Plants Producing 2N Gametes or Apomeiotic Gametes

Abstract

The invention relates to plants wherein the protein OSD1, involved in the transition from meiosis I to meiosis II is inactive. These plants produce Second Division Restitution (SDR) 2n gametes. The invention further relates to plants wherein the inactivation of OSD1 is combined with the inactivation of a gene involved in meiotic recombination in plants, and of a gene involved in the monopolar orientation of the kinetochores during meiosis. These plants produce apomeiotic gametes. These plants are useful in plant breeding.

1 - 13 . (canceled) 
     
     
         14 . A method for obtaining a plant producing Second Division Restitution 2n gametes, comprising inhibiting in said plant an Omission of Second Division 1 protein (OSD1),
 wherein said plant is maize,   wherein said OSD1 protein allows a second meiotic division to occur, and thereby is necessary for the transition from meiosis I to meiosis II,   and wherein the inhibition of the OSD1 protein is obtained by
 (i) mutating an OSD1 gene or its promoter and selecting a mutant plant having partially or totally lost OSD1 protein activity, or 
 (ii) expressing a silencing RNA targeting the OSD1 gene encoding said OSD1 protein in said plant, 
   
       and thereby obtaining a maize plant that forms dyads. 
     
     
         15 . The method of  claim 14 , wherein said OSD1 protein has at least 50% sequence identity with the OSD1 protein of  Oryza sativa  as set forth in SEQ ID NO: 35. 
     
     
         16 . The method of  claim 14 , wherein inhibition of the OSD1 protein is obtained by of mutating the OSD1 gene or of its promoter, and silencing a mutant plant having partially or totally lost the OSD1 protein activity. 
     
     
         17 . The method of  claim 14 , wherein the inhibition of the OSD1 protein is obtained by expressing in said plant of a silencing RNA targeting the gene encoding said protein. 
     
     
         18 . The method of  claim 17 , wherein expressing in said plant a silencing RNA comprises expression of a hairpin construct from an expression cassette comprising:
 a promoter functional in plant cell;   at least one DNA construct selected among:
 a) one or more DNA construct(s) of 200 to 1000 bp, each comprising a fragment of a cDNA of OSD1 or its complement, or having at least 95% identity with said fragment, said DNA sequence(s) being placed under transcriptional control of said promoter, 
 b) one or more hairpin DNA construct(s) capable, when transcribed, of forming a hairpin RNA targeting an OSD1 gene, or 
 c) one or more DNA construct(s) capable, when transcribed, of forming a miRNA targeting an OSD1 gene said DNA construct(s) being placed under transcriptional control of said promoter. 
   
     
     
         19 . The method of  claim 17 , wherein expressing in said plant a silencing RNA comprises expression of a hairpin construct from an expression cassette comprising:
 a promoter functional in plant cell; and   at least one hairpin DNA construct(s) capable, when transcribed, of forming a hairpin RNA targeting an OSD1 gene, said DNA construct(s) being placed under transcriptional control of said promoter.   
     
     
         20 . The method of  claim 14 , wherein inhibition of the OSD1 protein is obtained by mutagenesis of the OSD1 gene or its promoter to provide a plant mutant heterozygous for the mutation and self-fertilizing the mutant plant to obtain a mutant plant homozygous for the mutation. 
     
     
         21 . A method for obtaining a plant producing apomeiotic gametes,
 wherein said plant is maize,   wherein said method comprises an inhibition in said plant of the following native plant proteins:
 (a) an Omission of Second Division 1 protein (OSD1) 
 and, 
 (b) a plant protein involved in initiation of meiotic recombination in plants, said protein being selected among:
 (i) a plant sporulation 11-1 (SPO11-1) protein, wherein said protein has at least 40% sequence identity with the SPO11-1 protein of SEQ ID NO: 2; 
 (ii) a plant sporulation 11-2 (SPO11-2) protein, wherein said protein has at least 40% sequence identity with the SPO11-2 protein of SEQ ID NO: 3; 
 (iii) a plant putative recombination initiation defect 1 (PRD1) protein, wherein said protein has at least 25% sequence identity with the PRD1 protein of SEQ ID NO: 4; or 
 (iv) a plant homologous pairing aberration in rice 1 (PAIR1) protein, wherein said protein has at least 30% sequence identity with the PAIR1 protein of SEQ ID NO: 5; and 
 
 (c) a plant meiotic recombination protein 8 (Rec8), wherein said protein has at least 40% sequence identity with the Rec8 protein of SEQ ID NO: 6, 
   wherein the inhibition of at least one of the OSD1, SPO11-1, SPO11-2, PRD1, PAIR1, or Rec8 proteins is obtained by:
 (i) mutating the gene encoding said protein or its promoter and selecting a mutant plant having partially or totally lost an activity of said protein, or 
 (ii) expressing in said plant a silencing RNA targeting the gene encoding said protein. 
   
     
     
         22 . The method of claim  8 , wherein said OSD1 protein has at least 50% sequence identity with the OSD1 protein of  Oryza sativa  as set forth in SEQ ID NO: 35. 
     
     
         23 . The method of  claim 21 , wherein inhibition of at least one of the OSD1, SPO11-1, SPO11-2, PRD1, PAIR1, or Rec8 proteins is obtained by mutating the gene encoding said protein of or of its promoter, and selecting mutants having partially or totally lost the activity of said protein. 
     
     
         24 . The method of  claim 21 , wherein inhibition of at least one of the OSD1, SPO11-1, SPO11-2, PRD1, PAIR1, or Rec8 proteins is obtained by expressing a silencing RNA targeting the gene encoding said protein in said plant. 
     
     
         25 . The method of  claim 21  comprising the steps of:
 (a) providing a plant having a mutation within an allele of the OSD1 gene resulting in the inhibition of the protein encoded by this allele, said plant being heterozygous for this mutation; 
 (b) providing a plant having a mutation within an allele of a gene selected from the SPO11-1, SPO11-2, PRD1, PAIR1 gene resulting in the inhibition of the protein encoded by said allele, said plant being heterozygous for this mutation; 
 (c) providing a plant having a mutation within an allele of the REC8 gene resulting in the inhibition of the protein encoded by said allele, said plant being heterozygous for this mutation; and 
 (d) crossing the plants of steps a) b) and c) in order to obtain a plant having a mutation within an allele of the OSD1 gene, a mutation within an allele of a gene selected from the SPO11-1, SPO11-2, PRD1, PAIR1 gene, and a mutation within an allele of the REC8 gene, said plant being heterozygous for each mutation; 
 (e) self-fertilizing the plant of step d) in order to obtain a plant homozygous for the mutation within the OSD1 gene, for the mutation within an allele of a gene selected from the SPO11-1, SPO11-2, PRD1, PAIR1 gene, and for the mutation within an allele of the REC8 gene. 
 
     
     
         26 . A method for producing Second Division Restitution 2n gametes, wherein said method comprises cultivating a plant obtained by the method of  claim 14 , and recovering the gametes produced by said plant. 
     
     
         27 . The method for producing apomeiotic gametes, wherein said method comprises cultivating a plant obtained by the method of  claim 21 , and recovering the gametes produced by said plant.