Researcher ORCID Identifier

Graduation Year


Document Type

Campus Only Senior Thesis

Degree Name

Bachelor of Arts



Reader 1

Findley Finseth

Reader 2

Suryatapa Jha

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Terms of Use for work posted in Scholarship@Claremont.

Rights Information

© 2023 Lauren M McAllister


Epidermal petal cells are predominantly conical across numerous plant species, representing a distinct morphology rarely found in any other plant tissue. This conical cell shape plays an important role in plant-pollinator interactions. In Mimulus, several transitions from bee-pollination to self-pollination are accompanied by flatter epidermal petal cells. Mutants with less elaborate conical epidermal petal cells have been discovered, however, the genetic basis for epidermal conical cell shape has not been confirmed. Furthermore, the mechanisms behind the loss of conicality observed in transitions to self-pollination are unknown. The R2R3 MYB Subgroup 9A gene family is strongly associated with differentiation in epidermal cells and presents potential gene candidates. QTL mapping of a Mimulus cardinalis-Mimulus parishii RIL population strongly indicates GUIDELESS, MYBML1, and MYBML3 as candidate genes for governing epidermal petal cell shape. A gene tree analysis suggests GUIDELESS as the closest candidate to R2R3 MYB Subgroup 9A genes, reinforcing its significance. Evolutionary tests and analysis for loss-of-function mutations do not conclusively explain the mechanisms behind loss of conicality during transitions to self-pollination. However, analyses of amino acid sequences in M. lewisii, M. cardinalis, and M. parishii indicate several potential sites for loss-of-function mutations in M. parishii. In conclusion, this work reinforces the role of GUIDELESS in governing epidermal petal cell shape and opens avenues for understanding epidermal petal cell shape and the loss of conicality during transitions to self-pollination.

Available for download on Thursday, January 01, 2026

This thesis is restricted to the Claremont Colleges current faculty, students, and staff.