The developmental biology of the Nepenthes pitcher trap rim

: a fully wettable, directional, antiadhesive plant surface

Abstract

The pitcher rim (peristome) of Nepenthes exhibits a highly specialised epidermal and cuticular
structure unlike that of typical leaves. In contrast to most aerial plant surfaces, the peristome is
highly wettable, a property governed by both its surface chemistry and microtopography. An
intricate arrangement of radial ridges and grooves enables water to spread rapidly across the
surface, forming a thin, stable film that facilitates insect capture through aquaplaning. While
this wetness-activated trapping mechanism has been extensively studied, the developmental
processes underlying peristome formation remain poorly understood. Here, I first used cryo
scanning electron microscopy to characterise morphological changes during pitcher rim
development. I showed that the complex peristome microtopography arises through a
coordinated sequence of common epidermal patterning processes, including oriented cell
divisions, papillate cell formation, and directional cell elongation. I then employed transmission
electron microscopy and targeted staining to investigate the development of the peristome
cuticle, revealing that both its ontogeny and structure differ markedly from those of a typical
leaf cuticle. Given that papillate cell formation, cell elongation, and cuticle biosynthesis are
well characterised and often governed by conserved genetic pathways, I hypothesised that
Nepenthes achieves its unique surface properties by redeploying common genetic components
in novel combinations. To test this, I analysed gene expression patterns across key stages of
peristome morphogenesis and identified candidate regulators associated with papillate cell
differentiation, anisotropic growth, and cuticle modification. Together, these findings establish a
combined microscopic and molecular framework for understanding how Nepenthes transforms
a typical leaf epidermis into a highly specialised, superhydrophilic surface adapted for prey
capture.

Date of Award	17 Mar 2026
Original language	English
Awarding Institution	University of Bristol
Supervisor	Ulrike Bauer (Supervisor) & Heather M Whitney (Supervisor)