Characterization of the Relationship Between BODYGUARD2 and Abscisic Acid in Response to Osmotic Stress

Abstract

Plants have a cross-linked lipid matrix called the cuticle, which forms a hydrophobic protective layer that lies outside of the epidermal cells of the plant. It is primarily composed of wax and cutin and is essential for preventing water loss. In Arabidopsis thaliana, a gene called BODYGUARD2 (BDG2) has an effect on wax and cutin biosynthesis. It is a member of the BODYGAURD family that is made up of five genes. The first, called BODYGAURD1 (BDG1), has been characterized. The mutants of BDG1 were found to have less cutin, which resulted in greater water loss and cuticle permeability. Another study found that BDG1 induces the expression of abscisic acid (ABA) biosynthesis genes under drought stress. BDG2 and BDG1 have ~80% amino acid sequence similarity, indicating that they likely have similar functions. Therefore, BDG2 mutants are being tested for ABA levels, as well as the gene expression level of a precursor gene, 9-cis-epoxycarotenoid dioxygenase (NCED), that induces ABA synthesis under drought stress. There is also evidence that ABA induces BDG2 gene expression in stomata, which suggests BDG2 may have a role in ABA induced stomata closure. Plants will be grown on Agar, with Mannitol to mimic drought stress. ABA levels will be tested using Liquid Chromatography Mass Spectrometry (LC-MS). The gene expression level of NCED will be measured using Reverse Transcription Quantitative Polymerase Chain Reaction (RT-qPCR). Stomata closure will be measured in Wild type and mutant plants treated with ABA. Results from these experiments will create progress in the characterization of the BDG2 gene.