HMG2 promoter expression system and post-harvest production of gene products in plants and plant cell cultures

Abstract

The invention relates in part to plant HMG2 HMGR genes and in part to the “post-harvest” production method of producing gene product of interest in plant tissues and cultures. The HMG2 promoter elements are responsive to pathogen-infection, pest-infestation, wounding, or elicitor or chemical treatments. The HMG2 elements are also active in specialized tissues of the plant including pollen and mature fruits. HMG2 promoter elements and HMG2-derived promoters can be advantageously used to drive the expression of disease and pest resistance genes, whereby transgenic plants containing such gene constructs would be resistant to the targeted disease and pest. In particular, the HMG2 gene expression system can be utilized in developing nematode resistant plants. The post-harvest production method of the invention utilizes plant tissues and cell cultures of plants or plant cells engineered with a expression construct comprising an inducible promoter, such as the HMG2 promoter, operably linked to a gene of interest. Production of the desired gene product is obtained by harvesting, followed by inducing and processing the harvested tissue or culture. The post-harvest production method may be advantageously used to produce direct or indirect gene products that are labile, volatile, toxic, hazardous, etc.

What is claimed is:  
     
         1 . A method for producing a product encoded by a heterologous gene in a plant cell, comprising 
 a) constructing an expression vector comprising an inducible promoter element, or a functional portion thereof, operably linked to a second nucleotide sequence encoding a heterologous gene, wherein said inducible promoter element or a functional portion of said element controls the transcription of said heterologous gene sequence;    b) engineering a plant cell with said expression vector;    c) culturing said engineered plant cell;    d) harvesting said engineered plant cell;    e) inducing the expression of said heterologous gene; and    f) recovering the expressed heterologous gene product from said engineered plant cell.    
     
     
         2 . A method for producing a product encoded by a heterologous gene in harvested plant tissue, comprising 
 a) constructing an expression vector comprising an inducible promoter element, or a functional portion thereof, operably linked to a second nucleotide sequence encoding a heterologous gene, wherein said inducible promoter element or a functional portion of said element controls the transcription of said heterologous gene sequence;    b) engineering a plant with said expression vector;    c) cultivating said engineered plant;    d) harvesting tissue from said engineered plant;    e) inducing the expression of said heterologous gene; and    f) recovering the expressed heterologous gene product from said engineered plant.    
     
     
         3 . The method of  claim 1  or 2, wherein said inducible promoter element is an HMG2 promoter.  
     
     
         4 . The method of  claim 3 , wherein said inducible promoter is a tomato HMG2 promoter or a tomato HMG2 promoter homolog.  
     
     
         5 . The method of  claim 3 , wherein inducing the expression of said heterologous gene is by wounding or elicitor treatment.  
     
     
         6 . The method of  claim 4 , wherein inducing the expression of said heterologous gene is by wounding or elicitor treatment.  
     
     
         7 . The method of  claim 2 , wherein said harvested tissue is leaf, stem, root, flower, seed or fruit.  
     
     
         8 . The method of  claim 7 , wherein said harvested tissue is leaf.