Sex Determination in the Homosporous Fern Ceratopteris richardii

鸢尾蕨配子体雌雄同体或雌雄同体。在这种和许多其他蕨类植物中，主要的性别决定信号是一种由配子体分泌的类似赤霉素的信息素。有配子体存在时，幼配子体发育为雄性，没有配子体存在时，幼配子体发育为雌雄同体。本研究的主要目的是利用遗传和分子结合的方法来了解雄蜂配子体的性别。具体目标是：1)通过突变的产生和特征确定参与性别决定的关键调控基因；以及2)使用通过减法杂交方法识别两个mRNA群体之间丰度不同的mRNA的基因表达筛选，分离其表达因蒽醌而改变的基因；然后通过在转基因植物中表达它们的反义cDNA来评估它们的时空表达模式和研究它们的功能。对角翅龙性别决定过程的分析可能会促进我们对高等植物中类似过程的总体理解，并且还将涉及到有关所有生物生殖发育中涉及基因的激素控制的更一般的问题。

Gametophytes of the fern ceratipteris richardii are either hermaphroditic or male. The primary sex-determining signal in this and many other ferns is antheridiogen, a gibberellin-like pheromone that is secreted by the gametophyte. In its presence, a juvenile gametophyte develops as a male, whereas in its absence, the juvenile develops as a hermaphoxlite. The primary objective of this proposal is to use a combined genetic and molecular approach to understand how antheridiogen governs the sex of the gametophyte of Ceratopteris. The specific objectives are 1) to identify key regulatory genes involved in sex determination by generating and characterizing mutations; and 2) to isolate genes whose expression is altered in response to antheridiogen using a gene expression screen which identifies mRNAs that differ in abundance between two mRNA populations by a subtractive hybridization method; the temporal and spatial patterns of their expression will then be assessed and their function investigated by expressing their antisense cDNA in transgenic plants. %%% This analysis of the sex determining process in Ceratopterts may advance our general understanding of similar processes in higher plants, and will also relate to more general questions concerning hormonal control of genes involved in the reproductive development of all organisms.