scholarly journals From Plant to Paddy—How Rice Root Iron Plaque Can Affect the Paddy Field Iron Cycling

Soil Systems ◽  
2020 ◽  
Vol 4 (2) ◽  
pp. 28 ◽  
Author(s):  
Markus Maisch ◽  
Ulf Lueder ◽  
Andreas Kappler ◽  
Caroline Schmidt
Keyword(s):  
Paddy Field ◽  
Iron Oxidation ◽  
Microbial Transformation ◽  
Root Surface ◽  
Plaque Formation ◽  
Iron Plaque ◽  
Iron Cycling ◽  
Root Tips ◽  
Soil Matrix ◽  
Spatio Temporal

Iron plaque on rice roots represents a sink and source of iron in paddy fields. However, the extent of iron plaque in impacting paddy field iron cycling is not yet fully deciphered. Here, we followed iron plaque formation during plant growth in laboratory-controlled setups containing a transparent soil matrix. Using image analysis, microsensor measurements, and mineral extractions, we demonstrate that radial oxygen loss (ROL) is the main driver for rhizosphere iron oxidation. While O2 was restricted to the vicinity of roots, root tips showed highest spatio-temporal variation in ROL (<5–50 µM) following diurnal patterns. Iron plaque covered >30% of the total root surface corresponding to 60–180 mg Fe(III) per gram dried root and gradually transformed from low-crystalline minerals (e.g., ferrihydrite) on root tips, to >20% higher-crystalline minerals (e.g., goethite) within 40 days. Iron plaque exposed to an Fe(III)-reducing Geobacter spp. culture resulted in 30% Fe(II) remobilization and >50% microbial transformation to Fe(II) minerals (e.g., siderite, vivianite, and Fe–S phases) or persisted by >15% as Fe(III) minerals. Based on the collected data, we estimated that iron plaque formation and reductive dissolution can impact more than 5% of the rhizosphere iron budget which has consequences for the (im)mobilization of soil contaminants and nutrients.

scholarly journals Iron oxidation on the surface of adventitious roots and its relation to aerenchyma formation in rice genotypes

2014 ◽  
Vol 38 (1) ◽  
pp. 185-192 ◽  
Author(s):  
Marquel Jonas Holzschuh ◽  
Filipe Selau Carlos ◽  
Felipe de Campos Carmona ◽  
Humberto Bohnen ◽  
Ibanor Anghinoni
Keyword(s):  
Chemical Reduction ◽  
Rice Genome ◽  
Reduction Process ◽  
Root Surface ◽  
Plaque Formation ◽  
Iron Plaque ◽  
Rice Cultivars ◽  
Aerenchyma Formation ◽  
Free Oxygen ◽  
Rice Genotypes

Establishment of the water layer in an irrigated rice crop leads to consumption of free oxygen in the soil which enters in a chemical reduction process mediated by anaerobic microorganisms, changing the crop environment. To maintain optimal growth in an environment without O2, rice plants develop pore spaces (aerenchyma) that allow O2 transport from air to the roots. Carrying capacity is determined by the rice genome and it may vary among cultivars. Plants that have higher capacity for formation of aerenchyma should theoretically carry more O2 to the roots. However, part of the O2 that reaches the roots is lost due to permeability of the roots and the O2 gradient created between the soil and roots. The O2 that is lost to the outside medium can react with chemically reduced elements present in the soil; one of them is iron, which reacts with oxygen and forms an iron plaque on the outer root surface. Therefore, evaluation of the iron plaque and of the formation of pore spaces on the root can serve as a parameter to differentiate rice cultivars in regard to the volume of O2 transported via aerenchyma. An experiment was thus carried out in a greenhouse with the aim of comparing aerenchyma and iron plaque formation in 13 rice cultivars grown in flooded soils to their formation under growing conditions similar to a normal field, without free oxygen. The results indicated significant differences in the volume of pore spaces in the roots among cultivars and along the root segment in each cultivar, indicating that under flooded conditions the genetic potential of the plant is crucial in induction of cell death and formation of aerenchyma in response to lack of O2. In addition, the amount of Fe accumulated on the root surface was different among genotypes and along the roots. Thus, we concluded that the rice genotypes exhibit different responses for aerenchyma formation, oxygen release by the roots and iron plaque formation, and that there is a direct relationship between porosity and the amount of iron oxidized on the root surface.

scholarly journals Influence of Iron Plaque on Accumulation and Translocation of Cadmium by Rice Seedlings

2021 ◽  
Vol 13 (18) ◽  
pp. 10307
Author(s):  
Abu Bakkar Siddique ◽  
Mohammad Mahmudur Rahman ◽  
Mohammad Rafiqul Islam ◽  
Muhammad Tahir Shehzad ◽  
Bibhash Nath ◽  
...  
Keyword(s):  
Root Surface ◽  
Plaque Formation ◽  
Iron Plaque ◽  
Soil Types ◽  
Shoot Biomass ◽  
Rice Seedlings ◽  
Cd Accumulation ◽  
Rice Plants ◽  
The Impact ◽  
Rice Tissues

This study investigated the impact of soil type and rice cultivars on variations in the iron plaque formation and cadmium (Cd) accumulation by different portions of rice seedlings under the influence of Fe amendment. The experiments were performed in pots under glasshouse conditions using two typical paddy soils. Rice seedlings were exposed to three concentrations of Cd (0, 1 and 3 mg kg−1 soil) and Fe (0, 1.0 and 2.0 g kg−1 soil). The results revealed that shoot biomass decreased by 12.2–23.2% in Quest and 12.8–30.8% in Langi in the Cd1.0 and Cd3.0 treatments, while shoot biomass increased by 11.2–19.5% in Quest and 26–43.3% in Langi in Fe1.0 and Fe2.0 as compared to the Fe control. The Cd concentration in the roots and shoots of rice seedlings were in the order of Langi cultivar > Quest cultivar, but the Fe concentration in rice tissues showed the reverse order. Fe plaque formations were promoted by Fe application, which was 7.8 and 10.4 times higher at 1 and 2 g kg−1 Fe applications compared to the control Fe treatment. The Quest cultivar exhibited 13% higher iron plaque formation capacity compared to the Langi cultivar in both soil types. These results indicate that enhanced iron plaque formation on the root surface was crucial to reduce the Cd concentration in rice plants, which could be an effective strategy to regulate grain Cd accumulation in rice plants.

