Both plants and humans require mineral elements for their healthy growth and development. Mineral elements in the soil are taken up by the plant roots and transported to the edible parts for human ...consumption through various different transporters. An ideal future crop for human health should be rich in essential mineral elements but with less toxic elements in the edible parts. However, due to the great difference in the numbers and amounts of mineral elements required between plants and humans, it is a challenge to balance plant growth and nutrient requirement for humans. In this article, we mainly focus on the transport system of mineral elements from soil to grain in rice, a staple food for half of the world's population, and discuss recent progress on the underlying genetic and physiological mechanisms. Examples are given for silicon, zinc, and iron essential/beneficial for both plants and humans, selenium and iodine only essential for humans, and toxic cadmium and arsenic for all organisms. Manipulation of some transporters for these elements, especially those localized in the node for allocation of mineral elements to the grain, has been successful in generating rice with higher density and bioavailability of essential elements but with less accumulation of toxic elements. We provide our perspectives toward breeding future crops for human health.
An ideal future crop for human health should be rich in essential mineral elements but with less toxic elements in the edible parts. However, it is a challenge to balance plant growth and nutrient requirement for humans. This articlefocuses on recent progress made in rice on understanding the transport mechanisms of mineral elements that are closely related to human health. The authors also discuss how to manipulate mineral transporters for nutritious and safe crop production and provide some perspectives toward breeding future crops for human health.
Arsenic (As) contamination in paddy soil can cause phytotoxicity and elevated As accumulation in rice grain. Rice varieties vary in As uptake and tolerance, but the underlying mechanisms remain ...unclear. In this study, the aus variety Kasalath was found to be more tolerant to arsenate As(V) than the japonica variety Nipponbare, but the two varieties showed similar arsenite As(III) tolerance. Nipponbare took up more phosphate (Pi) and As(V) than Kasalath. The expression of genes for Pi transporters or Pi homeostasis regulation was quantified. Nipponbare showed 2- to 3-fold higher expression of the Pi transporter genes OsPT2 and OsPT8 than Kasalath. Two ospt8 mutants were isolated from the Kasalath background and compared with an ospt8 mutant in the Nipponbare background. Mutation in OsPT8 in both backgrounds decreased As(V) uptake by 33–57%, increased As(V) tolerance assayed by root elongation by >100-fold, and abolished the varietal differences in As(V) uptake and tolerance. The results show that OsPT8 plays a key role in As(V) uptake and that As(V) uptake mediated by OsPT8 exerts a profound toxic effect on root elongation. The results also suggest that differential OsPT8 expression explains the varietal differences in As(V) uptake and tolerance between Kasalath and Nipponbare.
SUMMARY
Glycosyltransferases (GTs) form a large family in plants and are important enzymes for the synthesis of various polysaccharides, but only a few members have been functionally characterized. ...Here, through mutant screening with gene mapping, we found that an Oryza sativa (rice) mutant with a short‐root phenotype was caused by a frame‐shift mutation of a gene (OsGT14;1) belonging to the glycosyltransferase gene family 14. Further analysis indicated that the mutant also had a brittle culm and produced lower grain yield compared with wild‐type rice, but the roots showed similar root structure and function in terms of the uptake of mineral nutrients. OsGT14;1 was broadly expressed in all organs throughout the entire growth period, with a relatively high expression in the roots, stems, node I and husk. Furthermore, OsGT14;1 was expressed in all tissues of these organs. Subcellular observation revealed that OsGT14;1 encoded a Golgi‐localized protein. Mutation of OsGT14;1 resulted in decreased cellulose content and increased hemicellulose, but did not alter pectin in the cell wall of roots and shoots. The knockout of OsGT14;1 did not affect the tolerance to toxic mineral elements, including Al, As, Cd and salt stress, but did increase the sensitivity to low pH. Taken together, OsGT14;1 located at the Golgi is required for growth of both roots and shoots in rice through affecting cellulose synthesis.
Significance Statement
Glycosyltransferases (GTs) form a large family in plants and are important enzymes for the synthesis of various polysaccharides, but only a few members have been functionally characterized. Here, through mutant screening with gene mapping and detailed functional analysis, we demonstrated that OsGT14;1 is required for the growth of both roots and shoots in rice through affecting cellulose synthesis.
