Confocal imaging of the cell cycle and cytokinin signaling during gynoecium development in Arabidopsis.

In angiosperms, the gynoecium is the female reproductive structure, whose function is to contain the ovules and promote their fertilization. In Arabidopsis, the gynoecium develops from a small primordium with meristematic properties to a complex structure with internal and external specialized tissues. Due to its anatomical and developmental complexity, it is challenging to study in vivo the developmental processes of the gynoecium. Although efforts have been made, there are still unanswered questions, especially those related to cell proliferation of internal tissues. Here, we use confocal imaging to study the cell cycle, the proliferation of internal tissues, and the relationship with cytokinin signaling. We observed that early gynoecium proliferation is complex and with a long cell cycle dynamics. Moreover, we observed a relationship between the region of highest proliferation and maximum cytokinin signaling, a rise in proliferation attributed to BAP treatment, ectopic tissue formation with cytokinin signaling, and alterations in the gynoecium primordium in mutant lines. Together, these results provide insights into cell cycle dynamics, meristematic maintenance, and medial tissue development in the Arabidopsis gynoecium.