Abstract:
A method for increasing and/or preserving yields and/or biomass in crop species including potatoes, beets, sugar cane, corn, soybeans and others by exogenous application of trehalose and/or trehalose derivatives at any time in the growing process such as before crop sowing, during sowing, or during plant establishment. The method, when applied early in crop production results in enhanced health and vigor of the mother plant resulting in healthier produce having reduced sugars from the mother plant.

Description:
CLAIM TO PRIORITY  
       [0001]    This application claims priority from Provisional Patent Application No. 61/533,872 filed on Sep. 13, 2011 and from Provisional Patent Application No. 61/538,653 filed Sep. 23, 2011. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    This invention relates to exogenous application of trehalose and/or trehalose derivatives to crop plants to signal enhanced transfer of photosynthates and derivatives of photosynthates, from the “mother” plant to the economic portion of crops such as seeds, tubers, fruits, etc. (photosynthates are compounds formed by photosynthesis). Furthermore, the exogenous application can be done most preferably shortly before harvest for rescuing usable photosynthates from the mother plant that would otherwise end up as field trash instead of incorporation into the daughter cells and plant of the next generation. 
         [0004]    The trehalose or trehalose derivative molecules can also be applied at planting or at other times during the growth of the crop plant. This earlier application results in a healthier crop plant, less prone to disease and early decay toward death. Moreover early application of trehalose to certain plants for example, potatoes, results in a plant with less reducing sugar content. Plants with high reducing sugar content can result in a potentially unhealthy situation when crop plant produce is fried in hot oil, for example for potato chips etc. Moreover, the exogenous signaling molecule(s) not only enhance yield but also enhance the apparent health of the plant and healthiness of processed foods if applied in the earlier stages of crop plant growth. 
         [0005]    2. Description of the Prior Art 
         [0006]    Trehalose is a disaccharide consisting of 2 linked glucose molecules, which is widely produced by plants, insects, and other organisms. It is produced abundantly by certain insects and a few plants, but is present at only trace amounts in most plant species. Until recently, its primary known biological activity was to act as a cryoprotectant when present at relatively high natural abundance in cells of certain organisms, or as an addition during cryopreservation procedures. However, in recent years it has emerged that trehalose and/or its related forms act as an extremely potent signaling molecule in plants, even though present at very low abundance. A form of trehalose functions as a central coordinating regulator of carbohydrate production and flow in plants. In part, it signals carbohydrate availability to promote growth or accumulation of reserves. It also suppresses activity of the kinase SnRK1, thus reducing a key factor that limits growth. 
         [0007]    A prior published patent application US 2010/0024066 describes the use of trehalose-6-Phosphate Synthase to modulate plant growth. The patent application presents a background section which indicates that the trehalose is a widespread disaccharide, occurring in bacteria, fungi, insects and plants. 
         [0008]    In most cases, trehalose synthesis is a two-step process in which trehalose-6-phosphate Synthase (TPS) synthesizes trehalose-6-phosphate (T6P) followed by dephosphorylation to trehalose by T6P phosphatase (TPP). Although in most plants trehalose is hardly detectable, multiple homologues of both TPS and TPP genes are present. European Patent EP 0901527 discloses the regulation of plant metabolism by modifying the level of T6P. More specifically, the European Patent describes an increase in yield of plants by increasing the intracelluar availability of T6P. 
         [0009]    The model described above is a one-way path of metabolism in plants: 
         [0000]    
       
                 
         
             
             
         
       
