PATTERNING AND FERTILIZATION OF THE Arabidopsis EMBRYO SAC IN Arabidopsis thaliana

DISTEFANO A; BELLIDO A; MARTIN, M. V.; FIOL D; EDUARDO JULIAN ZABALETA; PAGNUSSAT G

Rosario

Congreso; L Reuniòn Anual SAIB; 2014

Gamete formation in plants takes place in special haploid structures called gametophytes. The male gametophyte is the pollen grain, while the female gametophyte is the embryo sac, which develops enclosed by the maternal tissues of the ovule. In Arabidopsis, the embryo sac is a polarized structure composed by seven cells: the egg cell, the central cell, two synergids and three antipodal cells. In our lab, we are interested in the molecular mechanisms underlying cell specification during embryo sac development. Particularly, we are focusing our studies on mitochondrial proteins. By studying insertional mutants in genes encoding ROS detoxifying enzymes, we showed a crucial role for ROS in cell fate and fertilization. Additionally, we have identified and studied Arabidopsis mutants with insertions in genes that encode for members of the mitochondrial electron shuttle Adrenodoxin-Adrenodoxinreductase(ADXADXR). These mutants show cell fate abnormalities and aberrant pollen tube attraction, suggesting a role for this shuttle in cell specification and communication between the female and malegametophytes. In vertebrates and insects, ADX-ADXRmediates electron transfer to a cytochrome P450, which constitutes the first step in steroid hormonessynthesis. We are currently analyzing the possible occurrence of a similar pathwayin Arabidopsis and the female gametophyte steroid profile.