Genome-wide characterization of i-motifs and their potential roles in the stability and evolution of transposable elements in rice.

I-motifs (iMs) are non-canonical DNA secondary structures that fold from cytosine (C)-rich genomic DNA regions termed putative i-motif forming sequences (PiMFSs). The structure of iMs is stabilized by hemiprotonated C-C base pairs, and their functions are now suspected in key cellular processes in human cells such as genome stability and regulation of gene transcription. In plants, their biological relevance is still largely unknown. Here, we characterized PiMFSs with high potential for i-motif formation in the rice genome by developing and applying a protocol hinging on an iMab antibody-based immunoprecipitation (IP) coupled with high-throughput sequencing (seq), consequently termed iM-IP-seq. We found that PiMFSs had intrinsic subgenomic distributions, cis-regulatory functions and an intricate relationship with DNA methylation. We indeed found that the coordination of PiMFSs with DNA methylation may affect dynamics of transposable elements (TEs) among different cultivated Oryza subpopulations or during evolution of wild rice species. Collectively, our study provides first and unique insights into the biology of iMs in plants, with potential applications in plant biotechnology for improving important agronomic rice traits.

CF1 reduces grain-cadmium levels in rice (Oryza sativa).

Rice (Oryza sativa) is a leading source of dietary cadmium (Cd), a non-essential heavy metal that poses a serious threat to human health. There are significant variations in grain-Cd levels in natural rice populations, which make the breeding of low-Cd rice a cost-effective way to mitigate grain-Cd accumulation. However, the genetic factors that regulate grain-Cd accumulation have yet to be fully established, thereby hindering the development of low-Cd varieties. Here, we reported a low-Cd quantitative trait locus, CF1, that has the potential to reduce Cd accumulation in rice grains. CF1 is allelic to the metal transporter OsYSL2, which transports Fe from the roots to the shoots. However, it is incapable of binding Cd, and thus, reduces grain-Cd levels indirectly rather than directly in the form of upward delivery. Further analysis showed that high expression levels of CF1 improve Fe nutrition in the shoots, subsequently inhibiting Cd uptake by systemically inhibiting expression of the main Cd uptake gene OsNramp5 in the roots. Compared with the CF1 allele from '02428' (CF102428 ), higher expression levels of CF1 from 'TQ' (CF1TQ ) increased the Fe contents and decreased Cd levels in rice grains. In natural rice populations, CF1TQ was found to be a minor allele, while CF102428 is present in most japonica rice, suggesting that CF1TQ could be widely integrated into the japonica rice genome to generate low-Cd varieties. Overall, these results broaden our mechanistic understanding of the natural variation in grain-Cd accumulation, supporting marker-assisted selection of low-Cd rice.

Epigenomic features of DNA G-quadruplexes and their roles in regulating rice gene transcription.

A DNA G-quadruplex (G4) is a non-canonical four-stranded nucleic acid structure involved in many biological processes in mammals. The current knowledge on plant DNA G4s, however, is limited; whether and how DNA G4s impact gene expression in plants is still largely unknown. Here, we applied a protocol referred to as BG4-DNA-IP-seq followed by a comprehensive characterization of DNA G4s in rice (Oryza sativa L.); we next integrated dG4s (experimentally detectable G4s) with existing omics data and found that dG4s exhibited differential DNA methylation between transposable element (TE) and non-TE genes. dG4 regions displayed genic-dependent enrichment of epigenomic signatures; finally, we showed that these sites displayed a positive association with expression of DNA G4-containing genes when located at promoters, and a negative association when located in the gene body, suggesting localization-dependent promotional/repressive roles of DNA G4s in regulating gene transcription. This study reveals interrelations between DNA G4s and epigenomic signatures, as well as implicates DNA G4s in modulating gene transcription in rice. Our study provides valuable resources for the functional characterization or bioengineering of some of key DNA G4s in rice.