Geometric error is one of the important errors that affect the machining of five-axis machine tools and how to identify th8e vital geometric error is effective for compensation. For this reason, the ...global sensitivity analysis of geometric errors for five-axis machine tools is an effective means to find the vital geometric error items that affect the machining accuracy of machine tools. However, it is difficult to deal with the higher order items of error parameter coupling in the global sensitivity analysis. In this paper, a novel global sensitivity analysis method for vital geometric error based on multi-body theory and truncated Fourier expansion is proposed. First, multi-body system (MBS) and homogeneous transformation matric (HTM) methods are used to establish the position error of the machine tool. Then, the output value of the error parameter is represented as the amplitude of the truncated Fourier series and the global sensitivity index is represented by the ratio of its amplitude variance to the total function variance through normalization processing. Moreover, the global sensitivity analysis method is presented to calculate the sensitivity index of each geometric error parameter and the vital geometric error parameters have been identified. Finally, an experiment on compensating for vital geometric error parameters is performed and the experimental results show that the proposed method is feasible and accurate.
Thermal deformation is the main factor of the machining accuracy for grinding machines, which seriously restricts the precision improvement of grinding machines. However, at present, there are little ...researches on thermal error prediction, and the accuracy of the prediction model is comparatively low. Thus, a novel approach for thermal deformation prediction of grinding machine spindle based on heat energy conduction principle and neural network is proposed in this paper. Firstly, the temperature sensors’ pairs are applied to measure the temperature deviation between the spindle surface and its adjacent ambient which are directly related to the heat energy exchange. Secondly, the temperature deviations of each segment of the spindle are taken as inputs, which will exist and accumulate in the form of heat energy subsequently in the convolutional neural network. Meanwhile, the accumulated heat energy is mixed and transferred to the different segments of the spindle in the convolutional neural network. Thirdly, the thermal deformation caused by the increment of heat energy is considered as the output of thermal error prediction result based on the principle of heat energy conduction. Finally, the simulations and experiments are implemented to validate the feasibility and effectiveness of the proposed method.
At present, it is difficult to predict the operation accuracy of machine tools in the preliminary design stage. How to quantitatively reflect the contribution of tolerance on the position error of ...machine tool has a significant guidance for machine tool design stage. Thus, this paper presents a sensitivity analysis method based on components tolerance, which can clearly give the machine tool designer key the tolerances. Firstly, taking the translational axis as the research object, the operation accuracy model of Y-axis is established based on the homogeneous transform matrix (HTM) and multi-body system (MBS) theory. Meanwhile, the relationship between tolerances and geometric errors has been mapped by the Fourier expansion and the model of parameters have been identified by self-design simulation. As a basis, the tolerance sensitivity analysis (TSA) method based on the single-factor partial derivation is constructed to acquire the key tolerance parameters. Finally, the result of the experiment shows that the assembly tolerance of the Y-Z plane of the base, the manufacturing tolerance of the lead screw and the assembly tolerance of the X-Y plane of the carriage contribute a great deal to the position error, which needs to be strictly controlled in the future design to improve the accuracy of the machine tool.
