Challenges and opportunities to regulate mineral transport in rice

Iron (Fe) is an essential mineral for plants and its deficiency as well as toxicity severely affects plant growth and development. Although Fe is ubiquitous in mineral soils, its acquisition by plants is difficult to regulate particularly in acidic and alkaline soils. Under alkaline conditions, where lime is abundant, Fe and other mineral elements are sparingly soluble. In contrast, under low pH conditions, especially in paddy fields, Fe toxicity could occur. Fe uptake is complicated and could be integrated with copper (Cu), manganese (Mn), zinc (Zn), and cadmium (Cd) uptake. Plants have developed sophisticated mechanisms to regulate the Fe uptake from soil and its transport to root and above-ground parts. Here, we review recent developments in understanding metal transport and discuss strategies to effectively regulate metal transport in plants with a particular focus on rice.

Suberin plasticity to developmental and exogenous cues is regulated by a set of MYB transcription factors

Suberin is a hydrophobic biopolymer that can be deposited at the periphery of cells, forming protective barriers against biotic and abiotic stress. In roots, suberin forms lamellae at the periphery of endodermal cells where it plays crucial roles in the control of water and mineral transport. Suberin formation is highly regulated by developmental and environmental cues. However, the mechanisms controlling its spatiotemporal regulation are poorly understood. Here, we show that endodermal suberin is regulated independently by developmental and exogenous signals to fine-tune suberin deposition in roots. We found a set of four MYB transcription factors (MYB41, MYB53, MYB92, and MYB93), each of which is individually regulated by these two signals and is sufficient to promote endodermal suberin. Mutation of these four transcription factors simultaneously through genome editing leads to a dramatic reduction in suberin formation in response to both developmental and environmental signals. Most suberin mutants analyzed at physiological levels are also affected in another endodermal barrier made of lignin (Casparian strips) through a compensatory mechanism. Through the functional analysis of these four MYBs, we generated plants allowing unbiased investigation of endodermal suberin function, without accounting for confounding effects due to Casparian strip defects, and were able to unravel specific roles of suberin in nutrient homeostasis.

An Insect- and Rain-Proof Net Raises the Production and Quality of Chinese Bayberry by Preventing Damage From Insects and Altering Bacterial Communities

Chinese bayberry (Myrica rubra) is a popular, nutrient- and antioxidant-rich fruit in Asia. However, it is susceptible to Drosophila during ripening, which disrupts production and causes economic loss. This study compared the effects of insecticides, insect-proof nets (IPNs), and insect- and rain-proof nets (IRPNs) on Chinese bayberry production and quality. Drosophila was absent in fruits from IPN- or IRPN-treated trees but only significantly reduced by insecticides. IPNs and IRPNs significantly increased fruit diameter, weight, edible rate and the Brix/acid ratio, and IRPNs had the strongest effect. Analysis of 16S rDNA showed that fruits collected from differently treated trees had unique bacterial communities. In IRPN fruits, Acetobacter and Gluconobacter were significantly decreased, reducing sugar consumption and disease; in addition, PICRUSt analysis predicted imputed functional profiles related to carbohydrate and nitrogen metabolism and mineral transport for fruit growth and development. This study proposed the use of IRPNs for improving Chinese bayberry production and quality.

Assessing TBM performance in heterogeneous rock masses

A major challenge that TBM performance is requested to deal with for a successful and effective progress is tunnelling through lithologically and geomechanically heterogeneous rock masses. Such heterogeneous environments are common and recent tunnel examples in the UK include the Hinckley Point C offshore cooling tunnels being driven through interbedded carbonaceous mudstone/shales and argillaceous limestone and the Anglo American’s Woodsmith Mine Mineral Transport System tunnel in Redcar Mudstone with beds of ironstone. This inherent geological heterogeneity leads to difficult tunnelling conditions that initially stem from predicting a sound and representative ground model that can be used to preliminary assess the TBM performance. In this work, an exhaustive review of existing TBM Penetration Rate (PR) methods identified that no models address the issue of parameter selection for heterogeneous rock masses comprising layers with different rock strengths. Consequently, new approaches are required for estimating rock mass behaviour and machine performance in such environments. In the presented work the Blue Lias Formation (BLI), which is characterised by its layered rock mass, comprising very strong limestone, interbedded with weak mudstone and shales, is investigated. BLI formation is considered herein being a representative example of lithological heterogeneity. Based on the fieldwork carried out in three localities in the Bristol Channel Basin (S. Wales and Somerset), geological models are produced based on which a geotechnical model is developed, and four ground types are determined. Implications of the current findings for TBM performance are assessed, including faulting, groundwater inflow and excavation stability with a particular focus on both PR and advance rate. A modified approach using the existing empirical models is proposed, developed and presented in this paper that can be used as a guide to determine TBM performance in heterogeneous rock masses reducing the risk of cost and time overruns.

