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United States Department of Agriculture

Agricultural Research Service

ZONGRANG LIU

Research Molecular Biologist

Dr. Zongrang Liu 
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Research Molecular Biologist

 

Picture of Dr. Zongrang Liu

 

USDA-ARS-AFRS

2217 Wiltshire Road

Kearneysville, WV 25430

Voice: (304) 725-3451 x239

 

Professional Biographical Information:

 

Ph.D. in Plant Molecular Biology (1992), Cornell University                                      

M.S. in Pomology (1987), Cornell University

B.S. in  Pomology (1982), Northwestern Agricultural University, China 

 

2001- Present, Research Geneticst/Molecular Biologist,

USDA- ARS, Appalachian Fruit Research Station, Kearneysville, WV 25430

 

1994-2000, Research Associate, Department of Molecular and Cellular Biology, University of Arizona.

 

1992-1993, Postdoctoral Research Associate, Department of Biology, Dartmouth College.

 

Current CV

 

Lab Members

 

Mr. Dennis Bennett (Lab technician/ manager).

Dennis.bennett@ars.usda.gov

Dr. Jean-Michel Hily (Postdoctoral associate).

Jean-michel.hily@ars.usda.gov

Mr. Kyle Layman (Lab assistant)

 

Dr. Stacy Singer (Postdoctoral associate).

Stacy.singer@ars.usda.gov

Mr. Weirong Xu (Graduate student).

Weirong.xu@ars.usda.gov

Mr. Yazhou Yang (Graduate student).

Yazhou.yang@ars.usda.gov

 

 

Description of Research Projects

 

Viruses present one of the major challenges for fruit production worldwide. Given the rapid evolution of viruses and the complex life cycles and genetics of fruit trees, using conventional approaches to breed desired cultivars is often difficult. Recent advances in our understanding of gene silencing mechanisms have paved the way for the development of a new strategy (e.g. RNAi) to improve virus resistance in plants. Using this new tool, we are able to engineer plants resistant up to six stone fruit viruses. However, the gene silencing mechanism underlying the resistance becomes ineffective at lower temperatures, which raises questions regarding the stability of the engineered trait under field conditions. Another concern when engineering virus resistance in transgenic plants is transgene flow, which may facilitate the evolution of virus-resistant weeds or other invasive species. Therefore, our current research directly addresses these two problems.

 

 

Understanding and exploiting diverse gene silencing mechanisms to enhance capacity of the existing silencing technologies

 

Engineered transgenic traits using gene silencing will eventually be deployed in the field.  Whether these traits can be stably maintained and effective in the field will depend on the stability of the underlying silencing mechanism. Hence, it is crucial to understand the stability and behavior of each gene silencing mechanism under different environmental conditions to determine the best mechanism to use. Although RNA interference (RNAi) and artificial microRNA (amiRNA) are currently used as experimental- and transgenic-engineering tools, they each suffer unique drawbacks. For example, RNAi is ineffective at lower temperatures (15oC), whereas amiRNA is less robust overall. Whether they can serve as effective tools for engineering field-stable traits remains to be determined. Hence, our current research focuses on 1) characterization of the stability of the existing gene silencing mechanisms and engineered traits under various conditions; 2) study of possible synergistic or anti-synergistic interactions among them; and 3) identification and molecular elucidation of additional gene silencing mechanisms existed in plants. The information generated through this research is expected to facilitate the development of a new silencing technology for engineering agronomically-important traits and sterility that are effective and stable under various biotic and abiotic stresses.

 

Development of transgene containment technologies

 

Pollen-, seed- and fruit-mediated transgene flow into wild relatives has raised concerns regarding the possibility of creating super weeds and the potential ecological and environmental impact of such plants.  Gene flow is also recognized as a major force that drives the spread of invasive species, which poses a serious challenge for US agriculture. Thus, the environmentally-responsible utilization of transgenic technology for crop improvement requires the development of methods for transgene containment. Research in my lab directly addresses this need through the development of a Tissue-specific transgene REmoval and Containment System (TRECS).  TRECS is designed to carry all elements necessary for executing gene excision and containment events in a temporal manner to ensure that the transgene is efficiently and precisely excised in floral organ meristems.  Any escaped transgenes are later contained in pollen and young fruit by a TRECS-executed self-suicidal action. The TRECS unit (bracketed by two tandem sites accessible to multiple potential molecular scissors) is integrated as a single fragment into the plant genome and then excised in targeted tissues leading to viable and transgene-free pollen, fruit and seed. TRECS requires an efficient scissors gene and highly tissue-specific promoters. The objectives of our current research are to identify desired promoters and effective molecular scissors candidate genes, and to assemble and test TRECS constructs in plants. Our long term goal is to develop effective TRECS technology applicable to a variety of crops.


Last Modified: 10/12/2007