Plant galactinol synthase homologs

Abstract

Isolated nucleic acid fragments encoding galactinol synthase are disclosed. Recombinant DNA construct(s) for use in altering expression of endogenous genes encoding galactinol synthase are also disclosed.

1 . An isolated polynucleotide comprising:
 (a) a nucleotide sequence encoding a polypeptide having galactinol synthase activity, wherein the polypeptide has an amino acid sequence of at least 85% identity, when compared to one of SEQ ID NO: 2 or 4 or 95% identity when compared to one of SEQ ID NO:6, based on the Clustal V method of alignment,   (b) all or part of the isolated polynucleotide comprising (a) for use in co-suppression or antisense suppression of endogenous nucleic acid sequences encoding polypeptides having galactinol synthase activity, or   (c) a complement of the nucleotide sequence of (a) or (b), wherein the complement and the nucleotide sequence consist of the same number of nucleotides and are 100% complementary.   
     
     
         2 . The polynucleotide of  claim 1 , wherein the amino acid sequence of the polypeptide and the amino acid sequence of SEQ ID NO:2 or SEQ ID NO:4 have at least 90% identity based on the Clustal alignment method. 
     
     
         3 . The polynucleotide of  claim 1 , wherein the amino acid sequence of the polypeptide and the amino acid sequence of SEQ ID NO:2 or SEQ ID NO:4 have at least 95% identity based on the Clustal alignment method. 
     
     
         4 . The polynucleotide of  claim 1 , wherein the amino acid sequence of the polypeptide comprises one of SEQ ID NO:2, SEQ ID NO:4 or SEQ ID NO:6. 
     
     
         5 . The polynucleotide of  claim 1 , wherein the nucleotide sequence comprises one of SEQ ID NO:1, SEQ ID NO:3 or SEQ ID NO:5. 
     
     
         6 . A vector comprising the polynucleotide of  claim 1 . 
     
     
         7 . A recombinant DNA construct comprising the polynucleotide of  claim 1  operably linked to at least one regulatory sequence. 
     
     
         8 . A method for transforming a cell, comprising transforming a cell with the polynucleotide of  claim 1 . 
     
     
         9 . A cell comprising the recombinant DNA construct of  claim 7 . 
     
     
         10 . A method for producing a plant comprising transforming a plant cell with the polynucleotide of  claim 1  and regenerating a plant from the transformed plant cell. 
     
     
         11 . A plant comprising the recombinant DNA construct of  claim 7 . 
     
     
         12 . A seed comprising the recombinant DNA construct of  claim 7 . 
     
     
         13 . An isolated polypeptide having galactinol synthase activity, wherein the polypeptide has an amino acid sequence of at least 85% sequence identity when compared to one of SEQ ID NO: 2 or 4 or 95% identity when compared to SEQ ID NO: 6, based on the Clustal V method of alignment. 
     
     
         14 . The polypeptide of  claim 13 , wherein the amino acid sequence of the polypeptide has at least 90% sequence identity, based on the Clustal V method of alignment, when compared to one of SEQ ID NO: 2 or 4. 
     
     
         15 . The polypeptide of  claim 13 , wherein the amino acid sequence of the polypeptide has at least 95% sequence identity, based on the Clustal V method of alignment, when compared to one of SEQ ID NO: 2 or 4. 
     
     
         16 . The polypeptide of  claim 13 , wherein the amino acid sequence of the polypeptide comprises one of SEQ ID NO: 2, 4 or 6. 
     
     
         17 . A method for isolating a polypeptide having galactinol synthase activity comprising isolating the polypeptide from a cell or culture medium of the cell, wherein the cell comprises a recombinant DNA construct comprising the polynucleotide of  claim 1  operably linked to at least on regulatory sequence. 
     
     
         18 . A method for reducing the level of at least one raffinose saccharide in soybean comprising:
 (d) constructing a recombinant DNA construct comprising all or part of at least one isolated polynucleotide comprising a nucleotide sequence encoding a polypeptide having galactinol synthase activity for use in co-suppression or antisense suppression of endogenous nucleic acid sequences encoding polypeptides having galactinol synthase activity operably linked to at least one regulatory sequence; and   (e) transforming a soybean cell with the recombinant DNA construct of (a); and   (f) regenerating soybean plants from the transformed cells of step (c); and   (g) screening seeds obtained from the plants of (c) for an altered level of galactinol synthase in the transformed soybean cell when compared to a corresponding nontransformed soybean cell.   
     
     
         19 . The method of  claim 18 , wherein the total raffinose saccharide content in soybean seeds has been reduced by at least 27%. 
     
     
         20 . The method of  claim 18 , wherein the total stachyose content in soybean seeds has been reduced by at least 36%. 
     
     
         21 . The method of  claim 18 , wherein the total raffinose saccharide content in soybean seeds has been reduced by at least 71%.