In Vitro Study of Oscillatory Growth Dynamics of Camellia Pollen Tubes in Microfluidic Environment

A hallmark of tip-growing cells such as pollen tubes and fungal hyphae is their oscillatory growth dynamics. The multiple aspects of this behavior have been studied to identify the regulatory mechanisms that drive the growth in walled cells. However, the limited temporal and spatial resolution of data acquisition has hitherto prevented more detailed analysis of this growth behavior. To meet this challenge, we employed a microfluidic device that is able to trap pollen grains and to direct the growth of pollen tubes along microchannels filled with liquid growth medium. This enabled us to observe the growth behavior of Camellia pollen tubes without the use of the stabilizer agarose and without risking displacement of the cell during time lapse imaging. Using an acquisition interval of 0.5 s, we demonstrate the existence of primary and secondary peak frequencies in the growth dynamics. The effect of sucrose concentration on the growth dynamics was studied through the shift in these peak frequencies indicating the pollen tube's ability to modulate its growth activity.