Dropkin Postdoctoral Fellow
Education
PhD in Biology, 2016, Wesleyan University
BS in Biology, 2008, College of Charleston
Research
The central goal of my research is to understand how individual plants respond to environmental stresses, and how those responses influence the ecology and evolution of natural plant populations. To this end, I investigate how functional phenotypic diversity is generated through interactions among genetic variants, DNA methylation states, and both biotic and abiotic environmental stresses. My current work focuses on genetic variation for the stability of pathogen-induced changes in DNA methylation in the model plant Arabidopsis thaliana. Differences among plant genotypes in this aspect of epigenomic response are likely critical in determining the influence of epigenomic variation on evolutionary trajectories.
The A. thaliana–Pseudomonas syringae model system provides an excellent framework for addressing these issues. Recent research in this system has demonstrated that pathogen-induced changes in DNA methylation patterns play an important role in the plant immune response. There is also evidence in this system that offspring of infected plants can be transgenerationally “primed” for a quicker, more effective response to pathogen attack. However, it remains unclear how long pathogen-induced methylation changes persist, if these changes underlie transgenerational priming, and if natural plant genotypes vary in the stability of induced methylation changes. I am addressing these questions by examining the DNA methylomes of a diverse sample of A. thaliana genotypes experimentally infected with P. syringae across multiple generations.
Publications
Karasov, T., E. Chae, J.J. Herman, and J. Bergelson. 2017. Mechanisms to mitigate the tradeoff between growth and defense. The Plant Cell. doi: 10.1105/tpc.16.00931.
Herman, J.J. and S.E. Sultan. 2016. DNA methylation mediates genetic variation for adaptive transgenerational plasticity. Proceedings of the Royal Society Series B. doi
Herman, J.J., H.G. Spencer, K. Donohue, and S.E. Sultan. 2014. How stable ‘should’ epigenetic modifications be? Insights from adaptive plasticity and bet hedging. Evolution 68-3:632-643. doi: 10.1111/evo.12324. Faculty of 1000 Recommended Article.
Herman, J.J., S.E. Sultan, T. Horgan-Kobelski, and C. Riggs. 2012. Adaptive transgenerational plasticity in an annual plant: Grandparental and parental drought stress enhance seedling performance in dry soil. Integrative and Comparative Biology 52: 31-42. doi:10.1093/icb/ics041.
Herman, J.J. and S.E. Sultan. 2011. Adaptive transgenerational plasticity in plants: case studies, mechanisms, and implications for natural populations. Frontiers in Plant Science 2:102. doi: 10.3389/fpls.2011.00102.
Dillon, R.T. and J.J. Herman. 2009. Genetics, shell morphology, and life history of the freshwater pulmonate limpets Ferrissia rivularis and Ferrissia fragilis. Journal of Freshwater Ecology 24: 261-271. doi: 10.1080/02705060.2009.9664291.
Herman, J.J. and S.E. Sultan. In prep. Environmental stresses induce adaptive phenotypic plasticity and genotype-specific changes in DNA methylation in an annual plant.