Methods for Elevating Fat/Oil Content in Plants

Abstract

In some embodiments, the present invention provides a method of elevating lipid content in vegetative (non-seed) plant or algal cells, plant tissues, or whole plants by genetically modifying the plant or algae to express a protein or polypeptide associated with lipid metabolism (such as fat-specific protein 27) of animal origin or plant origin. Also provided are genetically-modified plant or algal cells, plant tissues, or whole plants with elevated cellular lipid content, expressing a protein or polypeptide associated with lipid metabolism (such as fat-specific protein 27) of animal (e.g. human) origin or plant origin.

We claim: 
     
         1 . A method for obtaining a plant cell or algal cell with elevated lipid content, wherein the method comprises:
 genetically modifying a plant cell or algal cell to express an exogenous protein or polypeptide associated with lipid metabolism, thereby obtaining a genetically-modified plant cell or algal cell with elevated lipid content;   wherein the protein or polypeptide associated with lipid metabolism induces adipogenesis, enhances the accumulation of cellular lipid droplets, and/or reduces lipase activity; and   wherein the expression of the protein or polypeptide associated with lipid metabolism increases lipid content of the genetically-modified plant cell or algal cell as compared to a wild-type plant cell or algal cell of the same type.   
     
     
         2 . A method according to  claim 1 , wherein the protein or polypeptide associated with lipid metabolism is selected from fat specific protein 27 (FSP27), PLIN1, PLIN2, SEIPIN, FIT1, FIT2, acyl-CoA: diacylglycerol acyltransferase 1 (DGAT-1), phospholipid: diacylglycerol acyltransferase 1 (PDAT-1), cell death activator (Cidea), leafy cotyledon 2 (LEC2), and WRINKLED1 (WRIT) protein or polypeptide. 
     
     
         3 . A method according to  claim 1 , wherein the protein or polypeptide associated with lipid metabolism is of animal origin. 
     
     
         4 . A method according to  claim 1 , wherein the protein or polypeptide associated with lipid metabolism is a fat specific protein 27 (FSP27) protein or polypeptide. 
     
     
         5 . A method according to  claim 1 , further comprising modifying the plant cell or algal cell to express a combination of exogenous proteins or polypeptides associated with lipid metabolism, wherein at least one exogenous protein or polypeptide associated with lipid metabolism is selected from fat specific protein 27 (FSP27), PLIN1, PLIN2, SEIPIN, FIT1, FIT2, acyl-CoA: diacylglycerol acyltransferase 1 (DGAT-1), phospholipid: diacylglycerol acyltransferase 1 (PDAT-1), cell death activator (Cidea), LEC2, and WRINKLED1 (WRI1) protein or polypeptide. 
     
     
         6 . A method according to  claim 1 , wherein the cell is a plant cell and the method further comprises regenerating the plant cell into a plant. 
     
     
         7 . A method according to  claim 1 , wherein the genetic modification of the plant cell or algal cell comprises transforming the plant cell or algal cell with a vector comprising a nucleic acid sequence encoding an exogenous protein or polypeptide associated with lipid metabolism, wherein the nucleic acid is operably linked to a promoter and/or a regulatory sequence. 
     
     
         8 . A method according to  claim 1 , wherein the exogenous protein or polypeptide associated with lipid metabolism is selected from  Arabidopsis thaliana  SEIPIN1, SEIPIN2, SEIPIN3, or leafy cotyledon 2 (LEC2). 
     
     
         9 . A method according to  claim 8 , wherein lipid droplet size is enhanced as compared to lipid droplet size of a wild-type cell of the same type. 
     
     
         10 . A transgenic plant cell or algal cell having elevated lipid content as compared to a wild-type plant cell or algal cell of the same type, wherein the transgenic plant cell or algal cell expresses an exogenous protein or polypeptide associated with lipid metabolism, wherein the protein or polypeptide associated with lipid metabolism induces adipogenesis, enhances the accumulation of cellular lipid droplets, and/or reduces lipase activity. 
     
     
         11 . A transgenic plant cell or algal cell according to  claim 10 , wherein the protein or polypeptide associated with lipid metabolism is selected from fat specific protein 27 (FSP27), PLIN1, PLIN2, SEIPIN, FIT1, FIT2, acyl-CoA:diacylglycerol acyltransferase 1 (DGAT-1), phospholipid:diacylglycerol acyltransferase 1 (PDAT-1), adipose triglyceride lipase (ATGL), cell death activator (Cidea), LEC2, and WRINKLED1 (WRI1) protein or polypeptide. 
     
     
         12 . A transgenic plant cell or algal cell according to  claim 11 , wherein the protein associated with lipid metabolism is a fat specific protein 27 (FSP27) protein or polypeptide. 
     
     
         13 . A transgenic plant cell according to  claim 10 , wherein the transcenic plant cell is in a plant or plant part. 
     
     
         14 . A transgenic plant cell according to  claim 13 , which is a non-seed cell. 
     
     
         15 . A transgenic plant cell according to  claim 14 , wherein the non-seed cell is a leaf, root, stem, shoot, bud, tuber, fruit, or flower cell. 
     
     
         16 . A transgenic plant cell according to  claim 13 , wherein the cell is a seed cell of a plant. 
     
     
         17 . A transgenic plant cell or algal cell according to  claim 11 , wherein the exogenous protein or polypeptide associated with lipid metabolism is selected from  A. thaliana  SEIPIN1, SEIPIN2, SEIPIN3, or LEC2. 
     
     
         18 . A transgenic plant cell or algal cell according to  claim 17 , wherein lipid droplet size is enhanced as compared to lipid droplet size of a wild-type cell of the same type. 
     
     
         19 . A method for screening for a functional protein or polypeptide associated with lipid metabolism for elevating lipid content and/or inducing lipid droplet accumulation in a plant or algal cell, wherein the method comprises:
 obtaining a test plant cell or algal cell genetically-modified to express a candidate exogenous protein or polypeptide associated with lipid metabolism; and   growing the genetically-modified test cell and selecting the genetically-modified test cell having elevated lipid content and/or increased lipid droplet size or number, when compared to a wild-type cell of the same type.   
     
     
         20 . A method according to  claim 19 , wherein the cell is a plant cell and the method further comprises regenerating the genetically-modified cell into a plant. 
     
     
         21 . The method according to  claim 20 , further comprising obtaining progeny of said plant.