229 research outputs found
Effect of aluminium exposure on the release of organic acids and genistein from the roots of Lupinus albus L. plants
No full textAluminum (Al) toxicity is one of the main factors limiting crop productivity in strongly acidic soils. Plant tolerance to Al toxicity has been widely studied even if the mechanisms involved in the plant response are yet not fully elucidated. White lupin is well known to release organic acids and flavonoids under nutrient deficiency, while less is known about its response to elevated Al concentrations. The aim of this work was therefore to shed light to the adaptive response of white lupin to Al toxicity, analysing the root exudate pattern. A pH buffer (MES) or inhibitor compounds were used in order to further investigate the mechanisms adopted by white lupin to release root exudates as response to Al toxicity. The results showed that not only organic acids but also phenolic compounds are involved in the response to elevated concentrations of Al together with the alkalinisation of the growth medium
Nitrate removal from polluted water by using a vegetated floating system
No full textNitrate (NO3−) water pollution is one of the most prevailing and relevant ecological issues. For instance, the wide
presence of this pollutant in the environment is dramatically altering the quality of superficial and underground
waters. Therefore,we set up a floating bed vegetatedwith a terrestrial herbaceous species (Italian ryegrass) with
the aim to remediate hydroponic solutions polluted with NO3−.
The floating bed allowed the plants to growand achieve an adequate development. Ryegrasswas not affected by
the treatments. On the contrary, plant biomass production and total nitrogen content (N-K) increased proportionally
to the amount of NO3− applied. Regarding to the water cleaning experiments, the vegetated floating
beds permitted to remove almost completely all the NO3− added from the hydroponic solutions with an initial
concentration of 50, 100 and 150 mg L−1. Furthermore, the calculation of the bioconcentration factor (BCF) indicated
this species as successfully applicable for the remediation of solutions polluted by NO3−. In conclusion, the
results highlight that the combination of ryegrass and the floating bed system resulted to be effective in the remediation
of aqueous solutions polluted by NO3−
Caratterizzazione fisiologica e molecolare del rilascio di essudati radicali in piante di melo sottoposte a stress nutrizionali
No full textEffetto della disponibilità di zolfo sull’assorbimento di nitrato e di solfato in barbatelle di vite allevate in soluzione idroponica
No full textInfluence of different trap solutions on the determination of root exudates in Lupinus albus L
No full textWhite lupin is very often used as a model plant for root exudation studies due to its capability to release huge amounts of organic acids and flavonoids. The complex nature of these organic compounds makes not only their analytical determination difficult but also their extraction from soil samples. For these reasons simplified approaches, as hydroponic-based systems are widely used to study the root exudation. Therefore, the composition of a trap solution is crucial to limit artefacts causing over/underestimation of exudation rates and/or a biased molecular composition of the collected compounds. The present study was aimed at assessing the influence of different trap solutions and collection times on the quali- and quantitative root exudation pattern of white lupin (Lupinus albus L.) grown under phosphorus (P) and iron (Fe) deficiency. Our results suggest that, in works aimed at studying root exudation processes, water is the most effective trap solution to collect the exudates like organic acids and flavonoids, especially in short time (e.g. 2 h). For longer times, low concentrations of Ca could be helpful to limit osmotic stress and possible passive leakage and/or diffusion. The use of bacteriostatic compounds as NaN3 and Micropur bias the results, due to interferences either with the metabolism or inhibition of the exudation processes, especially in the case of flavonoids such as quercetin. Also, the use of a pH buffer solution like 2-(N-morpholino)ethanesulfonic acid (MES) should be avoided for its undesired interferences with the release
Humic Substances Contribute to Plant Iron Nutrition Acting as Chelators and Biostimulants
