Unconventional effects of TAL effectors
N. Booher (1), S. Carpenter (2), Z. Dubrow (1), N. Falahi-Charkhabi (2), Y. He (1), L. Kladsuwan (1), A. Read (2), P. Singh (2), L. Wang (2), K. Wilkins (2), L. Maron (2), T. Tuan (4), B. Szurek (4), A. Bogdanove (1) (1) Cornell University, U.S.A.; (2) Cornell University, U.S.A.; (3) Cornell University, U.S.A.; (4) IRD, Montpelier, France

Xanthomonas TAL effectors play determinative roles in plant diseases by activating host susceptibility (S) or resistance (R) genes. They recognize their binding sites in DNA via a modular mechanism, which enables binding site prediction and construction of designer TAL effectors (dTALEs). S gene alleles unrecognized by TAL effectors may confer “passive” resistance. Understanding TAL effector and target diversity guides identification of such alleles and new R genes. We pursue this objective using a now almost rote approach: long-read pathogen whole genome sequencing, TAL effector gene mutagenesis, target identification by binding site prediction and host transcript profiling, and target functional characterization using dTALEs. We have identified for the first time TAL effectors important in bacterial pustule of soybean and bacterial leaf streak of wheat. In rice, we have identified potentially useful allelic variation at the TAL effector binding site of the bacterial leaf streak S gene OsSULTR3;6. However, we have also discovered three TAL effectors that function unconventionally. One contributes to virulence in a strictly host-genotype-dependent way. Another activates its target by reverse strand binding. The third appears to contribute to disease by some means other than protein-coding gene activation. These results at once inform disease control and reveal that a broader view must be taken to understand the variety of effects TAL effectors have in plant disease.

Abstract Number: P9-240
Session Type: Poster