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Purdue University (2009)

Characterization of Arabidopsis thaliana stress and anthocyanin mutants

Van Oosten, Michael J.

Titre : Characterization of Arabidopsis thaliana stress and anthocyanin mutants

Auteur : Van Oosten, Michael J.

Université de soutenance : Purdue University

Grade : Doctor of Philosophy (PhD) 2009

One of the key phenotypes of the salt overly sensitive3-1 (sos3-1) mutant is its propensity to hyper accumulate anthocyanins when subjected to high levels of NaCl (120 mM). The anthocyanin-impaired-response-1 (air1) mutant is unable to accumulate anthocyanins under salt stress. The air1 mutant was discovered in a screen of second site suppressor mutants of the sos3-1 mutant. This thesis describes the investigation of air1 in order to understand the connection between regulation of anthocyanin accumulation and the salt stress response. ^ The air1 mutant shows a defect in anthocyanin (flavonoid) production, specifically in response to salt stress. When exposed to other stresses such as high light, low phosphorous, Paraquat, temperature or drought stress, it accumulates anthocyanins normally. This indicates that air1 is specifically involved in the regulation of anthocyanins in response to salt stress and not simply anthocyanin biosynthesis. Analysis of this mutant has revealed a T-DNA insertion of the promoter region of the Arabidopsis thaliana gene encoding for a basic leucine zipper transcription factor. Although previous efforts have revealed that transcription factor is expressed in plants, no function has yet been attributed. The results presented here indicate that air1 is responsible for the regulation of various steps in the flavonoid and anthocyanins pathway and is itself regulated by the salt-stress response pathway. The discovery and characterization of air1 opens avenues to dissect the connections between abiotic stress and accumulation of antioxidants in the form of flavonoids and anthocyanins.

Mots-clés : Anthocyanins, Flavonoids, Salinity stress, Stress responses


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