No full textImprovement of plant iron nutrition as a consequence of metal complexation by humic substances (HS) extracted from different sources has been widely reported. The presence of humified fractions of the organic matter in soil sediments and solutions would contribute, depending on the solubility and the molecular size of HS, to build up a reservoir of Fe available for plants which exude metal ligands and to provide Fe-HS complexes directly usable by plant Fe uptake mechanisms. It has also been shown that HS can promote the physiological mechanisms involved in Fe acquisition acting at the transcriptional and post-transcriptional level. Furthermore, the distribution and allocation of Fe within the plant could be modified when plants were supplied with water soluble Fe-HS complexes as compared with other natural or synthetic chelates. These effects are in line with previous observations showing that treatments with HS were able to induce changes in root morphology and modulate plant membrane activities related to nutrient acquisition, pathways of primary and secondary metabolism, hormonal and reactive oxygen balance. The multifaceted action of HS indicates that soluble Fe-HS complexes, either naturally present in the soil or exogenously supplied to the plants, can promote Fe acquisition in a complex way by providing a readily available iron form in the rhizosphere and by directly affecting plant physiology. Furthermore, the possibility to use Fe-HS of different sources, size and solubility may be considered as an environmental-friendly tool for Fe fertilization of crops
Strategia di risposta alla carenza di fosforo in piante di lupino; relazioni tra la capacità di assorbimento del fosfato e il rilascio di essudati radicali
No full textTranscriptomic Analysis Highlights Reciprocal Interactions of Urea and Nitrate for Nitrogen Acquisition by Maize Roots
No full textEven if urea and nitrate are the two major nitrogen (N) forms applied as fertilizers in agriculture and occur concomitantly in soils, the reciprocal influence of these two N sources on the mechanisms of their acquisition are poorly understood. Therefore, molecular and physiological aspects of urea and nitrate uptake were investigated in maize (Zea mays), a crop plant consuming high amounts of N. In roots, the urea uptake was stimulated by the presence of urea in the external solution, indicating the presence of an inducible transport system. On the other hand the presence of nitrate depressed the induction of urea uptake and, at the same time, the induction of nitrate uptake was depressed by the presence of urea. The expression of about 60,000 transcripts of maize in roots was monitored by microarray analyses and the transcriptional patterns of those genes involved in nitrogen acquisition were analysed by real-time RT-PCR. In comparison to the treatment without added N, the exposure of maize roots to urea modulated the expression of only very few genes, such as asparagine synthase. On the other hand, the concomitant presence of urea and nitrate enhanced the overexpression of genes involved in nitrate transport (NRT2), assimilation (nitrate and nitrite reductase, glutamine synthetase 2) and determined a specific response of 41 transcripts, including glutamine synthetase 1-5, GOGAT, shikimate kinase and arogenate dehydrogenase. Based also on the real-time RT-PCR analysis, the transcriptional modulation induced by both sources might determine an increase in N-metabolism promoting a more efficient assimilation of taken-up nitrogen
Induction of nitrate uptake in Sauvignon Blanc and Chardonnay grapevines depends on the scion and is affected by the rootstock
No full textBackground and Aims
Nitrate is a major form of inorganic nitrogen present in cultivated soils; however, information on the mechanisms responsible for uptake of the anion in grapevines is scarce.
Methods and Results
The response to external nitrate was studied in two clones of the cultivars Chardonnay and Sauvignon Blanc. Grapevines, own-rooted or grafted on the two rootstocks SO4 and K5BB, were grown in nutrient solution and, after a period of nitrogen (N)-deprivation, exposed to 0.2 or 1mmol/L nitrate. The uptake was an inducible process, operated by high- and low-affinity transport systems. The magnitude and time dependence of the induction varied as a function of the clone. Uptake rate as a function of nitrate external concentration showed a multiphasic pattern. Although nitrate exposure caused a transient up-regulation of nitrate influx transporter genes, a clear correlation with the rise in nitrate uptake could not be found; in contrast, a negative relationship between changes in uptake rates and expression of a nitrate efflux transporter gene was observed.
Conclusions
In the grapevine, the response of low- and high-affinity transport systems to external nitrate was favoured by the presence of the rootstock and also dependent on the characteristics of the scion. Low-affinity uptake and efflux from root cells conceivably play an important role in the overall N-nitrate acquisition.
Significance of the Study
This study shows that activation of mechanisms involved in nitrate uptake in the grapevine is strongly affected by the scion-rootstock combination. Results may be significant for developing agronomic practices and selection programmes related to nitrogen use in the grapevine
Forme di ferro presenti in frazioni umiche a diversa solubilit : caratterizzazione chimica e valutazione della disponibilit da parte di radici di piante di cetriolo
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