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Diamanda Zizis

What happens when you cross plant species with two distinct sexual systems? An ex situ hybridization approach

Diamanda Zizis ’23

Faculty Mentor(s):
Dr. Chris Martine, Biology
Dr. Tanisha Williams, Biology
Funding Source:
The Presidential Fellowship and the David Burpee Endowment

The transitions from the hermaphroditic sexual system to the andromonoecious and dioecious sexual systems have been an area of intrigue in biology since Darwin’s time. While the vast majority of angiosperms display the hermaphroditic sexual system, both dioecy and andromonoecy are observed in Australian Solanum, in addition to hermaphroditism. Australian Solanum are therefore particularly useful for understanding the evolution of these sexual systems. Hybrid offspring of Solanum dioicum (dioecious) and Solanum ultraspinosum (andromonoecious) crosses were used to study hybridization boundaries within the two different sexual systems. Our main goal was to understand how the differing sexual systems manifest in hybrids, especially relative to their role as the pollen donor and pollen recipient. Morphometric analyses currently indicate that the pollen recipient exhibits the greatest influence on morphology in the F1 generation. In hybrids with S. ultraspinosum acting as the pollen donor, the andromonoecious breeding system manifested, indicated most importantly by the architecture of the inflorescence and the absence of inaperturate pollen in hermaphroditic flowers. The F1 generation was unsuccessful with S. dioicum acting as the pollen recipient. With the F1 generation appearing so similar to the pollen recipient, it is not yet possible to recognize early-generation hybrids, although hybridization is occurring. We are currently continuing crosses between the F1 generation hybrids to observe whether the pollen donor may have effects on hybrids in less immediate generations, particularly looking for whether inaperturate pollen will manifest, indicating changes in the sexual system incurred from the pollen donor.

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