A new species of Populus and the extensive hybrid speciation arising from it on the Qinghai-Tibet Plateau.

While the diversity of species formation is broadly acknowledged, significant debate exists regarding the universal nature of hybrid species formation. Through an 18-year comprehensive study of all Populus species on the Qinghai-Tibet Plateau, 23 previously recorded species and 8 new species were identified. Based on morphological characteristics, these can be classified into three groups: species in section Leucoides, species with large leaves, and species with small leaves in section Tacamahaca. By conducting whole-genome re-sequencing of 150 genotypes from these 31 species, 2.28 million single nucleotide polymorphisms (SNPs) were identified. Phylogenetic analysis utilizing these SNPs not only revealed a highly intricate evolutionary network within the large-leaf species of section Tacamahaca but also confirmed that a new species, P. curviserrata, naturally hybridized with P. cathayana, P. szechuanica, and P. ciliata, resulting in 11 hybrid species. These findings indicate the widespread occurrence of hybrid species formation within this genus, with hybridization serving as a key evolutionary mechanism for Populus on the plateau. A novel hypothesis, "Hybrid Species Exterminating Their Ancestral Species (HSEAS)," is introduced to explain the mechanisms of hybrid species formation at three different scales: the entire plateau, the southeastern mountain region, and individual river valleys.

A model of hybrid speciation process drawn from three new poplar species originating from distant hybridization between sections.

Although numerous studies have been conducted on hybrid speciation, our understanding of this process remains limited. Through an 18-year systematic investigation of all taxa of Populus on the Qinghai-Tibet Plateau, we discovered three new taxa with clear characteristics of sect. Leucoides. Further evidence was gathered from morphology, whole-genome bioinformatics, biogeography, and breeding to demonstrate synthetically that they all originated from distant hybridization between sect. Leucoides and sect. Tacamahaca. P. gonggaensis originated from the hybridization of P. lasiocarpa with P. cathayana, P. butuoensis from the hybridization of P. wilsonii with P. szechuanica, and P. dafengensis from the hybridization of P. lasiocarpa with P. szechuanica. Due to heterosis, the three hybrid taxa possess greater ecological adaptability than their ancestral species. We propose a hybrid speciation process model that incorporates orthogonal, reverse, and backcrossing events. This model can adequately explain some crucial evolutionary concerns, such as the nuclear-cytoplasmic conflict on phylogeny and the extinction of ancestral species within the distribution range of hybrid species.

The differential associative relationship between early risk factors, neonatal morbidities and early neurodevelopmental outcome in preterm infants <29 weeks' gestation.

BACKGROUND: Very preterm infants of <29 weeks' gestation are at high risk for adverse neurodevelopment due to multiple risk factors in the early stages of life. There is little information regarding the associative effects of risk factors in early life, neonatal morbidities and subsequent neurodevelopmental outcomes. AIMS: Investigate the association of early neurodevelopmental outcomes, neonatal complications and the risk factors in the early hours of life in a cohort of preterm infants <29 weeks' gestational age. METHODS: We enrolled all surviving preterm neonates born at gestation <29 weeks between January 2015 and June 2021 in the University of Hong Kong-Shenzhen Hospital. Demographic and clinical characteristics were collected from a database of the neonatal intensive care unit. Neurodevelopmental outcomes of the survivors were evaluated using the Ages and Stages Questionnaire (ASQ-3) which were measured at the adjusted age of 12 to 18 months. The multivariate linear regression model was used to determine correlation presented as ß coefficient (ß) with 95 % confidence intervals (CI). RESULTS: In this cohort of 56 survivors <29 weeks' gestation, urine output within the first 12 h of life and Apgar score at 5 min were positively associated with different domains of ASQ-3 score, however male sex and highest fraction of inspired oxygen (FiO2) in the first 12 h of life were negatively related with at least one of neurocognitive domains of ASQ-3 at adjusted age of 12 to 18 months. During hospitalization, in addition to the frequency of packed red cell transfusions, the development of severe necrotizing enterocolitis was inversely associated with both neuromotor and neurocognitive skills (gross motor domain: ß = -16.93, CI: -32.04, -1.82; fine motor domain: ß = -16.42, CI: -28.82, -4.02; problem solving domain: ß = -13.14, CI: -24.45, -1.83; all P < 0.05), whereas severe intraventricular hemorrhage had adverse effects on gross motor only (ß = -13.04, CI: -24.42, -1.65; P = 0.03). Bronchopulmonary dysplasia and retinopathy of prematurity were not related with ASQ-3. CONCLUSIONS: In this small cohort study of very preterm neonates born at <29 weeks' gestation, risk factors in the early hours of life and neonatal morbidities during hospitalization had differential associative relationships with ASQ-3 at 12-18 months adjusted age. This information may be important for parental counseling and management including early diagnosis and intervention.

