Methods of modulating seed and organ size in plants

Abstract

This invention relates to a plant E3 ubiquitin ligase (termed DA2) which acts synergistically with DA1 to control seed and organ size. Methods of increasing plant yield are provided that comprise reducing the expression or activity of DA2 in a plant that is deficient in DA1 expression or activity. Plants with increased yield and methods of producing such plants are also provided.

What is claimed is: 
     
         1 . A plant, or a plant cell thereof, comprising a mutation that reduces the expression or activity of a DA2 polypeptide, wherein the plant has increased seed size and/or organ size relative to a plant without the mutation. 
     
     
         2 . The plant of  claim 1 , wherein the DA2 polypeptide comprises an amino acid sequence having at least 90% sequence identity to one or more of SEQ ID NOs: 20 to 35. 
     
     
         3 . The plant of  claim 1 , wherein the mutation abolishes the expression or activity of the DA2 polypeptide. 
     
     
         4 . The plant of  claim 1 , wherein the mutation is in the nucleotide sequence that encodes the DA2 polypeptide or that regulates its expression. 
     
     
         5 . The plant of  claim 1 , wherein the DA2 polypeptide comprises a RING domain of SEQ ID NO: 1. 
     
     
         6 . The plant of  claim 1 , wherein the DA2 polypeptide comprises a RING domain of SEQ ID NO: 2. 
     
     
         7 . The plant of  claim 1 , wherein the DA2 polypeptide comprises a first consensus domain of SEQ ID NO: 36. 
     
     
         8 . The plant of  claim 1 , wherein the DA2 polypeptide comprises a second consensus domain of SEQ ID NO: 37. 
     
     
         9 . The plant of  claim 1 , wherein the plant is a monocotyledonous or dicotyledonous plant. 
     
     
         10 . The plant of  claim 1 , wherein the plant is an agricultural plant selected from the group consisting of  Lithospermum erythrorhizon, Taxus  spp, tobacco, cucurbits, carrot, vegetable brassica, melons, capsicums, grape vines, lettuce, strawberry, oilseed brassica, sugar beet, wheat, barley, maize, rice, soyabeans, peas, sorghum, sunflower, tomato, potato, pepper, chrysanthemum, carnation, linseed, hemp and rye. 
     
     
         11 . The plant of  claim 1 , wherein the plant is maize. 
     
     
         12 . The plant of  claim 1 , wherein the plant is not Arabidopsis thaliana. 
     
     
         13 . A maize plant, or a maize plant cell thereof, comprising a mutation that reduces the expression or activity of a DA2 polypeptide, wherein the maize plant has increased seed size and/or organ size relative to a maize plant without the mutation. 
     
     
         14 . The maize plant of  claim 13 , wherein the DA2 polypeptide comprises an amino acid sequence having at least 90% sequence identity to SEQ ID NO: 30 or 34. 
     
     
         15 . The maize plant of  claim 13 , wherein the mutation abolishes the expression or activity of the DA2 polypeptide. 
     
     
         16 . The maize plant of  claim 13 , wherein the mutation is in the nucleotide sequence that encodes the DA2 polypeptide or that regulates its expression. 
     
     
         17 . The maize plant of  claim 13 , wherein the DA2 polypeptide comprises a RING domain of SEQ ID NO: 1. 
     
     
         18 . A method of increasing the seed size and/or organ size of a plant, the method comprising:
 introducing within cells of the plant a mutation that reduces the expression or activity of a DA2 polypeptide.   
     
     
         19 . The method of  claim 18 , wherein the DA2 polypeptide comprises an amino acid sequence having at least 90% sequence identity to one or more of SEQ ID NOs: 20 to 35. 
     
     
         20 . The method of  claim 18 , wherein the plant is maize.