HR: 08:00h
AN: B41A-01 INVITED     [PDF]
TI: Plant DNA: A new substrate for carbon stable isotope analysis and a potential paleoenvironmental indicator
AU: * Jahren, H
EM: jahren@jhu.edu
AF: Johns Hopkins University, Department of Earth & Planetary Sciences, 301 Olin Hall 3400 N. Charles St., Baltimore, MD 21218 United States
AU: Petersen, G
EM: gittep@bot.ku.dk
AF: Botanical Institute, Department of Evolutionary Botany, University of Copenhagen, Gothersgade 140, Copenhagen K, DK-1123 Denmark
AU: Seberg, O
EM: oles@bot.ku.dk
AF: Botanical Institute, Department of Evolutionary Botany, University of Copenhagen, Gothersgade 140, Copenhagen K, DK-1123 Denmark
AB: The $\delta^{13}$C value of fossil plant materials can be used to gain insight into the dominant photosynthetic pathway, as well as other environmental attributes, of ancient plant ecosystems. Nucleotide sequences from land-plant nucleic acids extracted from 400 ka sediments have been recognized as the oldest authenticated fossil DNA, making the inference of plant taxonomy possible in substrates devoid of plant macro- and microfossils. If the C isotope relationship between bulk plant tissue and associated plant nucleic acids were known, fossil plant nucleic acids could be analyzed for $\delta^{13}$C values and used as land-plant isotopic substrates within mixed organic material. Toward this end, we present $\delta^{13}$C analyses of nucleic acids isolated from 12 higher-plant species that span the full phylogenetic diversity of seed plants. Extracted nucleic acids were dominated by double-stranded DNA containing fragments of rbcL gene $\sim 350$ base pairs in length. The C isotope compositions of plant nucleic acids were found to be enriched in $^{13}$C relative to bulk plant tissue by a constant value ($1.39 \permil$). This study represents the first comparison of the $\delta^{13}$C value of nucleic acids to the $\delta^{13}$C value of bulk tissue for multicellular organisms; our results contrasted with the minimal fractionations reported for microorganisms. Because the isotopic enrichment $\delta^{13}$C is constant across tracheophytes, the $\delta^{13}$C value of fossil plant DNA can be used as a paleoenvironmental indicator, eliminating the need for morphological recognition of fossil plant material in paleoenvironmental studies.
DE: 1615 Biogeochemical processes (4805)
DE: 1851 Plant ecology
DE: 3030 Micropaleontology
DE: 4870 Stable isotopes
DE: 9810 New fields (not classifiable under other headings)
SC: Biogeosciences [B]
MN: 2003 Fall Meeting