Putrescine treatment has a higher effect on 5mC DNA methylation profile of wheat leaves under white than under blue light conditions

Polyamines play a pivotal role in plant growth and development by modulating primary metabolism and gene expression patterns. However, their regulatory effect on epigenetics is still not clear. The impact of exogenous putrescine in wheat leaves was investigated to reveal novel insights into the intricate relationship between polyamines and DNA methylation. Since the outcome of putrescine treatment may vary depending on the light quality, the experiment was performed under both white and blue light, and MeDIP-seq method was applied to reveal the global methylation profile. Metabolite profiling revealed distinct changes induced by blue light and/or putrescine, and that the effect of putrescine in most cases was dominant under blue light. Blue light also exerted strong effects on methylation, and putrescine application could slightly induce further changes. Putrescine had a higher impact under white light, namely parallel with increased leaf spermidine level, a lower level of up-methylated genes involved in cellular component, but a higher level of down-methylated genes involved in molecular function and biological processes occurred compared to the blue light. Our results demonstrated that putrescine excess has a regulatory role in DNA methylation. These findings are also useful in understanding the relationship between polyamine metabolism and light conditions.