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.   
       soybeans not containing the chimeric gene of step (a). 
     
     
         2 - 21 . (canceled) 
     
     
         22 . A method for reducing the level of at least one raffinose saccharide in soybean comprising:
 (a) 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   (b) transforming a soybean cell with the recombinant DNA construct of   (a); and   (c) regenerating soybean plants from the transformed cells of step (c); and   (d) 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.   
     
     
         23 . The method of  claim 22 , wherein the total raffinose saccharide content in soybean seeds has been reduced by at least 27%. 
     
     
         24 . The method of  claim 22 , wherein the total stachyose content in soybean seeds has been reduced by at least 36%. 
     
     
         25 . The method of  claim 22 , wherein the total raffinose saccharide content in soybean seeds has been reduced by at least 71%.