OIWA REGULATES ROS HOMEOSTASIS DURING EMBRYO SAC DEVELOPMENT IN Arabidopsis thaliana

MARTIN, M. V.; EDUARDO JULIAN ZABALETA; PAGNUSSAT G

San Luis

Congreso; XLVII Reunión Anual de SAIB; 2011

Differentiation of gametes is a crucial step in the life cycle of allorganisms with sexual reproduction. In the model plantArabidopsis thaliana, the development of the female gametophyteinvolves three events of programmed cell death whose molecularbases are still poorly understood. In this work we present the studyof the gametophytic mutant oiwa, which carries an insertion in agene coding for a mitochondrial Mn-superoxide dismutase (Mn-SOD). While transient, localized oxidative bursts were observedassociated with cell death events in WT embryo sacs -followed by arapid restoration of the redox state-, mutant embryo sacs seem notable to reduce ROS levels after cell death, as observed by the use ofspecific probes at different stages of development both by confocaland DIC microscopy.To determine the specific stage of development affected in oiwa, acomprehensive phenotypic analysis was performed. Mutantembryo sacs appear to have difficulties attracting pollen tubes, as ahigh percentage of ovules are not fertilized. Also, in those fertilizedembryo sacs, embryogenesis is arrested at a zygotic stage,suggesting a maternal effect.Our results indicate that tight regulation of ROS homeostasis iscrucial for fertilization and embryogenesis and that Mn-SOD playsa critical role in its regulation during female gametophytedevelopment.