Poject available for master (and graduated) students!
Formation and functions of iron plaques at the root-soil interface in flooded soils
Specific topic: Influence of edaphic conditions on Fe plaque formation and Fe mobility
Salinization and increased flooding associated to global mean sea-level rise will threaten the ecosystem function of tidal fresh-water wetlands. In these environments, C sequestration is linked to soil Fe redox cycling, that is driven by microbe-plant-roots interactions. The project aims at investigating how soil properties affects the formation of the Fe plaques, triggered by the oxygen released by the roots of hydrophytes, under variable flooding and salinity stresses. Rice and close related wild species will be used as a model plant. The role of organic matter, carbonates and the nature and amount of iron oxides will be examined towards plaque formation rates, thickness and morphology. Dynamics of redox processes and effects of complexation on Fe mobilisation/immobilisation will be investigated.
If interest in the project, you are highly welcome to contact us!
Roots in armour! the ROLLBAR project
The project has been granted by the European Committee and referred to my
Marie Skลodowska-Curie individual fellowship H2020-MSCA-IF-2018-839542
ROLLBAR focused on the role of two contrasting strategies against sulfide toxicity of saltmarsh plant species: i) root radial oxygen loss (ROL) and ii) formation of a root barrier to ROL. The role of ROL and a root ROL barrier in protecting roots from phytotoxin intrusion in plant tissues is still controversial.
The project aims to address three major scientific questions: i) which chemical compounds trigger the formation of a root barrier to ROL? ii) can the ROL barrier prevent sulfide intrusion into roots? and iii) can ROL and iron plaques reduce sulfide intrusion into roots?
Project updates
02/09/2021 - The project has been recently concluded but additional results will be soon available! The work on iron plaques turned to be quite challenging during the lock-down but preliminary results interesting evidences on the physical effect of plaques on ROL. Data are under processing.
06/07/2021 - ROL can be measured in different ways, some are qualitative or semi-quantitative, others are quantitative and can be very precise. With my team and a fruitful collaborations with prof. Mikio Nakazono and dr. Juan Jiménez, we are summarising all the available methodologies for measuring ROL. From planar optodes to microsensors, we will provide protocols for new possible unexperienced users.
20/05/2021 - thanks to Lucas Peralta efforts, we have now published an exciting paper in New Phytologist on novel functions of the barrier to ROL in restricting diffusion of gases other than oxygen. Interesting, the barrier seems to have a potential role in drought tolerance, a trait that we are going to investigate further!
20/11/2020 - In presence of iron, plaque formation depends on root radial oxygen loss (ROL), soil redox and pH conditions. Salinity is also an important factor to consider, especially due to the expected increase of the sea level in coastal areas. Salinity can improve plaque formation but also can enhance plaque dissolution. Iron oxides dissolution in presence of salt can e.g. enhance iron uptake in plants. To test the hypothesis of plaque dissolution in presence of salt, the salt treatment will be imposed on artificial roots with well-formed plaques.
11/06/2020 - Iron plaques are commonly found on root surfaces of wetland and aquatic plants. Radial oxygen loss (ROL) is the main responsible for iron oxidation and precipitation on root surfaces. Nevertheless, plaques are formed when reduced iron is present, which is known to trig the formation of the ROL barrier and reduce rhizosphere oxidation. In order to disentangle the effect of the barrier and of iron plaques on ROL, I’m going to use artificial roots and induce plaques under controlled laboratory conditions.
15/11/2019 - the selection of a model plant using wild species is an effort. Many studies where conducted on rice genotypes but no information is available on wild wetland species about the presence of a constitutively formed or an inducible barrier to ROL. I am currently growing wild plants and testing the presence of a barrier using the methylene blue staining technique, a simple method to visualise the oxygen released radially from roots. When oxygen is loss, the methylene reagent turns to bluish and reflects the absence of a barrier.
Common reed die-back and climate change: where is the link?
L'Oréal-UNSECO award For Women in Science, year 2021
The reed die-back syndrome has severely affected Phragmites australis populations in Europe and North America. Eutrophication and salinity, caused by sea level rise, were indicated as causes of this phenomenon, but their mechanism of action is not clear. My hypothesis is that die-back resides on the impaired nutrient status of plants in brackish waters and on nutrient deficiency caused by modifications at the plant-soil inetrface. A key role could be played by Fe plaques, which can enhance or reduce the availability of specific micronutrients.
The project aims to clarify how changes in salinity and humic substances (amount and redox properties) affect the nutritional status of common reed (P. australis) through their effect on Fe plaques.
Thesis project offer!
Tentative project 1: Iron plaques as a winning trait against salt stress in Phragmites australis.
The aim of the project is to assess the advantage of individuals with iron plaques to tolerate moderate to high levels of salinity and their uptake ability towards key elements.
The hypothesis is that the presence of iron plaques can improve plant tolerance to salt stress, by regulating nutrient uptake.
Tentative project 2: Do humic substances interfere with iron plaque ability to modulate nutrient uptake in Pragmites australis?
The main objective is to characterised iron plaques formed in presence or absence of humic substances, in order to test the possible different ability of plaques to trap (and release) micro and micronutrients.
It is expected that plaques formed in presence of humic substances can differently affect plant growth because of their different structure and element "trapping" capacity.
SalStrAl
inter-departmental
project
The project aims to improve knowledge on action mechanisms of humic substances (HS) and halotolerant plant growth-promoting rhizobacteria (HT-PGPR) in alleviating salt stress in crops, in order to implement a combined protocol for maintaining acceptable crop yields in salt-affected soils. In particular, the project challenges the use of HS, derived from sources available in great quantity and at low costs, together with HT-PGPR strains, extracted from the rhizosphere of key halophytes, in improving germination and growth of two target crops, i.e. maize and soybean.
