Manuela Gouveia

Infection-Related Activation of the cg12 Promoter Is Conserved between Actinorhizal and Legume-Rhizobia Root Nodule Symbiosis

Two nitrogen-fixing root nodule symbioses between soil bacteria and higher plants have been described: the symbiosis between legume and rhizobia and actinorhizal symbioses between plants belonging to eight angiosperm families and the actinomycete Frankia. We have recently shown that the subtilisin-like Ser protease gene cg12 (isolated from the actinorhizal plant Casuarina glauca) is specifically expressed during plant cell infection by Frankia. Here we report on the study of C. glauca cg12 promoter activity in the transgenic legume Medicago truncatula. We found that cg12 promoter activation is associated with plant cell infection by Sinorhizobium meliloti. Furthermore, applications of purified Nod factors and mycorrhizal inoculation failed to trigger expression of the cg12-reporter gene construct. This indicates that at least part of the transcriptional environment in plant cells infected by endosymbiotic nitrogen-fixing bacteria is conserved between legume and actinorhizal plants. These results are discussed in view of recent data concerning molecular phylogeny that suggest a common evolutionary origin of all plants entering nitrogen-fixing root nodule symbioses.

In vitro evaluation of nematicidal properties of Solanum sisymbriifolium and S. nigrum extracts on Pratylenchus goodeyi

The root-lesion nematode, Pratylenchus goodeyi, is among the most economically damaging parasites of banana plants. Nematode control can benefit from searching for novel bio-nematicides. The present study was carried out to assess the potential nematicidal properties of two Solanum species (Solanum sisymbriifolium and S. nigrum) against P. goodeyi, using dichloromethane, acetone, ethanol and either cold or hot water extracts of the plants. Water extracts of both plants at a concentration of 10 mg ml−1 greatly affected nematode movement and also caused mortality. The analysis of sequential extracts at the same experimental concentrations showed that, although water extracts affect nematode mobility and mortality, the acetone extract from S. nigrum was the most efficient, causing 100% mortality after 23 h exposure. The results showed that S. sisymbriifolium and S. nigrum extracts contain chemical components that induce morphological changes in the body structure of the root-lesion nematode, affect mobility and cause mortality. The nematostatic and nematicidal potential of the extracts described herein merit further studies to find novel bio-nematicides against the root-lesion nematode.

Nematicidal activity of Solanum sisymbriifolium and S. nigrum extracts against the root-lesion nematode Pratylenchus goodeyi

The root-lesion nematode, Pratylenchus goodeyi, is a parasite of banana plants, frequently detected in Madeira Island (Portugal) affecting culture development and consequently the production, with economical damages. To identify the phytochemicals of Solanum sisymbriifolium and S. nigrum with nematicidal properties and determine the effect of those components on P. goodeyi, an extraction sequence of at least 10 hours each from dried plants was used. The chosen solvent sequence was: dichloromethane, acetone, ethanol and water. According to the results, both plants have in their composition chemical components mainly found in water extracts, which affects the mobility and mortality of the root-lesion nematode. S sisymbriifolium and S. nigrum have potential to be used as a natural and environmentally friendly nematicide to control P. goodeyi.

Extinctions of introduced game species on oceanic islands: curse for hunters or conservation opportunities?

In island ecosystems, a considerable portion of the limited conservation resources are often channelled to the eradication of vertebrate invasive species. Since the 1950s, nearly 900 successful invasive vertebrate eradications have taken place (DIISE 2015) with highly beneficial consequences for insular biodiversity (Caujape-Castells et al. 2010; Jones et al. 2016). Multiple invasive vertebrates are popular game species on islands worldwide—e.g. the mouflon Ovis gmelini in the Canaries (Nogales et al. 2006) or the Kalij pheasant Lophura leucomelanos in Hawaii (Lewin and Lewin 1984). Yet, despite the detrimental effects of alien wildlife on the native biodiversity, such populations are commonly restocked for recreational hunting. Hunting and biodiversity conservation frequently fall under the responsibility of the same governmental institutions, which have to balance the interests of

Ipomoea batatas (L.) Lam.: a rich source of lipophilic phytochemicals.

The lipophilic extracts from the storage root of 13 cultivars of sweet potato (Ipomoea batatas (L.) Lam.) were evaluated by gas chromatography-mass spectrometry with the aim to valorize them and offer information on their nutritional properties and potential health benefits. The amount of lipophilic extractives ranged from 0.87 to 1.32% dry weight. Fatty acids and sterols were the major families of compounds identified. The most abundant saturated and unsaturated fatty acids were hexadecanoic acid (182-428 mg/kg) and octadeca-9,12-dienoic acid (133-554 mg/kg), respectively. β-Sitosterol was the principal phytosterol, representing 55.2-77.6% of this family, followed by campesterol. Long-chain aliphatic alcohols and α-tocopherol were also detected but in smaller amounts. The results suggest that sweet potato should be considered as an important dietary source of lipophilic phytochemicals.