Biology Department Seminar

William S. Hillman’s pioneering work on photoperiodism using Lemna, commonly known as duckweed, laid the foundation for modern genetic and molecular dissection of the circadian clock. Hillman’s now classic experiments using skeleton photoperiods demonstrated the existence of an internal, circadian clock that governs photoperiodic responses. This profound insight has subsequently been confirmed in organisms from all Kingdoms of life. My own research has focused on understanding how light, temperature, and the circadian clock interact at the level of transcription to control rhythmic changes in the biology of the model flowering plant Arabidopsis thaliana. Using whole genome DNA microarrays in Arabidopsis, poplar and rice, I have identified conserved, time-of-day-specific transcriptional networks. These networks ensure that critical biological functions such as growth occur at the correct time of day and provide plants with flexible responses to changing environmental conditions. Currently, I am extending these findings to other plant species some of which may play a role in increasing biomass for biofuel production. One organism with remarkable potential for biofuel feedstocks is Lemna. This somewhat obscure flowering plant has thus brought my research full circle back to the unique system that Hillman pioneered so many years ago. Lemna, and the duckweeds more generally, provide a versatile system for carbon sequestration and high biomass production at a very low input cost with the added benefit of waste water bioremediation. With the advent of Next Generation sequencing and genomics, we are now poised to exploit the wealth of knowledge gained through the pioneering work of scientists such as Hillman.