Poster: Integrative plant physiology

Abs # 36: Engineered Tolerance to Peptide Deformylase Inhibitors in Nicotiana tabacum

Presenter:	Hou, Caixia , chou2@uky.edu
Authors	Hou, Caixia  (A)   Conn, Heather M (A)   Brightwell, Rachel  (A)   Dirk, Lynnette MA (A)   Williams, Mark A (A)
Affiliations:	(A): Department of Horticulture, University of Kentucky

Peptide deformylases (DEF) are responsible for the cleavage of N-terminal formyl groups from nascent polypeptides synthesized in prokaryotic cells and eukaryotic organelles, and have been shown to play an essential role in protein maturation. In Arabidopsis and Nicotiana, as well as many other plant species, two nuclear-encoded forms of peptide deformylase exist that are targeted to both mitochondria and chloroplast, and suffer inhibition by known peptide deformylase inhibitors such as actinonin. Studies in tobacco have shown that the herbicidal action of actinonin appears to be the processing and assembly of the D1 polypeptide into PSII complexes, ultimately resulting in a severe inhibition of photosynthesis and leaf necrosis. Recently, transgenic tobacco plants were produced to over-express Arabidopsis DEF1 or DEF2. High-level expression of AtDEF1 and 2 was confirmed and quantified in leaf extracts from transgenic plants using Western analysis and ELISA. These plants were subjected to normally lethal amounts of actinonin and evaluated for subsequent growth and development. The results dramatically demonstrate that over-expression of either AtDEF1 or 2 is sufficient to convey complete resistance to actinonin in transgenic plants. These observations provide critical evidence confirming that DEF activity is essential for plant survival and that DEF is an ideal herbicide target amenable to genetically engineered tolerance.