Profiling gene expression during early gametophyte development and sex determination in Ceratopteris richardii

<p>In the fern Ceratopteris richardii, every spore has the potential to develop as either a male or hermaphroditic gametophyte. Gametophyte sex is determined by a GA-like pheromone (ACE) that is secreted by hermaphrodites approximately 6 days after spore inoculation and induces male development in other juvenile gametophytes. Our goal is to better understand the genetic and molecular mechanisms involved in sex determination and to identify sex determination genes in Ceratopteris. RNA-Seq was used to create <em>de novo</em>transcriptome assemblies from gametophytes grown, with or without ACE, during the time that their sex is determined, and from male gametophytes in early development. We found that ACE alters the expression of 1,163 genes, including those involved in epigenetic reprogramming of the genome. This suggests that epigenetics plays an important role in the early establishment of the male program of expression. We also found that a large number of transcripts are stored in the dormant spore (18,437) and that the transcriptomes of male gametophytes early in development are incredibly dynamic. The research presented in this thesis was used to generate easily testable hypotheses and to identify candidate sex-determining genes that had been genetically characterized previously. We propose that the<em>HERMAPHRODITIC</em> gene encodes GID1, the ACE receptor, that the<em>TRANSFORMER</em> gene encodes a DELLA protein, and that the <em>FEMINIZATION</em>(<em>FEM</em>) gene encodes a MYB transcription factor. We also propose that FEM directly or indirectly blocks A_CE synthesis in the male by down-regulating the expression of a gene (<em>CPS/KS</em>) that is essential for GA biosynthesis.</p>

Name thesis:degree_name

Doctor of Philosophy (PhD)

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Botany and Plant Pathology

Year

2015

Author dc:creator

• Atallah, Nadia

Contributors dc:contributor

• Jo Ann Banks
• Joseph Ogas
• Michael Gribskov
• Peter B. Goldsbrough
• Olga Vitek
• Milos Tanurdzic

• Bioinformatics
• Developmental Biology
• Plant Sciences

Repository record dc:identifier

https://docs.lib.purdue.edu/open_access_dissertations/417

OAI identifier oai:identifier

oai:docs.lib.purdue.edu:open_access_dissertations-1239