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BACKGROUND: Excessive rates of nitrogen (N) fertilizers may result in elevated concentrations of nitrate (NO3 −) in plants. Considering thatmany programs of biofortification with trace elements are being performed, it has become important to study how the application of these elements affects plant physiology and, particularly, N utilization in leaf crops. The main objective of the present study was to determine whether the NO3 − accumulation and the nitrogen use efficiency was affected by the application of different doses of Zn in Lactuca sativa plants. RESULTS: Zn doses in the range 80–100 mol L−1 produced an increase in Zn concentration provoking a decrease of NO3 − concentration and increase of the nitrate reductase, glutamine synthetase and aspartate aminotransferase activities, as well as the photorespiration processes. As result, we observed an increase in reduced N, total N concentration and N utilization efficiency. Consequently, at a dose of 80 mol L−1 of Zn, the amino acid concentration increased significantly. CONCLUSION: Adequate Zn fertilization is an important critical player in lettuce, especially at a dose of 80 mol L−1 of Zn, because it could result in an increase in the Zn concentration, a reduction of NO3 − levels and an increase the concentration of essential amino acids, with all of them having beneficial properties for the human diet.

Cavacos su00e3o telhas de madeira produzidas com tu00e9cnicas desenvolvidas de forma empu00edrica durante muitas gerau00e7u00f5es e que ocorrem de forma manual e em pequena intensidade. Paradoxalmente, apesar das vantagens e do baixo custo em comparau00e7u00e3o u00e0s telhas de barro e de fibrocimento, os cavacos raramente su00e3o usados. O estudo realizado pelo Instituto Floresta Tropical apresenta as vantagens do uso do cavaco, de forma a resgatu00e1-lo como uma boa opu00e7u00e3o para a construu00e7u00e3o civil rural e para a gerau00e7u00e3o de renda, clamando a atenu00e7u00e3o das agu00eancias licenciadoras para a necessidade de regulamentau00e7u00f5es especu00edficas que simplifiquem o acesso aos produtos florestais originados tradicionalmente no mercado formal. Apresenta uma anu00e1lise de viabilidade econu00f4mica, de forma a comparar os custos associados u00e0 produu00e7u00e3o e ao uso do cavaco em comparau00e7u00e3o u00e0s telhas de barro e de fibrocimento. Os dados foram coletados no Centro de Manejo Florestal Roberto Bauch, Paragominas. Foram utilizadas duas u00e1rvores de Holopyxidium jarana. As coletas de dados ocorreram em duas etapas. Em 2009, foram selecionados aleatoriamente 30 cavacos para a mensurau00e7u00e3o de seu comprimento, largura e espessura. Em 2011, foram sorteados 20% da produu00e7u00e3o diu00e1ria e foram medidos produtividade no trabalho e consumo de combustu00edveis e de materiais. A produu00e7u00e3o e uso do cavaco apresenta vantagens em relau00e7u00e3o a produtos alternativos para a cobertura de casas e estruturas rurais, alu00e9m de ser uma opu00e7u00e3o de renda interessante para pequenos produtores rurais. Entretanto, tal pru00e1tica tem sido lentamente abandonada por diferentes razu00f5es, e buscamos atravu00e9s deste resumo resgatar o seu uso.

