Abstract

MJ 2-2 - Auxin transcriptional networks from beginning to end

Sunday, July 15
9:05 AM - 9:35 AM

Auxin controls growth and diverse physiological processes through a complex transcriptional network that includes thousands of genes. Auxin regulates gene expression by promoting the degradation of transcriptional repressors called Aux/IAA proteins. The 29 Aux/IAA genes in Arabidopsis exhibit unique but partially overlapping patterns of expression. Although some studies have suggested that individual Aux/IAA genes have specialized function, genetic analyses of the family have been limited by the lack of loss-of-function phenotypes, presumably because of overlapping function. Further, with a few exceptions, our knowledge of the factors that regulate Aux/IAA expression is limited. We hypothesize that transcriptional control of Aux/IAA genes plays a central role in the establishment of the auxin-signaling pathways that regulate organogenesis, growth, and environmental response. To identify transcription factors that regulate the Aux/IAA genes, we performed a yeast-1-hybrid screen with 15 Aux/IAA promoters against ~2000 Arabidopsis TFs. Our results indicate that the Aux/IAA genes are regulated by many transcription factors implicated in diverse processes. We have focused on regulation of Aux/IAA by the DREB2A/B transcription factors. The DREB2 proteins have been described as master regulators of ABA-independent responses to drought, heat and cold. Consistent with this, our genetic studies indicate that several Aux/IAA genesare required for drought tolerance. In my talk I will describe results that explain this requirement. 


 

Mark Estelle, PhD

Distinguished Professor and Chair
UC San Diego

Mark Estelle is Distinguished Professor and Chair of the Section of Cell and Developmental Biology at the University of California San Diego. Dr. Estelle trained in fruit fly genetics as a Ph.D. student at the University of Alberta and received his training in plant genetics as a postdoc at the Plant Research Lab at Michigan State University. Dr. Estelle has a long-standing interest in the mechanisms of auxin signaling and the integration of auxin signaling with other developmental and environmental programs. Estelle’s group discovered that auxin is perceived by a co-receptor complex consisting of the F-box protein TIR1 and a transcriptional repressor called an Aux/IAA protein. In addition, Dr. Estelle has made a number of important discoveries concerning the regulation of the ubiquitin-proteasome system.

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