Quartet breeding

Abstract

The invention relates to a method for the production of a set of seeds which are genetically identical to the male gametes from which they arise, which may comprise placing a limited number of paternal gametes that have the form of tetrads or dyads on the stigma of a flower to fertilize maternal egg cells to obtain a number of zygotes; and inducing the loss of maternal chromosomes from the zygotes to obtain a seed set containing a limited number of seeds in which the maternal chromosomes are absent. In a preferred embodiment the father plant exhibits suppression of chromosome recombination or second division restitution (SDR) during meiosis.

What is claimed is: 
     
         1 . A method for the production of a set of seeds which are genetically identical to the male gametes from which they arise, comprising:
 a) placing a limited number of paternal gametes that have the form of tetrads or dyads on the stigma of a flower to fertilize maternal egg cells to obtain a number of zygotes;   b) inducing the loss of maternal chromosomes from the zygotes to obtain a seed set containing a limited number of seeds in which the maternal chromosomes are absent.   
     
     
         2 . The method as claimed in  claim 1 , wherein the limited number of paternal gametes is equal to or lower than the number of egg cells contained in the female reproductive organ carrying the stigma. 
     
     
         3 . The method as claimed in  claim 1 , wherein the limited number of paternal gametes is two or four. 
     
     
         4 . The method as claimed in  claim 1 , wherein the paternal gametes that have the form of tetrads or dyads are the result of interference with microspore tetrad separation. 
     
     
         5 . The method as claimed in  claim 4 , wherein interference with microspore tetrad separation comprises interference with one or more target genes involved in the break-down of the pectin layer between the microspores resulting from a single meiotic division. 
     
     
         6 . The method as claimed in  claim 5 , wherein the one or more target genes are selected from the group consisting of QRT1, QRT2, QRT3, or their functional homologues. 
     
     
         7 . The method as claimed in  claim 4 , wherein interference with microspore tetrad separation is achieved by chemical means. 
     
     
         8 . The method as claimed in  claim 1 , wherein the father plant exhibits suppression of chromosome recombination. 
     
     
         9 . The method as claimed in  claim 1 , wherein the father plant exhibits second division restitution (SDR) during meiosis. 
     
     
         10 . The method as claimed in  claim 8 , wherein suppression of chromosome recombination is achieved by interfering with one or more target genes involved in recombination. 
     
     
         11 . The method as claimed in  claim 10 , wherein the one or more target genes are involved in double strand breaks, such as SPO11, MER1, MER2, MRE2, MEI4, REC102, REC104, REC14, MEK1/MRE4, RED1, HOP1, RAD50, MRE11, XRS2, or their functional homologues, or wherein the one or more target genes are involved in chromosome pairing and/or strand exchange, such as RHD54/TID1, DMC1, SAE3, RED1, HOP1, HOP2, REC8, MER1, MRE2, ZIP1, ZIP2, MEI5, RAD51, RAD52, RAD54, RAD55, RAD57, RPA, SMC3, SCC1, MSH2, MSH3, MSH6, PMS1, SOLODANCERS, HIM6, CHK2, or their functional homologues, or wherein the one or more target genes are involved in the meiotic recombination process, such as SGS1, MSH4, MSH5, ZIP1 and ZIP2, or their functional homologues, or wherein the one or more target genes are selected from the group consisting of PRD1, PRD2, PRD3, PHS1, NBS1, COM1, MND1, MER3/RCK, ZIP3, ZIP4, PTD, SHOC1, ZYP1, MLH1, MLH3, or their functional homologues. 
     
     
         12 . The method as claimed in  claim 5  or  10 , wherein the interfering with the one or more target genes consists of preventing transcription thereof. 
     
     
         13 . The method as claimed in  claim 12 , wherein transcription is preferably prevented by means of RNA oligonucleotides, DNA oligonucleotides or RNAi molecules directed against the target gene promoter, or wherein transcription is preferably prevented by means of the expression of a negatively acting transcription factor acting on the target gene promoter. 
     
