Dissecting seed genetic networks through the evolution of plant life-cycle transitions

现代生物圈由利用种子繁殖的植物主导，这对人类的农业和营养至关重要。种子是一种相对较新的进化创新，产生于单一植物群（有种子植物）中，起源于一种基于孢子的古老生殖机制，这种机制仍然存在于现存的无籽植物（如苔藓、苔类、蕨类）中。这种植物发育的巨大变化是如何发生的目前尚不清楚，识别与之相关的遗传变化将极大地促进我们对植物形态创新如何产生的基本理解，并提高我们对现代种子中具有经济价值的遗传网络功能的认识。该项目旨在确定在无籽植物发育过程中种子遗传网络首先出现的位置。我们将专注于一个单一的候选基因家族；SPOROCYTLESS (SPL)。SPL是开花植物种子发育的关键调节因子，但在不产生种子的物种中也发现了SPL。然而，它在无籽植物谱系中的功能目前尚不清楚。因此，在种子进化之前绘制SPL的表达和功能可以告诉我们植物种子是如何进化的。我们将使用反向遗传学的方法比较SPL基因家族在拟南芥（Arabidopsis thaliana）、苔藓Physcomitrium patens（代表早期分化的陆地植物）和新建立的蕨类遗传模型Ceratopteris richardii（属于最接近的无籽植物近亲）之间的功能和表达。分析技术将包括无籽植物中原生同源物的功能敲除和异位表达，使用荧光报告来绘制无籽基因表达和三个植物谱系之间的功能互补。

The modern biosphere is dominated by plants that reproduce using seeds, which are critical to human agriculture and nutrition. Seeds are a relatively recent evolutionary innovation, arising in a single plant group (the seed-bearing plants) from an ancestral spore-based reproductive mechanism still present in living seedless plants (e.g. mosses, liverworts, ferns). How this dramatic change in plant development occurred is presently unknown and identifying genetic changes associated with it will substantially advance our fundamental understanding of how novel innovations in plant form can arise and improve our knowledge of the functions of economically-valuable genetic networks in modern seeds. This project aims to determine from where in seedless plant development seed genetic networks first arose. We will focus on a single candidate gene family; SPOROCYTLESS (SPL). SPL is a crucial regulator of seed development in flowering plants but is also found in species that do not make seeds. However, its function in seedless plant lineages is currently unknown. Mapping SPL expression and function before the evolution of seeds can therefore tell us about how plant seeds evolved.We will use a reverse genetics approach to compare the function and expression of the SPL gene family between the seed-bearing genetic model Arabidopsis thaliana, the model moss Physcomitrium patens (representing early diverging land plants) and the newly-established fern genetic model Ceratopteris richardii (belonging to the closest seedless relatives of the seed-bearing plants).. Analytical techniques will include functional knockout and ectopic expression of native homologs in seedless plants, , use of fluorescent reporters to map seedless gene expression and functional complementation between the three plant lineages.