Today the Wagner Lab celebrates a hello and a farewell. The Wagner lab undergraduate researcher Renee Hastings has graduated and is off to graduate school at Stanford to continue her studies in Biophysics! Meanwhile, we also welcome Dr. Min Wang of whom traveled to our lab all the way from the University of Chinese Academy of Sciences in Beijing, China! We ate delicious Chinese food on a handsome day in Philly as we look forward to the future research of these talented women.
Zhu, Y., & Wagner, D. (2020). Plant inflorescence architecture: the formation, activity, and fate of axillary meristems. Cold Spring Harbor perspectives in biology, 12(1), a034652.
The above-ground plant body in different plant species can have very distinct forms or architectures that arise by recurrent redeployment of a finite set of building blocks—leaves with axillary meristems, stems or branches, and flowers. The unique architectures of plant inflorescences in different plant families and species, on which this review focuses, determine the reproductive success and yield of wild and cultivated plants. Major contributors to the inflorescence architecture are the activity and developmental trajectories adopted by axillary meristems, which determine the degree of branching and the number of flowers formed. Recent advances in genetic and molecular analyses in diverse flowering plants have uncovered both common regulatory principles and unique players and/or regulatory interactions that underlie inflorescence architecture. Modulating activity of these regulators has already led to yield increases in the field. Additional insight into the underlying regulatory interactions and principles will not only uncover how their rewiring resulted in altered plant form, but will also enhance efforts at optimizing plant architecture in desirable ways in crop species.
Arabidopsis floral meristems terminate after the carpel primordia arise. This is achieved through the timed repression of WUSCHEL (WUS), which is essential for stem cell maintenance. At floral stage 6, WUS is repressed by KNUCKLES (KNU), a repressor directly activated by AGAMOUS (AG). KNU was suggested to repress WUS through histone deacetylation. However, how the changes in the chromatin state of WUS are initiated and maintained to terminate the floral meristem remains elusive. Here, we show that KNU integrates initial transcriptional repression with polycomb-mediated stable silencing of WUS. After KNU is induced, it binds to the WUS promoter and causes eviction of SPLAYED (SYD), which is a known activator of WUS and can act in opposition to polycomb repression. KNU also physically interacts with FERTILIZATION-INDEPENDENT ENDOSPERM (FIE), a key PRC2 component, and mediates the subsequent deposition of the repressive histone H3 lysine 27 tri-methylation (H3K27me3) for stable silencing of WUS. This multi-step silencing of WUS leads to the termination of floral stem cells, ensuring proper carpel development. Thus, our work describes a detailed mechanism for heritable floral stem cell termination in a precise spatiotemporal manner.
This month the Wagner Lab celebrated Sammy’s and Run’s birthday. Sammy also presented some of her work for the Genomics and Computational Biology graduate program titled “Improving Resolution of Transcriptional Complex ChIP-Seq using Blacklisting in Arabidopsis“.
Dr. Doris Wagner is honored as a recipient of this year’s Fellow of American Society of Plant Biologists (ASBP) Award along side four other colleagues. The Fellow of ASPB Award was established in 2007 and is “granted in recognition of distinguished and long-term contributions to plant biology and service to the Society by current members in areas that include research, education, mentoring, outreach, and professional and public service.”
One of our favorite undergraduate students Renee Hastings turned 22 years of age! A song and scrumptious cake of all different flavors was served at lab meeting to celebrate!
Specification of new organs from transit amplifying cells is critical for higher eukaryote development. In plants, a central stem cell pool maintained by the pluripotency factor SHOOTMERISTEMLESS (STM), is surrounded by transit amplifying cells competent to respond to auxin hormone maxima by giving rise to new organs. Auxin triggers flower initiation through Auxin Response Factor (ARF) MONOPTEROS (MP) and recruitment of chromatin remodelers to activate genes promoting floral fate. The contribution of gene repression to reproductive primordium initiation is poorly understood. Here we show that downregulation of the STM pluripotency gene promotes initiation of flowers and uncover the mechanism for STM silencing. The ARFs ETTIN (ETT) and ARF4 promote organogenesis at the reproductive shoot apex in parallel with MP via histone-deacetylation mediated transcriptional silencing of STM. ETT and ARF4 directly repress STM, while MP acts indirectly, through its target FILAMENTOUS FLOWER (FIL). Our data suggest that – as in animals- downregulation of the pluripotency program is important for organogenesis in plants.
Beginning January 1, 2019, Dr. Doris Wagner along with Dr. Claudia Köhler have agreed to become Editors-in-Chief of the journal Current Opinion in Plant Biology.
The Biology Grad Student Extravaganza featured a host of lightening talks by first-year graduate students plus a keynote talk from this year’s Biology Retreat poster champion and Wagner Lab 5th-year graduate student, Run Jin. Her talk was titled: Identification of LEAFY, a plant transcription factor that determines floral cell fate, as pioneer transcription factor in Arabidopsis thaliana.