     
         14 . The method as claimed in  claim 5  or  10 , wherein the interfering with the one or more target genes consists of destabilizing the target gene mRNA or transcript, preferably by means of nucleic acid molecules that are complementary to the target gene mRNA or transcript, selected from the group consisting of antisense RNA, RNAi molecules, Virus-Induced Gene Silencing (VIGS) molecules, co-suppressor molecules, RNA oligonucleotides or DNA oligonucleotides, or wherein the interfering with the one or more target genes consists of inhibiting the target gene expression product, preferably by means of the expression product(s) of one or more dominant negative nucleic acid constructs, or preferably by means of one or more chemical compounds. 
     
     
         15 . The method as claimed in  claim 5  or  10 , wherein the interfering with the one or more target genes consists of the introduction of one or more mutations into the target gene, leading to perturbation of its biological function, and wherein the one or more mutations are preferably introduced randomly by means of one or more chemical compounds, such as ethyl methanesulphonate, nitrosomethylurea, hydroxylamine, proflavine, N-methyl-N-nitrosoguanidine, N-ethyl-N-nitrosourea, N-methyl-N-nitro-nitrosoguanidine, diethyl sulphate, ethylene imine, sodium azide, formaline, urethane, phenol and ethylene oxide, and/or by physical means, such as UV-irradiation, fast-neutron exposure, X-rays, gamma irradiation, and/or by insertion of genetic elements, such as transposons, T-DNA, retroviral elements, and/or wherein the one or more mutations are introduced specifically by means of homologous recombination or oligonucleotide-based mutation induction. 
     
     
         16 . The method as claimed in  claim 9 , wherein second division restitution occurs spontaneously, in particular without interference with the starting organism. 
     
     
         17 . The method as claimed in  claim 9 , wherein second division restitution is induced by means of genetic modification, wherein the genetic modification is transient, or wherein the genetic modification is achieved by stable incorporation into the genome of a genetic element increasing the number of second division restitution events in the organism, or wherein second division restitution is achieved by subjecting the father plant to environmental stress, such as temperature stress, NO 2 , nitrous oxide (N 2 O), or combinations thereof. 
     
     
         18 . The method as claimed in  claim 1 , wherein the loss of maternal chromosomes from the zygote is induced by using a haploid inducer line as the female. 
     
     
         19 . The method as claimed in  claim 18 , wherein the female is a plant of a different species. 
     
     
         20 . The method as claimed in  claim 1 , wherein the female plant is a transgenic plant that comprises a heterologous transgene expression cassette, the expression cassette comprising a promoter operably linked to a polynucleotide encoding a recombinantly altered CENH3, CENPC, MIS12, NDC80 or NUF2 polypeptide, and having a corresponding inactivated endogenous CENH3, CENPC, MIS12, NDC80 or NUF2 gene. 
     
     
         21 . A set of seeds containing a limited number of seeds in which the maternal chromosomes are absent, which set is composed of pairs of genetically complementary seeds which when plants grown from the seeds are crossed result in essentially the same hybrid, and which seed set is obtainable by a method as claimed in  claim 1 . 
     
     
         22 . A method for providing a set of parent plants for the production of a plant of which the genetic constitution is essentially identical to the genetic constitution of its male grandparent, comprising growing plants from seeds of the set of seeds as claimed in  claim 21 , after or prior to doubling the chromosome number of the seeds, and identifying two genetically complementary plants as the parent plants. 
     
     
         23 . The method as claimed in  claim 22 , wherein the set of seeds or the plants grown thereof are screened for their genetic constitution, to identify a plant of which the genetic constitution is essentially identical to the genetic constitution of its paternal grandfather, and to identify another plant of which the genetic constitution is essentially identical to the genetic constitution of its paternal grandmother. 
     
     
         24 . The method as claimed in  claim 22 , wherein a plant of which the genetic constitution is essentially identical to the genetic constitution of its paternal grandfather, is crossed to another plant of which the genetic constitution is essentially identical to the genetic constitution of its paternal grandmother, in order to obtain progeny plants of which the genetic constitution is essentially identical to the genetic constitution of their own grandfather.