Bridging Component Strategy in Phosphomolybdate-Based Sensors for Electrochemical Determination of Trace Cr(VI).

Rapid and sensitive electrochemical determination of trace carcinogenic Cr(VI) pollutants remains an urgent and important task, which requires the development of active sensing materials. Herein, four cases of reduced phosphomolybdates with formulas of the (H2bib)3[Zn(H2PO4)]2{Mn[P4Mo6O31H7]2}·6H2O (1), (H2bib)2[Na(H2O)]2[Mn(H2O)]2{Mn[P4Mo6O31H6]2}·5H2O (2), (H2bib)3[Mo2(µ2-O)2(H2O)4]2{Ni[P4Mo6O31H2]2}·4H2O (3), and (H2bib)2{Ni[P4Mo6O31H9]2}·9H2O (4) (bib = 4,4'-bis(1-imidazolyl)-biphenyl) were hydrothermally synthesized under the guidance of a bridging component strategy, which function as effective electrochemical sensors to detect trace Cr(VI). The difference of hybrids 1-4 is in the inorganic moiety, in which the reduced phosphomolybdates {M[P4MoV6O31]2} (M{P4Mo6}2) exhibited different arrangements bridged by different cationic components ({Zn(H2PO4)} subunit for 1, [Mn2(H2O)2]4+ dimer for 2, and [MoV2(µ2-O)2(H2O)4]6+ for 3). As a result, hybrids 1 and 3 display noticeable Cr(VI) detection activity with low detection limits of 14.3 nM (1.48 ppb) for 1 and 6.61 nM (0.69 ppb) for 3 and high sensitivities of 97.3 and 95.3 µA·mM-1, respectively, which are much beyond the World Health Organization's detection threshold (0.05 ppm) and superior to those of the contrast samples (inorganic Mn{P4Mo6}2 salt and hybrid 4), even the most reported noble-metal catalysts. This work supplies a prospective pathway to build effective electrochemical sensors based on phosphomolybdates for environmental pollutant treatment.

Backcrossing to different parents produced two distinct hybrid species.

Repeated homoploid hybrid speciation (HHS) events with the same parental species have rarely been reported. In this study, we used population transcriptome data to test paraphyly and HHS events in the conifer Picea brachytyla. Our analyses revealed non-sister relationships for two lineages of P. brachytyla, with the southern lineage being placed within the re-circumscribed P. likiangensis species complex (PLSC) and P. brachytyla sensu stricto (s.s.) consisted solely of the northern lineage, forming a distinct clade that is paratactic to both the PLSC and P. wilsonii. Our phylogenetic and coalescent analyses suggested that P. brachytyla s.s. arose from HHS between the ancestor of the PLSC before its diversification and P. wilsonii through an intermediate hybrid lineage at an early stage and backcrossing to the ancestral PLSC. Additionally, P. purpurea shares the same parents and an extinct lineage with P. brachytyla s.s. but backcrossing to the other parent, P. wilsonii at a later stage. We reveal the first case that backcrossing to different parents of the same extinct hybrid lineage produced two different hybrid species. Our results highlight the existence of more reticulate evolution during species diversification in the spruce genus and more complex homoploid hybrid events than previously identified.

Advances in terahertz metasurface graphene for biosensing and application.

Based on the extraordinary electromagnetic properties of terahertz waves, such as broadband, low energy, high permeability, and biometric fingerprint spectra, terahertz sensors show great application prospects in the biochemical field. However, the sensitivity of terahertz sensing technology is increasingly required by modern sensing demands. With the development of terahertz technology and functional materials, graphene-based terahertz metasurface sensors with the advantages of high sensitivity, fingerprint identification, nondestructive and anti-interference are gradually gaining attention. In addition to providing ideas for terahertz biosensors, these devices have attracted in-depth research and development by scientists. An overview of graphene-based terahertz metasurfaces and their applications in the detection of biochemical molecules is presented. This includes sensor mechanism research, graphene metasurface index evaluation, protein and nucleic acid sensors, and other chemical molecule sensing. A comparative analysis of graphene, nanomaterials, silicon, and metals to develop material-integrated metasurfaces. Furthermore, a brief summary of the main performance results of this class of devices is presented, along with suggestions for improvements to the existing shortcoming.

