The characterisation of AOP2: a gene associated with the biosynthesis of aliphatic alkenyl glucosinolates in Arabidopsis thaliana

Abstract

<p>Abstract</p> <p>Background</p> <p>Glucosinolates, a group of nitrogen and sulfur containing compounds associated with plant-insect interactions, are produced by a number of important <it>Brassicaceae </it>crop species. In <it>Arabidopsis </it>the <it>AOP2 </it>gene plays a role in the secondary modification of aliphatic (methionine-derived) glucosinolates, namely the conversion of methylsulfinylalkyl glucosinolates to form alkenyl glucosinolates, and also influences aliphatic glucosinolate accumulation.</p> <p>Results</p> <p>This study characterises the primary structural variation in the coding sequences of the <it>AOP2 </it>gene and identifies three different <it>AOP2 </it>alleles based on polymorphisms in exon two. To help determine the regulatory mechanisms mediating <it>AOP2 </it>expression amongst accessions, <it>AOP2 </it>5' regulatory regions were also examined however no major differences were identified. Expression of the <it>AOP2 </it>gene was found to be most abundant in leaf and stem tissue and was also found to be light dependent, with a number of light regulatory elements identified in the promoter region of the gene. In addition, a study was undertaken to demonstrate that the <it>Arabidopsis AOP2 </it>gene product is functional <it>in planta</it>. The over-expression of a functional <it>AOP2 </it>allele was found to successfully convert the precursor methylsulfinyl alkyl glucosinolate into the alkenyl form.</p> <p>Conclusions</p> <p>The expression of the <it>AOP2 </it>gene has been found to be influenced by light and is most highly expressed in the photosynthetic parts of the <it>Arabidopsis </it>plant. The level of <it>AOP2 </it>transcript decreases rapidly in the absence of light. <it>AOP2 </it>exists as at least three alleles in different <it>Arabidopsis </it>accessions and we have demonstrated that one of these, <it>AOP2-2</it>, is functionally able to convert methylsulfinyl glucosinolates into the alkenyl form. The demonstration of the <it>in planta </it>functionality of the <it>Arabisopsis AOP2 </it>gene is an important step in determining the feasibility of engineering glucosinolate profiles in food plants.</p