CAREER: Stable transformation of STEM identity by integrating cell cycle regulation with persistent infection in Agrobacterium

Rowan University, Glassboro NJ

Investigators

Abstract

This project will identify and detail relationships between how pathogenic plant-associated bacteria grow and develop throughout their life cycle, how they switch from associating with a host plant and being free-living in the soil, and pathogenesis. In particular, this project uses “nature’s genetic engineer,” Agrobacterium tumefaciens, as the model bacterium for study. Results from this project will be applied to increasing the efficiency of using this organism to genetically engineer and breed crops in a predictable, directed manner. Results from this project may also be applied to basic research questions involving genetic manipulation of a variety of plant species, providing a new set of tools for understanding the genomics and evolution of multiple plant species. Finally, results from this project may be applied to close relatives of Agrobacterium, some of which are involved in beneficial relationships with their hosts and some of which are potentially pathogenic to plants, livestock, and humans. This project provides education and outreach activities that emphasize solidifying the identity of students as scientists. These activities include incorporating research experiences into undergraduate coursework and supporting students and faculty from nearby colleges as summer research scientists in an active research lab. Both of these sets of activities will have participants performing hypothesis-driven experimental work in support of the research objectives of the project. The overall goal of this project is to detail the genetic framework governing cell cycle control in Agrobacterium tumefaciens and how cell cycle control is modulated in ecologically relevant contexts, contributing to persistent colonization. The central hypothesis tested in this work is that in Agrobacterium the PdhS-DivK-CtrA regulatory pathway is a central point of environmentally-responsive cell cycle regulation enabling efficient host colonization, niche construction, and pathogenesis. The first research objective will determine the molecular mechanism by which the PdhS sensor kinases coordinately regulate CtrA activity, specifically exploring the in vivo and in vitro interactions of protein components of this pathway. The second research objective will catalogue the full suite of genetic loci under CtrA transcriptional control using transcriptomics approaches. The third research objective will quantify the contribution of PdhS-DivK-CtrA pathway activity to niche construction and pathogenesis through competition assays during plant infection. The rationale for this project is that it will establish the validity of targeting cell cycle regulation to control plant colonization. This project will contribute to our understanding of the ecological significance of observed cell cycle changes during plant interactions in Agrobacterium and how such changes are effected. This work will expand our mechanistic understanding of cell cycle regulation in Agrobacterium, as well as how cell cycle control integrates with other phenotypes. This work will enable follow-on work in translational phytopathology, including development of new tools and targets for manipulation of interactions at the host plant-microbe interface. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.