Abiotic stress mediated modulation of chromatin landscape in Arabidopsis thaliana.

Limited information is available on abiotic-stress mediated alterations of the chromatin conformation influencing gene expression in plants. In order to characterize the effect of abiotic stresses on changes in chromatin conformation, we employed FAIRE-seq and DNase-seq to isolate accessible regions of chromatin from Arabidopsis thaliana seedlings exposed to either heat, cold, salt or drought stress. Approximately, 25% regions in the Arabidopsis genome were captured as open chromatin, majority of which included promoters and exons. A large proportion of chromatin regions apparently did not change its conformation in response to any of the four stresses. Digital footprints present within these regions had differential enrichment of motifs for binding of 43 different TFs. Further, in contrast to drought and salt stress, both high and low temperature treatments resulted in increased accessibility of the chromatin. Also, pseudogenes attained increased chromatin accessibility in response to cold and drought stresses. The highly accessible and inaccessible chromatin regions in drought stress correlated with Ser/Thr protein kinases MLK1 and MLK2 mediated reduction and increase of H3 phosphorylation (H3T3Ph) respectively. The presented results provide a deeper understanding of abiotic stress-mediated chromatin modulation in plants.