Iron plaque formation on wetland-plant roots accelerates removal of water-borne antibiotics

2018 ◽  
Vol 433 (1-2) ◽  
pp. 323-338 ◽  
Author(s):  
Yiping Tai ◽  
Nora Fung-Yee Tam ◽  
Rui Wang ◽  
Yang Yang ◽  
Jianhua Lin ◽  
...  
Keyword(s):  
Plaque Formation ◽  
Iron Plaque ◽  
Plant Roots ◽  
Wetland Plant ◽  
Water Borne

Iron plaque formation in the roots of Pistia stratiotes L.: importance in phytoremediation of cadmium

2019 ◽  
Vol 21 (2) ◽  
pp. 120-128 ◽  
Author(s):  
Kambam Tamna Singha ◽  
Abin Sebastian ◽  
Majeti Narasimha Vara Prasad
Keyword(s):  
Plaque Formation ◽  
Iron Plaque ◽  
Pistia Stratiotes

Biophysical interactions at the root–soil interface: a review

1998 ◽  
Vol 130 (1) ◽  
pp. 1-7 ◽  
Author(s):  
I. M. YOUNG
Keyword(s):  
Crop Yields ◽  
Farming Systems ◽  
Root Surface ◽  
Biological Properties ◽  
Water Dynamics ◽  
Limited Attention ◽  
Small Scale ◽  
Soil Matrix ◽  
Increased Risk ◽  
Soil Interface

Soil close to roots generally has chemical, physical and biological properties which are significantly different from those of soil located some distance away (Jenny & Grossenbacher 1963; Hawes & Pueppke 1986; Young 1995). The root–soil interface is defined as soil near to or adhered to the root surface to some small distance into the soil matrix. This distance may vary between <1 mm and c. 10 mm. Working definitions include rhizosphere, where ‘zones of influence’ are inferred, and rhizosheath, when soil adhered to the root is discussed. Most work carried out at the root–soil interface has concentrated on biological or chemical processes, due both to the fact that the relevant techniques required to examine these processes have been more advanced than the physical techniques, and also because the farmer is generally offered either biological or chemical solutions to his everyday problems, as these are readily accessible, easy to use and cheap. The main manipulation of soil physical conditions occurs during cultivations, and the addition or removal of water from the soil profile. Intensive cultivations are a regular occurrence in many farming systems, despite the potential drawbacks: damage of the soil structure, leading to reduced crop yields and an increased risk of erosion.The main aim of this review is not to cover all the complex issues related to the root–soil interface. Instead, it concentrates on the biophysical processes which, compared with conventional plant physiological and soil microbiological research, have attracted relatively limited attention (e.g. see Waisel et al. 1996). The review examines small-scale (μm-mm) interactions and, where possible, links their impact to the larger scale. Three interacting areas are investigated: the physical structure of the soil and root growth, water dynamics and microbial dynamics.

scholarly journals In Situ Phylogenetic Structure and Diversity of Wild Bradyrhizobium Communities

2009 ◽  
Vol 75 (14) ◽  
pp. 4727-4735 ◽  
Author(s):  
J. L. Sachs ◽  
S. W. Kembel ◽  
A. H. Lau ◽  
E. L. Simms
Keyword(s):  
Host Species ◽  
Root Surface ◽  
Small Subset ◽  
Root Tips ◽  
Phylogenetic Structure ◽  
Pure Cultures ◽  
Nodulation Status ◽  
Host Infection ◽  
Root Surfaces

ABSTRACTBacteria often infect their hosts from environmental sources, but little is known about how environmental and host-infecting populations are related. Here, phylogenetic clustering and diversity were investigated in a natural community of rhizobial bacteria from the genusBradyrhizobium. These bacteria live in the soil and also form beneficial root nodule symbioses with legumes, including those in the genusLotus. Two hundred eighty pure cultures ofBradyrhizobiumbacteria were isolated and genotyped from wild hosts, includingLotus angustissimus,Lotus heermannii,Lotus micranthus, andLotus strigosus. Bacteria were cultured directly from symbiotic nodules and from two microenvironments on the soil-root interface: root tips and mature (old) root surfaces. Bayesian phylogenies ofBradyrhizobiumisolates were reconstructed using the internal transcribed spacer (ITS), and the structure of phylogenetic relatedness among bacteria was examined by host species and microenvironment. Inoculation assays were performed to confirm the nodulation status of a subset of isolates. Most recovered rhizobial genotypes were unique and found only in root surface communities, where little bacterial population genetic structure was detected among hosts. Conversely, most nodule isolates could be classified into several related, hyper-abundant genotypes that were phylogenetically clustered within host species. This pattern suggests that host infection provides ample rewards to symbiotic bacteria but that host specificity can strongly structure only a small subset of the rhizobial community.

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