     
         [0010]    1) UDP-Glucose and Glucose-6-phosphate (G6P) are combined to form trehalose 6-phosphate (T6P) by the enzyme trehalose phosphate synthase (TPS) 
         [0011]    2) T6P is de-phosphorylated to Trehalose (Tre) by the enzyme trehalose phosphate phosphatase (TPP) 
         [0012]    3) Trehalose is broken down into 2 glucose molecules by the enzyme Trehalase 
         [0013]    The European Patent EP0901527 indicates that levels of T-6-P may be influenced by genetic engineering of an organism with gene constructs capable of influencing the level of T-6-P or by exogenously supplying compounds capable of influencing such level, although examples of such exogenous compounds are not mentioned or described. 
         [0014]    According to the model presented above, exogenous application of Trehalose to plants may be expected to increase accumulation of T6P by feedback inhibition of TPP. It has been noted that in the absence of available carbon, T6P accumulation can inhibit growth of Arabidopsis seeds (Schluepmann, et al. Plant Physiology, June 2004, Vol. 135, pp. 879-890). 
         [0015]    3. Identification of Objects of the Invention 
         [0016]    A primary object of the invention is to provide a method and composition for enhancing the productivity and growth of plants for agriculture. 
         [0017]    Another object is to provide a method for increasing the productivity of agriculture plants even where the plants are maturing and growing old. 
         [0018]    Another object is to provide a method and composition to enhance the productivity and growth of crop plants living under harsh environmental stresses. 
         [0019]    Another object is to provide a method and composition to enhance the productivity and growth of crop plants, by more complete transfer of whatever useful photosynthates and/or photosynthate derivatives that are left in the mother plant or even the senescing corpse of the mother plant to the “daughter” seed or other economic portion of the daughter plant growing on the mother plant; 
         [0020]    Another object is to provide a method and composition to enhance the productivity, growth and biomass of crop plants, by preventing loss of photosynthate or photosynthate derivatives, from the seed or other “daughter” economic portion of the plant, to the “mother” plant during the growing season; 
         [0021]    Another object is to provide a method and composition to enhance the productivity and growth of crop plants, by preventing loss of photosynthate or photosynthate derivatives, from the seed or other “daughter” economic portion of the plant, to the “mother” plant during the growing season, especially under various forms of stress to the mother plant, whether abiotic or biotic; 
         [0022]    Another object is to provide a method and composition to mitigate cell death in a plant; 
         [0023]    Another object is to provide a method and composition to increase production of ABA and/or ethylene in a plant; 
         [0024]    Another object is to provide a method and composition to increase plant resistance to insects and pests; 
         [0025]    Another object is to provide a method and composition for use at any time during the growth of the mother plant to increase as full a compliment as possible of photosynthate delivery to the daughter embryo and storage organs of same; 
         [0026]    Another object is to provide a method and composition for, at any time during the growth of the mother plant, enhancing acquisition of photosynthates of all and any cells including meristematic cells for increased performance of all and any cells including stem cells; 
         [0027]    Another object of the invention is to provide a method and composition to prevent excessive accumulation of photosynthates in temporary storage organs such as the leaves and stems of the mother plant, and transfer of these into harvestable storage organs of the plant; 
         [0028]    Another object of the invention is to provide a method and composition to reduce the negative feedback of excessive photosynthates residing in temporary storage organs like the leaves and stems of the mother plant; 
         [0029]    Another object of the invention is to provide a method and composition to enhance the vigor of all plant cells by adequate accumulation of photosynthates for optimal and maximum growth of all cells including stem cells; 
         [0030]    Considering the sheer amount of research into enhancing “food” production, there is a continued and unfulfilled need to improve crop plant productivity, far beyond the current level of knowledge. 
       SUMMARY OF THE INVENTION 
       [0031]    The objects identified, along with other features and advantages of the invention are incorporated in a method and composition for growing plants, especially crop plants, but not limited to crop plants, to be more productive by more completely and effectively using the photosynthates and/or the photosynthates accrued in the mother plant, by transferring same to all cells including stem cells and transferring same to the seed or other economic portion of the forming “daughter” plant or storage organs associated with the developing daughter plant. 
         [0032]    It has been discovered that certain “signaling” molecules can enhance crop yield by transferring more or even most completely, photosynthates or photosynthate derivatives, from what is an essentially the “corpse” of the senescing mother plant to the “daughter” embryo and embryo storage components, even as late as just shortly before harvest. Moreover, if these particular signaling molecules are applied earlier in the development of the crop and additionally before harvest as a “last chance” scenario, prevention of loss of apparent yield can be overcome, with near complete transfer of photosynthates or photosynthate derivatives to the growing embryo and embryo “food” storage anatomy. Even earlier application of these signaling molecules during development of the crop can beneficially transfer photosynthate not only for enhanced yield or harvest but also a healthier mother plant and healthier food produce. 
         [0033]    Exogenous application to a plant of signaling molecules such as trehalose and trehalose derivatives scavenges photosynthates that would otherwise be lost in the senescing corpse of the mother plant rather than be incorporated into the daughter embryos or storage organs of the small and juvenile daughter plants growing on the mother plant. Moreover, the signaling trehalose molecules are applied exogenously at any time before sowing, during sowing or during plant establishment and/or during any of the stages of the growth of the mother plant. Earlier application of the signaling molecules results in enhanced health and vigor of the mother plant with concomitant healthier food produce especially as related to excesses of reducing sugars in the composition of the food produce from the mother plant. The health benefit to the mother plant can be effective even where its seeds are treated prior to planting. 
     
