Poplar Allene Oxide Synthase 1 Gene Promoter Drives Rapid and Localized Expression by Wounding
Bin Lei
Department of Genetics and Biochemistry, Clemson University, USA.
Christopher J. Frost
BIO5 Institute, University of Arizona, USA.
Tao Xu
Department of Genetics and Biochemistry, Clemson University, USA.
Joshua R. Herr
Department of Plant Pathology, University of Nebraska, Lincoln, NE, USA and The Center for Plant Science Innovation, University of Nebraska, Lincoln, NE, USA.
John E. Carlson
The Schatz Center for Tree Molecular Genetics, Department of Ecosystem Science and Management, The Pennsylvania State University, University Park, PA, USA.
Haiying Liang *
Department of Genetics and Biochemistry, Clemson University, USA.
*Author to whom correspondence should be addressed.
Abstract
Promoters play critical roles in controlling the transcription of genes and are important as tools to drive heterologous expression for biotechnological applications. In addition to core transcription factor-binding motifs that assist in the binding of RNA polymerases, there are specific nucleotide sequences in a promoter region to allow regulation of gene expression. The allene oxide synthase (AOS) gene family are cytochrome P450s that are responsive to a variety of environmental stress, making them good candidates for the discovery of inducible promoters. Populus AOS homologs separate phylogenetically into two clades. Based on the 19 promoter motifs with significant abundance differences between the two clades, Clade I AOS genes are likely more responsive to hormones, salt, and pathogen, whereas clade II homologs are likely inducible by water stress. In this study, an upstream promoter from a Clade I poplar AOS encoding gene (AOS1) was cloned and used to drive the expression of a ß-glucuronidase (GUS) gene in Arabidopsis. AOS is an essential enzyme in the lipoxygenase pathway that is responsible for the production of many non-volatile oxylipins in plants, including the jasmonates, which are regulatory phytohormones coordinating a variety of biological and stress response functions. Consistent with AOS transcript expression patterns, we found that the poplar AOS1 promoter drives rapid and localized expression by wounding. The study provides insight on the responsive elements in the poplar AOS promoters, but more importantly identifies a strong wound-inducible and localized promoter for future applications.
Keywords: Gene expression, herbivory, non-systemic expression, populous