Characterization of functional relationships of R-loops with gene transcription and epigenetic modifications in rice.

We conducted genome-wide identification of R-loops followed by integrative analyses of R-loops with relation to gene expression and epigenetic signatures in the rice genome. We found that the correlation between gene expression levels and profiled R-loop peak levels was dependent on the positions of R-loops within gene structures (hereafter named "genic position"). Both antisense only (ASO)-R-loops and sense/antisense (S/AS)-R-loops sharply peaked around transcription start sites (TSSs), and these peak levels corresponded positively with transcript levels of overlapping genes. In contrast, sense only (SO)-R-loops were generally spread over the coding regions, and their peak levels corresponded inversely to transcript levels of overlapping genes. In addition, integrative analyses of R-loop data with existing RNA-seq, chromatin immunoprecipitation sequencing (ChIP-seq), DNase I hypersensitive sites sequencing (DNase-seq), and whole-genome bisulfite sequencing (WGBS or BS-seq) data revealed interrelationships and intricate connections among R-loops, gene expression, and epigenetic signatures. Experimental validation provided evidence that the demethylation of both DNA and histone marks can influence R-loop peak levels on a genome-wide scale. This is the first study in plants that reveals novel functional aspects of R-loops, their interrelations with epigenetic methylation, and roles in transcriptional regulation.

The Harbinger transposon-derived gene PANDA epigenetically coordinates panicle number and grain size in rice.

Transposons significantly contribute to genome fractions in many plants. Although numerous transposon-related mutations have been identified, the evidence regarding transposon-derived genes regulating crop yield and other agronomic traits is very limited. In this study, we characterized a rice Harbinger transposon-derived gene called PANICLE NUMBER AND GRAIN SIZE (PANDA), which epigenetically coordinates panicle number and grain size. Mutation of PANDA caused reduced panicle number but increased grain size in rice, while transgenic plants overexpressing this gene showed the opposite phenotypic change. The PANDA-encoding protein can bind to the core polycomb repressive complex 2 (PRC2) components OsMSI1 and OsFIE2, and regulates the deposition of H3K27me3 in the target genes, thereby epigenetically repressing their expression. Among the target genes, both OsMADS55 and OsEMF1 were negative regulators of panicle number but positive regulators of grain size, partly explaining the involvement of PANDA in balancing panicle number and grain size. Moreover, moderate overexpression of PANDA driven by its own promoter in the indica rice cultivar can increase grain yield. Thus, our findings present a novel insight into the epigenetic control of rice yield traits by a Harbinger transposon-derived gene and provide its potential application for rice yield improvement.

Natural variation in the HAN1 gene confers chilling tolerance in rice and allowed adaptation to a temperate climate.

Rice (Oryza sativa L.) is a chilling-sensitive staple crop that originated in subtropical regions of Asia. Introduction of the chilling tolerance trait enables the expansion of rice cultivation to temperate regions. Here we report the cloning and characterization of HAN1, a quantitative trait locus (QTL) that confers chilling tolerance on temperate japonica rice. HAN1 encodes an oxidase that catalyzes the conversion of biologically active jasmonoyl-L-isoleucine (JA-Ile) to the inactive form 12-hydroxy-JA-Ile (12OH-JA-Ile) and fine-tunes the JA-mediated chilling response. Natural variants in HAN1 diverged between indica and japonica rice during domestication. A specific allele from temperate japonica rice, which gained a putative MYB cis-element in the promoter of HAN1 during the divergence of the two japonica ecotypes, enhances the chilling tolerance of temperate japonica rice and allows it to adapt to a temperate climate. The results of this study extend our understanding of the northward expansion of rice cultivation and provide a target gene for the improvement of chilling tolerance in rice.

Characterization and fine mapping of a new dwarf mutant in Brassica napus.