    
     DESCRIPTION OF THE INVENTION 
       [0034]    Traditionally, the concept of affecting crop plant growth is often limited to the beginning of crop establishment, continuing until the economic portion of the crop is rather well developed, after which the crop is considered to senesce (that is, to grow old) and “prepare&#39; itself for maturation and dissemination of the seed etc. Moreover, though, as the growing season progresses, stress of various types can also set in whereby varying levels of autophagy can scavenge photosynthates from the “daughter”, i.e., seed and similar harvestable portions of the crop. (autophagy is the maintenance of plant nutrition by metabolism breakdown of certain bodily tissues) 
         [0035]    These scavenged photosynthates from the daughter embryos and storage organs thereof, are often returned to the mother plant as a “perceived” necessity to retain “fitness” of the mother plant to complete the gestation cycle of the daughter plants especially under varying levels of abiotic or biotic stress. The result of this autophagy is a “reduction” or loss in yield at harvest. This loss or apparent reduction in anticipated yield is very often manifested in crops, and mostly represents an imbalance of hormones and inadequate signaling for delivery of photosynthates to the daughter embryos and storage organs. 
         [0036]    A preferred implementation of the invention addresses one or more deficiencies of the prior art and furthermore results in achieving one or more of the objects identified above. 
         [0037]    According to the invention an aqueous solution that includes trehalose or a trehalose derivative is exogenously applied in small concentrations to crop plants to effect a substantial amount of photosynthate transfer close to the end of the growing season that would be totally lost to the trash heap of the mother plant corpse instead of accumulation into the young and juvenile daughter embryos and storage organs of the daughter embryos. Moreover, the signaling sugar treatment also prevents autophagy of the very juvenile embryos and storage organs of the embryos, being subjected to a perceived need for photosynthesis products (i.e., photosynthates) required by the mother plant to complete the reproductive cycle of the attached daughter plants. In contrast to perennial crops (e.g., fruits, nuts) in which the mother plant does require additional reserves for the succeeding years, the photosynthates in annual plants (corn, potatoes, soybeans, etc.) can be completely and irrevocably transferred to the attached daughter plants in a most complete fashion even to the point of leaving nothing but a mostly cellulose corpse of the mother plant. In this manner, yield of annuals at harvest time are hugely increased, thus maximizing the efficiency of crop production as regards already formed readily usable photosynthates. 
         [0038]    Moreover, the exogenously applied trehalose signaling molecule can be applied earlier during the growth of the mother plant which results in large positive influences on yield and health of the mother plant and healthiness of the food produced by the mother plant. This can be accomplished by altering the characteristics of production, metabolism, and trafficking of sugars in the plant, mediated in part by the plant kinases SnRK1 and TOR, which can be regulated by T6P and/or trehalose. 
         [0039]    The disease suppressing effect of the signaling molecules is exemplified with a highly significant reduction of zebra chip disease in potatoes. The healthier food is also exemplified by decreased reducing sugar content of signaling sugar-treated potatoes. A visual examination of untreated vs treated potatoes fried in hot oil shows the benefit of applying trehalose to two growing potato plants. 
         [0040]    Examples are presented below showing the enhanced effects on crop yield by application of trehalose. 
       EXAMPLE 1  
       [0041]    Field Corn, cultivar Asgrow 7371, was twice treated foliarly before harvest with an aqueous solution of trehalose at the rate of 100 grams of trehalose per acre, at 4 weeks after the V16 stage of growth, and once again foliarly at the same rate at 5 weeks after the V16 stage of growth. Yields were increased by up to 125% by treatment of trehalose (Table 1). 
         [0000]    
       
         
               
             
               
               
               
             
               
             
               
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
               
                 Effect of a foliar application of trehalose @ 100 grams per acre, 4 weeks 
               
               
                 after the V16 stage of growth and again at the same rate, 5 weeks 
               
               
                 after the V16 stage of growth on yield characteristics, Cultivar 7371. 
               
