Wall-associated kinase BrWAK1 confers resistance to downy mildew in Brassica rapa.

The plant cell wall is the first line of defence against physical damage and pathogen attack. Wall-associated kinase (WAK) has the ability to perceive the changes in the cell wall matrix and transform signals into the cytoplasm, being involved in plant development and the defence response. Downy mildew, caused by Hyaloperonospora brassicae, can result in a massive loss in Chinese cabbage (Brassica rapa L. ssp. pekinensis) production. Herein, we identified a candidate resistant WAK gene, BrWAK1, in a major resistant quantitative trait locus, using a double haploid population derived from resistant inbred line T12-19 and the susceptible line 91-112. The expression of BrWAK1 could be induced by salicylic acid and pathogen inoculation. Expression of BrWAK1 in 91-112 could significantly enhance resistance to the pathogen, while truncating BrWAK1 in T12-19 increased disease susceptibility. Variation in the extracellular galacturonan binding (GUB) domain of BrWAK1 was found to mainly confer resistance to downy mildew in T12-19. Moreover, BrWAK1 was proved to interact with BrBAK1 (brassinosteroid insensitive 1 associated kinase), resulting in the activation of the downstream mitogen-activated protein kinase (MAPK) cascade to trigger the defence response. BrWAK1 is the first identified and thoroughly characterized WAK gene conferring disease resistance in Chinese cabbage, and the plant biomass is not significantly influenced by BrWAK1, which will greatly accelerate Chinese cabbage breeding for downy mildew resistance.

Assembly of the non-heading pak choi genome and comparison with the genomes of heading Chinese cabbage and the oilseed yellow sarson.

Brassica rapa displays a wide range of morphological diversity which is exploited for a variety of food crops. Here we present a high-quality genome assembly for pak choi (Brassica rapa L. subsp. chinensis), an important non-heading leafy vegetable, and comparison with the genomes of heading type Chinese cabbage and the oilseed form, yellow sarson. Gene presence-absence variation (PAV) and genomic structural variations (SV) were identified, together with single nucleotide polymorphisms (SNPs). The structure and expression of genes for leaf morphology and flowering were compared between the three morphotypes revealing candidate genes for these traits in B. rapa. The pak choi genome assembly and its comparison with other B. rapa genome assemblies provides a valuable resource for the genetic improvement of this important vegetable crop and as a model to understand the diversity of morphological variation across Brassica species.

Natural variations of BrHISN2 provide a genetic basis for growth-flavour trade-off in different Brassica rapa subspecies.

Selection for yield during B. rapa breeding may have unintended consequences for other traits, such as flavour. LYH-type (light yellow head) Chinese cabbage (Brassica rapa ssp. pekinensis) and wucai (Brassica rapa L. ssp. chinensis var. rosularis) varieties are becoming popular because of their unique flavour and yellow leaves. However, the molecular mechanism underlying the interplay for these traits remains unknown. We conducted a fine mapping and genome-wide exploration analysis of the leaf yellowing of LYH and wucai, including transgenic plants, to identify causal genes. We identified that BrHISN2, a rate-limiting enzyme in histidine biosynthesis, causes leaf yellowing by destroying LYH chloroplasts. Normal growing Brhisn2 mutant plants became etiolated and senesced at the cotyledon-seedling stage. Sequence variations in the promoter confers cold-dependent expression on BrHISN2, probably resulting in leaf yellowing in LYH and wucai. Insertions of two DRE cis elements and the subsequent recruitment of two CBF2 proteins by the DREs to the promoter provided the cold-induced expression plasticity of BrHISN2 in plants. Both LYH and wucai are farmed in the fall, in which the temperature gradually decreases, therefore the CBF2-BrHISN2 module probably maximises the benefits of gene-environment interaction for breeding. We determined the mechanistic connections of chlorophyll synthesis and the growth-flavour trade-off in these B. rapa varieties.

A histone H4 gene prevents drought-induced bolting in Chinese cabbage by attenuating the expression of flowering genes.