Iodine nutrition status of pregnant women in Qingdao City from 2018 to 2020 / 中华地方病学杂志

Objective:To investigate the iodine nutritional status of pregnant women in Qingdao and the effect of prevention and treatment of iodine deficiency disorders (IDD), so as to provide a basis for residents to supplement iodine scientifically, and take targeted prevention measures and adjust intervention strategies.Methods:In accordance with the requirements of the "National Iodine Deficiency Disorders Surveillance Program (2016 edition)" and "Shandong Iodine Deficiency Disorders Surveillance Program", the cluster sampling method was adopted to select pregnant women from 10 districts (cities) in Qingdao from 2018 to 2020, to investigate their basic information and thyroid disease history. Meanwhile, household edible salt samples and random urine samples were collected to detect iodine content.Results:A total of 3 000 pregnant women were monitored from 2018 to 2020, the median age was 31 years, and the median gestational age was 18 weeks. There were significant differences in the distribution of age, gestational age, whether senile puerpera, and pregnancy in different years ( H/χ 2 = 29.35, 81.03, 65.62, 77.34, P < 0.001). The median salt iodine of edible salt ( n = 3 000) and iodized salt ( n = 2 700) in pregnant women's homes were 23.02 and 23.70 mg/kg, respectively. The qualified rate of iodized salt, the coverage rate of iodized salt and the consumption rate of qualified iodized salt were 89.59% (2 419/2 700), 90.00% (2 700/3 000) and 80.63% (2 419/3 000). The comparison of qualified rate of iodized salt, coverage rate of iodized salt and consumption rate of qualified iodized salt among different years was statistically significant (χ 2 = 48.09, 36.62, 61.08, P < 0.001), the coverage rate of iodized salt and the consumption rate of qualified iodized salt showed a downward trend year by year (χ 2trent = 35.54, 29.50, P < 0.001). A total of 3 000 urine samples were collected from pregnant women and the median urinary iodine of pregnant women was 147.85 μg/L. The urinary iodine level in the third trimester was lower than that in the first and second trimesters ( P < 0.001). The urinary iodine level in the non elderly group was higher than that in the elderly group ( Z = - 6.66, P < 0.001). The urinary iodine level in the group without thyroid disease was higher than that in the group with thyroid disease ( Z = - 1.99, P = 0.047). The urinary iodine level in iodized salt group was higher than that in non-iodized salt group ( Z = - 2.42, P = 0.015). Conclusions:The iodine nutrition of pregnant women in Qingdao is generally at an insufficient level, and the risk of iodine deficiency is high, which needs attention. In recent years, the coverage rate of iodized salt and the consumption rate of qualified iodized salt in Qingdao have shown a downward trend, and have failed to meet the requirements of national standards. In the future, we should strengthen the monitoring and health education of IDD in pregnant women.

Incidence rate of schizophrenia after the Tangshan earthquake in China: a 44-year retrospective birth cohort study.

Preliminary evidence indicates that natural disasters are associated with an increased risk for schizophrenia. With few longitudinal studies on earthquakes, this retrospective cohort study examined exposure to the 1976 Tangshan earthquake and the subsequent risk of schizophrenia. Population counts and visits to all nine psychiatric hospitals in Tangshan city were collected. We created three cohort groups by earthquake exposure: infant (August 1972 to July 1976 births), fetal (August 1976 to May 1977 births), and unexposed (June 1977 to May 1981 births). The cumulative incidence of schizophrenia in each cohort was calculated by dividing the number of schizophrenia patients by total births in the corresponding period. Altogether, 6424 schizophrenia patients were identified, with 2786 in the infant group, 663 in the fetal group, and 2975 in the unexposed group. The crude cumulative incidence of schizophrenia in the infant, fetal and unexposed groups were 7.64 (95% confidence interval [CI] = 7.36-7.92), 9.07 (95% CI = 8.38-9.76), and 7.40 (95% CI = 7.13-7.66) per thousand population respectively. Adjusted for mortality, the corresponding figures were 7.73 (95% CI = 7.44-8.01), 9.30 (95% CI = 8.60-10.01) and 7.44 (95% CI = 7.18-7.71) per thousand population respectively. The mortality-adjusted risk ratio (aRR) was 1.25 (95% CI = 1.15-1.36) between fetal and unexposed groups (χ2 = 27.31, P < 0.001). Males exposed as infants did not differ from the unexposed in cumulative schizophrenia incidence. People with fetal exposure to the 1976 earthquake had 25% higher risk of developing schizophrenia compared to unexposed counterparts.

