Overexpression of Starch Synthase in Plants

Abstract

The present invention relates to a process for increasing the phosphate content of starches of genetically modified plant cells in comparison with starches from corresponding wild-type plant cells by introducing a foreign nucleic acid molecule which codes for a soluble starch synthase II. The present invention furthermore relates to the overexpression of this soluble starch synthase II in the genetically modified plant cells. Furthermore, the present invention relates to rice starch and rice flour with improved quality characteristics, to rice grains comprising this rice starch, and to rice plants on which these rice grains grow.

1 . A method for increasing the phosphate content of starches of genetically modified plant cells to 150 to 500% in comparison with starches from corresponding wild-type plant cells comprising introducing a foreign nucleic acid molecule coding for a soluble starch synthase II into a plant cell, wherein said soluble starch synthase II is overexpressed. 
     
     
         2 . The method of  claim 1 , wherein said foreign nucleic acid molecule comprises the coding region of a heterologous soluble starch synthase II. 
     
     
         3 . The method of  claim 1 , wherein said soluble starch synthase II is from a monocotyledonous plant. 
     
     
         4 . The method of  claim 1 , wherein said soluble starch synthase II is from wheat. 
     
     
         5 . The method of  claim 1 , wherein said soluble starch synthase II comprises the nucleotide sequence of SEQ ID No. 1. 
     
     
         6 . The method of  claim 1 , wherein said genetically modified plant cells are potato, maize, or rice plant cells. 
     
     
         7 . A rice starch with a DSC T-onset temperature of between 70° C. and 80° C. 
     
     
         8 . The rice starch of  claim 7 , wherein said DSC T-onset temperature is between 72° C. and 79° C. 
     
     
         9 . A derivatized rice starch comprising the rice starch of  claim 7 . 
     
     
         10 . A composition comprising the rice starch of  claim 7 . 
     
     
         11 . A rice flour comprising the rice starch of  claim 7 . 
     
     
         12 . A composition comprising the rice flour of  claim 11 . 
     
     
         13 . A rice grain comprising the rice starch of  claim 7 . 
     
     
         14 . A composition comprising at least one rice grain of  claim 13 . 
     
     
         15 . A genetically modified rice plant comprising at least one rice grain of  claim 13 . 
     
     
         16 . A foodstuff comprising the rice flour of  claim 11 . 
     
     
         17 . An animal feed comprising the rice flour of  claim 11 . 
     
     
         18 . An isolated nucleic acid molecule coding for a soluble starch synthase H comprising the nucleotide sequence of SEQ ID NO. 1. 
     
     
         19 . The nucleic acid molecule of  claim 18 , wherein said nucleic acid molecule encodes the amino acid sequence of SEQ ID NO. 2. 
     
     
         20 . A vector comprising the nucleic acid molecule of  claim 18 . 
     
     
         21 . A plant cell comprising the nucleic acid molecule of  claim 18 . 
     
     
         22 . The plant cell of  claim 21 , wherein said plant cell is a pea, potato, sweet potato, cassaya, maize, or rice plant cell. 
     
     
         23 . A plant comprising the plant cell of  claim 21 . 
     
     
         24 . A method of producing modified starch comprising extracting said starch from a plant of  claim 23 . 
     
     
         25 . A rice starch with a 10 to 65% reduction in digestibility compared to wild type starch. 
     
     
         26 . The starch of  claim 25 , wherein said reduction in digestibility is 10-55% to wild type starch. 
     
     
         27 . The starch of  claim 26 , wherein said reduction in digestibility is 12-45% to wild type starch. 
     
     
         28 . The starch of  claim 27 , wherein said reduction in digestibility is 15-30% to wild type starch. 
     
     
         29 . A rice starch with a resistant starch (RS) content of 15-45% compared to wild type starch. 
     
     
         30 . The starch of  claim 29 , wherein said resistant starch (RS) content is 17-40% compared to wild type starch. 
     
     
         31 . The starch of  claim 30 , wherein said resistant starch (RS) content is 20-38% compared to wild type starch.