I metalli pesanti sono importanti inquinanti ambientali e la loro tossicità è un problema di crescente importanza per motivi ecologici, evolutivi, nutrizionali e ambientali. Il cadmio (Cd) è, tra i metalli pesanti non essenziali, quello che ha attirato maggiormente l'attenzione nel campo della nutrizione delle piante, a causa della sua potenziale tossicità per l'uomo, e anche la sua relativa mobilità nel sistema suolo-pianta. Il progetto di dottorato si è proposto lo studio dei meccanismi di risposta - su base micro e macroscopica, fisiologica, ecologica e biochimica - allo stress da cadmio, su una pianta di elevato interesse agricolo ed economico: l’orzo (Hordeum vulgare). In particolare, sono stati osservati gli effetti causati dal cadmio su piantine d’orzo esposte alle concentrazioni di 10-6 M, 10-5 M e 10-4 M. Sono stati determinati la presenza di danni ultrastrutturali indotti dalla presenza del cadmio mediante microscopia elettronica a scansione (SEM) e a trasmissione (TEM), e relazionati alla presenza e alle variazioni delle varie isoforme (citosolica, cloroplastica e mitocondriale) di Heat Shock Protein 70 (HSP70), nelle radici e nelle foglie, dei campioni stressati. Inoltre, è stata determinata la presenza di alterazioni fenotipiche delle piantine d’orzo, sia a livello della componente epigea (numero di foglie, lunghezza e larghezza delle foglie) che della parte ipogea (lunghezza delle radici primarie e numero di radici secondarie). Dall’analisi macroscopica si osserva una modificazione dell’apparato radicale in funzione della concentrazione di cadmio, con la riduzione della lunghezza delle radici primarie e un maggior numero di radici secondarie, risultati confermati anche dalla microscopia elettronica a scansione. Sono stati misurati importanti parametri eco-fisiologici come la percentuale di inibizione della crescita, il contenuto di acqua (WC), il contenuto di pigmenti fotosintetici (clorofilla a, clorofilla b e carotenoidi) e il contenuto d’amido. Tali parametri solo stati relazionati con i principali indici fotochimici: massima resa quantica del PSII (Fv/Fm), resa quantica del trasporto elettronico del PSII (QY), attività di trasporto elettronico (ETR) e quenching non-fotochimico (NPQ),allo scopo di valutare l’effetto dei metalli sull’efficienza di conversione della luce ai centri di reazione. Il cadmio causa, inoltre, una inibizione della crescita con conseguente minore produzione di biomassa, di un minor contenuto d’acqua, di pigmenti fotosintesi e di amido e questi risultati sono collegati alle alterazioni macroscopiche come la minore lunghezza e la maggiore larghezza delle foglie. La riorganizzazione dell’apparato radicale induce la presenza di una maggior superficie di assorbimento dell’azoto con conseguente incremento dell’attività della nitrato reduttasi. Lo stress non ha effetti verso le proteine Rubisco e D1, confermando che il cadmio influisce nella biosintesi della clorofilla, sui centri di reazione e nella catena di trasporto degli elettroni del PSII. Tali risultati sono correlati alla presenza di danni ultrastrutturali a livello dei cloroplasti che presentano una disorganizzazione tilacoidale e l’inclusione di briglie citopaslamtiche. L’attività della glucosio-6-fostato deidrogenasi (G6PDH), sia in foglie che i radici, risulta essere lievemente ridotta dalla presenza degli ioni cadmio anche se i livelli, nelle foglie, della isoforma Cyt della G6PDH rimangono invariati, i livelli dell’isoforma P2 aumentano alla concentrazione Cd++ 10-4 M, mentre i livelli dell’isoforma P1 presentano un andamento contrario rispetto l’isoforma P2; inoltre, non si osservano variazioni significative delle isoforme Cyt e P2 a livello radicale. Il cadmio induce un severo stress abiotico confermato dall’incremento in funzione dell’aumento di concentrazione del metallo dei livelli delle varie isoforme HSP70 e da una loro diminuzione in funzione del tempo e dell’entità del danno osservato. Infine, il cadmio induce una evidente variazione del profilo amminoacidico delle piantine stressate. In conclusione, il cadmio è tra i metalli più tossici per le specie vegetali e sebbene l’orzo rappresenti un organismo coltivato tra i più resistenti agli stress abiotici, sono stati riscontrati danni evidenti sulla sfera micro e macroscopica, fisiologica, ecologica e biochimica.

The aim of this work is to evaluate the effects of freshwater pollution in the heavily contaminated Sarno River (Campania, South Italy), using Pellia neesiana (Pelliaceae Metzgeriales) in order to propose this liverwort as a potential bioindicator, able to record the effects of water pollution, particularly the one related to metal (loid) contamination. Samples of P. neesiana in nylon bags were disposed floating for one week on the waters of Sarno River in three sites characterised by an increasing pollution. As control, some specimens were cultured in vitro in Cd- and Pb-added media, at the same pollutants' levels as measured in the most polluted site. P. neesiana cell ultrastructure was modified and severe alterations were observed in chloroplasts from samples exposed in the most polluted site, and Cd- and Pb-cultured samples. Concurrently, a strong increase in the occurrence of Heat shock proteins 70 (HSP70) was detected in gametophytes following the pollution gradient. In conclusion, ultrastructural damages can be directly related to HSP 70 occurrence in liverwort tissues, and proportional to the degree of pollution present in the river; thus our study suggests P. neesiana as an affordable bioindicator of freshwaters pollution.

Zn deficiency is currently listed as a major risk factor for human health. Recently, a complimentary solution to mineral malnutrition termed 'biofortification' has been proposed. The aim of this study was to investigate the possible effects of a Zn-biofortification program on Zn levels, amino acidic profile and the phytochemicals content in an edible leafy vegetable, such as Brassica oleracea cv. Bronco. Our results indicate that supplementation of 80-100μM Zn is optimal for maintaining the normal growth of plants and to promote the major Zn concentration in the edible part of B. oleracea. Any further increase of Zn supply induced an accumulation of total amino acids, and increased the enzymatic activities involved in sulfur assimilation and synthesis of phenols, finally resulting in a foliar accumulation of glucosinolates and phenolic compounds. Thus, it could be proposed that the growth of B. oleracea under 80-100μM Zn may increase the intake of this micronutrient and other beneficial compunds for the human health.

This study evaluate the effects of freshwater toxic metal pollution in the highly contaminated Sarno River (South Italy), by using the aquatic moss L. riparium in bags at 3 representative sites of the river. Biological damage was assessed by studying metal bioaccumulation, ultrastructural changes, oxidative stress, as Reactive Oxygen Species (ROS) production and Glutathione S-transferase (GST ) activity, and Heat Shock Proteins 70 (HSP70) induction. The results showed that L. riparium is a valuable bioindicator for toxic metal pollution of water ecosystem, accumulating different quantities of toxic metals from the aquatic environment. Toxic metal pollution caused severe ultrastructural damages, such as the increase of ROS production and the induction of GST and HSP70s in the samples from the polluted sites. To assess the role and the effects of toxic metals on plants, L. riparium samples cultured in vitro were exposed to Cd, Cr, Cu, Fe, Ni, Pb, Zn at the same concentrations as measured at the 3 sites. Ultrastructural damages, ROS, GST, HSP70s were also severely affected by toxic metals. From our finding we can conclude that L. riparium can be proposed as a model organism in biomonitoring projects, and GST and HSP70s as promising biomarkers of metal toxicity.

