Leaf gas exchange and isoprene emission in poplar in response to long-term experimental night-time warming and summer drought in a forest-steppe ecosystem

•We exposed poplar plants to field drought and warming treatments.•We related gas exchange data with isoprene emission and PaISPS expression levels.•Treatments led to few significant changes in isoprene parameters.•There was a strong seasonality effect on isoprene emission and PaISPS gene expression.•Isoprene emission correlated with temperature, photosynthesis and Ci concentration.