Molecular signatures of parallel adaptive divergence causing reproductive isolation and speciation across two genera.

Parallel evolution of reproductive isolation (PERI) provides strong evidence for natural selection playing a fundamental role in the origin of species. However, PERI has been rarely demonstrated for well established species drawn from different genera. In particular, parallel molecular signatures for the same genes in response to similar habitat divergence in such different lineages is lacking. Here, based on whole-genome sequencing data, we first explore the speciation process in two sister species of Carpinus (Betulaceae) in response to divergence for temperature and soil-iron concentration in habitats they occupy in northern and southwestern China, respectively. We then determine whether parallel molecular mutations occur during speciation in this pair of species and also in another sister-species pair of the related genus, Ostryopsis, which occupy similarly divergent habitats in China. We show that gene flow occurred during the origin of both pairs of sister species since approximately 9.8 or approximately 2 million years ago, implying strong natural selection during divergence. Also, in both species pairs we detected concurrent positive selection in a gene (LHY) for flowering time and in two paralogous genes (FRO4 and FRO7) of a gene family known to be important for iron tolerance. These changes were in addition to changes in other major genes related to these two traits. The different alleles of these particular candidate genes possessed by the sister species of Carpinus were functionally tested and indicated likely to alter flowering time and iron tolerance as previously demonstrated in the pair of Ostryopsis sister species. Allelic changes in these genes may have effectively resulted in high levels of prezygotic reproductive isolation to evolve between sister species of each pair. Our results show that PERI can occur in different genera at different timescales and involve similar signatures of molecular evolution at genes or paralogues of the same gene family, causing reproductive isolation as a consequence of adaptation to similarly divergent habitats.

LncRNA PITPNA-AS1/miR-223-3p/PTN axis regulates malignant progression and stemness in lung squamous cell carcinoma.

BACKGROUND: Long noncoding RNAs (lncRNAs) are a kind of molecule that cannot code proteins, and their expression is dysregulated in diversified cancers. LncRNA PITPNA-AS1 has been shown to act as a tumor promoter in a variety of malignancies, but its function and regulatory mechanisms in lung squamous cell carcinoma (LUSC) are yet unknown. METHODS: The mRNA and protein expression of genes were examined by RT-qPCR, western blot, and IHC assay. The cell proliferation, migration, invasion, and stemness were detected through CCK-8, colony formation, Transwell and spheroid formation assays. The CD44+ and CD166+ -positive cells were detected through flow cytometry. The binding ability among genes through luciferase reporter and RNA pull-down assays. The tumor growth was detected through in vivo nude mice assay. RESULTS: The lncRNA PITPNA-AS1 had increased expression in LUSC and was linked to a poor prognosis. In LUSC, PITPNA-AS1 also enhanced cell proliferation, migration, invasion, and stemness. This mechanistic investigation showed that PITPNA-AS1 absorbed miR-223-3p and that miR-223-3p targeted PTN. MiR-223-3p inhibition or PTN overexpression might reverse the inhibitory effects of PITPNA-AS1 suppression on LUSC progression, as demonstrated by rescue experiments. In addition, the PITPNA-AS1/miR-223-3p/PTN axis accelerated tumor development in vivo. CONCLUSIONS: It is the first time we investigated the potential role and ceRNA regulatory mechanism of PITPNA-AS1 in LUSC. The data disclosed that PITPNA-AS1 upregulated PTN through sponging miR-223-3p to enhance the onset and progression of LUSC. These findings suggested the ceRNA axis may serve as a promising therapeutic biomarker for LUSC patients.

Prenatal diagnosis of de novo isochromosome 4p with an unbalanced t(4;9) translocation in a fetus with congenital anomalies: A case report and literature review.