               
                   
               
             
             
               
                 Yield of field corn (bushels per acre) 
               
             
          
           
               
                   
                 Control Untreated 
                 103 bu/acre 
               
               
                   
                 Treated 4 and 5 wks after the V16 stage 
                 231 bu/acre 
               
               
                   
                 of growth 
               
               
                   
                 T test of mean of treated vs control, p = 
                 0.00058 
               
             
          
           
               
                 Weight of 1,000 kernels (grams) 
               
             
          
           
               
                   
                 Control Untreated 
                 288 grams 
               
               
                   
                 Treated 4 and 5 wks after the V16 stage 
                 368 grams 
               
               
                   
                 of growth 
               
               
                   
                 T test of mean of treated vs control, p = 
                 0.00018 
               
               
                   
                   
               
             
          
         
       
     
       EXAMPLE 2  
       [0042]    Field corn, Cultivar Dekalb C6805, was treated foliarly with an aqueous solution of trehalose at the rate of 100 grams per acre, either at the V16 stage of growth or 3 weeks before the V16 stage of growth, in southern Texas. Field corn yields were increased with this cultivar from 155 bushels per acre to an unprecedented 337 bushels per acre for this locale, characterized by hot, windy climate and poor soils and high levels of pests including disease and insects. Seed weights of the corn kernels were increased. 
         [0000]    
       
         
               
             
               
               
               
             
               
             
               
               
               
             
           
               
                 TABLE 2 
               
               
                   
               
               
                 Effect of a foliar application of trehalose @ 100 grams per acre, 
               
               
                 at either the V16 stage of growth or 3 weeks before the 
               
               
                 V16 stage of growth, Cultivar Dekalb C6805 
               
               
                   
               
             
             
               
                 Yield of field corn (bushels per acre) 
               
             
          
           
               
                   
                 Control Untreated 
                 155 
               
               
                   
                 Trehalose-treated at the V16 stage of 
                 311 
               
               
                   
                 growth 
               
               
                   
                 Trehalose-treated, 3 wk prior to V16 
                 327 
               
               
                   
                 growth stage 
               
               
                   
                 T test at V16 vs control, p = 
                 0.00000024 
               
               
                   
                 T test at 3 wk prior to V16 vs control, 
                 0.0000060 
               
               
                   
                 p = 
               
               
                   
                 T test V16 vs 3 weeks prior, p = 
                 0.024 
               
             
          
           
               
                 Weight of 1,000 kernels (grams) 
               
             
          
           
               
                   
                 Control Untreated 
                 261 
               
               
                   
                 Trehalose-treated at the V16 stage of 
                 286 
               
               
                   
                 growth 
               
               
                   
                 Trehalose-treated, 3 wk prior to V16 
                 294 
               
               
                   
                 growth stage 
               
               
                   
                 T test at V16 vs control, p = 
                 0.023 
               
               
                   
                 T test at 3 wk prior to V16 vs control, 
                 0.003 
               
               
                   
                 p = 
               
               
                   
                 T test V16 vs 3 weeks prior, p = 
                 0.092 
               
               
                   
                   
               
             
          
         
       
     
       EXAMPLE 3  
       [0043]    Potato, cultivar Eva, had increased yields with either an exogenous application of an aqueous solution of trehalose at the rate of 100 grams per acre applied foliarly at 4 weeks before harvest(Table 4). If applied at 4 weeks before harvest there was sufficient time in crop development to suppress reducing sugar concentrations for a healthier food product (Table 5). 
         [0000]    
       
         
               
             
               
               
               
             
               
               
               
               
               
               
             
               
               
               
               
               
               
               
             
           
               
                 TABLE 4 
               
             
             
               
                   
               
               
                 Yield of Eva potato variety treated with 4 rates of trehalose 
               
               
                 as foliar application 4 weeks before harvest. 
               
