The role of isoprene emission in two Arundineae species exposed to progressive drought stress

Isoprene is the most abundant biogenic volatile organic compound emitted from vegetation and has been suggested to have protective role in plants under different kinds of stress. In this study we compared the responses to drought stress of two Arundineae species which differ in their ability to emit isoprene – Arundo donax, a promising biofuel crop and isoprene emitter, and Hakonechloa macra, a non-emitting ornamental plant. Our results showed better recovery of photosynthesis in A. donax after rehydration in comparison to H. macra. H. macra had lower photosystem II (PSII) photochemical efficiency, increased non-photochemical quenching (NPQ) and high levels of leaf malondialdehyde (MDA) and proline content when exposed to drought stress. The isoprene emitting species A. donax showed enhanced drought tolerance and better recovery after rewatering than the non-emitting H. macra. Our results confirm the idea that in isoprene emitting species, the function of isoprene is closely associated with functioning of the photosynthetic apparatus.