Background and aims Plants are able to take up inorganic arsenic (As) and methylated As, but whether the mode of phytotoxicity and the detoxification mechanism differ between different As species ...remains unclear. This study aimed to investigate the differences in phytotoxicity and detoxification mechanism between arsenate As(V), monomethylarsonic acid MMA(V) and dimethylarsinic acid DMA(V). Methods Arabidopsis thaliana was grown in agarsolidified medium, hydroponic or soil pot experiments. Root and shoot growth, seed production, As accumulation and oxidative stress indicators of wild-type plants exposed to As(V), MMA(V) and DMA(V) were compared. The role of thiols in As detoxification was investigated using a specific inhibitor of glutathione (GSH) biosynthesis and the mutants defective in GSH synthesis (cad2-1), phytochelatin (PC) synthesis (cad1-3) or to-noplast transporters for As(III)-PCs (abcc1-2). Results Methylated As species, especially DMA(V), were more toxic than As(V) for growth and seed production in A. thaliana. Methylated As species were more efficiently translocated from roots to shoots and from shoots to seeds than As(V). DMA(V) exposure resulted in a greater oxidative stress than other As species. As(V) and MMA(V) induced the production of non-protein thiols (NPT), but DMA(V) did not. The GSH inhibitor BSO greatly enhanced the sensitivity to As(V) and MMA(V), but decreased the sensitivity to DMA(V). The mutants cad1-3, cad2-1 and abcc1-2 were similarly hypersensitive to As(V) and MMA(V), but not to DMA(V). As(V) and MMA(V) enhanced the expression of the sulphur assimilation genes encoding ATP Sulphurylase (ATPS) and adenosine-5′-phosphosulphate reductase (APR1) more than DMA(V). Conclusions DMA(V) is more toxic to A. thaliana than As(V) or MMA(V). The detoxification mechanism for MMA(V) is similar to that for As(V), involving thiol production, complexation with PCs and vacuolar sequestration. This mechanism is ineffective for the detoxification of DMA(V).
In the magnetic composite fluid (MCF) polishing process, appropriate polishing parameters are the basis of achieving high-quality polishing without damage. Appropriate polishing parameters are mainly ...based on an accurate polishing model and an excellent polishing parameters optimization algorithm. However, due to the complicated principle of MCF polishing and various influencing elements, traditional modeling methods have the limitations of low accuracy, poor application, and difficulty in correcting. Therefore, it is challenging to obtain the optimal polishing quality by optimizing the polishing parameters based on the traditional model. This study proposed an online modeling approach considering data cleaning based on machine learning modeling, and the particle swarm optimization (PSO) algorithm was used to optimize polishing parameters. Then, copper polishing experiments were carried out to validate the modeling and optimization methods. The results demonstrate that the proposed machine learning online modeling method can establish an accurate MCF polishing model, and the nano-scale fine polishing of copper can be achieved by the optimized polishing parameters of PSO, and the surface roughness of the copper sample was reduced by 85% to 0.031 μm.
WRKYs are transcriptional factors involved in stress tolerance and development of plants. In the present study, we characterized
, a group IIa WRKY gene, in rice, because its expression was found to ...be upregulated by arsenate exposure in previous transcriptomic studies. Subcellular localization using YFP-OsWRKY28 fusion protein showed that the protein was localized in the nuclei. Transgenic rice plants expressing
::GUS suggested that the gene was expressed in various tissues in the whole plant, with a strong expression in the root tips, lateral roots and reproductive organs. The expression of
was markedly induced by arsenate and other oxidative stresses. In a hydroponic experiment, loss-of-function mutation in
resulted in lower accumulation of arsenate and phosphate concentration in the shoots. The mutants showed altered root system architecture, with fewer lateral roots and shorter total root length than wild-type plants. In a soil pot experiment, the mutants produced lower grain yield than wild-type because of reduced fertility and smaller effective tiller numbers. Transcriptomic profiling using RNA-seq showed altered expression in the mutant of genes involved in the biosynthesis of phytohormones, especially jasmonic acid (JA). Exogenous JA treatments mimicked the phenotypes of the
mutants with inhibited root elongation and decreased arsenate/phosphate translocation. Our results suggested that
affected arsenate/phosphate accumulation, root development at the seedling stage and fertility at the reproductive stage possibly by influencing homeostasis of JA or other phytohormones.
This paper proposed an integrated geometric error identification and prediction method to solve the uncertainty problem of the PDGEs of rotary axis. First, based on homogeneous transform matrix (HTM) ...and multi-body system (MBS) theory, The transfer matrix only considering the C-axes rotated is derived to the position error model. Then a geometric errors identification of rotary axis is introduced by measuring the error increment in three directions. Meanwhile the geometric errors of C-axis are described as truncated Fourier polynomials caused by fitting discrete values. Thus, The geometric error identification is converted into the function coefficient. Finally, the proposed new prediction and identification model of PDGEs in the global frame are verified through simulation and experiments with double ball-bar tests.
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