Arabidopsis thaliana mitochondrial Superoxide Dismutase is essential for cell face specification during female gametogenesis by regulating ROS homeostasis

MARTIN, M. V.; FIOL D; SUNDARESAN V.; EDUARDO JULIAN ZABALETA; PAGNUSSAT G

PLANT CELL

AMER SOC PLANT BIOLOGISTS

Lugar: Rockville; Año: 2012

1040-4651

Reactive oxygen species (ROS) can work as signaling molecules, regulating key aspects of plant development, or as toxic compounds leading to oxidative damage. In this report, we show that control of ROS during megagametogenesis is largely dependent on MSD1, a mitochondrial Mn-superoxide dismutase. WT mature embryo sacs show ROS exclusively in the central cell, which appears to be the main source of ROS before pollination. Accordingly, expression of MSD1 shows a complementary pattern. MSD1 expression is maintained elevated in the egg apparatus at maturity, but is downregulated in the central cell. oiwa mutants are characterized by high levels of ROS detectable both in the central cell and in the micropylar cells. Remarkably, egg apparatus cells in oiwa show central cell features, indicating that high levels of ROS result in the expression of central cell-characteristic genes. Notably, ROS are detected in synergid cells after pollination. This ROS burst depends on stigma pollination but precedes fertilization, suggesting that embryo sacs sense the imminent arrival of pollen tubes and respond generating an oxidative environment. Altogether, we show that ROS play a crucial role during female gametogenesis and fertilization. MSD1 activity seems critical for maintaining ROS localization and important for embryo sac patterning.