菊花頭狀花序開花模式

菊花頭狀花序開花模式

Phyllotactic patterning of gerbera flower heads

(corresponding to Fig. 7). Simulation of the patterning of bract and floret primordia on an expanding disk. The simulation is effected using Model 2 (the disk model), overlaid on the composite images of heads up to the 34-primordium stage. The decreasing radius of the circles that represent primordia reflects the decreasing threshold distance for the insertion of new primordia according to the Hofmeister / Snow & Snow rule. The model captures the differences in the radial position of primordia that become visible at the 21-primordium stage and are pronounced at the 34-primordium stage, as highlighted by the simulation pause. The continuing simulation captures the emergence of parastichies based on the template of bracts and the patterning of florets, which stops when the entire receptacle surface is consumed.

corresponding to Fig. 9E). A variant of phyllotactic patterning in gerbera heads (Movie 5). The active ring becomes transiently elliptic during the patterning of florets. In spite of the loss of circular symmetry leading to the occurrence of some dislocations (local departures from the mathematically ideal spiral phyllotaxis), the final pattern closely resembles that produced with the circular active ring.

Model validation. (A and B) Comparison of predicted and observed positions of DR5 maxima in the early patterning phase. (C–F) Comparison of predicted and observed intermediate patterning stages with circular (C and D) and elliptic (E and F) pattern fronts. Chl, chlorophyll. (G and H) Comparison of predicted (G) and observed (H) positions of the first 21 bracts on the lower side of a gerbera head. (I and J) Comparison of predicted (I) and measured (J) distances of bracts from the stem center. For the measured distances, mean values in a set of 12 heads (horizontal lines) and the standard errors (vertical bars) are shown. (K and L) Comparison of the simulated head (K) with the SEM of a real head (L). [Scale bars: 5 mm (H); 1 mm (L).]

Cites:

https://www.pnas.org/content/118/13/e2016304118?fbclid=IwAR3lQnMaXNNFatWzDhHrfEvJfufPzM8iR746HAJu5aDGSGPaeL8jB27Dnh4