Extended Data Fig. 10: The working model of MLO-mediated vesicle fusion of CNGC18 to the plasma membrane in response to ovular signals.

a, Model of the MLOs-mediated CNGC18-vesicle fusion through the syntaxin (SYP) and VAMP to the plasma membrane site where the ovular signals are sensed. b, Model of pollen tube response to the ovule. In the wild-type, perception of ovular signals and MLO5/9/15-mediated CNGC18 recruitment to the direction of ovular signals, which is necessary for Ca²⁺ shift, are coupled to facilitate directional growth. In mlo5/9/15 pollen tubes, background Ca²⁺ gradient is maintained in the pollen tube tip, but lack of MLO5/9/15 causes failed shift of CNGC18 and Ca²⁺ gradient to the direction of ovule signals. But some machinery for ovular signal perception and pollen tube growth are still working. In this condition, the growth and the reorientation of pollen tubes are decoupled and the resulting two potential growth-points cause the pollen tubes grow forward and backward, and even turn in circles. c, The diagram of the pollen tube twisting phenotype of mlo5/9 and mlo5/9/15 mutants.