Poster: Epigenetics & gene silencing

Abs # 834: Agrodrench: a novel and efficient agroinoculation method for virus induced gene silencing in plant roots and various Solanaceae species

Presenter:	Ryu, Choong-Min , cryu@noble.org
Authors	Ryu, Choong-Min  (A)   Anand, Ajith  (A)   Kang, Li  (A)   Mysore, Kirankumar S. (A)
Affiliations:	(A): The Samuel Roberts Noble Foundation

Virus-induced gene silencing (VIGS) is an extremely powerful tool for plant functional genomics. We used Tobacco rattle virus (TRV) derived VIGS vectors that is in an Agrobacterium binary vector. The inoculation of agrobacteria containing the VIGS vectors initiates virus infection resulting in RNA silencing in plants. Leaf infiltration is the most common method of agroinoculation for VIGS. This method has limitations since it is laborious for large scale screening and also certain plants like pepper, maize and soybean are very hard to infiltrate leaves. Here we have developed a novel and simple method of agroinoculation by drenching the soil adjacent to the plant root with the Agrobacterium suspension carrying the TRV derived VIGS vectors. We call this method as agrodrench. We show that agrodrench is comparable to leaf-infiltration method of agroinoculation for VIGS in Nicotiana benthamiana. Using this method we successfully suppressed the expression of either phytoene desaturase (PDS) or 20s proteasome or Mg-protoporphyrin chelatase (Chl H) gene in important crops like tomato, pepper, tobacco, and Petunia belonging to the Solanaceae family. Agrodrench can also be used for VIGS in very young seedlings and this is currently not possible by leaf infiltration method, due to the requirement of fully expanded leaves for infiltration. We also demonstrate, for the fist time, that VIGS can be used to silence desirable genes in plant roots. Agrodrench method of agroinoculation was more efficient for VIGS in roots when compared to the leaf-infiltration method. Agrodrench will facilitate large-scale functional analysis of many ESTs in shorter time duration for plants that are not currently amenable to VIGS technology by conventional inoculation methods.