Flowering is an important trait in Chinese cabbage, because premature flowering reduces yield and quality of the harvested products. Water deficit, caused by drought or other environmental conditions, induces early flowering. Drought resistance involves global reprogramming of transcription, hormone signaling, and chromatin modification. We show that a histone H4 protein, BrHIS4.A04, physically interacts with a homeodomain protein BrVIN3.1, which was selected during the domestication of late-bolting Chinese cabbage. Over-expression of BrHIS4.A04 resulted in premature flowering under normal growth conditions, but prevented further premature bolting in response to drought. We show that the expression of key abscisic acid (ABA) signaling genes, and also photoperiodic flowering genes was attenuated in BrHIS4.A04-overexpressing (BrHIS4.A04OE) plants under drought conditions. Furthermore, the relative change in H4-acetylation at these gene loci was reduced in BrHIS4.A04OE plants. We suggest that BrHIS4.A04 prevents premature bolting by attenuating the expression of photoperiodic flowering genes under drought conditions, through the ABA signaling pathway. Since BrHIS4.A04OE plants displayed no phenotype related to vegetative or reproductive development under laboratory-induced drought conditions, our findings contribute to the potential fine-tuning of flowering time in crops through genetic engineering without any growth penalty, although more data are necessary under field drought conditions.

Genome-wide analysis of mRNA and lncRNA expression and mitochondrial genome sequencing provide insights into the mechanisms underlying a novel cytoplasmic male sterility system, BVRC-CMS96, in Brassicarapa.

KEY MESSAGE: Characterization of a novel and valuable CMS system in Brassicarapa. Cytoplasmic male sterility (CMS) is extensively used to produce F1 hybrid seeds in a variety of crops. However, it has not been successfully used in Chinese cabbage (Brassicarapa L. ssp. pekinensis) because of degeneration or temperature sensitivity. Here, we characterize a novel CMS system, BVRC-CMS96, which originated in B.napus cybrid obtained from INRAE, France and transferred by us to B.rapa. Floral morphology and agronomic characteristics indicate that BVRC-CMS96 plants are 100% male sterile and show no degeneration in the BC7 generation, confirming its suitability for commercial use. We also sequenced the BVRC-CMS96 and maintainer line 18BCM mitochondrial genomes. Genomic analyses showed the presence of syntenic blocks and distinct structures between BVRC-CMS96 and 18BCM and the other known CMS systems. We found that BVRC-CMS96 has one orf222 from 'Nap'-type CMS and two copies of orf138 from 'Ogu'-type CMS. We analyzed expression of orf222, orf138, orf261b, and the mitochondrial energy genes (atp6, atp9, and cox1) in flower bud developmental stages S1-S5 and in four floral organs. orf138 and orf222 were both highly expressed in S4, S5-stage buds, calyx, and the stamen. RNA-seq identified differentially expressed mRNAs and lncRNAs (long non-coding RNAs) that were significantly enriched in pollen wall assembly, pollen development, and pollen coat. Our findings suggest that an energy supply disorder caused by orf222/orf138/orf261b may inhibit a series of nuclear pollen development-related genes. Our study shows that BVRC-CMS96 is a valuable CMS system, and our detailed molecular analysis will facilitate its application in Chinese cabbage breeding.

Identification and fine mapping of qSB.A09, a major QTL that controls shoot branching in Brassica rapa ssp. chinensis Makino.

