The epigenetic control of gene expression under environmental changes is a field still not well developed but of high interest in a global changing world. The aim of this project is to reveal which epigenetic mechanisms are involved in the response of plants to vegetation proximity (also referred as shade). We used the Arabidopsis model plant to study two main epigenetic mechanisms: histone acetylation and Polycomb activity.
By screening of the multiple histone acetyltransferases and histone deacetylases (involved in the deposition and removal of the acetylation mark respectively) we could detect that altering the levels of histone acetylation, Arabidopsis seedlings have a milder response to shade, as the hypocotyl growth was impaired. However, studying short-term changes of gene expression of well-known shade-induced genes, mild changes were detected. This could be explained by the diversity and redundancy of the acetylation-related enzymes.
When Polycomb activity-related mutants were analysed, strong defective phenotypes were found, especially in the mutant of the histone remodeller LHP1 (LIKE HETEROCHROMATIN PROTEIN 1). The lhp1 mutant moreover, shows important changes on gene expression after shade treatment when compared with the wild-type lines. For that reason, our work was mainly focused on the role of LHP1 in shade signalling. By diverse experimental approaches (genetic analysis, western blot, gene expression, hormone quantification, etc.) we could relate LHP1 activity to multiple levels of the shade signalling cascade such the regulation of phyA stability, auxin synthesis and signalling, repression or activation of gene expression by different mechanisms, etc. The analysis of RNA sequencing results in wild-type and lhp1 mutant at different hours after shade will give a more complete picture of the effect of LHP1 activity on shade-regulated genes.
Furthermore, we could relate the Polycomb associated marks, particularly H3K27me3, with gene expression. We found subsets of shade-regulated genes differently affected by Polycomb-related activity. With the analysis of the ChIP sequencing results, we aim to give a better picture of the regulation.
The results generated during the progression of the project have been presented at scientific conferences, both national and international. The project has contributed to some scientific papers already published, and some are being currently written. The project has been also explained to the general public and students at different stages (from primary to master studies) with special attention on transmitting the scientific critical thinking and data analysis.