             
          
           
               
                   
                 Treatment pounds per 
                   
               
               
                   
                 graded size 
               
             
          
           
               
                   
                 #4 
                 #3 
                 #2 
                 #1 
                 Total 
               
               
                   
                   
               
             
          
           
               
                   
                 Control 
                 0.0 
                 6.8 
                 6.8 
                 0.8 
                 14.4 
               
               
                   
                 Trehalose - 25 g 
                 0.0 
                 8.6 
                 7.2 
                 1.1 
                 16.9 
               
               
                   
                 Trehalose - 50 g 
                 0.0 
                 8.3 
                 7.0 
                 0.9 
                 16.2 
               
               
                   
                 Trehalose - 100 g 
                 0.4 
                 8.4 
                 7.4 
                 0.8 
                 17.0 
               
               
                   
                   
               
               
                   
                 Size distribution: #5 = &gt;16 ounces, #4 = &gt;10 ounces, #3 = &gt;6 ounces, #2 = &gt;4 ounces, and #1 = 0 to 4 ounces. 
               
             
          
         
       
     
       EXAMPLE 4  
       [0044]    Potatoes, cultivar Eva in Pennsylvania, were treated either 4 or 2 weeks before harvest with a foliar application of trehalose at the rate of 100 grams per acre. The potatoes were harvested and shipped to College Station, Tex. for analysis of reducing sugars. During the more active growth period 4 weeks before harvest, the reducing sugars were decreased in the potato tubers; closer to the end of the growing season and end of the crop plants, the sugars appeared to have been more directly routed into the tubers. (Table 4). 
         [0000]    
       
         
               
             
               
               
               
             
               
               
               
               
             
           
               
                 TABLE 4 
               
             
             
               
                   
               
               
                 Effect of foliar treatments of trehalose, either 4 or 2 weeks before 
               
               
                 harvest on the reducing sugar content of the potato tubers, n = 16 
               
             
          
           
               
                   
                 Reducing Sugar Content of Tubers 
                   
               
               
                   
                 (absorbance at 570 nm) 
               
             
          
           
               
                   
                   
                 4 weeks before 
                 2 weeks before 
               
               
                   
                 Treatment 
                 Harvest 
                 Harvest 
               
               
                   
                   
               
               
                   
                 Control Untreated 
                 0.217 ± 0.15 
                 0.200 ± 0.08 
               
               
                   
                 Trehalose @ 100 
                 0.125 ± 0.03 
                 0.211 ± 0.12 
               
               
                   
                 grams/acre 
               
               
                   
                 T test control vs 
                 0.029 
                 NS 
               
               
                   
                 treated p = 
               
               
                   
                   
               
             
          
         
       
     
       EXAMPLE 5  
       [0045]    Potatoes, cultivar Snowden in Wisconsin, were treated either 4 or 2 weeks before harvest with a foliar application of trehalose at the rate of 100 grams per acre. The potatoes were harvested and shipped to College Station, Tex. for analysis of reducing sugars. There was a decrease in reducing sugar content, inversely proportional to the dose of trehalose applied to the plants. See the effect of trehalose application rate on content of reducing sugars in potato tubers as shown in Table 5 presented below. 

 
       EXAMPLE 6  
       [0046]    Sugar Beets were foliarly treated with Trehalose at the rate of 300 grams per acre in Yuma Colo. The treatment transferred nearly half an extra ton of sugar per acre to the beets; moreover, there was a decided reduction in % SLM with the sugar signaling just 2 weeks before harvest (Table 6). 
         [0000]    
       
         
               
             
               
               
               
             
               
             
               
               
               
             
               
             
               
               
               
             
               
             
               
               
               
             
               
             
               
               
               
             
           
               
                 TABLE 6 
               
             
             
               
                   
               
               
                 Effect of a foliar treatment of the aqueous solution of 
               
               
                 Trehalose @ 300 grams per acre on sugar beet yield and quality. 
               
