Imaging Ca 2+ Dynamics in Wild-Type and NADPH Oxidase-Deficient Mutant Pollen Tubes with Yellow Cameleon and Confocal Laser Scanning Microscopy.

While cytosolic calcium (Ca) plays a central role in a myriad of signaling pathways as a secondary messenger, how dynamic changes of cytosolic calcium relate to cell growth control remains poorly understood. The engineering and continuous improvements of genetically encoded calcium sensors such as the Yellow Cameleon (YC) sensors combined with advances in microscopy have allowed imaging with great resolution of the spatiotemporal characteristics of cytosolic [Ca] in individual cells. An exciting new step consists therefore in cautiously studying calcium dynamics in mutant backgrounds that display disturbed cellular growth behavior to further enhance our understanding on growth-related processes. Here, we describe methods to perform imaging of [Ca] dynamics in growing Arabidopsis thaliana wild-type and NADPH-oxidase deficient rbohH rbohJ pollen tubes stably expressing YC3.6 using confocal laser scanning microscopy. We also present different ways to extract meaningful qualitative and quantitative information about calcium dynamics during growth.