Calcium imaging in Arabidopsis pollen cells using G‐CaMP5

Calcium (Ca 2+ ) signaling has been implicated in pollen germination and pollen tube growth. To date, however, we still know very little about how exactly Ca 2+ signaling links to various physiological subcellular processes during pollen germination and pollen tube growth. Given that Ca 2+ signaling is tightly related to the cytosolic concentration and dynamics of Ca 2+ , it is vital to trace the dynamic changes in Ca 2+ levels in order to decode Ca 2+ signaling. Here, we demonstrate that G‐CaMP5 serves well as an indicator for monitoring cytosolic Ca 2+ dynamics in pollen cells. Using this probe, we show that cytosolic Ca 2+ changes dramatically during pollen germination, and, as reported previously, Ca 2+ forms a tip‐focused gradient in the pollen tube and undergoes oscillation in the tip region during pollen tube growth. In particular, using G‐CaMP5 allowed us to capture the dynamic changes in the cytosolic Ca 2+ concentration ([Ca 2+ ] cyt ) in pollen tubes in response to various exogenous treatments. Our data suggest that G‐CaMP5 is a suitable probe for monitoring the dynamics of [Ca 2+ ] cyt in pollen cells.