High-efficiency targeted modification of plant genomes using TALENs strategy
Qiwei Shan¹, Yanpeng Wang¹, Zhen Liang¹, Jun Li, Yi Zhang¹, Kang Zhang¹, Jinxing Liu¹, Kunling Chen¹, Yong Zhang², Caixia Gao^1*

¹Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China.
²School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu 610054, China.
^*Corresponding Author：Tel & Fax: (+8610) 6480 7727; E-mail: cxgao@genetics.ac.cn

Abstract
Recent advances in high-efficiency methods for targeted genome modification have equipped plant biologists with another powerful genetic tool to facilitate understanding gene functions and expedite translational research to develop crop varieties with higher productivity, enhanced nutrition and lower input costs.  Efficient genome modifications often require targeted cleavage of specific chromosomal sequences, which generates double strand DNA breaks (DSBs) and activates endogenous DNA repair pathways. We have recently developed platforms to design and generate highly specific and active TALE nucleases (TALENs), for recognizing and cleaving desired DNA sequences. The reagents and delivery methods have been optimized to achieve highly efficient targeted mutagenesis in a number of plant species, including rice, Brachypodium, wheat and tobacco. We have assembled  specific TALENs designed to modify more than 20 genes from rice, Brachypodium and wheat, e.g. from 35.2% of the transgenic rice resistant callus lines, TALENs introduced targeted mutations were detected. Such high efficiencies make it possible to recover genome modifications even without enrichment regimes, As the results, our technology opens the door to make targeted genome modification of plants a routine practice and promises to facilitate creation of new crop varieties to meet burgeoning agricultural demands.  Moreover, the potential impact of targeted genome engineering technology on regulatory decisions will also be presented. 

Key Words: TALENs; targeted genome modification