KEY MESSAGE: QTL mapping plus bulked segregant analysis revealed a major QTL for shoot branching in non-heading Chinese cabbage. The candidate gene was then identified using sequence alignment and expression analysis. Shoot branching is a complex quantitative trait that contributes to plant architecture and ultimately yield. Although many studies have examined branching in grain crops, the genetic control of shoot branching in vegetable crops such as Brassica rapa L. ssp. chinensis remains poorly understood. In this study, we used bulked segregant analysis (BSA) of an F2 population to detect a major quantitative trait locus (QTL) for shoot branching, designated shoot branching 9 (qSB.A09) on the long arm of chromosome A09 in Brassica rapa L. ssp. chinensis. In addition, traditional QTL mapping of the F2 population revealed six QTLs in different regions. Of these, the mapping region on chromosome A09 was consistent with the results of BSA-seq analysis, as well as being stable over the 2-year study period, explaining 19.37% and 22.18% of the phenotypic variation across multiple genetic backgrounds. Using extreme recombinants, qSB.A09 was further delimited to a 127-kb genomic region harboring 28 annotated genes. We subsequently identified the GRAS transcription factor gene Bra007056 as a potential candidate gene; Bra007056 is an ortholog of MONOCULM 1 (MOC1), the key gene that controls tillering in rice. Quantitative RT-PCR further revealed that expression of Bra007056 was positively correlated with the shoot branching phenotype. Furthermore, an insertion/deletion marker specific to Bra007056 co-segregated with the shoot branching trait in the F2 populations. Overall, these results provide the basis for elucidating the molecular mechanism of shoot branching in Brassica rapa ssp. chinensis Makino.

Natural variation in a calreticulin gene causes reduced resistance to Ca2+ deficiency-induced tipburn in Chinese cabbage (Brassica rapa ssp. pekinensis).

Tipburn is an irreversible physiological disorder of Chinese cabbage that decreases crop value. Because of a strong environmental component, tipburn-resistant cultivars are the only solution, although tipburn resistance genes are unknown in Chinese cabbage. We studied three populations of Chinese cabbage over four growing seasons under field conditions: (a) 194 diverse inbred lines, (b) a doubled haploid (DH100) population, and (c) an F2 population. The 194 lines were genotyped using single nucleotide polymorphism markers, and genome-wide-association mapping showed that 24 gQTLs were significantly associated with tipburn disease index. Analysis of the DH100 and F2 populations identified a shared tipburn-associated locus, gqbTRA06, that was found to cover the region defined by one of the 24 gQTLs. Of 35 genes predicted in the 0.14-Mb quantitative trait locus region, Bra018575 (calreticulin family protein, BrCRT2) showed higher expression levels during disease development. We cloned the two BrCRT2 alleles from tipburn-resistant (BrCRT2R ) and tipburn-susceptible (BrCRT2S ) lines and identified a 51-bp deletion in BrCRT2S . Overexpression of BrCRT2R increased Ca2+ storage in the Arabidopsis crt2 mutant and also reduced cell death in leaf tips and margins under Ca2+ -depleted conditions. Our results suggest that BrCRT2 is a possible candidate gene for controlling tipburn in Chinese cabbage.

[Effect of red blood cell storage duration on the clinical effect of exchange transfusion and internal environment in neonates with hyperbilirubinemia].

OBJECTIVE: To study the effect of red blood cell (RBC) storage duration on the clinical effect of exchange transfusion (ET) and internal environment in neonates with hyperbilirubinemia. METHODS: A retrospective analysis was performed for the clinical data of 135 neonates with hyperbilirubinemia who received ET between January 2015 and August 2018. According to RBC storage duration, the neonates were divided into short-term storage group (RBCs were stored for ≤7 days) with 56 neonates and long-term storage group (RBCs were stored for >7 days) with 79 neonates. The two groups were compared in terms of serum total bilirubin (TBIL) level and the rate of TBIL reduction at 0 and 12 hours after ET, as well as the duration of continued phototherapy and rate of repeated ET. Routine blood test parameters, electrolytes, blood glucose, and blood gas parameters were measured before ET and at 0 hour after ET. RESULTS: At 0 hour after ET, there were no significant differences in the TBIL level and the rate of TBIL reduction between the two groups (P>0.05). At 12 hours after ET, the long-term storage group had a significantly higher TBIL level and a significantly lower rate of TBIL reduction than the short-term storage group (P<0.01). The long-term storage group had a significantly longer duration of continued phototherapy after ET than the short-term storage group (P<0.05). Compared with the short-term storage group, the long-term storage group had significantly higher incidence rates of ET-related complications, including hyponatremia, hyperkalemia, and metabolic acidosis (P<0.05). CONCLUSIONS: The use of RBCs with a storage duration of >7 days in ET for neonates with hyperbilirubinemia does not affect the immediate effect of ET, but these neonates tend to have a poor outcome after continued phototherapy and high risk of hyponatremia, hyperkalemia, and metabolic acidosis.