BACKGROUND: Plant height is an important plant characteristic closely related to yield performance of many crops. Reasonable reduction of plant height of crops is beneficial for improving yield and enhancing lodging resistance. RESULTS: In the present study, we described the Brassica napus dwarf mutant bnd2 that was isolated using ethyl methanesulfonate (EMS) mutagenesis. Compared to wild type (WT), bnd2 exhibited reduced height and shorter hypocotyl and petiole leaves. By crossing the bnd2 mutant with the WT strain, we found that the ratio of the mutant to the WT in the F2 population was close to 1:3, indicating that bnd2 is a recessive mutation of a single locus. Following bulked segregant analysis (BSA) by resequencing, BND2 was found to be located in the 13.77-18.08 Mb interval of chromosome A08, with a length of 4.31 Mb. After fine mapping with single nucleotide polymorphism (SNP) and insertion/deletion (InDel) markers, the gene was narrowed to a 140-Kb interval ranging from 15.62 Mb to 15.76 Mb. According to reference genome annotation, there were 27 genes in the interval, of which BnaA08g20960D had an SNP type variation in the intron between the mutant and its parent, which may be the candidate gene corresponding to BND2. The hybrid line derived from a cross between the mutant bnd2 and the commercial cultivar L329 had similar plant height but higher grain yield compared to the commercial cultivar, suggesting that the allele bnd2 is beneficial for hybrid breeding of lodging resistant and high yield rapeseed. CONCLUSION: In this study, we identified a novel dwarf mutant of rapeseed with a new locus, which may be useful for functional analyses of genetic mechanisms of plant architecture and grain yield in rapeseed.

ZINC TRANSPORTER5 and ZINC TRANSPORTER9 Function Synergistically in Zinc/Cadmium Uptake.

The elements Zinc (Zn) and cadmium (Cd) have similar chemical and physical properties, but contrasting physiological effects in higher organisms. In plants, Zn/Cd transport is mediated by various transporter proteins belonging to different families. In this study, we functionally characterized two Zn transporter genes in rice (Oryza sativa), ZINC TRANSPORTER5 (OsZIP5) and ZINC TRANSPORTER9 (OsZIP9), which are tandem duplicates and act synergistically in Zn/Cd uptake. Both genes encode plasma membrane-localized proteins with influx transporter activity. The expression profiles of OsZIP5 and OsZIP9 overlap in the root epidermis and respond to the local Zn status in the root. However, OsZIP9 is also regulated by systemic signals of Zn status from the shoot. OsZIP5 functions redundantly to OsZIP9, but has a relatively weaker effect. Plants with the knockout mutations oszip5, oszip9, or oszip5oszip9 show impaired Zn/Cd uptake. The decreased Zn/Cd levels and growth retardation in the oszip5 mutant are less severe than in the oszip9 mutant. However, the double mutant oszip5oszip9 showed an enhanced Zn deficiency phenotype compared with the single mutants, and few double-knockout plants were able to survive the entire growth cycle without excessive Zn supply. Transgenic plants overexpressing OsZIP9 had markedly enhanced Zn/Cd levels in the aboveground tissues and brown rice. The results of our study fill a gap in current knowledge of Zn uptake and improve our understanding of Zn/Cd accumulation in rice.

Genetic architecture of subspecies divergence in trace mineral accumulation and elemental correlations in the rice grain.

KEY MESSAGE: Genome differentiation has shaped the divergence in element concentration between rice subspecies and contributed to the correlation among trace minerals in the rice grain. The balance between trace minerals in rice, a staple food for more than half of the world's population, is crucial for human health. However, the genetic basis underlying the correlation between trace minerals has not been fully elucidated. To address this issue, we first quantified the concentrations of 11 trace minerals in the grains of a diversity panel of 575 rice cultivars. We found that eight elements were accumulated at significantly different levels between the indica and japonica subspecies, and we also observed significant correlation patterns among a number of elements. Further, using a genome-wide association study, we identified a total of 96 significant association loci (SALs). The differentiation of the major-effect SALs along with the different number of high-concentration alleles present in the two subspecies shaped the different element performance in indica and japonica varieties. Only a few SALs located in clusters and the majority of SALs showed subspecies/subgroup differentiation, indicating that the correlations between elements in the diversity panel were mainly caused by genome differentiation instead of shared genetic basis. The genetic architecture unveiled in this study will facilitate improvement in breeding for trace mineral content.

