Abstract Detail

Plant epigenetics: phenotypic and functional diversity beyond the DNA sequence

Braeutigam, Katharina [1].

Epigenome analyses reveal a key developmental regulator responsible for sex determination.

The epigenome, chemical modifications to DNA and its associated proteins, represents a fascinating layer of genome regulation. Tightly interlinked with gene expression, it can control developmental trajectories and ultimately shape phenotypes. A central developmental step in a plant’s life is the formation of reproductive structures. While a majority of angiosperms is co-sexual, many lineages separate male and female function onto different individuals (dioecy). In addition, long-lived plants such as trees initiate flowering annually once they reach sexual maturity. This means differentiating meristems away from vegetative development (leaf formation) towards reproduction on a recurrent basis. Such processes require a highly coordinated interpretation of the genome and much remains to be learned about underlying molecular pathways in this context. Here, we study high-resolution epigenome maps with respect to sex determination in the genus Populus, comprising species with a wide distribution throughout the northern hemisphere and of considerable economic relevance. Poplars are generally dioecious. Using unbiased machine learning approaches on epigenome profiles allowed us to recently identify the key regulator of sex, a response regulator (RR) specific to female development. In males this regulator is silenced via RNA-directed DNA methylation. The full male and female developmental programs from reproductive meristems to mature flowers (catkins) were further characterized in-depth by RNAseq. Intriguingly, we found evidence for five successive waves of chromatin-alterations to ensure highly co-ordinated gene expression programs and hence correct spatial and temporal development. Mechanisms of sex determination will be discussed in the context of molecular functions and evolutionary plasticity.

1 - University Of Toronto Mississauga, Biology, 3359 Mississauga Road, Mississauga, ON, L5L 1C6, Canada

Keywords:
DNA methylation
chromatin
Gene expression
developmental program
sex determination
Dioecy
tree biology
Populus.

Presentation Type: Symposium Presentation
Session: SY1, Plant epigenetics: phenotypic and functional diversity beyond the DNA sequence
Location: Virtual/Virtual
Date: Monday, July 27th, 2020
Time: 12:15 PM
Number: SY1006
Abstract ID:792
Candidate for Awards:None