Analysis of the impacts of cellular dynamics on floral size in Nicotiana polyploids of different ages

Authors: Edie Russo, Elizabeth McCarthy, Timothy McGrath, Brooke Tillotson

SUNY Campus: SUNY Cortland

Presentation Type: Poster

Location: Old Union Hall

Presentation #: 16

Timeslot: Session A 9:00-10:00 AM

Abstract: Pollination depends on the size of the flower tube, ultimately determining what pollinator can approach. For example, pollinators must have longer tongues to reach nectar in longer tubes. Flower tube size is dependent on the cellular dynamics that underlie tissue formation, referring to cell division and elongation. We expect cells to divide early on in floral development and to elongate later. To measure this, we look at cell length, width, and number across development to understand how cells are changing and ultimately impact flower size. Another factor we investigate is polyploidy. Polyploids have duplicated genomes; therefore, their cells may be larger than those of diploids to hold the additional genetic information, which may influence flower size. To study this, we compare ~4-million-year-old Nicotiana section Repandae polyploids, first-generation synthetic N. tabacum lines, and their diploid progenitors. We stain the flowers at different developmental timepoints (20%, 40%, 60%, 85%, 95%, and 100% of mature flower length) with acid fuchsin and image them under a microscope to measure cell length, width, and number. These measurements allow us to understand the role that polyploidy plays in floral size differences in Nicotiana polyploids of different ages. Surprisingly, our preliminary results show that the older polyploids do not have larger cells than their diploid progenitors. It is known that genome sizes tend to decrease as polyploids age. We see a similar phenomenon with cell size as the polyploid age, suggesting that diploidization may occur at both the genomic and phenotypic levels.