Method for producing haploid, doubled haploid and/or dihaploid plants by gynogenesis

1. A method for producing haploid (H), doubled haploid (DH) and/or dihaploid (DiH) plants, doubled haploid (DH) and dihaploid (DiH) plants being homozygous or essentially homozygous, said method being by gynogenesis induced by irradiated pollen, said method comprising:

a stage of irradiation of the reproductive material from a male parent at a dose between about 165 and 185 Gamma Ray (Gy) and a stage of selection of haploid (H), or dihaploid (DiH), or haploid (H) and dihaploid (DiH) plants by the use of molecular marker(s),

wherein the parent plants are selected from the species Cucurbita pepo.

2. The method as claimed in claim 1 , comprising the following successive stages:

a) Use reproductive material from a male parent;

b) Irradiate said reproductive material from the male parent at a dose between 165 and 185 Gamma Ray;

c) Pollinate the reproductive material from a hybrid female parent with said irradiated reproductive material from the male parent;

d) Harvest the fruits whose seeds bear embryos;

e) Extract the seeds from said fruits;

f) Extract the embryos from said seeds;

g) Place the embryos in culture on a suitable medium until a plant is obtained; and

h) Selecting the haploid plants (H), or dihaploid plants (DiH), or haploid (H) and dihaploid (DiH) plants by the use of molecular marker(s).

3. The method as claimed in claim 2 , wherein that stage h of selection of the haploid plants (H), or dihaploid plants (DiH), or haploid (H) and dihaploid (DiH) plants comprises:

—I— the use of specific molecular marker(s) of given allele(s) contained in the genetic material from the male parent for selecting, from the plants obtained at the end of stage g), the plants that are free from genetic material from the male parent or that possess an insufficient amount thereof to cause, in the progeny of said plants, a disjunction of a phenotypic and/or genotypic character; and,

—II— the use of specific molecular marker(s) of given allele(s) contained in the genetic material from the hybrid female parent, to determine the homozygous/heterozygous state of the plants to be selected, i.e. the plants obtained at the end of stage g), said marker(s) being used for selecting homozygous or essentially homozygous plants.

4. The method as claimed in claim 1 further comprising a stage i) of doubling of the chromosome stock of the haploid plants (H).

5. The method as claimed in claim 4 , wherein that stage i) of doubling of the chromosome stock is performed by means of colchicine.

6. The method as claimed in claim 1 , for producing haploid (H), doubled haploid (DH) and/or dihaploid (DiH) plants, doubled haploid (DH) and dihaploid (DiH) plants being homozygous or essentially homozygous, by gynogenesis induced with irradiation of the reproductive material from the male parent,

comprising a prior stage of determination of the suitable irradiation dose or doses for increasing the yields of said plants as a function of multiple given factors, selected from the group consisting of the genotypes of the male parent and of the female parent; the climatic and physiological conditions; the time of harvesting of the fruits; the level of growth of the embryos collected with a view to culture thereof; and the level of development of the embryos placed in culture; said prior stage comprising:

i) testing, for a given factor, different irradiation doses on the reproductive plant material from the male parent,

ii) employing, for each irradiation dose tested, a stage h′) of selection of haploid plants (H), or dihaploid plants (DiH), or haploid (H) and dihaploid (DiH) plants, said stage h′) comprising:

—I— the use of specific molecular marker(s) of allele(s) of the genetic material from the male parent for selecting, from the plants obtained as a result of gynogenesis induced by the irradiated pollen, the plants that are free from plant material from the male parent or which possess an insufficient amount thereof to cause, in the progeny of said plants, a disjunction of a phenotypic and/or genotypic character; and

—II— the use of specific molecular marker(s) of given specific allele(s) of the genetic material of the hybrid female parent employed in gynogenesis, to determine the homozygous/heterozygous state of the plants to be selected, i.e. of the plants obtained as a result of gynogenesis, said marker(s) being used for selecting homozygous or essentially homozygous plants;

iii) counting, for each irradiation dose tested, haploid plants (H), or dihaploid plants (DiH), or haploid (H) and dihaploid (DiH) plants obtained;

iv) calculating, for each irradiation dose tested and from the counts obtained in (iii), the yield of haploid plants (H), or dihaploid plants (DiH), or haploid (H) and dihaploid (DiH) plants obtained; and

v) comparing the counts obtained in (iii) and/or the yields found in (iv) for deducing the suitable irradiation dose or doses.

7. The method of claim 1 , wherein the molecular marker(s) used is/are a microsatellite marker or microsatellite marker(s) (SSR).

8. The method of claim 1 , wherein the molecular marker(s) used is/are selected from the markers defined by a primer pair or primer pairs of nucleotide sequences SEQ ID No. 1 to 16.