Methods for Optimising Metabolite Production in Genetically Modified Plants and for Processing These Plants

Abstract

The present invention relates to the field of producing particular metabolites of interest by engineered crop plants such as transgenic crop plants. Provided are methods that are easily applicable by farmers to determine when the metabolites of interest have reached an optimal content in the plant. These methods also help to facilitate decisions about the timeframe for preparing harvest or harvesting the engineered crop plant.

1 . A method for determining a plant property at which an optimal content of a metabolite of interest is reached for harvesting an engineered plant or a harvestable part thereof, wherein the synthesis of said metabolite of interest is modulated through a genetic modification, and which method comprises:
 (i) cultivating the engineered plant and making a correlation between an accumulation pattern of the metabolite of interest and the plant growth stage or other plant property;   (ii) determining a time at which the optimal content for harvest of said metabolite of interest in the harvestable part of the engineered plant is reached; and   (iii) identifying a corresponding plant property as an indicator of the optimal metabolite of interest content for harvest in the engineered plant.   
     
     
         2 . The method of  claim 1 , wherein the engineered plant is a transgenic oil crop plant. 
     
     
         3 . The method of  claim 2 , wherein the transgenic oil crop plant is a transgenic Brassica sp. 
     
     
         4 . The method of  claim 2 , wherein the harvestable part is a seed. 
     
     
         5 . The method according to  claim 1  te-4, wherein the metabolite of interest is a Very Long Chain Polyunsaturated Fatty Acid (VLCPUFA). 
     
     
         6 . The method of  claim 5 , wherein the VLCPUFA comprises eicosapentaenoic acid (EPA) and/or docosahexaenoic acid (DHA). 
     
     
         7 . The method according to  claim 1 , wherein the optimal content of the metabolite of interest is increased content as compared to control plants. 
     
     
         8 . The method according to  claim 1 , wherein said plant property is a growth stage of the engineered plant. 
     
     
         9 . A method for determining a growth stage at which an optimal content of a metabolite of interest is reached in harvestable parts of an engineered plant and expressing it as a Growing Degree Day (GDD) value, wherein the synthesis of said metabolite of interest is modulated through a genetic modification, and which method comprises:
 (i) choosing a suitable planting day;   (ii) recording the daily temperatures during growth of the engineered plant;   (iii) determining a time during plant growth at which the optimal content of the metabolite of interest in the harvestable parts of the engineered plant is reached;   (iv) determining a suitable starting point during plant growth for calculating the GDD to the time when the optimal content of the metabolite of interest in the harvestable parts of the engineered plant is reached; and   (v) determining the accumulated GDD from the start of step (iii) to the time when the optimal content of the metabolite of interest in the harvestable parts is reached.   
     
     
         10 . The method of  claim 9 , wherein the engineered plant is a transgenic oil crop, preferably a transgenic Brassica sp. 
     
     
         11 . The method according to  claim 9 , wherein the harvestable parts are seeds. 
     
     
         12 . The method according to  claim 9 , wherein the metabolite of interest comprises a VLCPUFA, preferably EPA and/or DHA. 
     
     
         13 . The method of  claim 9 , wherein the GDD is used as a predictor for a suitable swathing date. 
     
     
         14 . A method for determining the optimal time for swathing or harvesting of genetically engineered Brassica species that synthesize VLCPUFAs, and in particular EPA and/or DHA in seeds, which method comprises 
 (i) choosing a suitable planting day to allow the seeds to reach maturity,   (ii) recording the daily temperatures during growth of the transformed Brassica sp. for calculating the GDD;   (iii) sampling the transformed Brassica sp. plants, determining the accumulation of EPA and/or DHA in the developing and/or mature seeds, and defining the point in time at which the maximal level of EPA and/or DHA in the seeds is reached;   (iv) monitoring the GDD from the start of flowering to the point in time where the maximal content of EPA and/or DHA in the seeds is reached; and   (v) calculating the accumulated GDD from the start of flowering to the point in time where the maximal content of EPA and/or DHA in the seeds is reached.   
     
     
         15 . The method of  claim 14  wherein the GDD value corresponding to the point in time where the maximal content of EPA and/or DHA in the seeds is reached is the bottom limit of a range of GDD values representing the optimal time window for swathing or harvesting. 
     
     
         16 . (canceled) 
     
     
         17 . (canceled) 
     
     
         18 . A method for the commercial production of oil enriched with a VLCPUFA from seeds of a transgenic  Brassica napus  variety capable of producing said VLCPUFA, which method comprises:
 (i) calculating the Growing Degree Days (GDD) in °F, starting from the appearance of the first open flower, 
 (ii) swathing the plants when the GDD reaches a value of at least 1600, 
 (iii) harvesting the seeds at a suitable maturation stage and processing the seeds to produce oil enriched in said VLCPUFA. 
 
     
     
         19 . The method of  claim 18 , wherein the VLCPUFA comprises EPA and/or DHA. 
     
     
         20 . The method of  claim 18 ,wherein the plants are swathed in a range of growing GDD between, with increasing order of preference, 1600 and 2200 GDD, between 1600 and 2100 GDD, between 1600 and 2000 GDD, between 1600 and 1900 GDD, between 1600 and 1800 GDD.