OBJECTIVE: We present the first case of prenatally diagnosed isochromosome 4p with whole 4q arm translocating to chromosome 9p23 and review the literature. CASE REPORT: A 26-year-old woman underwent amniocentesis at 25 weeks of gestation because of an abnormal ultrasound examination. Routine chromosome analysis on cultured amniocytes showed a karyotype of 46,XX, ?idic(4)(q11),der(9)t(4;9)(q11;p23). Single nucleotide polymorphism (SNP) array analysis on uncultured amniocytes detected two copy number variations (CNVs): arr [GRCh37] 4p16.3p11(68345-49089361) × 3; arr [GRCh37] 9p24.3p23(208454-10039391) × 1. The karyotypes of the parents were normal, indicating that the chromosomal rearrangement was de novo. According to the fetal-parent trios SNP analysis, both the abnormal chromosomes were originated from the father. The pregnancy was terminated at 30 weeks of gestation, and a malformed fetus was delivered with dysmorphic craniofacial, short neck, wide-spaced nipples and rocker-bottom feet. CONCLUSION: The combined application of traditional cytogenetic technology and molecular diagnosis technology in prenatal diagnosis helps identify genetic components and the origin of isochromosome, which enable clinicians to precisely predict the fetal prognosis and provide accurate genetic counselling and fertility guidance.

Familial Aggregation and Heritability of Myopia: A Local Population Survey in Shanxi, China.

PURPOSE: To further determine the roles of environmental and genetic factors in the development of myopia, a comprehensive survey was performed. The guidance for myopia-susceptible people is established which might help prevent or delay the onset and development of myopia. METHODS: 1,852 students were recruited using the multistage sampling approach from the Gaoping county in Shanxi. The refractive status of students was examined using an autorefractometer, and the refractive status of students' first-degree relatives was collected using a well-designed questionnaire. Family aggregation of myopia was analyzed according to the myopic status of the students (nonmyopic or myopic group). The prevalence and heritability of myopia in students and their first-degree relatives were further explored by subdividing into mild, moderate, and high myopia groups. Significance analysis among each group was performed by the χ 2 test using SPSS 25.0 software. Falconer's method was used to calculate the inheritability of myopia. RESULTS: A total of 1,852 subjects were recruited in this study, and 1,813 subjects were finally included. The family aggregation of myopia in the myopic student group (34.7%) was significantly higher than that in the nonmyopic group (8.5%). The prevalence of mild, moderate, and high myopia in children (students and siblings) was higher than that in their parents. The rate of high myopia (6.33%) was significantly higher among students with one or both myopic parents than those without myopic parents (3.85%). The heritability of mild, moderate, and high myopia among parents-offspring was 3.72%, 20.47%, and 48.00%, respectively. The heritability of mild, moderate, and high myopia among siblings was 17.50%, 86.09%, and 78.75%, which is significantly higher than that among parents-offspring. In addition to genetic factors, extensive near-work time, higher education pressure, and minimal outdoor activities contribute significantly to mild and moderate myopia. CONCLUSIONS: Myopia is of high risk due to familial aggregation. Students with a family history of myopia are more likely to have high myopia than those without family history. The occurrence and development of high myopia are affected by both the genetic and environmental factors, which could either weaken or strengthen myopia. Therefore, students with a family history of myopia should pay close attention to their eye health to avoid the occurrence of myopia and the deepening of diopter, which may lead to high myopia and its related complications.

Efficacy of hyperbaric oxygen combined with escitalopram in depression and its effect on cognitive function.

OBJECTIVE: To investigate the efficacy of hyperbaric oxygen (HBO) combined with escitalopram in patients with depression and its effect on cognitive function. METHODS: From 2016 to 2018, seventy patients with depression aged 18-65 years treated in Affiliated Hospital of Hebei University were selected. Seventy patients with depression meeting the diagnostic criteria of ICD-10 were selected and randomly divided into control group and observation group using a random number table, with 35 patients in each group. The control group was treated with escitalopram, while the observation group was additionally treated with HBO on this basis. The patients were assessed using the Hamilton Depression Scale (HAMD) and Montreal Cognitive Assessment Scale (MoCA) before treatment and two, four and six weeks after treatment. RESULTS: Two weeks after treatment, HAMD score showed a statistically significant difference between the two groups (P < 0.05). No statistically significant differences were found in HAMD score between the two groups four and six weeks after treatment (P > 0.05). Four and six weeks after treatment, MoCA score presented statistically significant differences between the two groups (P < 0.05). CONCLUSION: Escitalopram combined with HBO in the treatment of depression presents rapid efficacy and a certain effect in improving cognitive function.