             
          
           
               
                   
                   
                 Trehalose @ 300 g/a Foliar, 2 weeks 
               
               
                   
                 Control Untreated 
                 before harvest 
               
               
                   
                   
               
             
          
           
               
                 Sugar Beet yield (tons per acre) 
               
             
          
           
               
                   
                 27.79 
                 28.4 
               
             
          
           
               
                 Percent Sugar 
               
             
          
           
               
                   
                 15.83% 
                 17.23% 
               
             
          
           
               
                 Pounds of Sugar per acre 
               
             
          
           
               
                   
                 8797 
                 9770 
               
             
          
           
               
                 Percent SLM 
               
             
          
           
               
                   
                 1.85 
                 1.22 
               
               
                   
                   
               
             
          
         
       
     
       EXAMPLE 7  
       [0047]    Sugar Cane, grown in southern Texas was treated 4 weeks before harvest with an aqueous solution of Trehalose at the rate of 450 grams per acre, gave an extra 897 pounds of sugar from sugar cane production. 
         [0000]    
       
         
               
             
               
               
               
             
           
               
                 TABLE 7 
               
               
                   
               
               
                 Effect of trehalose @ 450 grams per acre on increase 
               
               
                 in lb of sugar per acre from sugar cane 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 Control Untreated 
                  0 
               
               
                   
                 Trehalose @ 450 g/a Foliar, 4 weeks 
                 897 lb 
               
               
                   
                 before harvest 
               
               
                   
                   
               
             
          
         
       
     
       EXAMPLE 8  
       [0048]    Wheat, grown in Ontario Canada, was treated foliarly with an aqueous solution of trehalose at the rate of 100 grams per acre, 4 weeks before harvest. 
         [0000]    
       
         
               
             
               
               
               
             
           
               
                 TABLE 8 
               
               
                   
               
               
                 Effect of foliar application of Trehalose on increase 
               
               
                 in yield of winter wheat 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 Control Untreated 
                 0% 
               
               
                   
                 Trehalose @ 100 g/a Foliar, 
                 9.5%, highly significant 
               
               
                   
                 4 weeks before harvest 
               
               
                   
                   
               
             
          
         
       
     
       Mechanisms and Modes of Action 
       [0049]    As described above current models of trehalose synthesis in plants suggest there is a one-way path of metabolism: 
         [0000]    
       
                 
         
             
             
         
       
     
         [0050]    1) UDP-Glucose and Glucose-6-phosphate (G6P) are combined to form the potent signal molecule trehalose 6-phosphate (T6P) by the enzyme trehalose phosphate synthase (TPS) 
         [0051]    2) T6P is de-phosphorylated to Trehalose (Tre) by the enzyme trehalose phosphate phosphatase (TPP) 
         [0052]    3) Trehalose is broken down into 2 glucose molecules by the enzyme Trehalase 
         [0053]    According to this one way model, application of Trehalose to a plant might not be expected to increase production of T6P. However, biological activity from application of trehalose to a plant may result at least in part from increased T6P inside the plant after application of trehalose to the plant. This may be due to a feedback inhibition on TPP activity by the higher amounts of added Tre, or it may be due to conversion of Tre to T6P by a currently unknown enzyme activity or kinase activity. 
         [0054]    An activity of T6P/Tre of primary importance in plants is its influence on sugar-related signaling. As such, Tre/T6P exercises a central, controlling role in plant growth and development including germination, growth, differentiation, flowering, fruit/grain formation, and carbohydrate storage. Trehalose also inhibits starch breakdown, leading to increased starch accumulation. This may be a basis for observed increases in yield of starch-storing crops such as potato and corn. 
         [0055]    The increased yield in a plant when Trehalose is applied to it may be due to the trehalose molecule itself or other possible derivatives of T6P or trehalose as active principles from application of trehalose. If trehalose application to a plant increases abundance of T6P in the plant, then known plant responses to T6P may result as listed below. 
         [0056]    Here are the possible biochemical mechanisms on a plant resulting from the application of Trehalose: 
         [0057]    Trehalose/T6P acts as potent signals of sugar status in the plant, which can alter photosynthate partitioning, primary carbon fixation, carbohydrate retention, and/or growth of the plant; 
         [0058]    Trehalose/T6P increases production of abscisic acid (ABA) and/or ethylene in the plant, which advances or improves the ripening process of fruits, grains, or other plant products; 
         [0059]    Trehalose/T6P increases production and storage of sugars in sugar beets, sugar cane, and other crops; 
         [0060]    Trehalose/T6P increases production and inhibits breakdown of starch, increasing retention of stored carbohydrate in potatoes and other crops; and/or 
         [0061]    Trehalose/T6P induces flowering by acting as a sugar status signal preparing the plant to enter floral transition.