The Role of Arabidopsis thaliana 14 - 3-3λ in the Biosynthesis of Flavonols During Development and Drought Stress

Abstract

My research interest is in developing plants that are a source of the flavonoid compounds and that are also tolerant to abiotic stress. The focus of this study is a family of proteins called 14 – 3-3 which are known signaling factors in eukaryotes. My strategy is to map the nodes of the phenylpropanoid pathway affected by 14 – 3-3. This data will be used to manipulate the 14 – 3-3 genes that would result in increased production of flavonoids. Our laboratory has identified an isoform (14 – 3-3 λ) that demonstrates a role in drought tolerance and also affects the biosynthesis of flavonoids. To determine the role of 14 – 3-3λ in the phenylpropanoid pathway, a reverse genetics approach was employed, in which the amounts of secondary metabolites produced in a 14 – 3-3 λ knockout mutant were compared to the wild-type Arabidopsis thaliana (Columbia-0) throughout their development and in drought conditions by LC-MS. The results from the developmental study revealed that silencing 14 – 3-3λ results in increased biosynthesis of flavonol glycosides until the fourth week of development, where they are catabolized. The results obtained in the drought study indicate that flavonol glycosides are not involved in drought stress response in wild-type A. thaliana, however a significant increase in a lignin compound was observed in both wild-type and knockout species, implicating a role of 14 – 3-3λ in lignin biosynthesis. These results indicate that 14 – 3-3λ may be a negative modulator in flavonol glycoside biosynthesis is wild-type Arabidopsis during both development and drought stress response.