FeVO4 Nanopolyhedron Photoelectrodes for Stable and Efficient Water Splitting.

Crystalline FeVO4 nanopolyhedron (FVO NPH) photoelectrodes are successfully prepared by using an in situ solid-state transformation from hydrothermal FeOOH films via adding vanadium precursor and following thermal treatments. The FVO NPH photoelectrodes possess uniformly dispersed polyhedral nanocrystals that directly grow on the conductive substrate with tunable film thicknesses. The unique morphology enables an outstanding photo-electrocatalytic performance, and the optimized FVO NPH photoelectrode, which was annealed at 550 °C for 4 h with a film thickness of ∼560 nm, exhibits excellent photocurrent densities of ∼0.47 and ∼0.68 mA cm-2 at 1.0 and 1.2 V vs. Ag/AgCl, respectively. After decorating CoPi co-catalyst, FVO/CoPi shows a highly efficient water splitting performance with O2 and H2 evolution rates of 7.53 and 15.32 µmol cm-2 h-1 , respectively, which are ∼1.88 and ∼1.80 times, respectively, of these of the FVO NPH. The proposed photoelectrodes also show excellently chemical and physical stabilities in solar water splitting. This is the first time reported the preparation of well-organized nanostructured FeVO4 films, which warrants further optimization studies on morphologies and compositions of FeVO4 -based photoelectrodes.

Organic Moiety-Regulated Photocatalytic Performance of Phosphomolybdate Hybrids for Hexavalent Chromium Reduction.

Visible-light-driven photocatalytic Cr(VI) reduction is a promising pathway to moderate environmental pollution, in which the development of photocatalysts is pivotal. Herein, three hourglass-type phosphomolybdate-based hybrids with the formula of: (H2 bpe)3 [Zn(H2 PO4 )][Zn(bpe)(H2 O)2 ]H{Zn[P4 Mo6 O31 H6 ]2 } ⋅ 6H2 O (1) Na6 [H2 bz]2 [ZnNa4 (H2 O)5 ]{Zn [P4 Mo6 O31 H3 ]2 } ⋅ 2H2 O (2) and (H2 mbpy) {[Zn(mbpy)(H2 O)]2 [Zn(H2 O)]2 }{Zn[P4 Mo6 O31 H6 ]2 } ⋅ 10H2 O (3) (bpe=trans-1,2-bi(4-pyridyl)-ethylene; bz=4,4'-diaminobiphenyl; mbpy=4,4'-dimethyl-2,2'bipyridine) were synthesized under the guidance of the functional organic moiety modification strategy. Structural analysis showed that hybrids 1-3 have similar 2D layer-like spatial arrangements constructed by {Zn[P4 Mo6 ]2 } clusters and organic components with different conjugated degree. With excellent redox properties and wide visible-light absorption capacities, hybrids 1-3 display favourable photocatalytic activity for Cr(VI) reduction with 79%, 70% and 64% reduction rates, which are superior to that of only inorganic {Zn[P4 Mo6 ]2 } itself (21%). The investigation of organic components on photocatalytic performance of hybrids 1-3 suggested that the organic counter cations (bpe, bz and mbpy) can effectively affect the visible-light absorption, as well as the recombination of photogenerated carriers stemmed from {Zn[P4 Mo6 ]2 } clusters, further promoting their photocatalytic performances towards Cr(VI) reduction. This work provides an experimental basis for the design of functionalized photocatalysts via the modification of organic species.

Bioinformatic analysis of chromatin organization and biased expression of duplicated genes between two poplars with a common whole-genome duplication.

