Most flowering land plants employ the canonical C3 mode of photosynthetic carbon assimilation. However, during the past 60 million years, variations in C3 photosynthesis, C4 photosynthesis, and C3-C4 photosynthesis have evolved frequently and independently, ~70 times. The majority of C4 plant species display a distinct Kranz leaf-anatomy and co-evolved metabolic and biochemical features that are not encountered in C3 plants. In C4, primary fixation of CO2 is spatially separated from carbon assimilation and reduction by the Calvin Benson Cycle. The work employs comparative pangenomics and synthetic biology to address aspects of the evolutionary transition from C3 to C4 and further examines the long-term implications of this evolution for global photosynthesis and climate change.
We host five endowed lectures throughout the academic year. Endowed lectures are paid for with private funds invested and held by the Regents of the University.
The Daniel I. Arnon Lecture was established with resources from the Charles F. Kettering Foundation. The endowment also supports graduate students who are designated Arnon Fellows.
The Bob B. Buchanan and Harry Tsujimoto Lectures were established with a generous gift from the K/T (Kase/Tsujimoto) Foundation of San Francisco. The endowment also supports graduate students who are designated "Kase Fellows".
The Taylor-White Lecture is a unique collaboration between Tom White, an entrepreneur, and John Taylor, a professor in the department. Together they performed research and published papers.
The Kustu Lecture is supported by donations from students, faculty and staff who worked with Sydney Kustu, a professor in the department.
Upcoming PMB Endowed Lectures
For a schedule of all Plant & Microbial Biology events, seminars, and lectures visit our calendar.
Kustu Memorial Lecture: Fun Times with Fungi: What the Clock of a Fungus can Teach Us about the Importance of a Healthy Circadian Rhythm
Circadian rhythms are highly conserved, 24-hour, oscillations that tune physiology to the day/night cycle, enhancing fitness by ensuring that appropriate activities occur at biologically advantageous times. Circadian rhythms are a phenomenon that exist across the tree of life and throughout biological scales, with broadly conserved atomic-level timekeepers enhancing fitness at the organismal level. Chronic disruption of proper circadian synchronization negatively impacts organisms throughout the kingdom of life, from disrupting metabolic networks in fungi to increasing the risk for Alzheimer’s disease and Related Dementias (ADRD) in humans. The paradigm for circadian regulation over physiology was that transcriptional programing via a transcription-translation based negative feedback loop (TTFL), or “clock”, drives temporally specific waves of gene expression to time cellular processes. However, using systems biological approaches in fungi, we have demonstrated that transcriptional programing from the TTFL cannot completely account for cellular circadian regulation. Our work has also begun to demonstrate the proteins involved in the repressive arm of the TTFL, enabled by their regions of protein disorder, act as “hub” proteins for the formation of large macromolecular complexes to impart circadian post-transcriptional regulation. Finally, we have used systems biology approaches to show that circadian post-transcriptional regulation tightly controls metabolism, affecting both fungal physiology and the mammalian immune response, the disruption of which increases the severity of ADRD symptoms. Our across-scales approach to studying circadian rhythms using fungi elucidates the fundamental principles of circadian timing, revealing the mechanisms of circadian control over molecular, cellular, and organismal physiology.
Past Endowed Lectures
Tsujimoto Lecture: Changing Paradigms in Natural Product Discovery: A Molecule to Microbe Approach
Microbial natural products remain an important source of lead compounds for drug discovery. Traditional approaches to microbial natural product discovery take a microbe first approach in which individual strains are cultured in the lab and bioassays used to guide the isolation of active compounds. While once productive, the limitations to this approach are now well documented and include the recognition that only a small percentage of the bacteria present in the environment are readily obtained in culture. We have developed a new approach to microbial natural product discovery in which compounds are isolated directly from the environments in which they are produced thus bypassing the initial need for laboratory cultivation. This culture independent approach, which we call Small Molecule In Situ Resin Capture (SMIRC), is agnostic to the biological source of the compounds and requires no up-front knowledge of cultivation requirements or the cues needed to induce biosynthesis. Initial SMIRC deployments have yielded extensive, biome specific chemical diversity including compounds previously reported from marine plants, invertebrates, and bacteria. Mining compounds that could not be identified has yielded unprecedented carbon skeletons and demonstrated that sufficient yields can be obtained for bioactivity testing and NMR-based structure elucidation. These results suggest a path forward to access new chemical space for drug discovery and to address the ecological functions of marine natural products.
Buchanan Lecture: How Plants do the Twist: An Interdisciplinary Approach to Elucidate the Evolution and Development of Climbing Plants
One of the most striking, yet poorly understood, forms of plant movement is the climbing capacities of woody vines, also known as "lianas". These plants weave through the forest, attaching to host branches as they grow towards light at the top of the canopy. Surprisingly, this complex and unusual phenotype has independently evolved in at least one-third of vascular plant families and can represent upwards of 40% of the leaf area in tropical forests. Thus, the ability to climb is a strategic lifeform in the evolution of plants to compete for light. Despite the evolutionary and ecological significant of lianas, we still lack an understanding of how plants evolved to climb.
In this talk, I will present a multi-scaled approach to elucidate the evolution and development (evo-devo) of cells and phylogenetics, developmental anatomy, comparative transcriptomics, to cell wall biology. I begin by discussing the role of "vascular variants" i.e., aberrations in the distribution and abundance of vascular tissues, in the large neotropical liana tribe, Paullinieae (Sapindaceae). I will conclude by discussing our ongoing efforts to elucidate the developmental mechanism underlying twining motion of common bean vines, through hormonal perturbation, RNA seq, and our efforts to understand the link between microtubule orientation and whole-form architecture.
Kustu Lecture: Leveraging human population biology to dissect the immunopathogenesis of tuberculosis
Mycobacterium tuberculosis is an obligate human pathogen. However, our understanding of the MTB biology in humans is limited by the difficulty of accessing the sites of infection. Bacterial population genetics provides mechanistic insights into the biology of MTB in people. We have leveraged MTB population genetics to identify genes that are evolving to increase the bacterium’s ability to survive drug pressure. This analysis has revealed a novel regulatory circuit governing the integration of chromosomal replication and cell division. Genetic variation in the circuit components alters cell cycle and the ability to restart growth after antibiotic stress.
Arnon Lecture: Photoprotection of photosynthesis through cyclic electron transport in chloroplasts
Cyclic electron transport around photosystem-I, and the associated cyclic photophosphorylation process in chloroplasts is enabled by two pathways, which depend on the PGR5 protein and the chloroplast NADH dehydrogenase-like complex, respectively. When both pathways are defective, photosynthesis and plant growth are significantly impaired. The pgr5 mutant of Arabidopsis is particularly sensitive to fluctuations in light intensity, which can lead to photodamage of photosystem-I. The lecture will discuss the molecular mechanism of the photoprotection of photosystem-I, afforded by this cyclic electron transport process.
[Tsujimoto Lecture] Phenomics of Stomata and Water Use Efficiency in C4 crops
The Leakey group takes an integrative approach to understanding and improving the water use efficiency of C4 grasses. The talk will highlight recent work in physiology, genomics, genetics, agronomy that exploits new AI-enabled phenotyping techniques.