Biochemistry & Biophysics

Xiuren Zhang

zhang Assistant Professor of Biochemistry & Biophysics
Institute for Plant Genomics & Biotechnology

Phone: (979) 458-0596
Email: xiuren.zhang@tamu.edu
M.S. Auburn University (1999)
Ph.D Cornell University (2003)
Postdoc. Rockefeller University (2003-2008)

Joined Texas A & M University (2008)


AGOs-mics / RNA silencing and viral suppression


RNA silencing has emerged as a key regulatory process that controls various aspects of biology in eukaryotes including growth and development, antiviral defense and chromosome gardening. The common themes under RNA silencing include the biogenesis of small RNAs by DICERs and the incorporation of the small RNAs into Argonaute (AGO)-centered RNA-induced silencing complexes (RISCs). The RISCs execute the repressive or regulatory functions on target genes at the transcriptional or post-transcriptional levels.

Our laboratory focuses on systemic analysis of biochemical, molecular and biological functions of AGO family proteins (AGOs-mics) in genetically tractable Arabidopsis and economically important crops (i.e. rice). We'd like to identify the small RNAs, mRNA targets and protein components which associate with these AGOs. We will study protein/RNA and protein/protein interactions in these RISC assembly events. Our goal is to understand how these AGOs are functionally specialized or redundant corresponding to endogenous development cues and external environmental stimuli. Particularly, we'd like to learn how plants reprogram their gene expression through the small RNAs and AGOs to construct a new cellular niche in responses to environmental challenges and biotic stresses.

Another aspect of our research involves host/virus interaction. Plants take advantage of RNA silencing pathways to defend themselves from exogenous nucleic acid invaders (i.e. viruses). As an anti-host defense mechanism, viruses encode suppressors that can block RNA silencing responses. We have recently demonstrated that CMV 2b disables AGO1 cleavage activity to inhibit RNA silencing and to counter host defense. We are now extending our study to suppressors of several other viruses and the molecular mechanisms of their suppression.

Recent Publications


  1. Catala R, Ouyang J, Abreu IA, Hu Y, Seo H, Zhang X & Chua NH (2007) The Arabidopsis E3 SUMO ligase SIZ1 regulates plant growth and drought responses. Plant Cell 19: 2952-66
  2. Zhang X, Henriques R, Lin SS, Niu QW & Chua NH (2006) Agrobacterium-mediated transformation of Arabidopsis thaliana using the floral dip method. Nat Protoc 1: 641-6
  3. Zhang X, Buehner NA, Hutson AM, Estes MK & Mason HS (2006) Tomato is a highly effective vehicle for expression and oral immunization with Norwalk virus capsid protein. Plant Biotechnol J 4: 419-32
  4. Zhang X, Yuan YR, Pei Y, Lin SS, Tuschl T, Patel DJ & Chua NH (2006) Cucumber mosaic virus-encoded 2b suppressor inhibits Arabidopsis Argonaute1 cleavage activity to counter plant defense. Genes Dev 20: 3255-68
  5. Zhang X & Mason H (2006) Bean Yellow Dwarf Virus replicons for high-level transgene expression in transgenic plants and cell cultures. Biotechnol Bioeng 93: 271-9
  6. Zhang X, Garreton V & Chua NH (2005) The AIP2 E3 ligase acts as a novel negative regulator of ABA signaling by promoting ABI3 degradation. Genes Dev 19: 1532-43
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