The nonrandom three-dimensional organization of chromatin plays an important role in the regulation of gene expression. However, it remains unclear whether this organization is conserved and whether it is involved in regulating gene expression during speciation after whole-genome duplication (WGD) in plants. In this study, high-resolution interaction maps were generated using high-throughput chromatin conformation capture (Hi-C) techniques for two poplar species, Populus euphratica and Populus alba var. pyramidalis, which diverged ~14 Mya after a common WGD. We examined the similarities and differences in the hierarchical chromatin organization between the two species, including A/B compartment regions and topologically associating domains (TADs), as well as in their DNA methylation and gene expression patterns. We found that chromatin status was strongly associated with epigenetic modifications and gene transcriptional activity, yet the conservation of hierarchical chromatin organization across the two species was low. The divergence of gene expression between WGD-derived paralogs was associated with the strength of chromatin interactions, and colocalized paralogs exhibited strong similarities in epigenetic modifications and expression levels. Thus, the spatial localization of duplicated genes is highly correlated with biased expression during the diploidization process. This study provides new insights into the evolution of chromatin organization and transcriptional regulation during the speciation process of poplars after WGD.

The ubiquitin E3 ligase SR1 modulates the submergence response by degrading phosphorylated WRKY33 in Arabidopsis.

Oxygen deprivation caused by flooding activates acclimation responses to stress and restricts plant growth. After experiencing flooding stress, plants must restore normal growth; however, which genes are dynamically and precisely controlled by flooding stress remains largely unknown. Here, we show that the Arabidopsis thaliana ubiquitin E3 ligase SUBMERGENCE RESISTANT1 (SR1) regulates the stability of the transcription factor WRKY33 to modulate the submergence response. SR1 physically interacts with WRKY33 in vivo and in vitro and controls its ubiquitination and proteasomal degradation. Both the sr1 mutant and WRKY33 overexpressors exhibited enhanced submergence tolerance and enhanced expression of hypoxia-responsive genes. Genetic experiments showed that WRKY33 functions downstream of SR1 during the submergence response. Submergence induced the phosphorylation of WRKY33, which enhanced the activation of RAP2.2, a positive regulator of hypoxia-response genes. Phosphorylated WRKY33 and RAP2.2 were degraded by SR1 and the N-degron pathway during reoxygenation, respectively. Taken together, our findings reveal that the on-and-off module SR1-WRKY33-RAP2.2 is connected to the well-known N-degron pathway to regulate acclimation to submergence in Arabidopsis. These two different but related modulation cascades precisely balance submergence acclimation with normal plant growth.

CHYR1 ubiquitinates the phosphorylated WRKY70 for degradation to balance immunity in Arabidopsis thaliana.

It is critically important for plants to control the trade-off between normal growth and pathogen immunity. However, the underlying molecular mechanism remains largely unknown. Here we report such a mechanism controlled by WRKY70 and its partner CHYR1 in Arabidopsis. We found that both levels of the WRKY70 target gene SARD1 and the phosphorylated forms of WRKY70 were increased in WRKY70OE plants upon Pst DC3000 infection. Mechanistically, phosphorylation of WRKY70 at Thr22 and Ser34 occurs, which then activates SARD1 expression through binding to a WT box. Phosphorylated WRKY70 is degraded by 26S proteasome via CHYR1 when resuming normal growth after infection. In addition, nonphosphorylated WRKY70 represses SARD1 expression by binding to both W (inhibitory activity site) and WT (active activity site) boxes. The binding of WRKY70 to alternative cis-elements of SARD1 through a phosphorylation-mediated switch controlled by CHYR1 contributes to modulating the balance between immunity and growth.

A chromosome-level genome assembly for the tertiary relict plant Tetracentron sinense oliv. (trochodendraceae).

Tetracentron sinense and Trochodendron aralioides are two Tertiary relict species of large trees in the family Trochodendraceae with narrow distributions on the mainland and islands of eastern Asia. They belong to the order Trochodendrales, which is one of the four early-diverged eudicot lineages. These two relict species provide a good system in which to examine genomic changes that occurred as they survived during repeated climatic oscillations in the Quaternary. We sequenced the genome of Te. sinense and compared it with that of Tr. aralioides. We found that Te. sinense has a smaller genome size (986.3 Mb) than that of Tr. aralioides (1610 Mb). Repetitive elements made the major contribution to the contrasting genome sizes in the two species, with most bursts of repeats occurring within the past four million years when the climate oscillated greatly. These species share two rounds of whole-genome duplications. The mainland species Te. sinense had a larger effective population size than the island species Tr. aralioides after the largest glaciation during the Quaternary climatic oscillation. However, soon after this recovery stage, the effective population sizes of both species continued to decrease, although the current effective population size of Te. sinense is still larger than that of Tr. aralioides. We recovered three distinctly diverged clades through resequencing the genomes of 50 individuals across the distributional range of Te. sinense in China. Our results provide an important genomic resource with which to examine early trait evolution in the core eudicots and assist efforts to conserve this relict tree species.

