Violeta Velikova, Tommaso
We investigated the consequences of recurrent winter flooding with saline water on a lemon (Citrus × limon (L.) Burm.f.) orchard, focussing on photosynthesis limitations and emission of secondary metabolites (isoprenoids) from leaves and fruits. Measurements were carried out immediately after flooding (December), at the end of winter (April) and after a dry summer in which plants were irrigated with optimal quality water (September). Photosynthesis was negatively affected by flooding. The effect was still visible at the end of winter, whereas the photosynthetic rate was fully recovered after summer, indicating an unexpected resilience capacity of flooded plants. Photosynthesis inhibition by flooding was not due to diffusive limitations to CO2 entry into the leaf, as indicated by measurements of stomatal conductance and intercellular CO2 concentration. Biochemical and photochemical limitations seemed to play a more important role in limiting the photosynthesis of flooded plants. In young leaves, characterised by high rates of mitochondrial respiration, respiratory rates were enhanced by flooding. Flooding transiently caused large and rapid emission of several volatile isoprenoids. Emission of limonene, the most abundant compound, was stimulated in the leaves, and in young and mature fruits. Flooding changed the blend of emitted isoprenoids, but only few changes were observed in the stored isoprenoids pool.
Martini V, Michelozzi M, Capretti P, Comparini C, Scala A, , Foliar terpenoids of Rosmarinus officinalis L. and its relationships to the attack of Alternaria alternata (Fr.) Keissl. VIII Congresso SISEF – Univ. della Calabria ottobre 2011. Abstract-Book: Posters
The objective of these studies was to investigate the relationships between foliar monoterpene composition and the susceptibility to Alternaria alternata (Fr.) Keissl. in R. officinalis. Results showed that 1,8-cineole (37,93%), ( )-alpha-pinene (28,46%), and (-)-alpha-pinene (6%) were major components in the foliar tissue samples of rosemary. Most of the compounds did not show significant variations in the relative content between samples collected from the same clones planted on three sites that differ in environmental conditions. Changes in monoterpene composition were observed between juvenile and mature foliar tissues, while the terpene percentages in these mature tissues remained stable through seasons. In-vitro the major antifungal activities were observed for ()-alpha -pinene, (-)-alpha -pinene, ( )-limonene, (-)-limonene, (-)-beta-pinene, and myrcene. Discussion is focused on the potential roles of variations in these constitutive terpenes and the attack of this pathogenic fungus and the possibility to use terpene markers as an aid in selecting for rosemary plants which could be less sensitive to the attack of A. alternata.