TY - JOUR

T1 - Uncovering Signatures of DNA Methylation in Ancient Plant Remains From Patterns of Post-mortem DNA Damage

AU - Wagner, Stefanie

AU - Plomion, Christophe

AU - Orlando, Ludovic

N1 - Publisher Copyright: © Copyright © 2020 Wagner, Plomion and Orlando.

PY - 2020/1/31

Y1 - 2020/1/31

N2 - The ultra-short DNA molecules still preserved in archeological remains can provide invaluable genetic information about past individuals, species, and communities within the half to 1-million-year time range. The sequence data are, however, generally affected by post-mortem DNA damage and include specific patterns of nucleotide mis-incorporations, which can help data authentication. Recent work in ancient mammals has shown that such patterns can also help assess past levels of DNA methylation in CpG contexts. Despite pioneering work in barley and sorghum, ancient epigenetic marks have received limited attention in plants and it remains unknown whether ancient epigenetic signatures can be retrieved in any of the three main sequence contexts (CG, CHG, and CHH). To address this question, we extended a statistical methylation score originally proposed to trace cytosine methylation in mammal sequence data to accommodate the three methylation contexts common in plants. We applied this score to a range of tissues (wood, cobs, and grains) and species (oak, maize, and barley), spanning both desiccated and waterlogged archeological samples. Ancient sequence data obtained for USER-treated DNA extracts yielded methylation scores on par with DNA methylation levels of modern organellar and nuclear genomes. At the quantitative level, scores were (1) positively correlated to post-mortem cytosine deamination, and (2) replicated relative contributions of CG, CHG, and CHH contexts to DNA methylation assessed by bisulfite DNA sequencing of modern plant tissues. This demonstrates that genuine DNA methylation signatures can be characterized in ancient plant remains, which opens new avenues for investigating the plant evolutionary response to farming, pollution, epidemics, and changing environmental conditions.

AB - The ultra-short DNA molecules still preserved in archeological remains can provide invaluable genetic information about past individuals, species, and communities within the half to 1-million-year time range. The sequence data are, however, generally affected by post-mortem DNA damage and include specific patterns of nucleotide mis-incorporations, which can help data authentication. Recent work in ancient mammals has shown that such patterns can also help assess past levels of DNA methylation in CpG contexts. Despite pioneering work in barley and sorghum, ancient epigenetic marks have received limited attention in plants and it remains unknown whether ancient epigenetic signatures can be retrieved in any of the three main sequence contexts (CG, CHG, and CHH). To address this question, we extended a statistical methylation score originally proposed to trace cytosine methylation in mammal sequence data to accommodate the three methylation contexts common in plants. We applied this score to a range of tissues (wood, cobs, and grains) and species (oak, maize, and barley), spanning both desiccated and waterlogged archeological samples. Ancient sequence data obtained for USER-treated DNA extracts yielded methylation scores on par with DNA methylation levels of modern organellar and nuclear genomes. At the quantitative level, scores were (1) positively correlated to post-mortem cytosine deamination, and (2) replicated relative contributions of CG, CHG, and CHH contexts to DNA methylation assessed by bisulfite DNA sequencing of modern plant tissues. This demonstrates that genuine DNA methylation signatures can be characterized in ancient plant remains, which opens new avenues for investigating the plant evolutionary response to farming, pollution, epidemics, and changing environmental conditions.

KW - ancient DNA

KW - barley

KW - DNA methylation

KW - genomics

KW - maize

KW - oak

KW - post-mortem DNA damage

U2 - 10.3389/fevo.2020.00011

DO - 10.3389/fevo.2020.00011

M3 - Journal article

AN - SCOPUS:85079489642

VL - 8

JO - Frontiers in Ecology and Evolution

JF - Frontiers in Ecology and Evolution

SN - 2296-701X

M1 - 11

ER -