Related Experiment Video
Updated: Jul 11, 2026

Measuring Gene Expression in Bombarded Barley Aleurone Layers with Increased Throughput
Published on: March 30, 2018
The Arabidopsis E3 SUMO ligase SIZ1 regulates plant growth and drought responses
Rafael Catala1, Jian Ouyang, Isabel A Abreu
1Laboratory of Plant Molecular Biology, The Rockefeller University, New York, NY 10021, USA.
Abstract:
Posttranslational modifications of proteins by small ubiquitin-like modifiers (SUMOs) regulate protein degradation and localization, protein-protein interaction, and transcriptional activity. SUMO E3 ligase functions are executed by SIZ1/SIZ2 and Mms21 in yeast, the PIAS family members RanBP2, and Pc2 in human. The Arabidopsis thaliana genome contains only one gene, SIZ1, that is orthologous to the yeast SIZ1/SIZ2. Here, we show that Arabidopsis SIZ1 is expressed in all plant tissues. Compared with the wild type, the null mutant siz1-3 is smaller in stature because of reduced expression of genes involved in brassinosteroid biosynthesis and signaling. Drought stress induces the accumulation of SUMO-protein conjugates, which is in part dependent on SIZ1 but not on abscisic acid (ABA). Mutant plants of siz1-3 have significantly lower tolerance to drought stress. A genome-wide expression analysis identified approximately 1700 Arabidopsis genes that are induced by drought, with SIZ1 mediating the expression of 300 of them by a pathway independent of DREB2A and ABA. SIZ1-dependent, drought-responsive genes include those encoding enzymes of the anthocyanin synthesis pathway and jasmonate response. From these results, we conclude that SIZ1 regulates Arabidopsis growth and that this SUMO E3 ligase plays a role in drought stress response likely through the regulation of gene expression.
Related Concept Videos
Responses to Drought and Flooding
Cell Signaling in Plants
Regulation of Transpiration by Stomata
Adaptations that Reduce Water Loss
Gene Regulation During Sporulation
Responses to Salt Stress
