Personal norms in the online public good game

This paper shows that personal norms have a prominent role in explaining pro-social contribution in an online public good game. This finding suggests that the role of social norms might be loosened when subjects are distanced and interaction occurs online and in complete anonymity. Moreover, we found no statistically significant difference between the elicited norms and the norms that were elicited in a group of subjects not facing the contribution task, thus ruling out a potential self-justification bias

Effects of single or combined water deficit and aphid attack on tomato volatile organic compound (VOC) emission and plant-plant communication

Plants release a broad spectrum of volatile organic compounds (VOCs). The composition of the released VOC blend is dependent on the physiological status and, consequently, is affected by biotic and abiotic stresses. Stress-related VOCs can be perceived by different organisms, including natural enemies of herbivores and neighboring plants. Here, the responses of tomato plants (emitters) to single or combined abiotic (water stress) and biotic (aphid attack) stresses, and the effect of VOC released by emitters on neighboring unstressed plants (receivers), have been investigated. Emissions of α-pinene and methyl salicylate from plants exposed to single or combined stress, and of camphene from plants exposed to water or combined stress were significantly higher than in unstressed plants. In receivers, only the release of methyl salicylate increased when companion emitters were stressed. The expression of genes related to VOC biosynthesis and plant defense responses was unaffected or declined in water-stressed emitters, and was generally higher in receivers than in emitters. The gene coding for methyl salicylate biosynthesis was particularly active in aphid-attacked emitters and in receivers that were conditioned by the infested emitters. In addition, VOCs emitted by stressed plants induce VOC emission in unstressed receivers, and this increases attraction of parasitic wasps, which may improve protection against aphid attacks under conditions of reduced water availability

DMSP:Occurrence in plants and response to salinity in <i>Zea mays</i>

Dimethylsulfoniopropionate (DMSP) is a secondary sulfur compound that is present in high levels in several marine algal species and some higher plant species. DMSP has also been detected in low levels in some other plant species, though its overall occurrence within the plant kingdom remains unclear. The physiological function of DMSP in saline algae and plants is largely unsolved. It is presumed that the compound can function as a constitutive osmolyte and/or antioxidant. In the current study the occurrence of DMSP within the plant kingdom was analyzed. DMSP was present in nanomolar concentrations in all investigated plant species, indicating that it appears to occur widespread within the plant kingdom. Maize (Zea mays) appeared also to be a low-DMSP containing species. Shoot DMSP content in this crop increased upon exposure to salinity, also in the presence of atmospheric H2S and anoxia. This showed that the DMSP content in maize responded in a similar pattern to salinity exposure which has been observed in DMSP-accumulating plants