Chromosome-scale genome assembly provides insights into the molecular mechanisms of tissue development of Populus wilsonii.

Populus wilsonii is an important species of section Leucoides, and the natural populations mainly grow in southwest China. In this study, a single genotype of wild P. wilsonii was sequenced and assembled at genome size of 477.35 Mb in 19 chromosomes with contig N50 of 16.3 Mb. A total of 38,054 genes were annotated, and 49.95% of the genome was annotated as repetitive elements. Phylogenetic analysis identified that the divergence between P. wilsonii and the ancestor of P. deltoides and P. trichocarpa was 12 (3-23) Mya. 4DTv and Ks distributions supported the occurrence of the salicoid WGD event (~65 Mya). The highly conserved collinearity supports the close evolutionary relationship among these species. Some key enzyme-encoding gene families related to the biosynthesis of lignin and flavonoids were expanded and highly expressed in the stems or leaves, which probably resist the damage of the natural environment. In addition, some key gene families related to cellulose biosynthesis were highly expressed in stems, accounting for the high cellulose content of P. wilsonii variety. Our findings provided deep insights into the genetic evolution of P. wilsonii and will contribute to further biological research and breeding as well as for other poplars in Salicaceae.

Genome-Wide Investigation of the PtrCHLP Family Reveals That PtrCHLP3 Actively Mediates Poplar Growth and Development by Regulating Photosynthesis.

Chlorophyll (Chl) plays a crucial role in plant photosynthesis. The geranylgeraniol reductase gene (CHLP) participates in the terminal hydrogenation of chlorophyll biosynthesis. Although there are many studies related to the genome-wide analysis of Populus trichocarpa, little research has been conducted on CHLP family genes, especially those concerning growth and photosynthesis. In this study, three CHLP genes were identified in Populus. The evolutionary tree indicated that the CHLP family genes were divided into six groups. Moreover, one pair of genes was derived from segmental duplications in Populus. Many elements related to growth were detected by cis-acting element analysis of the promoters of diverse PtrCHLPs. Furthermore, PtrCHLPs exhibit different tissue expression patterns. In addition, PtrCHLP3 is preferentially expressed in the leaves and plays an important role in regulating chlorophyll biosynthesis. Silencing of PtrCHLP3 in poplar resulted in a decrease in chlorophyll synthesis in plants, thus blocking electron transport during photosynthesis. Furthermore, inhibition of PtrCHLP3 expression in poplar can inhibit plant growth through the downregulation of photosynthesis. Ultimately, PtrCHLP3 formed a co-expression network with photosynthesis and chlorophyll biosynthesis-related genes, which synergistically affected the growth and photosynthesis of poplars. Thus, this study provides genetic resources for the improved breeding of fast-growing tree traits.

Genome-wide analysis and expression profiling of Cation/H+ exchanger (CAX) family genes reveal likely functions in cadmium stress responses in poplar.

