lot the average diameter was <NUM> and <NUM> respectively. This means that the diameter of pericarp free seeds is <NUM> - <NUM> % smaller than the diameter of conventional seeds.

A deposit of a representative sample of a pericarp free spinach 1520124NZ was made on February <NUM>, <NUM> at NCIMB Limited; Ferguson Building; Craibstone Estate; Bucksburn Aberdeen; Scotland, AB21 9YA, United Kingdom and was registered as NCIMB <NUM>.

A relatively thin layer of polymer is supplied to the seed; to this polymer fungicides or insecticides can be added to protect the seed against soil borne pathogens and insect damage. Additionally, a dye can be added, giving the opportunity to check for correct drilling of the seeds. Alternatively, also other beneficial compounds can be added as micronutrients or benificials micro-organisms promoting the growth of the young seedlings.

By encrusting the seeds not only are covered with a polymer with or without extra substances as described above but also the seeds are provided with a smooth surface. This makes drilling easier and the added weight enables a more precise direct drilling of seeds treated this way.

With pelleting the seeds are covered with more material, e.g. polymer bound clay, to produce a regularly shaped, round pellet. This pellet, besides eventually having the protecting substances described above, can be constructed in such a way that it will melt or split after water uptake.

Priming or pre-germination is a treatment were seeds are given enough moisture to have a onset of growth of the embryo inside the seed. This results in a faster emergence of the seedling, a higher emergence rate and better growth. It is believed that this head-start results in a good root system going down the soil early and faster growth.

Dormancy prevents the germination of a seed for a certain period of time; normally dormancy prevents germination under unfavourable conditions but this delay can eventually be for a period of several months or even years.

Claim 1:
Spinacia oleracea seeds wherein said seeds are free of pericarp and said seeds are obtainable by crossing a female Spinacia oleracea parent plant with a male Spinacia oleracea parent plant resulting in seed production by said female Spinacia oleracea parent plant, said female Spinacia oleracea parent homozygously comprises in its genome a recessive trait preventing pericarp formation on said produced seeds and harvesting Spinacia oleracea seeds free of pericarp, wherein said recessive trait preventing pericarp formation is obtainable, or is obtained from a Spinacia oleracea plant deposited at NCIMB under deposit number NCIMB <NUM> on February <NUM>, <NUM>.