Browsing by Subject "Poplar"

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Site-dependent differences in DNA methylation and their impact on plant establishment in Populus trichocarpa
(2016) Schönberger, Brigitte; Ludewig, Uwe
Phosphate (Pi) limits total biomass production in natural tree ecosystems. Due to the low mobility of Pi in soil, higher plants, like trees, require special adaptations for phosphorus (P) acquisition. The genetic and physiological basis of this adaptation has been studied extensively. In addition, phosphorus starvation was recently suggested to affect epigenetic modifications in varying annual plant species. However, the impact of differential DNA methylation and microRNAs (miRNAs) on gene expression as well as site-dependent P-related physiology is largely unknown in perennials. In this study Populus trichocarpa clones, established from stem cuttings from two different locations, were grown in hydroponic culture with different P levels. Morphological and physiological parameters as well as, using bisulfite sequencing, site-specific genome-wide methylomes were determined. Gene and miRNA expression of differentially methylated regions was quantified via qPCR. Site-dependent differences in plant establishment were encountered, together with site-specific differentially methylated chromosomal regions. Methylation differences were nucleotide context-specific and extensively regulated miRNAs and their target genes in an organ-specific way. Though no direct relation between differential methylation in coding regions and their corresponding gene expression was observed, a general site-dependent transcriptional repression by DNA methylation was detected. Nevertheless, differential DNA methylation and gene expression was not affected by P nutrition, although recent studies described P-starvation induced DNA methylation changes, suggesting species-specific epigenetic mechanisms. However, differentially methylated miRNAs, together with their target genes, showed P-dependent expression profiles, indicating miRNA expression changes as a P-related epigenetic modification in poplar. Hence, it was shown that differences in DNA methylation or differentially methylated miRNAs might influence plant establishment and partially correlate with P acquisition, and thus be responsible for a site-dependent adaptation and growth performance, interesting for plant breeding, conservation biology and biodiversity studies of vegetatively propagated perennials.