Cadmium, a toxic heavy metal, seriously affects human health and ecological security. The cation/H+ exchanger (CAX) family is a unique metal transporter that plays a crucial role in Cd acquisition, transfer, and remission in plants. Although there are many studies related to the genome-wide analysis of Populus trichocarpa, little research has been done on the CAX family genes, especially concerning Cd stress. In this study, genome-wide analysis of the Populus CAX family identified seven stress-related CAX genes. The evolutionary tree indicated that the CaCA family genes were grouped into four clusters. Moreover, seven pairs of genes were derived by segmental duplication in poplars. Cis-acting element analysis identified numerous stress-related elements in the promoters of diverse PtrCAXs. Furthermore, some PtrCAXs were up-regulated by drought, beetle, and mechanical damage, indicating their possible function in regulating stress response. Under cadmium stress, all CAX genes in the roots were up-regulated. Our findings suggest that plants may regulate their response to Cd stress through the TF-CAXs module. Comprehensively investigating the CAX family provides a scientific basis for the phytoremediation of heavy metal pollution by Populus.

UVB-Pretreatment-Enhanced Cadmium Absorption and Enrichment in Poplar Plants.

The phenomenon of cross adaptation refers to the ability of plants to improve their resistance to other stress after experiencing one type of stress. However, there are limited reports on how ultraviolet radiation B (UVB) pretreatment affects the enrichment, transport, and tolerance of cadmium (Cd) in plants. Since an appropriate UVB pretreatment has been reported to change plant tolerance to stress, we hypothesized that this application could alter plant uptake and tolerance to heavy metals. In this study, a woody plant species, 84K poplar (Populus alba × Populus glandulosa), was pretreated with UVB and then subjected to Cd treatment. The RT-qPCR results indicated that the UVB-treated plants could affect the expression of Cd uptake, transport, and detoxification-related genes in plants, and that the UVB-Pretreatment induced the ability of Cd absorption in plants, which significantly enriched Cd accumulation in several plant organs, especially in the leaves and roots. The above results showed that the UVB-Pretreatment further increased the toxicity of Cd to plants in UVB-Cd group, which was shown as increased leaf malonaldehyde (MDA) and hydrogen peroxide (H2O2) content, as well as downregulated activities of antioxidant enzymes such as Superoxide Dismutase (SOD), Catalase (CAT), and Ascorbate peroxidase (APX). Therefore, poplar plants in the UVB-Cd group presented a decreased photosynthesis and leaf chlorosis. In summary, the UVB treatment improved the Cd accumulation ability of poplar plants, which could provide some guidance for the potential application of forest trees in the phytoremediation of heavy metals in the future.

Genome-wide investigation and expression profiling of polyphenol oxidase (PPO) family genes uncover likely functions in organ development and stress responses in Populus trichocarpa.

BACKGROUND: Trees such as Populus are planted extensively for reforestation and afforestation. However, their successful establishment greatly depends upon ambient environmental conditions and their relative resistance to abiotic and biotic stresses. Polyphenol oxidase (PPO) is a ubiquitous metalloproteinase in plants, which plays crucial roles in mediating plant resistance against biotic and abiotic stresses. Although the whole genome sequence of Populus trichocarpa has long been published, little is known about the PPO genes in Populus, especially those related to drought stress, mechanical damage, and insect feeding. Additionally, there is a paucity of information regarding hormonal responses at the whole genome level. RESULTS: A genome-wide analysis of the poplar PPO family was performed in the present study, and 18 PtrPPO genes were identified. Bioinformatics and qRT-PCR were then used to analyze the gene structure, phylogeny, chromosomal localization, gene replication, cis-elements, and expression patterns of PtrPPOs. Sequence analysis revealed that two-thirds of the PtrPPO genes lacked intronic sequences. Phylogenetic analysis showed that all PPO genes were categorized into 11 groups, and woody plants harbored many PPO genes. Eighteen PtrPPO genes were disproportionally localized on 19 chromosomes, and 3 pairs of segmented replication genes and 4 tandem repeat genomes were detected in poplars. Cis-acting element analysis identified numerous growth and developmental elements, secondary metabolism processes, and stress-related elements in the promoters of different PPO members. Furthermore, PtrPPO genes were expressed preferentially in the tissues and fruits of young plants. In addition, the expression of some PtrPPOs could be significantly induced by polyethylene glycol, abscisic acid, and methyl jasmonate, thereby revealing their potential role in regulating the stress response. Currently, we identified potential upstream TFs of PtrPPOs using bioinformatics. CONCLUSIONS: Comprehensive analysis is helpful for selecting candidate PPO genes for follow-up studies on biological function, and progress in understanding the molecular genetic basis of stress resistance in forest trees might lead to the development of genetic resources.

