Comparing In Vivo and In Vitro Pollen Tube Attraction Assays for Arabidopsis and Maize

Pollen tube attraction is a crucial step in the reproduction of angiosperms, ensuring that the male gametophytes, which carry two sperm cells, accurately target the compatible female gametophytes, or embryo sacs, in order to achieve double fertilization. Various experimental systems have been developed to study this process in vivo and in vitro, particularly in the model plant Arabidopsis thaliana (Arabidopsis). However, fewer methods have been described for other plant species, including grasses, which generate much thicker reproductive tissues and organs. Here, we present and compare optimized protocols for tracing individual pollen tubes in Arabidopsis, which are required, for example, for studies in which wild-type and mutant pollen tubes exhibit different growth speeds, as well as for studying maize pollen tube growth and for characterizing potential attraction molecules. Together, these protocols contribute to the necessary tools to investigate the conserved and divergent mechanisms of pollen tube attraction in both eudicot and monocot species, offering valuable insights into reproductive signaling pathways that are relevant to both basic biology and applied breeding.