Polyploid trees: Do they have greater resilience in a changed climate?

The PolyTree network has investigated advantages and disadvantages of using polyploid trees in forestry. The network members have found that under climate change conditions, polyploid trees may become another tool in the box for tree breeders and forestry, potentially increasing forest resilience.
Text: Network members


Forest stand of Betula pubescens, a natural polyploid. Photo: Erkki Oksanen, Luke

Polyploids have multiple sets of chromosomes compared to the more common diploid state, two copies, encountered in a majority of plants and animals (including humans). Polyploidy is a normal thing for plants, and it is very common in agriculture because polyploids tend to yield larger fruits, seeds and tubers. In fact most crops are polyploids or have polyploid origins, such as banana, coffee, oat, peanut, potato, sweet potato, strawberry, corn and wheat, to name a few.

Yet, in forestry polyploids have found little use – so far. Through three workshops, the PolyTree network has been looking at polyploid trees from different angles to investigate whether polyploid trees could be used in forestry to prepare forests against climate change.

Photo: Thor Strömvik

We analyzed the literature on polyploid trees, and our findings can be summarized as:

  • There are many natural polyploid tree species – although we don’t know the exact number because the topic has not been studied much.
  • A few of the polyploid species are found in Nordic forests, for example, downy birch (Betula pubescens ) and sycamore (Acer pseudoplatanus L.).
  • It is possible to create artificial polyploids – and although polyploids are not easily discerned from diploids, their biological properties are different and their growth may be altered.
  • Polyploidy appears to provide more plasticity, for example, there are many cases where polyploids are more drought-resistant than diploids. Hence, polyploid trees should be investigated for increased resilience in a changed climate, where hotter, drier summers are expected.
  • Still, there are many things that we don’t know about polyploid trees: Will they perform better than diploids under the elevated CO2 concentrations predicted to occur in future? Since the genetics are more complex, is the use of polyploids applicable to large-scale forest tree breeding? How will polyploid trees impact the environment?
  • We suggest that polyploidy could become another tool in the box for tree breeders and forest owners under climate change. However, more fundamental research, testing and careful observation will be needed before this can be realized.

See Anders Raebild in interview about the networks efforts

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