Plant Development and Regeneration
What gives plants their remarkable capacity to regenerate whole organs? Plants grow indeterminately in adulthood through the activity of their meristems, which contain initials, or stem cells, that constantly replenish cells for continual organogenesis. We employ a regeneration system in which we completely excise most of the root meristem, including stem cells. The root then regenerates the entire meristem and resumes normal growth. We use this system to ask basic questions about the establishment of tissue organization long after embryogenesis is complete. We combine live imaging of regenerating roots with single-cell RNA-Seq analysis to coordinate the timing of events at the microscopic and molecular level, at the resolution of the single cell.
Algal Evolution Using Fluorescent Properties
Algal cultivation is a promising system for biofuels but, unlike agricultural cultivars, algae have not been adapted for human production systems. We use Fluorescence Activated Cell Sorting (FACS) to apply selective forces on algal populations to target very specific traits for biofuel improvement. We have adapted protocols that make use of fluorescent dyes or fluorescent properties of algae and can be used as readouts for specific traits. We select traits over multiple generations, similar to the domestication of crops in which repeated selection over many generations led to highly specialized agricultural crops. Here we optimize biofuel traits such as growth and oil accumulation using the algae/FACS system.
Evolution of Plant Roots
How did plant roots and the special cell types they contain evolve? The seedless vascular plant Selaginella is in a plant lineage whose ancestors appear to have branched off early in the evolution of land plants. This group of plants, the lycophytes, is the first to display a true root. It’s not clear that the Selaginella root is homologous to the roots of flowering plants. However, they share a remarkably similar structure, with a root cap, root hairs, endodermis, and auxin-triggered development. One striking difference is that most Selaginella roots in the mature organism arise from shoot structures, leading to a long-standing debate over whether the early outgrowth – called a rhizophore – is root- or shoot-like. We have employed transcriptional analysis of all Selaginella meristems in a global comparison of the similarity between the rhizophore transcriptome the embryonic root or the early shoot structure.