quantitative analysis of ovule primordium architecture and female germ cells precursors formation in maize

INES, OUEDRAOGO; MARC LARTAUD; MATTHIEU, DEJEAN; JEAN-LUC VERDEIL; DELGADO LUCIANA; GENEVIEVE, CONEJERO ; AUTRAN, DAPHNÉ

Praga

Conferencia; International Conference on sexual plant reproduction; 2022

In higher plants, the formation of female gametes is a crucial step in theplant reproductive cycle and determines seed formation, henceparticipating in crop yields. The plant female germline initiates in the ovuleprimordium, with the specification of the MMC, the Megaspore MotherCell, the only cell which will undergo meiosis to produce gametes.However, reproductive cell fate in the early ovule appears flexible.Genetic variants and apomictic species show that somatic cellsneighboring the MMC can enter the MMC identity program or evendirectly produce female gametophytes without meiosis. Moreover, thisdevelopmental plasticity is at least partially controlled by ovule tissuegrowth, as shown recently in Arabidopsis. However, we don’t know if suchmodel is conserved in grasses ovules, and could be part of themechanisms explaining the shift from sexual to apomictic reproductivemode in these species. To set up a framework to study ovulemorphogenesis and MMC formation in grasses, in 3D and at cellular level,we use maize as a sexual plant model and multiphoton microscopy tomonitor step by step ovule primordium development. Such 3Dquantitative atlas allows to correlate organ level morphogenetic changeswith a first precise cellular description of gradual MMC formation, and willbe further used as a reference to explore reproductive fate plasticity inaposporous ovules.