Molly Cadle-Davidson
Molly Cadle-Davidson Chief Science Officer, ABM

Molly Cadle-Davidson first started with ABM as a consultant in 2013, but it wasn’t long before she was working full time as assistant chief scientific officer in January 2014. Now as chief science officer, she works to enhance ABM genomics strategies and to foster next-generation product development. Cadle-Davidson is an expert in the field of genetics and is well versed in the application of genomics and next-generation sequencing techniques for trait-based research and development. Prior to joining ABM, she was involved in government work with SRC, Inc. and aided other government-funded programs with the Departments of Homeland Security, State, Defense and Justice. While at SRC, Inc., her work resulted in one trade secret, two patents pending and one patent application currently being prepared for the company. Cadle-Davidson holds a Bachelor of Science in genetics from the University of California, as well as a Master of Science in plant pathology from Washington State University and a doctorate in plant breeding and genetics from Cornell University.

There are three primary effects that biologicals have on plants: communication between the plant and the microbe, changes in plant gene expression and physiological changes.

One thing we’ve learned is that different microbial organisms communicate differently. For example, there’s a plant root growing through the soil: When it needs nitrogen, it releases a chemical signal into the soil, and if Bradyrhizobium is present, it will migrate to the plant. Once in the rhizosphere, the Bradyrhizobium releases a signal, causing the plant to curl a root hair around the Bradyrhizobium. This is the beginning of the nodulation process to make nitrogen.

This is just one of many communication mechanisms between plants and microbials. In the case of Trichoderma, it emits signals to plant roots, which then trigger changes in gene expression in the plant. The gene expression relies on signaling cascades, meaning one change has a compound effect, triggering other key systems in the plant.

An example of how a plant might respond at the molecular level is changing its biochemical pathways. As the Trichoderma colonizes the roots, it sends a signal to the plant, telling it to upregulate whole biochemical pathways. One such pathway is the Reactive Oxygen Cycling pathway, which is what plants use to purge free radicals, or toxins, from their cells. If the plant can’t eliminate the toxins, DNA and protein can become damaged leading to decreased photosynthesis and yield.

Reactive oxygen species also cause damage in human systems; however, we can take vitamins and consume high antioxidant foods, such as dark chocolate and red wine, to rid us of these toxins. The difference is that plants can’t take vitamins and instead use their own biochemistry to convert these free radicals to a harmless state.

By upregulating the biochemical pathway, as in the example above, the plant cells are better able to mitigate stress, such has drought, high heat, disease and so on, thus enabling the plant to perform at its highest potential even in the presence of stress. While the effect of biologicals on plant performance appears simple, the colonization, signaling, and plant responses suggest a synergy that is elegant in its complexity.