第1283回生物科学セミナー
Chromatin-guided transposition generates high rates of directed mutations into adaptive trait genes
Leandro Quadrana, PhD（CNRS）
2019年05月08日(水) 16:50-18:35 理学部2号館 講堂
Transposable elements (TEs) are mobile parasitic sequences that
have been repeatedly repurposed during evolution to generate new
functions and rewire gene regulatory networks. Yet, the contribute of
active transposition to the creation of spontaneous heritable
mutations remains unknown. In this talk I will present our results
obtained using TE accumulation lines in Arabidopsis thaliana. Once
initiated, transposition produces an exponential spread of TE copies
leading rapidly to high mutation rates, with most insertions occurring
near or within genes. Targets differ between TE families and we
uncovered a major role of the histone variant H2A.Z in directing the
preferential integration of Ty1/copia retrotransposons within
environmentally responsive genes and away from essential genes.
We also found that epigenetic silencing of newly inserted Ty1/copia
copies can both exacerbate or mask their effects on major traits,
such as flowering time. Our findings establish TEs as potent
episodic (epi) mutagens that, thanks to their chromatin tropisms, can
limit their burden on the genome while increasing the potential for
rapid adaptation.
