Evolution of Sexual Reproduction in Plants

在过去的五年里，研究已经提供了大量的新的见解配子生理学和机制参与受精拟南芥。这一进展确立了配子是具有高度特异性转录谱的高分化细胞类型的观点。基于荧光报告和活细胞成像的显微镜技术的进步也改变了研究能力，并提供了对配子传递、相互作用和染色质重编程机制的见解。然而，我们对显花植物双受精的复杂性的理解还远远没有完成，更重要的是，我们缺乏关于双受精之前机制起源的任何知识。在这里，我们建议使用新兴的模型，代表植物进化的关键阶段，提供深入了解配子分化和受精的祖先机制。我们将通过生成地钱，苔藓立碗藓和现存的基生开花植物Amborella的表达图谱来建立基因协同功能网络。这些将与来自拟南芥和重要作物玉米、番茄和水稻的共功能网络相补充。绿色披衣者将作为外群。这些网络将用于研究开花植物中控制雄性和雌性配子发生、花粉管生长和受精机制的基因协同功能网络的保守性。此外，这些研究将提供新的作物育性分子标记。例如，我们的目标是确定在单子叶植物（禾本科植物）和真双子叶植物进化过程中从古代被子植物中丢失的受精因子，以及在被子植物谱系中重新进化的受精因子。我们还将直接测试雄配子发育所需的既定监管机构的功能，以及从我们的网络分析中新发现的监管机构，以评估这些监管网络的进化保守程度。预期的研究结果将允许识别特定的机制，在作物有性生殖过程中的环境压力的目标，并将有助于选择抗应激品种。最后，染色质修饰的重编程是动物有性生殖的既定特征。该项目产生的数据将提供第一个全面的植物配子和受精产物中染色质重编程发生的图谱。更好地了解表观遗传重编程事件对于了解生物和非生物胁迫下表观遗传标记的跨代遗传至关重要，因此是环境变化下提高作物生产力的重要组成部分。总之，EVOREPRO项目的成果将加深对重要经济植物物种有性生殖进化的理解。

Research during the past five years has delivered tremendous new insights into gamete physiology and the mechanisms involved in fertilization in Arabidopsis. This progress has established the view that gametes are hyper-differentiated cell types with highly specific transcriptional profiles. Advances in microscopy based on fluorescent reporters and live cell imaging have also transformed research capability and provided insights into the mechanisms involved in gamete delivery, interaction and the reprogramming of chromatin. Yet, our understanding of the complexity of double fertilization that characterises flowering plants is far from complete.Importantly, we lack any knowledge on the origin of mechanisms that predate double fertilization. Here, we propose to use emerging models, representing key stages in plant evolution, to provide insight into the ancestral mechanisms of gamete differentiation and fertilization. We will establish gene co-function networks by generating expression atlases for the liverwort Marchantia, the moss Physcomitrella and the extant basal flowering plant Amborella. These will be complemented with co-function networks from Arabidopsis and the important crops maize, tomato and rice. The green alga Chlamydomonas will serve as an outgroup. These networks will be used to study the conservation of gene co-function networks governing male and female gametogenesis, pollen tube growth and fertilization mechanisms in flowering plants. Moreover, these investigations will provide novel molecular markers of fertility in crops. We aim to identify, for example, fertilization factors which were lost from ancient angiosperms during the evolution of monocots (grasses) and eudicots and those which have evolved de novo in the angiosperm lineage. We will also directly test the function of established regulators required for male gamete development, as well as those newly identified from our network analyses, to assess the extent of evolutionary conservation of these regulatory networks. The expected findings will allow the identification of specific mechanisms that are targeted by environmental stresses during sexual reproduction in crops and will assist in the selection of stress-resistant cultivars. Finally, the reprogramming of chromatin modifications is an established feature of sexual reproduction in animals. Data generated in this project will provide the first comprehensive map of the occurrence of chromatin reprogramming in plant gametes and fertilization products. A better understanding of the epigenetic reprogramming events is pivotal for understanding transgenerational inheritance of epigenetic marks following exposure to biotic and abiotic stress and thus is an essential component for the improvement of crop productivity under environmental changes.In summary, the outputs of the EVOREPRO project will provide a deeper understanding of the evolution of sexual reproduction of economically important plant species.