Functional analysis of the complete MADS-box gene family in the moss, physcomitrella patens

在所有种子植物中，MADS-box基因是模式形成的遗传编程中不可或缺的元件，包括被子植物花的节段组织。因此，MADS-box基因在调控顶端分生组织向花序分生组织和花分生组织的转变以及决定花器官(萼片、花瓣、雄蕊和心皮)的特性方面发挥着重要的作用。在非开花植物中也发现了它们，包括针叶树、Gnetum、蕨类植物、一种丛生苔藓和一种苔藓。在少数情况下，研究表明，特定的非开花植物MADS-box基因表现出与开花植物MADS-box基因不同亚群相似的表达模式。因此，非开花植物基因的发现提出了一种有趣的可能性，即在高等植物和至少一些低等植物中，控制生殖结构分化和其他重要发育转变的机制基本上是相似的，并且在进化上是保守的。为了获得现在参与调控特殊发育过程(如花的生成)的基因的祖先功能的线索，这里提出的研究将确定苔藓植物Physcomitrella patens的整个MADS-box基因的作用和表达模式。这种植物模型系统为这类研究提供了独特的机会，因为它的整个基因组已经测序，而且它可以进行复杂的遗传分析。所获得的结果，结合有关该基因家族在其他植物中的信息，应该可以更深刻地理解MADS-box多基因家族的进化及其功能，以及各种主要陆地植物类群和结构的进化，例如被子植物的花，它们定义了每一个植物。

MADS-box genes are indispensable elements in the genetic programming of pattern formation, including the segmental organisation of angiosperm flowers, in all seed plants. Thus, MADS-box genes are best known for their roles in regulating the transition of shoot apical meristems into inflorescence and floral meristems and in the determination of floral organ (sepal, petal, stamen and carpel) identities. They have also been discovered in non-flowering plants including conifers, Gnetum, ferns, a clubmoss and a moss. In a few cases, it has been shown that specific non-flowering plant MADS-box genes display similar expression patterns to distinct subsets of flowering plant MADS-box genes. Therefore, discovery of the non-flowering plant genes has raised the intriguing possibility that mechanisms governing the differentiation of reproductive structures, and other important developmental transitions, in higher and at least some lower plants are fundamentally similar and evolutionarily conserved. To obtain clues about the ancestral functions of genes that are now involved in regulating specialised developmental processes such as the generation of flowers, the research proposed here will determine the roles and expression patterns of the entire complement of MADS-box genes of the moss, Physcomitrella patens. This plant model system offers unique opportunities for these kinds of study because its entire genome has been sequenced and it is amenable to sophisticated genetic analysis. The results obtained, when combined with information about this gene family in other plants, should provide a more profound comprehension of the evolution of the MADS-box multigene family and its functions as well as of the evolution of the various major land plant groups and structures, such as angiosperm flowers, which define each of them.