OsZIP7 functions in xylem loading in roots and inter-vascular transfer in nodes to deliver Zn/Cd to grain in rice.

Rice has lower zinc (Zn) but higher cadmium (Cd) content in grains than other staple crops. Understanding the molecular mechanisms involved in Zn and Cd transportation could benefit homeostatic control, facilitating optimisation of Zn and Cd levels to provide maximum nutrition and safety. In this study, we functionally characterised in planta the rice (Oryza sativa) transporter OsZIP7, which encodes a plasma membrane-localised protein with influx transport activity for both Zn and Cd. OsZIP7 was expressed in parenchyma cells of vascular bundles in roots and nodes. OsZIP7 knockout resulted in retention of Zn and Cd in roots and basal nodes, which hindered their upward delivery to upper nodes and brown rice. And a short-term labelling experiment with the stable 67Zn isotope showed that Zn was distributed toward roots and basal regions and away from leaves in the mutant compared with wild-type rice. Thus, OsZIP7 plays an integral role in xylem loading in roots and inter-vascular transfer in nodes to preferentially deliver Zn and Cd to developing tissues and rice grains.

Integrated analysis of phenome, genome, and transcriptome of hybrid rice uncovered multiple heterosis-related loci for yield increase.

Hybrid rice is the dominant form of rice planted in China, and its use has extended worldwide since the 1970s. It offers great yield advantages and has contributed greatly to the world's food security. However, the molecular mechanisms underlying heterosis have remained a mystery. In this study we integrated genetics and omics analyses to determine the candidate genes for yield heterosis in a model two-line rice hybrid system, Liang-you-pei 9 (LYP9) and its parents. Phenomics study revealed that the better parent heterosis (BPH) of yield in hybrid is not ascribed to BPH of all the yield components but is specific to the BPH of spikelet number per panicle (SPP) and paternal parent heterosis (PPH) of effective panicle number (EPN). Genetic analyses then identified multiple quantitative trait loci (QTLs) for these two components. Moreover, a number of differentially expressed genes and alleles in the hybrid were mapped by transcriptome profiling to the QTL regions as possible candidate genes. In parallel, a major QTL for yield heterosis, rice heterosis 8 (RH8), was found to be the DTH8/Ghd8/LHD1 gene. Based on the shared allelic heterozygosity of RH8 in many hybrid rice cultivars, a common mechanism for yield heterosis in the present commercial hybrid rice is proposed.

Multiple cold resistance loci confer the high cold tolerance adaptation of Dongxiang wild rice (Oryza rufipogon) to its high-latitude habitat.

KEY MESSAGE: Dongxiang wild rice is phylogenetically close to temperate japonica and contains multiple cold resistance loci conferring its adaptation to high-latitude habitat. Understanding the nature of adaptation in wild populations will benefit crop breeding in the development of climate-resilient crop varieties. Dongxiang wild rice (DXWR), the northernmost common wild rice known, possesses a high degree of cold tolerance and can survive overwintering in its native habitat. However, to date, it is still unclear how DXWR evolved to cope with low-temperature environment, resulting in limited application of DXWR in rice breeding programs. In this study, we carried out both QTL mapping and phylogenetic analysis to discern the genetic mechanism underlying the strong cold resistance. Through a combination of interval mapping and single locus analysis in two genetic populations, at least 13 QTLs for seedling cold tolerance were identified in DXWR. A phylogenetic study using both genome-wide InDel markers and markers associated with cold tolerance loci reveals that DXWR belongs to the Or-III group, which is most closely related to cold-tolerant Japonica rice rather than to the Indica cultivars that are predominant in the habitat where DXWR grows. Our study paves the way toward an understanding of the nature of adaptation to a northern habitat in O. rufipogon. The QTLs identified in DXWR in this study will be useful for molecular breeding of cold-tolerant rice.

