Isoprenoids emission in Stipa tenacissima L.: Photosynthetic control and the effect of UV light. (January 2016) - Guidolotti, Gabriele
Abstract: Fluxes of CO2 and isoprenoids were measured for the first time in Stipa tenacissima L (alfa grass), a perennial tussock grass dominant in the driest areas of Europe. In addition, we studied how those fluxes were influenced by environmental conditions, leaf ontogeny and UV radiation and compared emission rates in two contrasting seasons: summer when plants are mostly inactive and autumn, the growing season in this region. Leaf ontogeny significantly affected both photosynthesis and isoprenoids emission. Isoprene emission was positively correlated with photosynthesis, although a low isoprene emission was detected in brown leaves with a net carbon loss. Moreover, leaves with a significant lower photosynthesis emitted only monoterpenes, while at higher photosynthetic rates also isoprene was produced. Ambient UV radiation uncoupled photosynthesis and isoprene emission. It is speculated that alfa grass represent an exception from the general rules governing plant isoprenoid emitters. Highlights: Stipa tenacissima L. is a grass emitting either monoterpenes and isoprene. The emission has reasonable rates even in senescent leaves. Isoprene emission is positively correlated with CO2 assimilation. Ambient UV radiation uncouples photosynthesis and isoprene emission. Leaves with lower photosynthetic rates emit only monoterpenes. Abstract : We proved for the first time that alfa grass emit both isoprene and monoterpene, and we provide some innovative aspects about the UV effect and the behavior of Stipa tenacissima .