External application of nitrogen alleviates toxicity of cadmium on poplars via starch and sucrose metabolism.

Phytoremediation technology can help achieve moderate cost and considerable effect with respect to the remediation of heavy metal (HM) pollution in soil and water. Many previous studies have suggested the role of nitrogen (N) in the alleviation of effects of HM on plants. Herein, we sought to determine the molecular mechanisms by which additional N supplementation mitigates cadmium (Cd) toxicity in poplars using a combination of physiological, transcriptomic and phosphoproteomic analyses. The application of N can alleviate the toxicity of Cd to Populus by reducing chlorophyll degradation, maintaining the stability of ions inside and outside the cell membrane and increasing the soluble sugar content. Plant samples from the control, Cd stress and Cd_N treatments were used for an integrated analysis of the transcriptome, as well as for phosphoproteomics analysis. Moreover, 1314 differentially expressed genes and 119 differentially expressed kinase genes were discovered. Application of additional N under Cd stress promoted the phosphorylation process. Furthermore, 51 significantly enriched phosphorylated protein sites and 23 differentially expressed kinases were identified using phosphoproteomic and proteomic analyses. Importantly, transcriptomic and phosphoproteomic analyses jointly determined that the application of N could activate corresponding gene expression [UDP-glucose-dehydrogenase (UGD), GAUT, PME, pectin lyase, UDP-glucose-pyrophosphorylase 2 (UGP2), sucrose phosphate synthase (SPS), SUS and SPP2] and protein phosphorylation (UGP2 and SPS) in the sugar and starch synthesis pathways, which promoted the synthesis of sucrose and soluble sugar and subsequently alleviated the damage caused by Cd.

Genome-Wide Investigation of the NF-X1 Gene Family in Populus trichocarpa Expression Profiles during Development and Stress.

Poplar are planted extensively in reforestation and afforestation. However, their successful establishment largely depends on the environmental conditions of the newly established plantation and their resistance to abiotic as well as biotic stresses. NF-X1, a widespread transcription factor in plants, plays an irreplaceable role in plant growth, development, and stress tolerance. Although the whole genome sequence of Populus trichocarpa has been published for a long time, little is known about the NF-X1 genes in poplar, especially those related to drought stress, mechanical damage, insect feeding, and hormone response at the whole genome level. In this study, whole genome analysis of the poplar NF-X1 family was performed, and 4 PtrNF-X1 genes were identified. Then, bioinformatics analysis and qRT-PCR were applied to analyze the gene structure, phylogeny, chromosomal localization, gene replication, Cis-elements, and expression patterns of PtrNF-X1genes. Sequence analysis revealed that one-quarter of the PtrNF-X1 genes did not contain introns. Phylogenetic analysis revealed that all NF-X1 genes were split into three subfamilies. The number of two pairs of segmented replication genes were detected in poplars. Cis-acting element analysis identified a large number of elements of growth and development and stress-related elements on the promoters of different NF-X1 members. In addition, some PtrNF-X1 could be significantly induced by polyethylene glycol (PEG) and abscisic acid (ABA), thus revealing their potential role in regulating stress response. Comprehensive analysis is helpful in selecting candidate NF-X1 genes for the follow-up study of the biological function, and molecular genetic progress of stress resistance in forest trees provides genetic resources.

