My research experiences have been quite broad, from dissecting signaling pathways in Arabidopsis to understanding whole plant phenotypes to abiotic stress in maize. However, all of my work generally involves studying how plant respond to their environment.
Past: Dissecting hormone signaling pathways in Arabidopsis
Despite years of studying auxin responses and signaling mechanisms, we still do not understand how many auxin responses are regulated. Multiple studies have suggested roles for mitogen‐activated protein kinase (MPK) signaling cascades in a variety of auxin‐related processes. My thesis research provided new insights into how auxin and kinases regulate growth and development in Arabidopsis. Mutants defective in the upstream MAP kinase kinase MKK3 or the MAP kinase MPK1 display hypersensitivity in auxin‐responsive cell expansion assays, suggesting that this MPK cascade affects auxin‐influenced cell expansion. I found that MPK1 interacts with and phosphorylates ROP BINDING PROTEIN KINASE 1 (RBK1), a protein kinase that interacts with members of the Rho‐like GTPases from Plants (ROP) small GTPase family. Mutants defective in RBK1 also display auxin hypersensitivity, consistent with a possible role for RBK1 downstream of MPK1 in influencing auxin‐responsive cell expansion. I found that RBK1 directly phosphorylates ROP4 and ROP6, supporting the possibility that RBK1 effects on auxin‐responsive cell expansion are mediated through phosphorylation‐dependent modulation of ROP activity. Our data suggest a MKK3 • MPK1 • RBK1 phosphorylation cascade that may provide a dynamic module for altering cell expansion.
My graduate work taught me how to use reverse genetics and molecular biology skills to increase understanding of complex signaling pathways. I am looking forward to using these skills in my future but wanted to gain a broader perspective during my postdoctoral work, and studying topics more directly applicable to increasing crop production in the face of a changing climate.
Present: Studying abiotic stress responses in maize
The yields of maize and other crops may be reduced substantially within the next century due to global climate change. Creating crop varieties that are resilient in the face of stress will be critical for providing a stable source of food for a growing population living on a changing planet. A main focus of my post-doctoral research has involved the use of new phenotyping technologies to monitor plant responses to temperature stress. I have developed a computer vision approach to enable the measurement of morphological traits in maize seedlings exposed to cold temperature stress. We have built a simple, affordable image acquisition system paired with custom image analysis software to phenotype plant seedlings in an easy and reproducible manner. By monitoring image-derived traits over time we can document a “phingerprint” of phenotypic responses to abiotic stress in diverse genotypes of maize, enabling approaches to map the genomic basis for this variation. I have also begun to use a new type of image generated by hyperspectral cameras. Rather than reporting only 3 values per pixel (RGB), hyperspectral cameras provide information on the reflectance of hundreds of wavelengths. This provides opportunities to “see” plant responses and variation that are not visible to the naked eye. I have gathered hyperspectral data for maize seedlings exposed to temperature stress to further probe the variability of responses in diverse genotypes and to provide early detection of stress responses prior to other manifestations.
In addition to imaging-based phenotypes, we are investigating molecular responses to temperature extremes using both transcriptomic and phosphoproteomic methods on a time series of samples, collected throughout our standard cold-stress assay we use for the image-based phenotyping experiments described above. These initial data sets will increase understanding of how both transcriptomes and phosphoproteomes of maize seedlings are impacted throughout our experiments and will help me narrow a focus for plant physiological assays in the future.
The combination of these diverse approaches will allow for a better understanding and characterization of the dynamics of responses of maize seedlings to temperature extremes. Integrating these data sets across genotypes and growth conditions will uncover the dynamics of maize responses to changing temperatures and allow for the discovery of genomic loci that could provide improved tolerance. Undergraduate students have been integral to the successful completion of many of these experiments, helping to care for the plants, take images, and analyze data.
Future: Vision for my future
These varied projects have given me expertise in many approaches, and reinforced my interest in signaling, genetics, and cell biology. In my future research career, I envision drawing on my past and current work to characterize how model plant species grow, develop, and respond to abiotic stress environments. I hope to utilize the high throughput image-based phenotyping and genomics skills I am developing during my postdoctoral work to propose hypothesis-driven questions I can answer using the reverse and forward genetics skills I learned during my graduate work to better understand plant stress biology and link traits to genes.