Arbuscular mycorrhizal symbiosis can mitigate the negative effects of night warming on physiological traits of Medicago truncatula L.

Elevated night temperature, one of the main climate warming scenarios, can have profound effects on plant growth and metabolism. However, little attention has been paid to the potential role of mycorrhizal associations in plant responses to night warming, although it is well known that symbiotic fungi can protect host plants against various environmental stresses. In the present study, physiological traits of Medicago truncatula L. in association with the arbuscular mycorrhizal (AM) fungus Rhizophagus irregularis were investigated under simulated night warming. A constant increase in night temperature of 1.53 °C significantly reduced plant shoot and root biomass, flower and seed number, leaf sugar concentration, and shoot Zn and root P concentrations. However, the AM association essentially mitigated these negative effects of night warming by improving plant growth, especially through increased root biomass, root to shoot ratio, and shoot Zn and root P concentrations. A significant interaction was observed between R. irregularis inoculation and night warming in influencing both root sucrose concentration and expression of sucrose synthase (SusS) genes, suggesting that AM symbiosis and increased night temperature jointly regulated plant sugar metabolism. Night warming stimulated AM fungal colonization but did not influence arbuscule abundance, symbiosis-related plant or fungal gene expression, or growth of extraradical mycelium, indicating little effect of night warming on the development or functioning of AM symbiosis. These findings highlight the importance of mycorrhizal symbiosis in assisting plant resilience to climate warming.

Integrated analysis of miRNA and mRNA expression profiles in response to Cd exposure in rice seedlings.

BACKGROUND: Independent transcriptome profile analyses of miRNAs or mRNAs under conditions of cadmium (Cd) stress have been widely reported in plants. However, a combined analysis of sRNA sequencing expression data with miRNA target expression data to infer the relative activities of miRNAs that regulate gene expression changes resulting from Cd stress has not been reported in rice. To elucidate the roles played by miRNAs in the regulation of changes in gene expression in response to Cd stress in rice (Oryza sativa L.), we simultaneously characterized changes in the miRNA and mRNA profiles following treatment with Cd. RESULTS: A total of 163 miRNAs and 2,574 mRNAs were identified to be differentially expressed under Cd stress, and the changes in the gene expression profile in the shoot were distinct from those in the root. At the miRNA level, 141 known miRNAs belonging to 48 families, and 39 known miRNAs in 23 families were identified to be differentially expressed in the root and shoot, respectively. In addition, we identified eight new miRNA candidates from the root and five from the shoot that were differentially expressed in response to Cd treatment. For the mRNAs, we identified 1,044 genes in the root and 448 genes in the shoot that were up-regulated, while 572 and 645 genes were down-regulated in the root and shoot, respectively. GO and KEGG enrichment analyses showed that genes encoding secondary, metabolite synthases, signaling molecules, and ABC transporters were significantly enriched in the root, while only ribosomal protein and carotenoid biosynthesis genes were significantly enriched in the shoot. Then 10 known miRNA-mRNA interaction pairs and six new candidate ones, that showed the opposite expression patterns, were identified by aligning our two datasets against online databases and by using the UEA sRNA toolkit respectively. CONCLUSIONS: This study is the first to use high throughput DNA sequencing to simultaneously detect changes in miRNA and mRNA expression patterns in the root and shoot in response to Cd treatment. These integrated high-throughput expression data provide a valuable resource to examine global genome expression changes in response to Cd treatment and how these are regulated by miRNAs.

OsMYB103L, an R2R3-MYB transcription factor, influences leaf rolling and mechanical strength in rice (Oryza sativa L.).

