Method for increasing stress tolerance in plants

Abstract

The present invention provides methods and compositions for improving the drought resistance of plants. More specifically, the present invention utilizes overexpression of a molybdenum cofactor sulfurase in plants and plant cells.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application claims benefit to U.S. Provisional Application Ser. No. 60 / 317,724, filed on Sep. 6, 2001, incorporated herein by reference in its entirety.STATEMENT OF GOVERNMENTAL SPONSORSHIP [0002] The invention described herein was supported by NSF grants IBN-9808398 and DBI-9813360. The government may have certain rights in this invention.BACKGROUND OF THE INVENTION [0003] 1. Field of the Invention [0004] The present invention relates to methods and compositions for increasing stress tolerance in plants. More specifically, the present invention provides methods and compositions for improving drought resistance, salt tolerance, and resistance to freezing. [0005] 2. Background of the Invention [0006] Plants respond to environmental challenges in part by altering their gene expression profile that ultimately leads to various adaptive responses at cellular and whole plant levels (Bray, 1993; Thomashow, 1999; Hasegawa et al., 2000; Zhu...

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Benefits of technology

[0009] It is an object of the present invention to provide methods and compositions for increasing stress tolerance in plants.

[0010] It is another object of the present invention to provide plants and plant cells which have increased stress resistance.

[0019] The present invention has been accomplished using a reporter gene approach to genetically dissect ABA and stress signal transduction in Arabidopsis. ABA and stress responsive bioluminescent plants were constructed by introducing the firefly luciferase reporter gene under control of the RD29A promoter (containing both ABRE and DRE / CRT elements; Yamaguchi-Shinozaki and Shinozaki, 1994) into Arabidopsis. The RD29A-LUC plants were mutagenized, and mutants with abnormal bioluminescence in response to cold, drought, salt or ABA were isolated (Ishitani et al., 1997). One group of mutants exhibit reduced luminescence responses to NaCl stress. Here, we present the characterization and cloning of two allelic mutants from this group. These two mutants, designated los5-1 and los5-2 (low expression of osmotically responsive genes), show reduced expression of stress-responsive genes under both cold and osmotic stress conditions. While the role of LOS5 in osmotic stress regulation of gene expression is mediated by ABA, the regulation of cold responsiveness by LOS5 is not dependent on ABA. The function of LOS5 in cold and osmotic stress responsive gene expression is independent of CBF / DREB1 or DREB2A transcription factors. los5 mutant plants are more susceptible to damage by freezing, salt and drought stresses, suggesting that LOS5 is critical for plant stress tolerance. The mutant plants also show enhanced transpirational water loss and accumulate less ABA in response to drought stress. Allelic tests show that los5 is allelic to the aba3 mutation. Map-based cloning of LOS5 / ABA3 reveals that it encodes a putative molybdenum cofactor (MoCo) sulfurase that catalyzes the sulfuration of the desulfo form of MoCo, which is consistent with previous findings that the aba3 lesion is in the introduction of S into MoCo (Schwartz et al., 1997a). Sulfurylated MoCo is a cofactor of ABA-aldhyde oxidase that functions in the last step of ABA biosynthesis. Expression of the LOS5 / ABA3 gene is up-regulated by ABA, salt and drought stresses. These data provide important insights into ABA biosynthesis and significantly further an understanding of stress gene regulation and stress tolerance.

Problems solved by technology

Secondly, the expression of many stress-responsive genes is induced by exogenous ABA, and their stress-inducibility is decreased in mutant plants defective in ABA biosynthesis or responsiveness.

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