Modulation of polyamine metabolism in Arabidopsis thaliana by salicylic acid.

Polyamines (PAs) play important roles in plant defense against pathogens, but the regulation of PA metabolism by hormone-mediated defense signaling pathways has not been studied in depth. In this study, the modulation of PA metabolism by salicylic acid (SA) was analyzed in Arabidopsis by combining the exogenous application of this hormone with PA biosynthesis and SA synthesis/signaling mutants. SA induced notable modifications of PA metabolism, mainly consisting in putrescine (Put) accumulation both in whole-plant extracts and apoplastic fluids. Put was accumulated at the expense of increased biosynthesis by ARGININE DECARBOXYLASE 2 and decreased oxidation by copper amine oxidase. Enhancement of Put levels by SA was independent of the regulatory protein NONEXPRESSOR OF PATHOGENESIS-RELATED GENES 1 (NPR1) and the signaling kinases MKK4 and MPK3, but depended on MPK6. However, plant infection by Pseudomonas syringae pv. tomato DC3000 elicited Put accumulation in an SA-dependent way. The present study demonstrates a clear connection between SA signaling and plant PA metabolism in Arabidopsis and contributes to understanding the mechanisms by which SA modulates PA levels during plant-pathogen interactions.

The midwifery-led care model: a continuity of care model in the birth path.

BACKGROUND AND AIM OF THE STUDY: The birth path is affected by a fragmentation in the patient care process, creating a discontinuity of this last one. The pregnant woman has to interface with many professionals, both during the pregnancy, the childbirth and the puerperium. However, during the last ten years, there has been an increasing of the pregnancy care operated by the midwife, who is considered to be the operator with the right competences, who can take care of every pregnancy and may avail herself of other professionals' contributions in order to improve the outcomes of maternal and neonatal health. AIM: To verify whether there are proofs of effectiveness that support the caseload midwifery care model, and if it is possible to apply this model in the birth path in Italy. METHODS: A revision of literature has been done using some search engine (Google, Bing) and specific databases (MEDLINE, CINAHL, Embase, Home - ClinicalTrials.gov). There has also been a consultation of the Italian regulations, the national guidelines and the recommendations of WHO. RESULTS: The search string, properly adapted to the three databases, has given the following results: MEDLINE 64 articles, CINAHL 94 articles, Embase 88 articles. From this selection, 14 articles have been extracted: 1 systematic review, 3 controlled random trial, 7 observational studies, 3 qualitative studies. CONCLUSIONS: The caseload midwifery care seems to be an effective and reliable organisational/caring method. It responds to the criterions of quality and security, to the needs of women not only during the pregnancy but also during the post-partum phase. For these reasons, it seems very useful also for the birth path in the Italian reality.

Apoplastic polyamine oxidation plays different roles in local responses of tobacco to infection by the necrotrophic fungus Sclerotinia sclerotiorum and the biotrophic bacterium Pseudomonas viridiflava.

The role of polyamine (PA) metabolism in tobacco (Nicotiana tabacum) defense against pathogens with contrasting pathogenic strategies was evaluated. Infection by the necrotrophic fungus Sclerotinia sclerotiorum resulted in increased arginine decarboxylase expression and activity in host tissues, as well as putrescine and spermine accumulation in leaf apoplast. Enhancement of leaf PA levels, either by using transgenic plants or infiltration with exogenous PAs, led to increased necrosis due to infection by S. sclerotiorum. Specific inhibition of diamine and PA oxidases attenuated the PA-induced enhancement of leaf necrosis during fungal infection. When tobacco responses to infection by the biotrophic bacterium Pseudomonas viridiflava were investigated, an increase of apoplastic spermine levels was detected. Enhancement of host PA levels by the above-described experimental approaches strongly decreased in planta bacterial growth, an effect that was blocked by a PA oxidase inhibitor. It can be concluded that accumulation and further oxidation of free PAs in the leaf apoplast of tobacco plants occurs in a similar, although not identical way during tobacco defense against infection by microorganisms with contrasting pathogenesis strategies. This response affects the pathogen's ability to colonize host tissues and results are detrimental for plant defense against necrotrophic pathogens that feed on necrotic tissue; on the contrary, this response plays a beneficial role in defense against biotrophic pathogens that depend on living tissue for successful host colonization. Thus, apoplastic PAs play important roles in plant-pathogen interactions, and modulation of host PA levels, particularly in the leaf apoplast, may lead to significant changes in host susceptibility to different kinds of pathogens.