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.

Description

[0001] This application is a continuation-in-part of co-pending application Ser. No. 08 / 100,816 filed Aug. 2, 1993, which is hereby incorporated by reference in its entirety.1. INTRODUCTION[0002] The present invention relates in part to HMG2 promoters, active fragments thereof, and their use to drive the expression of heterologous genes. Expression vectors may be constructed by ligating a DNA sequence encoding a heterologous gene to an HMG2 promoter or a promoter modified with an HMG2 cis-regulatory element. Such constructs can be used for the expression of proteins and RNAs in plant cell expression systems in response to elicitor or chemical induction, or in plants in response to wounding, pathogen infection, pest infestation as well as elicitor or chemical induction.[0003] The present invention also relates to a method of producing gene products in harvested plant tissues and cultures. The "post-harvest" production method utilizes tissues or cultures from transgenic plants or plan...

AI Technical Summary

Benefits of technology

[0033] As demonstrated by the examples described herein, plants may be engineered with expression constructs comprising an inducible promoter, such as the HMG2 promoter, operably linked to a sequence encoding a protein or RNA. Tissues harvested from the engineered plants may be induced to express the encoded protein or RNA by treatment with the appropriate inducer or inducing condition. With the post-harvest production method, the amount of encoded gene product produced from an expression construct utilizing an inducible promoter may surpass that produced by an expression construct utilizing a strong constitutive promoter. Moreover, such harvested plant tissues can maintain, for up to two weeks after harvesting, their capability for strong induced production of the gene product encoded in the expression construct.

[0034] The post-harvest production method of the invention may be advantageously used to produce desired gene products that are adverse to plant or plant cell growth or development. In plants or plant cells engineered with expression constructs comprising inducible promoters operably linked to sequences encoding the desired gene product, the expression of the desired but plant-deleterious gene product would remain dormant during the growth of the plant or culture line, thus allowing for productive and efficient cultivation or culturing of the engineered plant or culture line. When the engineered plant or culture line has attained optimal condition for harvest or processing, the expression of the desired gene product may be artificially triggered by treatment with the appropriate inducer or inducing condition, which, in the case with expression constructs comprising the HMG2 promoter, is mechanical wounding or elicitor or chemical induction. The desired product, either encoded by the induced gene or a compound produced by the induced gene product, may then be extracted from the induced plant, harvested plant tissue, or culture line after allowing for a short expression period.

Problems solved by technology

Plant diseases caused by fungal, bacterial, viral and nematode pathogens cause significant damage and crop loss in the United States and throughout the world.

The conversion of 3-hydroxy-3-methylglutaryl CoA to mevalonic acid appears to be the rate-limiting step of isoprenoid biosynthesis.

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