A cytological framework of female meiosis in Arabidopsis

Female and male meiosis often differ in many aspects, such as their duration and the frequency as well as the positioning of crossovers. However, studying female meiosis is often very challenging and thus, much less is known about female versus male meiosis in many species including plants. To approach this gap, we have developed a live-cell imaging system for female meiocytes in Arabidopsis. This allowed us to obtain a temporally resolved cytological framework of female meiosis in the wildtype that serves as a guiding system for future studies. Here, we have applied this imaging system to study mutants in cyclin- dependent kinase inhibitors, in which a designated female meiocyte undergoes several mitotic divisions before entering meiosis. This enabled us to address when a meiocyte is committed to meiosis, a key question during reproductive development and in particular for the analysis of apomictic species in which meiosis is skipped. HighlightsEstablishment of a live-cell imaging system captures dynamic features of female meiosis. Identification of cytological landmarks ensures robust assignment of meiotic stages. Time-lapse imaging enables quantitative dissection of meiotic phases. Application of the framework reveals great plasticity in the commitment to meiosis.