Abiotic Stress/Whole Plant Bio


CS-4-2 - The XBAT family of RING-type E3 ubiquitin ligases and plant response to environmental stress

Sunday, July 15
1:23 PM - 1:43 PM

The ubiquitination pathway is involved in almost every aspects of plant biology. The pathway involves the attachment of ubiquitin, a small, highly conserved protein to select substrates. The attachment of a polyubiquitin chain targets protein to the 26S proteasome for degradation. Plants utilize the ubiquitin proteasome system (UPS) to regulate protein abundance to facilitate responses to and ultimately survival of unfavourable environmental conditions. Ubiquitin-dependent degradation prohibit, activate, attenuate and terminate stress signalling events to ensure that the proper response occurs at the appropriate time only for the needed duration. At the center of the UPS is a large and diverse family of substrate recruiting ubiquitin ligase (E3) enzymes. Of interest are the XBAT E3s, each of which contain a RING-HCa domain and Ankyrin repeats that facilitate substrate interactions.  XBAT E3s have very diverse roles including regulating ethylene biosynthesis, abscisic acid signalling, and response to abiotic stresses. Most recently, XBAT35.2 was shown to induce cell death and reduce pathogen susceptibility. Interestingly, stress stimulus prohibit self-ubiquitination leading to stabilization of the XBAT35.2 and degradation of its substrate. We are currently working on defining the role for XBAT31 in abiotic stress tolerance. XBAT31 transcript is alternatively spliced to produce XBAT31.1 and XBAT31.2. XBAT31.1 transcript, but not XBAT31.2, increase in response to iron deficiency. xbat31-1 seedlings have decreased iron content compared to wild type when grown under iron-deficient conditions,which correlates with lower expression of Iron-Regulated Transporter 1 (IRT1). Surprisingly, the growth of xbat31-1 seedlings are less affected by iron deficient conditions. Also, xbat31-1 ismore tolerant of heat stress. We hypothesize that XBAT31.1 mediate ubiquitin-dependent degradation of multiple substrates to promote iron deficiency response and root iron uptake as well as thermotolerance. To further understand the function of XBAT31.1 we are currently engaged in identifying substrates for the E3.  



Nathieli Schiavi – Dalhousie Univeristy; Michon McDonald – Dalhousie Univeristy

Sophia L. Stone, PhD

Dalhousie Univeristy

Sophia Stone is a Professor in the Department of Biology at Dalhousie University (NS, Canada). She earned her PhD at York University and completed a HFSP fellowship at the University of California-Davis. She is the recipient of a number of research awards including the 2016 C.D. Nelson Award in Plant Biology from CSPB. She has a long standing research interest in the regulatory role of the ubiquitin proteasome system (UPS) in plant development, reproduction and response to environmental stresses. Her current research focuses on the role of ubiquitin-dependent protein degradation in regulating abscisic acid (ABA) signalling. She is also interested in identifying proteins that are targeted for degradation by the UPS to mediate responses to biotic and abiotic stresses (e.g. iron deficiency and temperature stress) and determining how the enzymes of the UPS are themselves regulated to facilitate growth under suboptimal conditions.


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CS-4-2 - The XBAT family of RING-type E3 ubiquitin ligases and plant response to environmental stress

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