10 Mechanisms by Which Amino Acids May Enhance Mineral Absorption in Animals

Both macro- and trace minerals of the diet face similar barriers to their absorption. Minerals residing in the lumen of the GI tract, whether it be the rumen, stomach, small or large intestine of an animal, have to cross the apical and basolateral membranes of enterocytes or perhaps the tight junctions between cells of the epithelium layer to enter the interstitial space below the epithelium. Once there they can diffuse into the venous blood of the GI tract in order to reach the cells of the body requiring the minerals for various functions. Considerable evidence suggests that amino acids can enhance the absorption of minerals, particularly the trace minerals. However, the exact mechanisms by which amino acids enhance mineral absorption remain elusive. In this presentation, the role dietary amino acids may play in forming ionic and hydrogen bonds with trace minerals to enhance their solubility over the absorptive epithelium is discussed. In addition, minerals covalently bonded to amino acids have been utilized as a means of enhancing trace mineral absorption, particularly for Cu, Fe, Zn and Mn. These forms of trace minerals can be more effectively absorbed than traditional sulfate forms of these minerals. It has been suggested the amino acid bonding to the trace mineral works by preventing formation of insoluble mineral complexes with dietary chelators within the lumen of the GI tract. It has also been suggested that the amino acid -mineral complex can utilize the more efficient amino acid transporters to cross the apical membrane of the enterocytes instead of the usual mineral transport mechanisms for each mineral. The evidence for each of these mechanisms will be discussed along with the possible repercussions these mechanisms might have on mineral requirements of the animal.

Endocrine Diseases of Newborn: Epidemiology, Pathogenesis, Therapeutic Options, and Outcome “Current Insights Into Disorders of Calcium and Phosphate in the Newborn”

The physiology and regulation of bone minerals in the fetus and the newborn is significantly different from children and adults. The bone minerals calcium, phosphate and magnesium are all maintained at higher concentrations in utero to achieve adequate bone accretion. This is an integral component of normal fetal development which facilitates safe neonatal transition to post-natal life. When deciphering the cause of bone mineral disorders in newborns, the potential differential diagnosis list is broad and complex, including several extremely rare conditions. Also, significant discoveries including new embryological molecular genetic transcription factors, the role of active placental mineral transport, and hormone regulation factors have changed the understanding of calcium and phosphate homeostasis in the fetus and the newborn. This article will guide clinicians through an updated review of calcium and phosphate physiology, then review specific conditions pertinent to successful neonatal care. Furthermore, with the advancement of increasingly rapid molecular genetic testing, genomics will continue to play a greater role in this area of fetal diagnostics and prognostication.

Suberin plasticity to developmental and exogenous cues is regulated by a set of MYB transcription factors

Suberin is a hydrophobic biopolymer that can be deposited at the periphery of cells, forming protective barriers against biotic and abiotic stress. In roots, suberin forms lamellae at the periphery of endodermal cells where it plays crucial roles in the control of water and mineral transport. Suberin formation is highly regulated by developmental and environmental cues. However, the mechanisms controlling its spatiotemporal regulation are poorly understood. Here, we show that endodermal suberin is regulated independently by developmental and exogenous signals to fine tune suberin deposition in roots. We found a set of four MYB transcription factors (MYB41, MYB53, MYB92 and MYB93), that are regulated by these two signals, and are sufficient to promote endodermal suberin. Mutation of these four transcription factors simultaneously through genome editing, lead to a dramatic reduction of suberin formation in response to both developmental and environmental signals. Most suberin mutants analyzed at physiological levels are also affected in another endodermal barrier made of lignin (Casparian strips), through a compensatory mechanism. Through the functional analysis of these four MYBs we generated plants allowing unbiased investigations of endodermal suberin function without accounting for confounding effects due to Casparian strip defects, and could unravel specific roles of suberin in nutrient homeostasis.