Method and means for modulating plant cell cycle proteins and their use in plant cell growth control

Abstract

The present invention provides a new Arabidopsis thaliana nucleotide sequence and polypeptide sequence having a molecular weight of about 10.5 kDa. Modulation of the expression of the polypeptides encoded by the nucleotide sequences according to the invention has an advantageous influence on plant cell division characteristics especially on the endoreduplication whereby plant cell size and storage capacity of plant cells is influenced.

1 . An isolated and/or recombinant nucleic acid molecule, preferably DNA, encoding at least a functional part of a plant CKS1 protein, which protein in  Arabidopsis thaliana  comprises the sequence as depicted in SEQ.ID.NO.3 or SEQ.ID.NO.4 or a functional part thereof.  
     
     
         2 . A nucleic acid molecule according to  claim 1  comprising at least a part of the sequence as depicted in SEQ.ID.NO.1 or SEQ.ID.NO.2 or a sequence at least substantially homologous thereto.  
     
     
         3 . A nucleic acid molecule according to  claim 1  comprising at least a part of the sequence as depicted in SEQ.ID.NO.1 or SEQ.ID.NO.2 or a sequence which hybridizes under conventional conditions to at least a part of said sequence or its complementary sequence.  
     
     
         4 . A polypeptide encoded by a nucleic acid sequence comprised in a nucleic acid molecule according to any of the  claims 1  to  3 .  
     
     
         5 . A polypeptide according to  claim 4  comprising at least a functional part of a plant CKS1.  
     
     
         6 . An  Arabidopsis thaliana  polypeptide comprising the amino acid sequence according to SEQ.ID.NO. 3 or SEQ.ID.NO.4 and/or fragments thereof.  
     
     
         7 . A chimeric gene comprising the following operably linked polynucleotides: 
 a. a nucleic acid molecule according to  claim 1  to  3     b. one or more control sequences    
     
     
         8 . A vector comprising a nucleic acid molecule according to  claim 1  to  3  or comprising a chimeric gene according to  claim 7 .  
     
     
         9 . A plant cell comprising a recombinant nucleic acid molecule according to any of the  claims 1  to  3  or comprising a chimeric gene according to  claim 7 .  
     
     
         10 . A plant cell comprising a recombinant polypeptide with an amino acid sequence according to SEQ.ID.NO.3 or SEQ.ID.NO.4 and/or functional fragments and/or functional derivatives thereof.  
     
     
         11 . A plant comprising a recombinant nucleic acid molecule according to any of the  claims 1  to  3  or comprising a chimeric gene according to  claim 7 .  
     
     
         12 . Plant material such as roots, flowers, fruit, leaves, pollen, seeds, seedlings or tubers obtainable from a plant according to  claim 11 .  
     
     
         13 . Progeny of a plant according to  claim 11 .  
     
     
         14 . A method for transforming plants with a nucleic acid molecule according to any of the  claims 1  to  3  or with a chimeric gene according to  claim 7 .  
     
     
         15 . A process for producing a transgenic plant comprising the steps of introducing a nucleic acid molecule of  claim 1  to  3  or introducing a chimeric gene according to  claim 7  into at least one plant cell and regenerating a plant from said cell.  
     
     
         16 . A method for modulating plant cell division and/or growth comprising modulation of the expression and/or activity of a polypeptide and/or fragment thereof encoded by a nucleotide sequence comprised in a nucleic acid molecule according to  claim 1  to  3 .  
     
     
         17 . A method for modulating endoreduplication in plants or parts thereof by modifying the plant cell division.  
     
     
         18 . A method according to  claim 17  whereby modulation of endoreduplication in plants or parts thereof is achieved by means of plant genetic engineering.  
     
     
         19 . A method for modulating endoreduplication according to  claim 17  or  18  wherein the expression of one or more plant cell cycle genes and/or the activity of one or more plant cell cycle proteins is modified.  
     
     
         20 . Use of cell cycle genes, preferably plant cell cycle genes, to modulate endoreduplication in plants or parts thereof.  
     
     
         21 . Use of CKS1 genes, preferably plant CKS1 genes, to modulate endoreduplication in plants or parts thereof.  
     
     
         22 . Use of CDC2 genes, preferably plant CDC2 genes, to modulate endoreduplication in plants or parts thereof  
     
     
         23 . Use of plant CDC2b genes to modulate endoreduplication in plants or parts thereof.  
     
     
         24 . Use of dominant negative mutants of cyclin dependent kinases, preferably dominant negative mutants of plant cyclin dependent kinases and most preferably dominant negative mutants of plant CDC2b genes to modulate endoreduplication in plants or parts thereof.  
     
     
         25 . Plant cells and/or plants obtainable by a method according to  claims 17  to  19 .