ROLLBAR · Roots in armour - a barrier induced to protect against intrusion of soil phytotoxins?
Horizon 2020 — Marie Skłodowska-Curie Actions
- Duration
- 2019-09-02 → 2021-09-01
- EU contribution
- €207,312
- Participants
- 1
- Scheme
- MSCA-IF-EF-ST
Lines connect the coordinator with its partners.
Results in brief
Roots in armour - a barrier induced to protect against intrusion of soil phytotoxins?
The ROLLBAR project has investigated the interaction of roots of wetland plants with the surrounding soil. Emphasis has been on radial oxygen loss (ROL) from the roots to the soil and the root trait that several wetland plants have evolved to reduced ROL, called barrier to ROL. This root trait confers flood tolerance to wetland plants and it is widely studied in rice. The barrier to ROL is a deposition of chemical compounds in the outer cell layers of roots physically restricting the loss of oxygen from the roots to the anoxic soil. High internal oxygen status enables plants to thrive in flooded soils, where oxygen is low, and to possibly restrict the intrusion of volatile phytotoxins (e.g. sulfides). In the absence of a ROL barrier, oxygen escapes from the roots and oxidizes the rhizosphere resulting in precipitation of iron at the root surfaces, with the formation of the so-called iron plaques consisting of rust. Plaques can potentially reduce gas exchanges and phytotoxin intrusion acting as a physical shield, an armour. The objective of the ROLLBAR project was to investigate the role of the ROL barrier and of iron plaques in restricting the diffusion of gases, allowing plants to grow in flooded anoxic soils. In addition, ROLLBAR aimed at elucidating the potential role of iron plaques to assist oxygen retention in roots by restricting oxygen diffusion to the soil. This restriction potentially affects any other gas, including organic volatile molecules or sulfide that are commonly produced in anoxic soils. The society will benefit from the project via inclusion of this root trait in future climate-smart crops that possess genes involved in ROL barrier formation but also from possible new approaches in phytoremediation with plants showing large ROL resulting in high amount of iron plaques. The ROL barrier as well as iron plaques are key features enabling growth in flooded soils and plaques could have an important role in flooded and salt-affected soils, since salt affects the formation of iron crusts. Therefore, these two traits will receive large attention in the future, considering that agricultural fields and natural areas will be more exposed to flooding due to increase of the mean sea level and climate change resulting in extreme weather events.
Data: CORDIS, © European Union
Project objective
ROLLBAR focuses 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. Plants inhabiting tidal environments with frequent floods possess internal gas-filled spaces in their tissues (aerenchyma), facilitating oxygen (O2) diffusion from shoot to roots. This trait enables tolerance to the inherently low O2 availability in flooded soils. Such soils show high levels of reduced compounds harmful for plants, amongst which sulfide is a potent phytotoxin. The role of ROL and a root ROL barrier in flood tolerance is widely recognised whereas the function of these traits in protecting roots from phytotoxin intrusion in plant tissues is still controversial. The ROLLBAR project aims to shed light on this topic. O2 escapes from roots via ROL and oxidises the rhizosphere; sulfides are chemically oxidised to sulfate and reduced iron [Fe(II)] is oxidised to Fe(III), which can precipitate on root surfaces as iron minerals called iron plaques. Both ROL and iron plaques can protect plants from sulfide intrusion. When the root ROL barrier (suberin depositions in the outer cell layer) is developed, oxidation of sulfides occurs inside roots, as a result of the better O2 status further enhanced by photosynthesis in light. The ROL barrier could impede sulfide intrusion acting as a shield, although there is no experimental evidence to support this function. 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? The novelty of the project relies on obtaining direct measurements of O2 and sulfides at the root-rhizosphere interface of key species using advanced contemporary technology such as microsensors, root-sleeving electrodes and planar optodes.
Original text from CORDIS.
Participants
- KOBENHAVNS UNIVERSITET · KOBENHAVNCoordinatorDenmark
Links
Data: CORDIS, © European Union