Cadmium represents one of the most toxic pollutants in plant ecosystems: at high concentrations it can cause severe effects, such as plant growth inhibition, decrease in photosynthesis and changes in plant basal metabolism. Changes in pigments’ content, RubisCO large subunit, and D1 protein indicated a severe reduction in photosynthetic efficiency. Furthermore, the decrease of nitrate reductase activity and changes in free amino acids levels show a general stress condition of nitrogen assimilation. Cadmium increased the activities of ROS scavenging enzymes; among these, ascorbate peroxidase rate was the most noticeably increased. It is worth noting that glucose-6-phosphate dehydrogenase (G6PDH; EC 1.1.1.64), showed changes in both activities and occurrence during cadmium stress. Interestingly, our data suggest that G6PDH would modulate redox homeostasis under metal exposure, and possibly satisfy the increased request of reductants to counteract the oxidative burst induced by cadmium. Therefore, the results suggest that APX and G6PDH may play a pivotal role to counteract the oxidative stress induced by cadmium in young barley plants.

Zinc (Zn) deficiency is a major problem in agricultural crops of many world regions. N metabolism plays an essential role in plants and changes in their availability and their metabolism could seriously affect crop productivity. The main objective of the present work was to perform a comparative analysis of different strategies against Zn deficiency between two plant species of great agronomic interest such as Lactuca sativa cv. Phillipus and Brassica oleracea cv. Bronco. For this, both species were grown in hydroponic culture with different Zn doses: 10μM Zn as control and 0.01μM Zn as deficiency treatment. Zn deficiency treatment decreased foliar Zn concentration, although in greater extent in B. oleracea plants, and caused similar biomass reduction in both species. Zn deficiency negatively affected NO3(-) reduction and NH4(+) assimilation and enhanced photorespiration in both species. Pro and GB concentrations were reduced in L. sativa but they were increased in B. oleracea. Finally, the AAs profile changed in both species, highlighting a great increase in glycine (Gly) concentration in L. sativa plants. We conclude that L. sativa would be more suitable than B. oleracea for growing in soils with low availability of Zn since it is able to accumulate a higher Zn concentration in leaves with similar biomass reduction. However, B. oleracea is able to accumulate N derived protective compounds to cope with Zn deficiency stress.

The effects of freshwater pollution in the highly contaminated river Sarno (Campania, Southern Italy) have been evaluated using bags containing the aquatic plant Lemna minor (Lemnacee, Arales), in order to determine morpho-physiological modifications as a response to pollutants. The exposition of Lemna bags for 7 days on three different sites along the river path showed alterations in chloroplasts and vacuoles shape and organization. Moreover, some specimens were exposed in vitro at the same heavy metal (HM) concentrations measured in the polluted sites of the river, and compared with data from the bag experiment; to verify the dose and time dependent effects, samples were exposed to HM in vitro at concentrations ranging from 10−6 to 10−4 M up to 7 days. Transmission electron microscopy (TEM) observations on in vitro plants confirmed that ultrastructural alterations affected most of plastids and the shape of different subcellular structures, namely vacuoles; in in vitro stressed specimens, Heat Shock Proteins 70 (Hsp70) levels changed, in dependence of changing levels of HM measured in different sites along the river path. Thus L. minor exhibited a possible correlation between the levels of HM pollution and Hsp70 occurrence; interestingly, the data presented showed that copper specifically increased Hsp70 levels at concentrations detected in polluted river waters, whereas cadmium and lead did not; on the other side, the latter represent highly toxic elements when specimens were exposed to higher levels in vitro. The effects of specific elements in vitro are compared to those observed in bags exposed along the river path; thus results are examined in order to propose L. minor as an organism able to be utilized to monitor heavy metals pollution; the possibility of using Hsp70 s as specific markers of HM pollution is discussed.

We report here the first characterization of a GLNB1 gene coding for the PII protein in leguminous plants. The main purpose of this work was the investigation of the possible roles played by this multifunctional protein in nodulation pathways. The Lotus japonicus LjGLB1 gene shows a significant transcriptional regulation during the light-dark cycle and different nitrogen availability, conditions that strongly affect nodule formation, development, and functioning. We also report analysis of the spatial profile of expression of LjGLB1 in root and nodule tissues and of the protein’s subcellular localization. Transgenic L. japonicus lines overexpressing the PII protein were obtained and tested for the analysis of the symbiotic responses in different conditions. The uncoupling of PII from its native regulation affects nitrogenase activity and nodule polyamine content. Furthermore, our results suggest the involvement of PII in the signaling of the nitrogen nutritional status affecting the legumes’ predisposition for nodule formation.