Plants having improved tolerance to various types of environmental stress, their production, and polyamine metabolism-related enzyme gene

Abstract

The present invention relates to isolated plant-derived polyamine metabolism-related enzyme genes characterized in that their level of expression changes when exposed to environmental stress; antisense DNA or antisense RNA to such genes; plants and their progeny having improved environmental stress tolerance, in which such genes are retained in a stable manner; methods for producing such plants, and methods for producing calli of such plants; method for selecting transformed plants which grow improved more than plants lacking an exogenous polyamine metabolism-related enzyme gene; and microorganims and plants which are transformed by such genes

1 .- 51 . (canceled)  
   
   
       52 . A method for producing transgenic plants with improved environmental stress tolerance against at least one environmental stress selected from drought stress, cold stress, salt stress, osmotic stress, or herbicidal stress as compared to wild-type plants of the same species, the method comprising 
 (1) integrating into the genome of at least one cell of the plant, a vector comprising a DNA molecule encoding an exogenous spermidine synthase, and wherein the spermidine synthase is naturally occurring and has spermidine synthase activity, and wherein the DNA molecule encoding spermidine synthase is a base sequence of (i) or (ii) below: 
 (i) a base sequence encoding for an amino acid sequence having at least 82% homology to SEQ ID NO: 2; or  
 (ii) a base sequence hybridizing under stringent conditions with the base sequence of (i) above, wherein said stringent conditions comprise hybridization at a salt concentration of 6×SSC or 6×SSPE, followed by washing with a solution containing 0.5×SSC at 42° C.; and  
   (2) growing said plant, wherein said DNA molecule is expressed and wherein said spermidine synthase confers on said transgenic plant an improved tolerance to said environmental stress.    
   
   
       53 . A method for producing transgenic plants with improved growth in conditions of environmental stress, the method comprising: 
 (1) integrating into the genome of at least one cell of the plant, a vector comprising a DNA molecule encoding an exogenous spermidine synthase, and wherein the spermidine synthase is naturally occurring and has spermidine synthase activity, and wherein the DNA molecule encoding spermidine synthase is a base sequence of (i) or (ii) below: 
 (i) a base sequence encoding for an amino acid sequence having at least 82% homology to SEQ ID NO: 2; or  
 (ii) a base sequence hybridizing under stringent conditions with the base sequence of (i) above, wherein said stringent conditions comprise hybridization at a salt concentration of 6×SSC or 6×SSPE, followed by washing with a solution containing 0.5×SSC at 42° C.; and  
   (2) growing said plant in conditions of environmental stress selected from drought stress, cold stress, salt stress, osmotic stress, or herbicidal stress, wherein said DNA molecule is expressed and wherein said spermidine synthase confers on said transgenic plant improved growth compared to wild type plants of the same species in conditions of said environmental stress.    
   
   
       54 . A method for producing transgenic plants with improved environmental tolerance against at least one environmental stress selected from drought stress, cold stress, salt stress, osmotic stress, and herbicidal stress, as compared to wild-type plants, the method comprising: 
 (1) integrating into the genome of at least one cell of the plant, a vector comprising a DNA molecule encoding an exogenous spermidine synthase, and wherein the DNA molecule encoding spermidine synthase is a base sequence of (i) or (ii) below: 
 (i) a base sequence encoding for an amino acid sequence having at least 82% homology to SEQ ID NO: 2; or  
 (ii) a base sequence hybridizing under stringent conditions with the base sequence of (i) above, wherein said stringent conditions comprise hybridization at a salt concentration of 6×SSC or 6×SSPE, followed by washing with a solution containing 0.5×SSC at 42° C.; and,  
   (2) increasing the content of free spermidine and/or free spermine, and    (3) growing said plant, wherein said DNA molecule is expressed and wherein said spermidine synthase confers on said transgenic plant an improved tolerance to said environmental stress.    
   
   
       55 . A method for producing plants that stably retains an exogenous spermidine synthase (SPDS) gene under the control of one or more promoters that can function within the plant, and that has improved environmental stress tolerance against at least one environmental stress selected from drought stress, cold stress, salt stress, osmotic stress, and herbicidal stress as compared to wild-type plants of the same species, the method comprising the step of transforming plant cells with said SPDS gene, wherein the SPDS gene is a base sequence of (i) or (ii) below: 
 (i) a base sequence encoding for an amino acid sequence having at least 82% homology to SEQ ID NO: 2; or    (ii) a base sequence hybridizing under stringent conditions with the base sequence of (i) above, wherein said stringent conditions comprise hybridization at a salt concentration of 6×SSC or 6×SSPE, followed by washing with a solution containing 0.5×SSC at 42° C.    
   
   
       56 . A plant and its progeny produced from the method of  claim 52 .  
   
   
       57 . A transgenic plant and its progeny produced from the method of  claim 52 , wherein said progeny comprises said DNA molecule.  
   
   
       58 . The plant or progeny of  claim 57 , wherein the plant has improved cold stress tolerance, improved salt stress tolerance, improved herbicidal stress tolerance, improved drought stress tolerance, or improved osmotic stress tolerance compared to a wild-type plant of the same species, wherein said progeny comprises said DNA molecule.  
   
   
       59 . Leaves, stems, flowers, ovaries, fruit, seeds, fibers, or callus obtained from the plant or progeny of the plant of  claim 57 , wherein said leaves, stems, flowers, ovaries, fruit, seeds, fibers, or callus comprise said DNA molecule.  
   
   
       60 . The plant of  claim 52 , wherein the plant is  Arabidopsis thaliana.    
   
   
       61 . The plant of  claim 52 , wherein the plant is a dicotyledon.  
   
   
       62 . Transgenic plants and their progeny, which retain an exogenous spermidine synthase gene in a stable manner under control of a promoter or promoters capable of functioning in plants and have improved environmental stress tolerance against at least one environmental stress selected from drought stress, cold stress, salt stress, osmotic stress, and herbicidal stress as compared to plants lacking the exogenous spermidine synthase gene, wherein the spermidine synthase gene has a base sequence of (i) or (ii) below: 
 (i) a base sequence hybridizing under stringent conditions with the base sequence of (a) above, wherein said stringent conditions comprise hybridization at a salt concentration of 6×SSC or 6×SSPE, followed by washing with a solution containing 0.5×SSC at 42° C., or    (ii) a base sequence coding for a protein with spermidine synthase activity, comprising the base sequence of (a) or (b) with 1 or more bases deleted, substituted, inserted, or added.    
   
   
       63 . Plants and their progeny of  claim 62 , wherein said plants comprise transformants obtained by the transformation of plants lacking the exogenous spermidine synthase gene with expression vector containing the spermidine synthase gene under the control of a promoter or promoters capable of functioning in plants.  
   
   
       64 . Leaves, stems, flowers, ovaries, fruit, seeds, or calli obtained from the plants and their progeny of  claim 62 .  
   
   
       65 . A plant characterized by being transformed with a plasmid containing a plant-derived spermidine synthase gene, wherein the expression level of the gene changes when exposed to low temperatures.