Friday, March 30, 2018 at 12:20pm
Graduate Student, Roeder Lab, Plant Biology, Cornell University
Ploidy and size phenomena have been correlated across several biological scales, from subcellular to organismal. My thesis work quantifies nuclear size, cell size, and organ size in the Arabidopsis sepal to measure scaling relationships between ploidy and size. Our early experiments describe endopolyploidy (developmentally programmed ploidy change in individual cells); later experiments use an isogenic series of plants that are diploid, tetraploid, and octoploid to investigate the size effects of a change in “base” ploidy level. Highlights of our findings include:
-Altering the level of endoreduplication does not affect organ size.
-Cell area increases linearly with ploidy in polyploid plants, but organ area increases more modestly due to a compensatory decrease in cell number. This decrease arises late in development.
-A fixed karyoplasmic ratio describes the relationship between nuclear size and cell size, but cell size is not directly dependent on nuclear size.
These results shed light on how size is regulated in plants and how cells and organisms of differing sizes are generated by ploidy change.