Primary objectives are: i) to investigate how appropriate HS preparations may modify the rhizosphere; ii) and to individuate HS properties affecting HT-PGPR inoculation success in soil.
Thesis project offer!
Tentative project 1: Response of halo tolerant plant growth-promoting bacteria to reactive organic matter
The aim of the project is to analysed the benefits that rizobacteria can obtain from the presence of humic substances in soils.
The idea is that humic substances can boost baterial activity which in turn can facilitate plant growth.
Tentative project 2: Can plant growth-promoting bacteria improve salt stress resistence in crops?
Inoculation of halo tolerant strains isolated from the rhizosphere of halopthytes can promote plant growth of crops. They can act on physiological processes of the plant following a hormon-like activity.
The project aims at applying this theory on salt affected soils cultivated with maize and soybean.
Mercury contamination
Environmental Risk Assessment for Hg: from soil to crops
The Environmental Risk Assessment is a complex approach aimed at investigating the "spread" of a contaminant in different compartments of the environment, up to human health. Specifically, our focus is on the toxicity of Hg to soil microbial biomass and its potential uptake by crops in contaminated soils.
Thesis project offer!
Tentative project: Mobility of chemical forms of mercury in soils affected by seawater intrusion
Preliminary data shows that mercury mobility is enahnced at increasing soil salinity, and especially for methyl mercury. The hypothesis is that seawater intrusion can strongly affect contaminated soils in terms of microbial activity and plant uptake. Even in soils characterised by stable Hg forms (cinnabar), the increase of salinity can affect cultivated fields exposed to seawater intrusion.
A
new agreement will be established in 2022
with the regional administration (Regione FVG) and new projects will be soon available.
Internships
Students in connection with companies
Our group collaborates with the companies SICIT Group and HARPO S.p.A. on joined research project. Short term projects and internships are available with these two companies.
Prof. Marco Contin has a long established collaboration with SICIT group on biostimulants. The company is among the few companies in the world using amino acids in the market of biostimulants in agriculture, of which it is now a world leader.
HARPO S.p.A. develops green roofing systems and has a particular interest on substrates. It aims at increasing substrate quality and performance while mantaining plant biomass productivity.
Want to do an experience abroad? Transboundary projects for students!
in collaboration with the University of Neuchâtel
Pedofauna biodiversity of three plantations
Biodiversity of tree plantations improves the quality of soil organic matter by its humification and its organic-mineral complexes stabilization. Earthworms play a fundamental role in soil mixing and favour aggregation of soil mineral particles that in turn leads to improved soil structure. Should we expect some effects of plant species richness on earthworm populations?
The main aim of the work is to investigate the effect of tree biodiversity on the composition of pedofauna in soils of 20 years old tree plantations and in relation to potential soil C sequestration. The study will focus on earthworms and on the relationships between ecological categories, biomass and abundance.
Plant invasion in the karst environment
Ailanthus altissima is one of the most aggressive and dangerous species in the north east of Italy. The species releases from roots allelopathic substances to avoid competition and its growth rate is much larger that that of autochthonous species. Plant invasion affects vegetation dynamics, soil properties, microbial communities and pedofauna biodiversity.
The main objective of the work is to investigate the effect A. altissima invasion on soil biodiversity, focusing on earthworm community as target group. We expect a larger biodiversity in natural environments compared to monospecific populations of A. altissima , even if the abundance of earthworms could be larger due to the larger plant biomass of the invader.
Selected ongoing reserach projects
Plant tissue porosity explains plant survival during flooding
The 48-h access to the SYRMEP beamline at ELETTRA synchrotrone (Trieste, IT) enabled us to obtain high-resolution tomograms of two target wetland species. The visualization is now being processed and will be used to model internal oxygen diffusion from shoot to roots of the two species. We aim to better understand aerenchyma (air spaces inside tissues) connectivity and the reasons of the ability of these plants to survive under water.
Competition or facilitation under flooding stress?
Competition commonly prevails upon environmental stresses (eg. flooding) in extreme habitats like saltmarshes. Some species could facilitate the spread of other plants or compete for space and resources. The main aim of the project is to detect the possible facilitation or competition ability of wetland species along the flooding gradient.
Influence of iron plaques on radial oxygen loss
Iron plaques are reported to reduce root ROL (radial oxygen loss) in some species. However, the presence of reduced iron can induce the formation of a barrier to ROL. The project aims at measuring the physical reduction in gas exchanges mediated by the plaque, using artifical roots or roots of species withouht exodermis (not able to develop apoplastic barriers).
Overview of selected past student projects
SPS method for soil AVS determination
A new colorimetric method was developed at the University of Udine, Soil Chemistry section, for the field determination of soil AVS, a particular fraction of soil sulfides.
(bachelor thesis F. Bertolutti, 2015)
SEM/AVS approach for potential toxicity risk assessment
The SEM/AVS approach is a simple index to estimate the potential toxicity risk for plants and animals due to soil metals. When the ratio is > 1, a plausible risk is expected.
(master thesis P. Bartolucci, 2017)
Hg uptake in crops
Hg uptake was tested in barley using natural contaminated soils (Isonzo river) or lab treated sediments. The treatments referred to different chemical forms of Hg, with consequently different bioavailability.
(bachelor thesis S. Clinori, 2018)
Silvia's thesis was awarded in 2021 as best bachelor thesis on ecosystems and waters of the Isonzo area.