Lignification reduction in plants

Abstract

The present invention provides an expression cassette containing a polynucleotide coding sequence for a hydroxycinnamoyl-CoA hydratase-lyase (HCHL), which is operably linked to a heterologous promoter. Also provided are methods of engineering plants that have reduced lignification, as well as cells, plant parts, and plant tissues from such engineered plants.

1 . An engineered plant comprising a heterologous hydroxycinnamoyl-CoA hydratase-lyase (HCHL) operably linked to a promoter. 
     
     
         2 . The engineered plant of  claim 1 , wherein the promoter is a secondary cell wall-specific promoter. 
     
     
         3 . The engineered plant of  claim 2 , wherein the secondary cell wall-specific promoter is an IRX5 promoter. 
     
     
         4 . The engineered plant of  claim 1  wherein the HCHL is  Pseudomonas fluorescens  HCHL. 
     
     
         5 . (canceled) 
     
     
         6 . The engineered plant of  claim 1 , wherein the plant is a dicot. 
     
     
         7 . The engineered plant of  claim 1  wherein the plant is selected from the group consisting of  Arabidopsis , poplar, eucalyptus, rice, corn, switchgrass, sorghum, millet, miscanthus, sugarcane, pine, alfalfa, wheat, soy, barley, turfgrass, tobacco, hemp, bamboo, rape, sunflower, willow, and Brachypodium. 
     
     
         8 . (canceled) 
     
     
         9 . A part of the plant of claim  1 . 
     
     
         10 . (canceled) 
     
     
         11 . Biomass comprising the plant, or part of the plant, of  claim 1 . 
     
     
         12 . An isolated expression cassette comprising a polynucleotide sequence encoding a hydroxycinnamoyl-CoA hydratase-lyase (HCHL) and a heterologous promoter, the promoter operably linked to the polynucleotide sequence, wherein the promoter is a secondary cell wall-specific promoter. 
     
     
         13 . The expression cassette of  claim 12 , wherein the HCHL is  Pseudomonas fluorescens  HCHL. 
     
     
         14 . The expression cassette of  claim 12 , wherein the promoter is an IRX5 promoter. 
     
     
         15 . A plant cell comprising the expression cassette of  claim 12 . 
     
     
         16 . A method for engineering a plant having reduced lignification, the method comprising:
 (1) introducing a polynucleotide encoding a hydroxycinnamoyl-CoA hydratase-lyase (HCHL) into a plant, wherein the polynucleotide in the plant is operably linked to a promoter; and   (2) culturing the plant under conditions in which the HCHL is expressed, thereby reducing lignification in the plant.   
     
     
         17 . The method of  claim 16 , wherein the promoter is heterologous to the plant. 
     
     
         18 . (canceled) 
     
     
         19 . The method of  claim 16 , wherein the promoter is a secondary cell wall-specific promoter. 
     
     
         20 . The method of  claim 19 , wherein the secondary cell wall-specific promoter is an IRX5 promoter. 
     
     
         21 . The method of  claim 16 , wherein the HCHL is  Pseudomonas fluorescens  HCHL. 
     
     
         22 . (canceled) 
     
     
         23 . The method of  claim 16 , wherein the plant is a dicot. 
     
     
         24 . The method of  claim 16 , wherein the plant is selected from the group consisting of  Arabidopsis , poplar, eucalyptus, rice, corn, switchgrass, sorghum, millet, miscanthus, sugarcane, pine, alfalfa, wheat, soy, barley, turfgrass, tobacco, hemp, bamboo, rape, sunflower, willow, and Brachypodium. 
     
     
         25 . A method of obtaining soluble sugars, the method comprising incubating the biomass of  claim 11  in a saccharification reaction.