Biological Sciences Colloquium: Xiaosa Jack Xu

Dr. Xiaosa Jack Xu, Professor of Plant Biology at University of California Davis, will be presenting a talk about his work entitled “An Evolutionary View of Plant Inflorescence Development from Single-Cell and Spatial Profiling.”  The abstract is as follows:

Inflorescence architecture is a major determinant of reproductive success and crop yield, yet how its developmental regulation evolves across phylogenetic scales remains incompletely understood. Here, we integrate single-cell transcriptomics, spatial gene expression, and gene editing to examine inflorescence development across three hierarchical evolutionary levels: a deep comparison between monocots and eudicots, a closer comparison within cereal monocots, and a near-scale comparison between maize and its wild progenitor, teosinte.

At the broadest scale, we generated a comparative single-cell atlas of developing inflorescences in Arabidopsis and maize. This analysis recovered thousands of stem cells marked by CLAVATA3 and WUSCHEL and uncovered conserved stem cell regulators, including members of the SERPINE1 mRNA-binding protein family, revealing deeply conserved mechanisms underlying shoot meristem maintenance across monocots and eudicots.

At an intermediate scale, we performed an integrative analysis of single-cell transcriptomes from developing inflorescences of five cereal crops: maize, wheat, barley, rice, and sorghum. We identified shared cell populations and resolved distinct meristem subdomains, revealing a conserved core of meristematic cell identities and regulatory programs, alongside divergence in transcriptional programs associated with lateral organ initiation and differentiation that likely underlie species-specific cereal inflorescence architectures.

At the closest scale, we constructed a single-cell atlas of developing teosinte ears and compared it with maize to investigate domestication-associated changes in ear development. We identified cell-type-specific differentially expressed genes in inflorescence stem cells and axillary meristem-initiating cells, many showing signatures of selection during domestication. Higher-order mutants in SPL, UB2, UB3, TSH4, and GLUTAREDOXIN genes reverted ear morphology toward teosinte-like forms.

The presentation will begin at 3:00 PM in Lapham Hall N101, preceded by an informal reception from 2:45 – 3:00PM.