Evaluation of the Nutritional Quality of Chinese Kale (Brassica alboglabra Bailey) Using UHPLC-Quadrupole-Orbitrap MS/MS-Based Metabolomics.

Chinese kale (Brassica alboglabra Bailey) is a widely consumed vegetable which is rich in antioxidants and anticarcinogenic compounds. Herein, we used an untargeted ultra-high-performance liquid chromatography (UHPLC)-Quadrupole-Orbitrap MS/MS-based metabolomics strategy to study the nutrient profiles of Chinese kale. Seven Chinese kale cultivars and three different edible parts were evaluated, and amino acids, sugars, organic acids, glucosinolates and phenolic compounds were analysed simultaneously. We found that two cultivars, a purple-stem cultivar W1 and a yellow-flower cultivar Y1, had more health-promoting compounds than others. The multivariate statistical analysis results showed that gluconapin was the most important contributor for discriminating both cultivars and edible parts. The purple-stem cultivar W1 had higher levels of some phenolic acids and flavonoids than the green stem cultivars. Compared to stems and leaves, the inflorescences contained more amino acids, glucosinolates and most of the phenolic acids. Meanwhile, the stems had the least amounts of phenolic compounds among the organs tested. Metabolomics is a powerful approach for the comprehensive understanding of vegetable nutritional quality. The results provide the basis for future metabolomics-guided breeding and nutritional quality improvement.

[Pathogen distribution, risk factors, and outcomes of nosocomial infection in very premature infants].

OBJECTIVE: To study the pathogen distribution and risk factors of nosocomial infection in very preterm infants, as well as the risk of adverse outcomes. METHODS: A retrospective analysis was performed for the clinical data of 111 very preterm infants who were born between January and December, 2016 and had a gestational age of <32 weeks and a birth weight of <1 500 g. According to the presence or absence of nosocomial infection after 72 hours of hospitalization, the infants were divided into infection group and non-infection group. The infection group was analyzed in terms of pathogenic bacteria which caused infection and their drug sensitivity. A multivariate logistic regression analysis was used to investigate the potential risk factors and risk of adverse outcomes of nosocomial infection in very preterm infants. RESULTS: Gram-negative bacteria were the main pathogens for nosocomial infection in very preterm infants and accounted for 54%, among which Pseudomonas aeruginosa was the most common one; the following pathogens were fungi (41%), among which Candida albicans was the most common one. The drug sensitivity test showed that Gram-negative bacteria were highly resistant to ß-lactam and carbapenems and highly sensitive to quinolones, while fungi had low sensitivity to itraconazole and high sensitivity to 5-fluorocytosine and amphotericin B. Early-onset sepsis, duration of peripherally inserted central catheter, steroid exposure, and duration of parenteral nutrition were risk factors for nosocomial infection in very preterm infants (P<0.05). Compared with the non-infection group, the infection group had significantly higher risks of pulmonary complications (P<0.05), as well as a significantly longer length of hospital stay and a significantly higher hospital cost (P<0.001). CONCLUSIONS: Nosocomial infection in very preterm infants is affected by various factors and may increase the risk of adverse outcomes. In clinical practice, reasonable preventive and treatment measures should be taken with reference to drug sensitivity, in order to improve the prognosis of very premature infants.

Effects of Endogenous Salicylic Acid During Calcium Deficiency-Induced Tipburn in Chinese Cabbage (Brassica rapa L. ssp. pekinensis).

