Plant Defense Signal Peptides

Abstract

A 23 amino acid peptide, AtPtpl, plays an important role as a signaling component of the innate immune system of Arabidopsis. The peptide precursor gene is transcribed in response to elicitors generated by pathogens, and AtPep1 is produced to amplify the signaling pathways. Seven paralogs of the AtproPep1 gene have been identified in the Arabidopsis genome, and orthologs have been identified in species of several agriculturally important families. AtPcpl and its paralogs and orthologs play important roles as endogenous signals to amplify innate immunity. The sequence of two AtPep1 receptors from Arabidopsis are also provided.

Description

CROSS-REFERENCE TO RELATED CASES[0001]This application claims priority from U.S. provisional patent application Ser. No. 06 / 647,708, filed Jan. 26, 2005, which is incorporated herein by reference.STATEMENT OF GOVERNMENT RIGHTS[0002]The invention was supported, at least in part, by a grant from the Government of the United States of America (grant no. IBN 0090766 from the National Science Foundation). The Government may have certain rights to the invention.BACKGROUND[0003]1. Technical Field[0004]The present invention relates to materials and methods for enhancing plant disease resistance.[0005]2. Background Information[0006]Plants are exposed to numerous denizens of their environment, including bacteria, viruses, fungi, and nematodes. Although many of the interactions between these organisms and plants, particularly via the roots of the plants, are beneficial, many of the interactions are harmful to the plants. The decimation of agricultural crops, ornamental plants, and other plants...

AI Technical Summary

Benefits of technology

[0022]We have identified a novel defense signal peptide from Arabidopsis and a variety of other plants, including many crop plants of commercial importance. In addition, we have identified genes encoding polypeptides that are processed in plant cells to produce the shorter peptides, as well as receptors for the peptides. Transgenic plants in which these defense signal peptides are expressed under the control of a heterologous promoter, such as a constitutive promoter, exhibit improved yield of plant product, reduced disease symptoms, and / or enhanced resistance to disease infestation. Peptides that comprise as few as ten amino acid residues from the carboxy-terminus of AtPep1, a 23 amino acid defense signal peptide from Arabidopsis thaliana, retain significant activity. In addition, individual amino acid residues that are important for activity have been defined by amino acid substitutions. Peptides and other substances that have defense signal peptide activity can be readily screened using an alkalinization assay that is described herein, and their identity can be confirmed by exogenous application to plants or transgenic expression in plants.

[0025]Such compositions comprising peptide or polypeptide compositions may further comprise biologically acceptable carriers and / or other substances used in formulating peptides and polypeptides. For example, such compositions may be agricultural formulations that are suitable for application to plants. Accordingly, in another embodiment of the invention, plants or seeds of plants are provided that comprise such a composition applied to a plant or seed surface, respectively. When applied to plants under suitable conditions, such compositions induce the plants' innate immunity and enhancing their defense against attack by pathogens.

[0028]According to another embodiment of the invention, an isolated polynucleotide is provided that comprises a sequence that encodes a defense signal peptide operably linked to a heterologous promoter. Polynucleotides for expression in plant, bacterial, fungal (including yeast), insect, and other types of cells are contemplated. In one embodiment, expression of the polynucleotide in a cell of a plant causes the plant to exhibit an improvement compared to a control plant lacking the polynucleotide that is selected from the group consisting of improved yield of plant product, reduced disease symptoms, and enhanced resistance to disease infestation. The heterologous promoter may, for example, be a constitutive promoter or a non-constitutive promoter, including, but not limited to, an organ- or tissue-specific promoter or an inducible promoter.

[0032]According to another embodiment of the invention, methods are provided for making a transgenic plant, comprising introducing into a cell of a plant one or more of the above-described polynucleotides of the invention, thereby producing a transformed cell, and regenerating a transgenic plant from the transformed cell, wherein, compared to a control plant lacking the polynucleotide, the transgenic plant exhibits a characteristic selected from the group consisting of substantially improved yield of plant product, substantially reduced disease symptoms, and substantially enhanced resistance to disease infestation.

[0035]According to another embodiment of the invention, methods are provided for growing a plant comprising planting a seed that comprises one or more of the above-mentioned polynucleotides of the invention, and growing the seed to produce a plant, wherein, compared to a control plant lacking said polynucleotide sequence, the plant grown from the seed exhibits a characteristic selected from the group consisting of substantially improved yield of plant product, substantially reduced disease symptoms, and substantially enhanced resistance to disease infestation.

Problems solved by technology

Although many of the interactions between these organisms and plants, particularly via the roots of the plants, are beneficial, many of the interactions are harmful to the plants.

The decimation of agricultural crops, ornamental plants, and other plants by diseases caused by plant pathogens is a worldwide problem that has enormous economic impact.

Damage to plants is caused by pathogens of multiple genera.

The activity of these compounds is typically limited to several species.

As a consequence of the large number and diversity of plant pathogens, these compounds have not provided an effective solution to limiting infections in plants.

However, resistance may be limited to certain genera of pathogens, or crops of agronomic interest may not exhibit sufficient resistance.

Thus, natural plant defenses often do not provide sufficient protection against pathogens.

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