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SUMMARY:The Wolffia effect: from biological to physical anchoring — meni
 scus engineering in a rootless duckweed
DTSTART;VALUE=DATE-TIME:20260930T101500Z
DTEND;VALUE=DATE-TIME:20260930T103000Z
DTSTAMP;VALUE=DATE-TIME:20260916T130451Z
UID:indico-contribution-2918@cern.ch
DESCRIPTION:Speakers: Leone Ermes Romano (University of Naples Federico II
 )\nThe transition from land to water in Lemnaceae represents an extreme ca
 se of reductive evolution\, culminating in the minute\, rootless genus Wol
 ffia. Aerenchyma explains buoyancy\, but not how microscopic fronds remain
  upright\, avoid rolling\, and aggregate into cohesive colonies without an
 y biological anchor. We addressed this in Wolffia globosa combining micros
 copy\, surface metrology\, histochemistry and mathematical modelling.\n\nH
 igh-magnification and laser imaging revealed that the waterline around eac
 h frond is not flat: reflective points along the perimeter mark localised 
 deformations of the air–water interface\, while ESEM excluded any anatom
 ical protrusion. Laser scanning profilometry showed alternating upward and
  downward menisci\, with a bimodal distribution of contact angles (θup = 
 78.0 ± 3.0°\, θdown = 96.1 ± 2.2°\; n = 68). Neutral Red histochemist
 ry mapped a matching wettability pattern: an undulated contact line betwee
 n the unstained hydrophobic dorsal epidermis and the stained hydrophilic v
 entral one. Removing surface tension with a surfactant abolished the menis
 ci and submerged the plants\, showing that aerenchyma provides buoyancy wh
 ile surface tension provides anchoring and orientation.\n\nA finite-elemen
 t model parameterised on these values reproduces the observed multipolar c
 apillary field and predicts a short-range (<0.4 mm) attractive force betwe
 en neighbouring fronds — the "Cheerios effect" — sufficient to drive p
 assive self-assembly into stable rafts.\n\nWe propose that biologically pa
 tterned epidermal wettability functionally replaces the root system lost i
 n derived Lemnaceae\, with implications for colony dynamics\, mat behaviou
 r in cultivation systems\, and bio-inspired interfacial engineering.\n\nht
 tps://indico.unina.it/event/117/contributions/2918/
LOCATION:Department of Agricultural Sciences of the University of Napoli F
 ederico II\, Portici\, Italy Sala Cinese
URL:https://indico.unina.it/event/117/contributions/2918/
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