BACKGROUND: The shape of grass leaves possesses great value in both agronomy and developmental biology research. Leaf rolling is one of the important traits in rice (Oryza sativa L.) breeding. MYB transcription factors are one of the largest gene families and have important roles in plant development, metabolism and stress responses. However, little is known about their functions in rice. RESULTS: In this study, we report the functional characterization of a rice gene, OsMYB103L, which encodes an R2R3-MYB transcription factor. OsMYB103L was localized in the nucleus with transactivation activity. Overexpression of OsMYB103L in rice resulted in a rolled leaf phenotype. Further analyses showed that expression levels of several cellulose synthase genes (CESAs) were significantly increased, as was the cellulose content in OsMYB103L overexpressing lines. Knockdown of OsMYB103L by RNA interference led to a decreased level of cellulose content and reduced mechanical strength in leaves. Meanwhile, the expression levels of several CESA genes were decreased in these knockdown lines. CONCLUSIONS: These findings suggest that OsMYB103L may target CESA genes for regulation of cellulose synthesis and could potentially be engineered for desirable leaf shape and mechanical strength in rice.

Effects of cluster nursing strategy on neurological and motor functions in patients with moderate to severe traumatic brain injury.

OBJECTIVES: This study aimed to explore the effects of the cluster nursing strategy applied to traumatic brain injury (TBI) patients. Ninety-eight TBI patients admitted to the hospital were selected as the study subjects. METHODS: They were randomized into two groups: the control group and the cluster group, with 49 cases in each group. The control group received routine nursing methods, while the cluster group received cluster nursing strategy. The intervention effects were compared between the two groups. RESULTS: After three months, the total occurrence of complications in the cluster group was significantly lower than that in the control group. Post-intervention, the cluster group had a significantly lower National Institutes of Health Stroke Scale (NIHSS) score and significantly higher Fugl-Meyer score and Loewenstein Occupational Therapy Cognitive Assessment (LOTCA) score compared to the control group. The serum level of glial fibrillary acidic protein (GFAP) in the control group was significantly higher than that in the cluster group, while the serum level of brain-derived neurotrophic factor (BDNF) was significantly lower. CONCLUSIONS: The application of the cluster nursing strategy in the care of TBI patients could effectively reduce the risk of complications and improve neurological, motor, and cognitive functions.

Overexpression of microRNA319 impacts leaf morphogenesis and leads to enhanced cold tolerance in rice (Oryza sativa L.).

MicroRNA319 (miR319) family is one of the conserved microRNA (miRNA) families among diverse plant species. It has been reported that miR319 regulates plant development in dicotyledons, but little is known at present about its functions in monocotyledons. In rice (Oryza sativa L.), the MIR319 gene family comprises two members, Osa-MIR319a and Osa-MIR319b. Here, we report an expression pattern analysis and a functional characterization of the two Osa-MIR319 genes in rice. We found that overexpressing Osa-MIR319a and Osa-MIR319b in rice both resulted in wider leaf blades. Leaves of osa-miR319 overexpression transgenic plants showed an increased number of longitudinal small veins, which probably accounted for the increased leaf blade width. In addition, we observed that overexpressing osa-miR319 led to enhanced cold tolerance (4 °C) after chilling acclimation (12 °C) in transgenic rice seedlings. Notably, under both 4 and 12 °C low temperatures, Osa-MIR319a and Osa-MIR319b were down-regulated while the expression of miR319-targeted genes was induced. Furthermore, genetically down-regulating the expression of either of the two miR319-targeted genes, OsPCF5 and OsPCF8, in RNA interference (RNAi) plants also resulted in enhanced cold tolerance after chilling acclimation. Our findings in this study demonstrate that miR319 plays important roles in leaf morphogenesis and cold tolerance in rice.

THIS1 is a putative lipase that regulates tillering, plant height, and spikelet fertility in rice.

