Supplemental material : 'Isoprene emission-free poplars - a chance to reduce the impact from poplar plantations on the atmosphere

Depending on the atmospheric composition, isoprene emissions from plants can have a severe impact on air quality and regional climate. For the plant itself,
isoprene can enhance stress tolerance and also
interfere with the attraction of herbivores and parasitoids. Here, we tested the growth performance and fitness of Populus á canescens in which
iso-prene emission had been knocked down by RNA
interference technology (PcISPS-RNAi plants) for two growing seasons under outdoor conditions. Neither the growth nor biomass yield of the PcISPS-RNAi
poplars was impaired, and they were even
temporarily enhanced compared with control poplars. Modelling of the annual carbon balances revealed a reduced carbon loss of 2.2% of the total gross primary
production by the absence of isoprene
emission, and a 6.9% enhanced net growth of PcISPS-RNAi poplars. However, the knock down in isoprene emission resulted in reduced susceptibility to fungal
infection, whereas the attractiveness for
herbivores was enhanced. The present study promises potential for the use of non- or low-isoprene-emitting poplars for more sustainable and environmentally
friendly biomass production, as reducing
isoprene emission will presumably have positive effects on regional climate and air quality.