Analysis of Genes AT5G64110 and IAA18 as Potential Downstream Targets of ARF-19

Abstract

Auxin is a crucial hormone in plants that provokes many different responses involved with physiological processes of plants including lateral root development, primary root growth, and gravitropism. In the plant Arabidopsis thaliana, the hormone enhances the expression of auxin response factor (ARF) transcription factors. This study focuses on ARF-19, which is crucial for the lateral root development in plants. This work aims to identify a direct downstream target of ARF-19 and to further understand how plant transcription factors work. An Arabidopsis gene of interest was selected and inserted into a plasmid which was amplified through transformation into E. coli. The plasmid with the promoter insert of the gene was then expressed in yeast, Saccharomyces cerevisiae. Observing the expression of the gene in yeast helps us determine if ARF-19 uses the gene’s promoter to drive its transcription. Gene expression was measured using qRT-PCR, confocal microscopy, and plate reader assays. The first gene of choice was AT5G64110, however, error in the formation of the plasmid forced the transition to analyze the IAA18 gene as a potential target. Expression quantification experiments indicate that ARF-19 does not bind to the IAA18 gene promoter. This gene is not a direct target of ARF-19 through the auxin-mediated pathway. Further characterization of the IAA18 gene can reveal more about this transcription factors role in plant growth, independent of auxin.