Proper branching and successful reproductive growth is of great importance for rice productivity. Substantial progress has been made in uncovering the molecular mechanisms underlying tillering control and spikelet sterility. However, rice tillering is developmentally controlled, and how it is regulated coordinately with reproductive growth remains unclear. This study characterized a rice mutant, the most obvious phenotypes of which are high tillering, reduced height, and infertile spikelets (named this1). Similarly to the high tiller number and dwarf mutants in rice, the increased tiller number of this1 plants is ascribed to the release of tiller bud outgrowth rather than to increased tiller bud formation. In the this1 mutant, however, the accelerated rate of branching was delayed until the stem elongation stage, while other mutants lost the ability to control branching at all developmental stages. The seed-setting rate of this1 was less than half that of the wild type, owing to defects in pollen maturation, anther dehiscence, and flower opening. Histological analyses showed that the mutation in this1 resulted in anisotropic cell expansion and cell division. Using a map-based cloning approach, This1 was found to encode a class III lipase. Homology searches revealed that THIS1 is conserved in both monocots and eudicots, suggesting that it plays fundamental role in regulating branch and spikelet fertility, as well as other aspects of developmental control. The relative change in expression of marker genes highlighted the possibility that This1 is involved in phytohormone signalling pathways, such as those for strigolactone and auxin. Thus, This1 provides joint control between shoot branching and reproductive development.

Stress and Internet Addiction: Mediated by Anxiety and Moderated by Self-Control.

Background: The link between stress and Internet addiction (IA) has been confirmed. However, the mechanism underlying the correlation is poorly understood. Thus, the current study proposed a moderated mediation model to test the mediating role of anxiety and the moderating role of self-control (SC) in the link between stress and IA. Methods: Eight hundred and sixty-one Chinese college students (Mage = 20.62 years; SD = 1.58; male = 47.7%) were required to complete an online questionnaire package, including a depression-anxiety-stress scale, a self-control scale, and an Internet addiction test. The PROCESS macro developed based on SPSS was used to test the moderated mediation model. Results: When controlling for gender and age, the results revealed that anxiety partially mediated the link between stress and IA. Specifically, the more stressed college students are, the higher their anxiety level is, and the more likely they are to become addicted to the Internet. Additionally, the direct and indirect links between stress and IA were all moderated by SC. SC buffered the effect of stress on anxiety and anxiety on IA but enhanced stress on IA. Conclusion: These findings emphasized the predictor role of stress on IA and provided insights on intervening in college students' excessive Internet use behaviors for educators, such as reducing anxiety levels and improving self-control abilities.

Phenotypic and genetic dissection of the contents of important metallic elements in hybrid rice grown in cadmium-contaminated paddy fields.

Rice (Oryza sativa L.) is a staple food that feeds over half of the world's population, and the contents of metallic elements in rice grain play important roles in human nutrition. In this study, the contents of important metallic elements were determined by ICP-OES, and included cadmium (Cd), zinc (Zn), manganese (Mn), copper (Cu), iron (Fe), nickel (Ni), calcium (Ca), and magnesium (Mg) in brown rice, in the first node from the top (Node 1), in the second node from the top (Node 2), and in roots of 55 hybrids and their parental lines. The heritability of metallic element contents (MECs), the general combining ability (GCA) for MEC, and the correlation between MECs in different organs/tissues of hybrids were also analyzed. The results indicated that: (1) there was a positive correlation between the contents of Cd and Zn in nodes and roots, but a negative correlation between the contents of Cd and Zn in brown rice of the hybrids(2) the GCA for MECs can be used to evaluate the ability of the parental lines to improve the metal contents in brown rice of the hybrids(3) the contents of Cd, Zn, Ca, and Mg in brown rice were mainly affected by additive genetic effects(4) the restorer lines R2292 and R2265 can be used to cultivate hybrids with high Zn and low Cd contents in the brown rice.