Increase of yield in crop plants through selection of epigenetically modified populations

Abstract

Methods are provided to select plants and populations of epigenetically fixed crop plants with improved yield.

That which is claimed: 
     
         1 . A  Brassica  oilseed rape plant, a  Brassica  oilseed rape seed or a  Brassica  oilseed rape population of plants, obtained by selecting a population of  Brassica  oilseed rape plants or s  Brassica  oilseed rape seeds with a high energy use efficiency comprising the steps of:
 a. providing a population consisting of a plurality of individual  Brassica  oilseed rape plants which are genetically uniform;   b. isolating a tissue sample or explant from individual plants of said population in a manner which allows further cultivation of said sampled individual plants;   c. determining the cellular respiration rate of said individual plants by analyzing said sample of said plants;   d. selecting a number of plants wherein said sample exhibits a cellular respiration which is lower than the average cellular respiration of samples from said population;   e. growing the selected plants and propagating from each of the selected plants a line of cloned progeny plants;   f. determining the energy use efficiency for each line of cloned progeny plants;   g. selecting a line of clone plants wherein said energy use efficiency is higher than the average of the energy use efficiency of all lines of cloned progeny plants;   h. growing a population of individual plants from said selected line of clone progeny plants;   i. repeating at least once steps b to h on said subsequent population; and   j. obtaining a  Brassica  oilseed rape plant, a  Brassica  oilseed rape seed or a  Brassica  oilseed rape population of plants with high energy use efficiency.   
     
     
         2 . A  Brassica  oilseed rape plant with high energy use efficiency characterized in that said plant has a low cellular respiration and at least one of the following characteristics:
 i. a high ascorbate content;   ii. a high NAD(P)H content;   iii. a high respiratory chain complex I activity; or   iv. a low photorespiration.   
     
     
         3 . The plant according to  claim 2 , wherein said plant is a hybrid plant. 
     
     
         4 . The plant according to  claim 2 , which is a plant with higher growth, yield or biomass production under restricted water conditions than a isogenic control plant. 
     
     
         5 . The plant according to  claim 2 , wherein said cellular respiration rate is between 85% and 95% of the cellular respiration rate of a control plant. 
     
     
         6 . The plant according to  claim 2 , wherein said cellular respiration rate is between 85% and 95% of the cellular respiration rate of a control plant, and/or wherein said NAD(P)H content is between 95% and 105% of the NAD(P)H content of a control plant, and/or wherein activity of said complex I of the mitochondrial respiratory chain activity is between 120% and 140% of the activity of a control plant, and/or wherein said ascorbate content is between 150% and 220% of the ascorbate content of a control plant, and/or wherein said ascorbate content is between 150% and 220% of the ascorbate content of a control plant, and/or wherein said photorespiration is between 80% and 92% of the photorespiration of a control plant. 
     
     
         7 . The plant, seed or population of plants according to  claim 1 , wherein said individual plants are genetically identical. 
     
     
         8 . The plant, seed or population of plants according to  claim 1 , wherein said individual plants are doubled haploid plants, or wherein said individual plants are produced by vegetative reproduction or wherein said plants are inbred plants. 
     
     
         9 . The plant, seed or population of plants according to  claim 1 , wherein said step i is repeated at least twice. 
     
     
         10 . The plant, seed or population of plants according to  claim 1 , wherein said step i is repeated at least five times. 
     
     
         11 . The plant, seed or population of plants according to  claim 1 , wherein said propagating is achieved by self-pollination of said selected plant and harvesting the seeds or by vegetative multiplication. 
     
     
         12 . The plant, seed or population of plants according to  claim 1 , wherein said energy use efficiency is determined by:
 a. i. determining the cellular respiration rate in said sample;
 ii. determining the NAD(P)H content in said sample; and 
 iii. dividing the NAD(P)H content by the cellular respiration rate to determine the energy use efficiency, or 
   b. measuring the ascorbate content in said sample, or   c. measuring the activity of complex I of the mitochondrial respiratory chain in said sample.   
     
     
         13 . The plant, seed or population of plants according to  claim 1 , wherein the steps of determining the energy use efficiency for each line of cloned progeny plants and selecting a line of clone plants wherein said energy use efficiency is higher comprise:
 a. determining the cellular respiration rate in said samples and at least one of the following parameters:
 i. ascorbate content in said sample; 
 ii. NAD(P)H content in said sample; 
 iii. activity of complex I of the mitochondrial respiratory chain in said sample; or 
 iv. photorespiration in said sample; and 
   b. identifying plants with low cellular respiration in said sample and a high ascorbate content, or a high respiratory chain complex I activity or low photorespiration.   
     
     
         14 . The plant, seed or population of plants according to  claim 1 , wherein said cellular respiration rate is between 85 and 95% of the cellular respiration rate of a control plant, and/or wherein said NAD(P)H content is between 95 to 105% of the NAD(P)H content of a control plant, and/or wherein activity of said complex I of the mitochondrial respiratory chain activity is between 120 to 140% of activity of a control plant, and/or wherein said ascorbate content is between 150 to 220% of the ascorbate content of a control plant, and/or wherein said ascorbate content is between 150 to 220% of the ascorbate content of a control plant, and/or wherein said photorespiration is between 80 to 92% of the photorespiration of a control plant. 
     
     
         15 . The plant, seed or population of plants according to  claim 1 , wherein said tissue sample is isolated by severing the hypocotyl from the epicotyl, whereby the hypocotyl constitutes said sample and the epicotyl is further grown to a plant. 
     
     
         16 . The plant, seed or population of plants according to  claim 1 , wherein between step b) and c) said tissue samples or explants are cultured for 0 to 10 days:
 a. under conditions mimicking drought conditions;   b. on a medium containing polyethylene glycol;   c. on a medium comprising sucrose; or   d. on a callus inducing medium   
     
     
         17 . The plant, seed or population of plants according to  claim 1 , wherein at step g) a line of clone plants is selected with the highest energy use efficiency of all lines of cloned progeny plants. 
     
     
         18 . The plant, seed or population of plants according to  claim 2 , which is a parent line or maintainer line for hybrid production. 
     
     
         19 . The plant, seed or population of plants according to  claim 1 , which has an increased yield, and/or increased vigor and/or increased tolerance to adverse abiotic conditions compared to a control plant. 
     
     
         20 . The plant according to  claim 1 , wherein the high energy use efficiency is epigenetically fixed. 
     
     
         21 . The plant according to  claim 20 , wherein the high energy use efficiency is transmitted to successive generations. 
     
     
         22 . The plant according to  claim 2 , wherein the high energy use efficiency is epigenetically fixed. 
     
     
         23 . The plant according to  claim 22 , wherein the high energy use efficiency is transmitted to successive generations.