[Isolation of a wild-type virulent phage of Helicobacter pylori and its simulated treatments of gastrointestinal Hp in vitro].

OBJECTIVE: To isolate the wild-type virulent phage of Helicobacter pylori (Hp) and simulate the treatments in vitro to investigate the methods for oral Hp-assisted penetration of the phage through the gastric barrier and offspring phage release for infection and treatment of gastrointestinal Hp. METHODS: The Hp strain was cultured with the candle cylinder method and the virulent phage was isolated by single plate or double plate experiment. A simulated gastric juice was applied and the bactericidal effect of the phage was tested with double flats experiment. RESULTS: After a 1.5-h treatment in simulated gastric juice, the orally derived Hp-borne phage was still capable of forming plaques while the control phage was not. CONCLUSION: The oral Hp can help the phage resist the gastric juice and then infect the gastrointestinal Hp.

[Transforming of the drug resistance plasmid from Staphylococcus aureus into Escherichia coli].

OBJECTIVE: To discuss the possible mechanism of drug resistance transmission between Staphylococcus and Escherichia coli. METHODS: The chloramphenicol resistance plasmid of Staphylococcus aureus was extracted to transform the sensitive Escherichia coli, and the drug-resistant Escherichia coli were screened by drug sensitivity test. RESULTS: The drug-resistant Escherichia coli were successfully obtained. CONCLUSION: Staphylococcus may have a natural shuttle plasmid of drug resistance, which can transform Escherichia coli under specific conditions.

[Effects of Newcastle disease virus on the expression of survivin and cell cycle in human tongue squamous carcinoma TSCCa cells].

OBJECTIVE: To investigate the effects of Newcastle disease virus (NDV) infection on the expression of survivin and cell cycle in human tongue squamous carcinoma TSCCa cells. METHODS: The proliferation of TSCCa cells infected with NDV in vitro was evaluated by means of MTT assay, and survivin expression in the infected cells was detected using RT-PCR and Western blotting. Flow cytometry was performed to assess the changes in the cell apoptosis, cell cycle and cell proliferation index (PI) of the cells. RESULTS: NDV infection resulted in decreased survivin expression and increased apoptosis of TSCCa cells, with reduced cell percentage in G2/M and S phases and lowered PI of the cells, showing significant differences from those of the negative control cells (P<0.05). CONCLUSION: NDV infection can inhibit survivin expression, affect the cell cycle of TSCCa cells and induce their apoptosis.

QTL mapping of Fusarium moniliforme ear rot resistance in maize. 1. Map construction with microsatellite and AFLP markers.

To map the QTLs of Fusarium moniliforme ear rot resistance in Zea mays L., a total of 230 F2 individuals, derived from a single cross between inbred maize lines R15 (resistant) and Ye478 (susceptible), were genotyped for genetic map construction using simple sequence repeat (SSR) markers and amplified fragment length polymorphism (AFLP) markers. We used 778 pairs of SSR primers and 63 combinations of AFLP primers to detect the polymorphisms between parents, R15 and Ye478. From the polymorphic 30 AFLP primer combinations and 159 SSR primers, we scored 260 loci in the F2 population, among which 8 SSR and 13 AFLP loci could not be assigned to any of the linkage groups. An integrated molecular genetic linkage map was constructed by the remaining 151 SSR and 88 AFLP markers, which distributed throughout the 10 linkage groups of maize and spanned the genome of about 3463.5 cM with an average of 14.5 cM between two markers. On 4 chromosomes, we detected 5 putative segregation distortion regions (SDRs), including 2 new ones (SDR2 and SDR7). The other 3 SDRs were located near the regions where gametophyte genes were mapped, indicating that segregation distortion could be partially caused by gametophytic factors.