Coordination of proximal-distal and adaxial-abaxial patterning during early ovule development of Arabidopsis thaliana

有性生殖是植物的一个显著方面。在被子植物的花内，雌蕊群携带一个或多个胚珠，这是雌性的主要生殖器官。胚珠内有卵细胞，在种子形成过程中，胚珠是受精和胚发育的场所。除了它们令人兴奋的生物学，模式植物拟南芥的胚珠作为研究器官发生的一个突出的模型系统也受到了关注。一个主要的问题涉及模式形成的早期胚珠原基的分子基础。在以前的研究中，我们确定了一些基因在早期胚珠发育的作用。我们的遗传证据表明，NOZZLE（NZZ），编码一个假定的转录因子，协调近端远端和近轴-远轴（前-后）模式的形成在早期胚珠负调节INNER NO OUTER（INO）自动调节反馈回路。INO是YABBY家族的一员，其隐含在侧部器官的远轴身份的调节中，并且影响外珠被发育。这个想法是INO的过早激活最终导致异常的P-D模式形成。因此，合点沿着近轴-远轴的分化可能在沿着P-D轴的发育进行到一定程度之前才开始。我们还获得了体外数据，表明NZZ和至少一些YABBY蛋白，包括INO，直接相互作用。本提案的第一个目标是使用生物化学、体内成像和分子遗传学方法来测试NZZ-INO相互作用是否在体内发生。第二线实验旨在更好地理解这种相互作用的分子基础，并评估NZZ-YABBY蛋白相互作用的一般性。第三个目标是在分子特征的一个新的遗传因素参与早期外珠被的发展。

Sexual reproduction is a salient aspect of plants. Within the flower of angiosperms the gynoecium carries one or multiple ovules, the major female reproductive organs. The ovule harbors the egg cell, it is the site where fertilization occurs and the embryo develops during seed formation. Apart from their exciting biology, the ovules of the model plant Arabidopsis thaliana have gained attraction as a prominent model system to study organogenesis. A major question relates to the molecular basis of pattern formation in the early ovule primordium. In previous research we identified a number of genes with a role in early ovule development. Our genetic evidence suggests that NOZZLE (NZZ), encoding a putative transcription factor, coordinates proximaldistal and adaxia-abaxial (anterior-posterior) pattern formation in the early ovule by negatively regulating the INNER NO OUTER (INO) autoregulatory feedback loop. INO is a member of the YABBY family, which is implied in the regulation of abaxial identity in lateral organs, and affects outer integument development. The idea is that precocious activation of INO eventually results in aberrant P-D pattern formation. Thus, differentiation along the adaxial-abaxial axis in the chalaza may not begin before development along the P-D axis has proceeded to a certain extent. We also obtained in vitro data indicating that the NZZ and at least some YABBY proteins, including INO, interact directly. The first goal of this proposal is to test if the NZZ-INO interaction occurs in vivo using biochemical, in vivo imaging and molecular-genetic approaches. The second line of experiments aims at a better understanding of the molecular basis of this interaction and assesses the generality of the NZZ-YABBY protein interactions. The third goal consists in the molecular characterisation of a new genetic factor involved in early outer integument development.