Geometric and mechanical guidance: Role of stigmatic epidermis in early pollen tube pathfinding in arabidopsis
Fig 3
Papilla prototypes and pollen tube trajectories without guidance on WT and ktn1-5 papillae.
(A) Three dimensional shapes of WT and ktn1-5 papillae. The papilla long axis is oriented along the z axis. z = 0 corresponds to the papilla pole. Scale bar = 10 m. (B) Three-dimensional view of the top region of a ktn1-5 papilla showing the initial position of the pollen grain (z0, red dot) and the initial direction of the pollen tube upon emergence from the grain (
, red arrow). The vector
represents a papilla surface tangent vector pointing in the longitudinal direction.
(
) indicates an initial tube direction towards the papilla base (pole). Scale bar = 10
m. (C) Examples of simulated pollen tube trajectories on ktn1-5 papilla surfaces, varying in initial positions z0 of the pollen grain and initial directions
of the emerging pollen tube (indicated by black arrows). The numbers in brackets denote the normalized initial positions (
) and the initial directions (
) for each trajectory. T (below each papilla) represents the number of turns the pollen tube makes to reach the papilla base . Each configuration is labelled from a to h. Trajectories on WT stigma with identical initial conditions are shown in S2 Fig. (D) Morphological phase diagrams of the pollen tube turn number T depending on the initial pollen grain position z0 (normalised to the papilla distance head length
) and the initial pollen tube direction (
) on WT and ktn1-5 papillae.
denotes the papilla pole,
the frontier between the head and cylindrical shaft, and
the pollen grain landing limit. The colour code indicates the number of turns the trajectories undergoes before it reaches the papilla base. In the white region (caged), the tube path is trapped by its own trajectory, preventing it from reaching the papilla base; such trajectories were categorised as having T>2.5. The letters a to h correspond to the example configurations depicted in (C). (E) Comparison of simulated (solid lines) and experimental (squares) cumulative distributions of pollen tube turn numbers. To calculate the cumulative fraction for experimental data, we utilized data from Ref [6], where we examined 251 WT and 327 ktn1-5 pollinated papillae; error bars represent the standard error of the mean. The label ktn1 refers to the ktn1-5 mutant.