The paleosymbiosis hypothesis: host plants can be colonized by root symbionts that have been inactive for centuries to millenia

Paleoecologists have speculated that post-glacial migration of tree species could have been facilitated by mycorrhizal symbionts surviving glaciation as resistant propagules belowground. The general premise of this idea, which we call the “paleosymbiosis hypothesis”, is that host plants can access and be colonized by fungal root symbionts that have been inactive for millennia. Here, we explore the plausibility of this hypothesis by synthesizing relevant findings from a diverse literature. For example, the paleoecology literature provided evidence of modern roots penetrating paleosols containing ancient (> 6000 yr) fungal propagules, though these were of unknown condition. With respect to propagule longevity, the available evidence is of mixed quality, but includes convincing examples consistent with the paleosymbiosis hypothesis (i.e. > 1000 yr viable propagules). We describe symbiont traits and environmental conditions that should favour the development and preservation of an ancient propagule bank, and discuss the implications for our understanding of soil symbiont diversity and ecosystem functioning. We conclude that the paleosymbiosis hypothesis is plausible in locations where propagule deposition and preservation conditions are favourable (e.g. permafrost regions). We encourage future below-ground research to consider and explore the potential temporal origins of root symbioses

The Chester Standard - July 23, 1857

The collection consists of issues of the Chester Standard, a weekly newspaper printed in Chester S.C. from 1854 to 1869, after changing its name from the Palmetto Standard. This issue, scanned from microfilm is from July 23, 1857 (volume VIII, number 30).https://digitalcommons.winthrop.edu/chesterstandard1857/1029/thumbnail.jp

The Chester Standard - September 17, 1857

The collection consists of issues of the Chester Standard, a weekly newspaper printed in Chester S.C. from 1854 to 1869, after changing its name from the Palmetto Standard. This issue, scanned from microfilm is from September 17, 1857 (volume VIII, number 38).https://digitalcommons.winthrop.edu/chesterstandard1857/1037/thumbnail.jp

The Chester Standard - February 12, 1857

The collection consists of issues of the Chester Standard, a weekly newspaper printed in Chester S.C. from 1854 to 1869, after changing its name from the Palmetto Standard. This issue, scanned from microfilm is from February 12, 1857 (volume VIII, number 7).https://digitalcommons.winthrop.edu/chesterstandard1857/1006/thumbnail.jp

The Chester Standard - July 9, 1857

The collection consists of issues of the Chester Standard, a weekly newspaper printed in Chester S.C. from 1854 to 1869, after changing its name from the Palmetto Standard. This issue, scanned from microfilm is from July 9, 1857 (volume VIII, number 28).https://digitalcommons.winthrop.edu/chesterstandard1857/1027/thumbnail.jp

The Chester Standard - June 25, 1857

The collection consists of issues of the Chester Standard, a weekly newspaper printed in Chester S.C. from 1854 to 1869, after changing its name from the Palmetto Standard. This issue, scanned from microfilm is from June 25, 1857 (volume VIII, number 26).https://digitalcommons.winthrop.edu/chesterstandard1857/1025/thumbnail.jp

The Chester Standard - October 28, 1857

The collection consists of issues of the Chester Standard, a weekly newspaper printed in Chester S.C. from 1854 to 1869, after changing its name from the Palmetto Standard. This issue, scanned from microfilm is from October 28, 1857 (volume VIII, number 44).https://digitalcommons.winthrop.edu/chesterstandard1857/1043/thumbnail.jp

The Chester Standard - March 12, 1857

The collection consists of issues of the Chester Standard a weekly newspaper printed in Chester, S.C. from 1854 through 1857 after changing its name from the Plametto Standard. This issue, scanned from microfilm is from March 12, 1857 (volume VIII, number 11).https://digitalcommons.winthrop.edu/chesterstandard1857/1010/thumbnail.jp

The Chester Standard - April 9, 1857

The collection consists of issues of the Chester Standard, a weekly newspaper printed in Chester S.C. from 1854 to 1869, after changing its name from the Palmetto Standard. This issue, scanned from microfilm is from April 9, 1857 (volume VIII, number 15).https://digitalcommons.winthrop.edu/chesterstandard1857/1014/thumbnail.jp