SRA

During their lifespan, plants continuously respond to a multitude of stressful factors that affects their development and reproductive fitness through a sophisticated variety of physiological, biochemical, transcriptional, and epigenetic mechanisms. Dynamic changes in chromatin structure and concomitant transcriptional variations play an important role in both stress response and adaptation. Epigenetic memory mechanisms seem to be involved because chromatin and expression patterns can be indeed stably maintained during cell division, once the triggering stimulus has been removed. In this study we performed transcriptome and genome-wide analysis of histone modifications of maize plants subjected to a mild and prolonged drought stress followed by a complete recovery phase. Results led to the identification of stress-responsive genes in which variations in transcript and/or histone modification levels persist after stress removal. Genes not showing an immediate response to stress, but perceiving and storing stress signal for a delayed response were also identified. This provides valuable information about genes and mechanisms utilized by plants to adapt to stressful environment and potentially involved in stress memory. We also report that drought stress alters flowering and inflorescences patterning, possibly by affecting expression and chromatin of flowering regulatory genes. Overall design: ChIP-Seq analysis of three histone modifications (H3K4me3, H3K9ac and H3K27me3) on maize young leaves collected from drought stressed (WS) and control (NS) plants after 10 days of progressive mild drought stress (WST0 and NST0) and subsequent 7 days of recovery period (WST7 and NST7)