I study the molecular interactions between Xanthomonas axonopodis pv. manihotis (Xam) and its host plant cassava. Bacterial pathogens like Xam deliver type III effector proteins into plant cells where they function to counteract plant immune responses and promote bacterial fitness. One class of effectors, the Transcription Activator Like (TAL) effectors, promote pathogenesis by directly binding DNA in host gene promoters and reprogramming host gene expression. Our lab has generated draft genome sequences for 65 Xam strains and determined that all of the strains contain TAL effectors. The major questions that my research addresses are 1) Which Xam TALEs are important for symptom formation and bacterial growth in the plant? 2) What genes are Xam TAL effectors activating in cassava? 3) How do the activated genes contribute to host susceptibility? I’m employing genetic and transcriptomic approaches to address these questions. 


Cohn, M.M., Bart, R., Shybut, M., Dahlbeck, D., Gomez, M., Morbitzer, R., Hou, Bi-Huei, Frommer, W.B., Lahaye, T., Staskawicz, B.J. (2014) Xanthomonas axonopodis virulence is promoted by a transcription activator like (TAL) effector mediated induction of a SWEET sugar transporter in cassava. Mol Plant Microbe Interact. 27(11):1186-98. doi: 10.1094/MPMI-06-14-0161-R.

Bart, R., Cohn, M.M., Kassen, A., McCallum, E.J., Shybut, M., Petriello, A., Krasileva, K., Dahlbeck, D., Medina, C., Alicai, T., Kumar, L., Moreira, L.M., Rodriguez Neto, J., Verdier, V., Angelica Santana, M., Kositcharoenkul, N., Vanderschuren, H., Gruissem, W., Bernal, A., and Staskawicz, B.J. (2012) High-throughput genomic sequencing of Cassava bacterial blight strains identifies conserved effectors to target for durable resistance. Proc. Natl. Acad. Sci. USA. 109:E1972–9

Leivar, P., Tepperman, J.M., Cohn, M.M., Monte, E., Al-Sady, B., Erickson, E., and Quail, P.H. (2012) Dynamic antagonism between phytochromes and PIF-family bHLH factors generates selective reciprocal responses during deetiolation and shade-avoidance in a rapidly light-responsive transcriptional network. Plant Cell 24(4):1398-419.

Li, F., Pignatta, D., Bendix, C., Brunkard, J.O., Cohn, M.M., Tung, J., Sun, H., Kumar, P., and Baker, B. (2012) MicroRNA regulation of plant innate immune receptors. Proc. Natl. Acad. Sci. USA. 109:1790-5.

Leivar, P., Monte, E., Cohn M.M., and Quail, P.H. (2012) Phytochrome signaling in green Arabidopsis seedlings: impact assessment of mutually-negative phyB-PIF feedback loop. Mol. Plant. 5(3):208-23.


QB3 Lab Fundamentals Bootcamp (June 2014, Instructor)

PMB40 The Secret Life of Plants (January-May 2013, Graduate Student Instructor)

PMB C112 General Microbiology (August-December 2011, Graduate Student Instructor)

Honors and Awards

Outstanding Graduate Student Instructor Award (2012)

National Institutes of Health Genetics Training Grant (2011-2013)

National Science Foundation Pre-Graduate Fellowship (2010-2015)