Hybrid speciation via inheritance of alternate alleles of parental isolating genes.

It is increasingly realized that homoploid hybrid speciation (HHS), which involves no change in chromosome number, is an important mechanism of speciation. HHS will likely increase in frequency as ecological and geographical barriers between species are continuing to be disrupted by human activities. HHS requires the establishment of reproductive isolation between a hybrid and its parents, but the underlying genes and genetic mechanisms remain largely unknown. In this study, we reveal by integrated approaches that reproductive isolation originates in one homoploid hybrid plant species through the inheritance of alternate alleles at genes that determine parental premating isolation. The parent species of this hybrid species are reproductively isolated by differences in flowering time and survivorship on soils containing high concentrations of iron. We found that the hybrid species inherits alleles of parental isolating major genes related to flowering time from one parent and alleles of major genes related to iron tolerance from the other parent. In this way, it became reproductively isolated from one parent by the difference in flowering time and from the other by habitat adaptation (iron tolerance). These findings and further modeling results suggest that HHS may occur relatively easily via the inheritance of alternate parental premating isolating genes and barriers.

The PalWRKY77 transcription factor negatively regulates salt tolerance and abscisic acid signaling in Populus.

High salinity, one of the most widespread abiotic stresses, inhibits photosynthesis, reduces vegetation growth, blocks respiration and disrupts metabolism in plants. In order to survive their long-term lifecycle, trees, such as Populus species, recruit the abscisic acid (ABA) signaling pathway to adapt to a saline environment. However, the molecular mechanism behind the ABA-mediated salt stress response in woody plants remains elusive. We have isolated a WRKY transcription factor gene, PalWRKY77, from Populus alba var. pyramidalis (poplar), the expression of which is repressed by salt stress. PalWRKY77 decreases salt tolerance in poplar. Furthermore, PalWRKY77 negatively regulated ABA-responsive genes and relieved ABA-mediated growth inhibition, indicating that PalWRKY77 is a repressor of the ABA response. In vivo and in vitro assays revealed that PalWRKY77 targets the ABA- and salt-induced PalNAC002 and PalRD26 genes by binding to the W-boxes in their promoters. In addition, overexpression of both PalNAC002 and PalRD26 could elevate salt tolerance in transgenic poplars. These findings reveal a novel negative regulation mechanism for the ABA signaling pathway mediated by PalWRKY77 that results in more sensitivity to salt stress in poplar. This deepens our understanding of the complex responses of woody species to salt stress.

WRKY33 interacts with WRKY12 protein to up-regulate RAP2.2 during submergence induced hypoxia response in Arabidopsis thaliana.

Tolerance of hypoxia is essential for most plants, but the underlying mechanisms are largely unknown. Here we show that adaptation to submergence induced hypoxia in Arabidopsis involves up-regulation of RAP2.2 through interactive action of WRKY33 and WRKY12. WRKY33- or WRKY12-overexpressing plants showed enhanced resistance to hypoxia. Y2H, BiFC, Co-IP and pull-down experiments confirmed the interaction of WRKY33 with WRKY12. Genetic experiments showed that RAP2.2 acts downstream of WRKY33/WRKY12. WRKY33 and WRKY12 can bind to and activate RAP2.2 individually. Genetic and molecular experiments demonstrate that the two WRKYs can synergistically enhance activation towards RAP2.2 to increase hypoxia tolerance. WRKY33 expression is increased in RAP2.2-overexpressing plants, indicating a feedback regulation by RAP2.2 during submergence process, which was corroborated by EMSA, ChIP, dual-LUC and genetic experiments. Our results show that a regulatory cascade module involving WRKY33, WRKY12 and RAP2.2 plays a key role in submergence induced hypoxia response of Arabidopsis and illuminate functions of WRKYs in hypoxia tolerance.