Chitooligosaccharides and methods for use in enhancing soybean growth

Abstract

Disclosed are methods of enhancing growth of soybean plants, comprising treating soybean seed or the soybean plant that germinates from the seed with an effective amount of at least one chitooligosaccharide, wherein upon harvesting the soybean plant exhibits at least one of increased plant yield measured in terms of bushels/acre, increased root number, increased root length, increased root mass, increased root volume and increased leaf area, compared to untreated soybean plants or soybean plants harvested from untreated soybean seed.

1 . A method of enhancing growth of soybean plants, comprising treating soybean seed with an effective amount of at least one chitoogilosaccharide (CO) and at least one lipo-chitooligosaccharide (LCO) represented by the following formula: 
       
         
           
           
               
               
           
         
       
       wherein R 1  represents C14:0, 3OH—C14:0, iso-C15:0, C16:0, 3-OH—C16:0, iso-C15:0, C16:1, C16:2, C16:3, iso-C17:0, iso-C17:1, C18:0, 3OH—C18:0, C18:0/3-OH, C18:1, OH—C18:1, C18:2, C18:3, C18:4, C19:1 carbamoyl, C20:0, C20:1, 3-OH—C20:1, C20:1/3-OH, C20:2, C20:3, C22:1, and C18-26(w−1)-OH (which according to D'Haeze, et al., supra, includes C18, C20, C22, C24 and C26 hydroxylated species and C16:1Δ9, C16:2 (Δ2,9) and C16:3 (Δ2,4,9)); R 2  represents hydrogen or methyl; R 3  represents hydrogen, acetyl or carbamoyl; R 4  represents hydrogen, acetyl or carbamoyl; R 5  represents hydrogen, acetyl or carbamoyl; R 6  represents hydrogen, arabinosyl, fucosyl, acetyl, sulfate ester, 3-O—S-2-O-MeFuc, 2-O-MeFuc, and 4-O—AcFuc; R 7  represents hydrogen, mannosyl or glycerol; R 8  represents hydrogen, methyl, or —CH 2 OH; R 9  represents hydrogen, arabinosyl, or fucosyl; R 10  represents hydrogen, acetyl or fucosyl; and n represents 0, 1, 2 or 3, and wherein, upon harvesting, the plants grown from said seed exhibit at least one of increased plant yield measured in terms of bushels/acre, increased root number, increased root length, increased root mass, increased root volume and increased leaf area, compared to untreated soybean seed. 
     
     
         2 . The method of  claim 1 , wherein the at least one CO is represented by the formula: 
       
         
           
           
               
               
           
         
       
       wherein R 1  and R 2  each independently represents hydrogen or methyl; R 3  represents hydrogen, acetyl or carbamoyl; R 4  represents hydrogen, acetyl or carbamoyl; R 5  represents hydrogen, acetyl or carbamoyl; R 6  represents hydrogen, arabinosyl, fucosyl, acetyl, sulfate ester, 3-O—S-2-O-MeFuc, 2-O-MeFuc, and 4-O—AcFuc; R 7  represents hydrogen, mannosyl or glycerol; R 8  represents hydrogen, methyl, or —CH 2 OH; R 9  represents hydrogen, arabinosyl, or fucosyl; R 10  represents hydrogen, acetyl or fucosyl; and n represents 0, 1, 2 or 3. 
     
     
         3 . The method of  claim 1 , wherein the at least one CO comprises a CO represented by the formula: 
       
         
           
           
               
               
           
         
       
     
     
         4 . The method of  claim 1 , wherein the at least one CO comprises a CO represented by the structure: 
       
         
           
           
               
               
           
         
       
     
     
         5 . The method of  claim 1 , wherein the at least one CO comprises a CO represented by the formula: 
       
         
           
           
               
               
           
         
       
       wherein n=1 or 2; R 1  represents hydrogen or methyl; and R 2  represents hydrogen or SO 3 H. 
     
     
         6 . The method of  claim 1 , wherein the at least one CO comprises a CO represented by the structure: 
       
         
           
           
               
               
           
         
       
     
     
         7 . The method of  claim 1 , wherein the at least one CO comprises a CO represented by the structure: 
       
         
           
           
               
               
           
         
       
     
     
         8 . The method of  claim 1 , wherein the at least one CO comprises at least one synthetic CO. 
     
     
         9 . The method of  claim 1 , wherein the at least one CO comprises at least one recombinant CO. 
     
     
         10 . The method of  claim 1 , wherein the at least one CO and at least one LCO are applied to the soybean seed prior to planting or at about the time of planting. 
     
     
         11 . The method of  claim 10 , wherein the at least one CO is applied in an amount ranging from about 10 −5  Molar to about 10 −14  Molar. 
     
     
         12 . The method of  claim 1 , wherein the at least one CO and at least one LCO are applied to the soybean seed in furrow. 
     
     
         13 . The method of  claim 12 , wherein the at least one CO is applied in an amount ranging from about 1 μg/acre to about 70 μg/acre. 
     
     
         14 . The method of  claim 1 , wherein the at least one LCO comprises an LCO represented by the structure: 
       
         
           
           
               
               
           
         
       
     
     
         15 . The method of  claim 1 , wherein the at least one LCO comprises an LCO represented by the structure: 
       
         
           
           
               
               
           
         
       
     
     
         16 . The method of  claim 1 , wherein the at least one LCO comprises an LCO represented by the structure: 
       
         
           
           
               
               
           
         
       
     
     
         17 . The method of  claim 1 , wherein the at least one LCO comprises an LCO represented by the structure: 
       
         
           
           
               
               
           
         
       
     
     
         18 . The method of  claim 1 , further comprising applying to the soybean seed at least one micronutrient. 
     
     
         19 . The method of  claim 18 , wherein the micronutrient is selected from the group consisting of vitamins and trace minerals. 
     
     
         20 . The method of  claim 1 , further comprising applying to the soybean seed at least one fatty acid or fatty acid derivative. 
     
     
         21 . The method of  claim 1 , further comprising applying to the soybean seed at least one plant signal molecule. 
     
     
         22 . The method of  claim 21 , wherein the at least one plant signal molecule comprises one or more of the following: chitinous compounds, flavonoids, jasmonic acid and derivatives thereof, linoleic acid and derivatives thereof, linolenic acid and derivatives thereof, and karrikins and derivatives thereof. 
     
     
         23 . The method of  claim 1 , further comprising applying to the soybean seed at least one herbicide, at least one insecticide, and/or at least one fungicide. 
     
     
         24 . The method of  claim 1 , further comprising applying to the soybean seed at least one phosphate solubilising microorganism, at least one diazotroph (Rhizobial inoculants), and/or at least one mycorrhizal fungus. 
     
     
         25 . The method of  claim 24 , wherein the at least one phosphate solubilizing microorganism comprises a strain of the fungus  Penicillium.    
     
     
         26 . The method of  claim 24 , wherein the at least one phosphate solubilizing microorganism comprises a strain of  P. bilaiae.    
     
     
         27 . The method of claim  31 , wherein the strain of  P. bilaiae  is selected from the group consisting of NRRL 50162, NRRL 50169, ATCC 20851, ATCC 22348, and ATCC 18309. 
     
     
         28 . The method of  claim 24 , wherein the at least one phosphate solubilizing microorganism comprises a strain of  P. gaestrivorus.