Paper · 2013 · UA Campus Repository (The University of Arizona)

A Numerical Study of Pattern Forming Fronts in Phyllotaxis

Matthew Pennybacker

6
claims
12
verbatim quotes
2
citations
3
research areas
—
Not open access

Abstract

Using a partial differential equation model derived from the ideas of the Meyerowitz and Traas groups on the role of the growth hormone auxin and those of Green and his group on the role compressive stresses can play in plants, we demonstrate how all features of spiral phyllotaxis can be recovered by the passage of a pushed pattern forming front. The front is generated primarily by a PIN1 mediated instability of a uniform auxin concentration and leaves in its wake an auxin fluctuation field at whose maxima new primordia are assumed to be initiated. Because it propagates through a slowly changing metric, the patterns have to make transitions between spirals enumerated by decreasing parastichy numbers. The point configurations of maxima coincide almost exactly with those configurations generated by the use of discrete algorithms based on optimal packing ideas which suggests that pushed pattern forming fronts may be a general mechanism by which natural organisms can follow optimal strategies. We also describe in detail a numerical method that is used to efficiently and accurately integrate the model equations while preserving the variational structure from which they are derived.

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Claims 6

Method / resourceobservedoriginal resultpositivesimulated

Claim · model-written summary

The pushed-front model reproduced all features of spiral phyllotaxis.

Taxon
plantsViridiplantaee1
Outcome
all features of spiral phyllotaxise0
Comparator
pushed pattern forming fronte0

Verbatim

e0

“all features of spiral phyllotaxis can be recovered by the passage of a pushed pattern forming front”

✓ located verbatim in the source · abstract, characters 247–347 · show in text ↑
e1

“in plants”

✓ located verbatim in the source · abstract, characters 217–226 · show in text ↑
Mechanismauthor interpretationoriginal resultsimulated

Claim · model-written summary

A PIN1-mediated instability of uniform auxin concentration primarily generated the front.

Taxon
plantsViridiplantaee1
Gene
PIN1e0
Outcome
front is generatede0
Qualifier
instability of a uniform auxin concentratione0

Verbatim

e0

“The front is generated primarily by a PIN1 mediated instability of a uniform auxin concentration”

✓ located verbatim in the source · abstract, characters 349–445 · show in text ↑
e1

“in plants”

✓ located verbatim in the source · abstract, characters 217–226 · show in text ↑
Mechanismhypothesisoriginal resultsimulated

Claim · model-written summary

Modelled auxin fluctuation maxima were assumed to initiate new primordia.

Taxon
plantsViridiplantaee1
Outcome
new primordia are assumed to be initiatede0
Qualifier
auxin fluctuation field at whose maximae0

Verbatim

e0

“an auxin fluctuation field at whose maxima new primordia are assumed to be initiated”

✓ located verbatim in the source · abstract, characters 469–553 · show in text ↑
e1

“in plants”

✓ located verbatim in the source · abstract, characters 217–226 · show in text ↑
Mechanismobservedoriginal resultsimulated

Claim · model-written summary

Slowly changing metric forced transitions between spirals with decreasing parastichy numbers.

Taxon
plantsViridiplantaee1
Outcome
transitions between spirals enumerated by decreasing parastichy numberse0
Qualifier
slowly changing metrice0

Verbatim

e0

“Because it propagates through a slowly changing metric, the patterns have to make transitions between spirals enumerated by decreasing parastichy numbers”

✓ located verbatim in the source · abstract, characters 555–708 · show in text ↑
e1

“in plants”

✓ located verbatim in the source · abstract, characters 217–226 · show in text ↑
Method / resourceobservedoriginal resultpositivesimulated

Claim · model-written summary

Front maxima configurations almost exactly coincided with discrete optimal-packing algorithm configurations.

Taxon
plantsViridiplantaee1
Outcome
point configurations of maxima coincide almost exactlye0
Comparator
configurations generated by the use of discrete algorithmse0

Verbatim

e0

“point configurations of maxima coincide almost exactly with those configurations generated by the use of discrete algorithms based on optimal packing ideas”

✓ located verbatim in the source · abstract, characters 714–869 · show in text ↑
e1

“in plants”

✓ located verbatim in the source · abstract, characters 217–226 · show in text ↑
Method / resourceobservedoriginal resultpositivebasis n/a

Claim · model-written summary

The authors described a numerical integration method that preserves the equations’ variational structure.

Taxon
plantsViridiplantaee1
Outcome
efficiently and accurately integrate the model equationse0
Comparator
variational structuree0

Verbatim

e0

“a numerical method that is used to efficiently and accurately integrate the model equations while preserving the variational structure from which they are derived”

✓ located verbatim in the source · abstract, characters 1032–1194 · show in text ↑
e1

“in plants”

✓ located verbatim in the source · abstract, characters 217–226 · show in text ↑