By cultivating tipburn-susceptible plants in modified Hoagland's medium containing of gradient exogenous calcium (Ca2+), we have shown that Ca2+ deficiency is one of the main causes of tipburn in Chinese cabbage (Brassica rapa L. ssp. pekinensis). The effect of endogenous plant Ca2+ concentrations on tipburn was also studied in a doubled haploid (DH) population consisting of 100 individuals, but no correlation was found. We then examined the expression of 12 Ca2+ transporter genes that function in cytosolic Ca2+ homeostasis in both tipburn-susceptible and tipburn-resistant plants under normal and tipburn-inducing conditions. Expression patterns for most of these genes differed between the two types of plants. Salicylic acid (SA) accumulated in response to conditions of calcium deficiency in our study, and both total SA and SA ß-glucoside (SAG) in tipburn-susceptible plants was ∼3-fold higher than it was in resistant plants following Ca2+ deficiency treatment. Also, the changes observed in SA levels correlated well with cell death patterns revealed by trypan blue staining. Therefore, we speculate that the cytoplasmic Ca2+ fluctuation-induced downstream signaling events, as well as SA signaling or other biological events, are involved in the plant defense response to tipburn in Chinese cabbage.

[Effect of Berberine on the Insulin Resistance and TLR4/IKKbeta/NF-kappaB Signaling Pathways in Skeletal Muscle of Obese Rats with Insulin Resistance].

OBJECTIVE: To explore the possible mechanism of berberine improve insulin resistance in skeletal muscle of obese rats. METHODS: Forty Wistar rats were divided into normal control group (NC group, n =10) and high fat food group (HF group, n=30). After the obese model rats established successfully, the rats of NC group (n=10) and HF group (n=10) were sacrificed. The level of fasting plasma endotoxin (ET) was detected. The expression of Toll-like receptor 4 (TLR4) mRNA in skeletal muscle were detected by real time quantitative PCR. The expression of TLR4, IkappaB kinase beta (IKKbeta), phospho-IKKbeta(Ser181) (p-IKKbeta(Ser181)), nuclear factor-kappaB (NF-kappaB), tumor necrosis factor-alpha (TNF-alpha), insulin receptor (IR), insulin receptor substrate-1 (IRS-1), phospho-IRS-1(Ser307) (p-IRS-1(ser307)) and the tyrosine phosphorylation of IR and IRS-1 (p-IR(Tyr) and p-IRS-1(Tyr)) protein in skeletal muscle were detected by Western blot. The twenty HF group rats were randomly divided into two group: the fat model control group (FC group, n=10) were fed with high fat diet and distilled water. The fat berberine group (FB group, n=10) were fed with high fat diet and berberine. All rats were sacrificed after effective interventions of eight weeks. The same indexes as the first part of experiment were detected. Results The results showed that the level of ET was increased. The TLR4/IKKneta/NF-kappaB signaling pathway is activated and the expression of TNF-alpha was increased of the skeletal muscle in obese rats. However, the insulin signaling pathways of the skeletal muscle in obese rats was inhibited. Berberine could reduce the level of ET of obese rats, down-regulate the TLR4/IKKbeta/NF- kappaB inflammation signaling pathway and improve insulin resistance of skeletal muscle in obese rats. CONCLUSION: Our study revealed that berberine could reduce the level of ET of obese rats, down-regulate the TLR4/IKKbeta/NF-kappaB inflammation signaling pathway in skeletal muscle and berberine can improve insulin resistance of skeletal muscle through inhibiting the active of the TLR4/IKKbeta/NF-kappaB signaling pathway.

[Umbilical Cord-derived Mesenchymal Stem Cells Grafts for Neonatal Rats Model of HIBD: the Mechanism of PI3K/Akt Signaling Pathway].

OBJECTIVE: To investigate the role of phosphatidylinositol 3 kinase/protein kinase B (PI3K/Akt) signaling pathway for umbilical cord-derived mesenchymal stem cells (UC-MSCs) treating in neonatal rats with hypoxia-ischemia brain damage (HIBD). METHODS: P10 SD rats were divided into sham group, MSCs group, inhibitor (LY 294002) group (LY group) and HIBD group randomly. To establish a neonatal rat model of HIBD, UC-MSCs labeled with Brd U were transplanted into the lateral ventricle of rats. At 24 and 48 h after transplantation, the number of apoptotic cells was detected by TUNEL, while the expression of caspase3 protein and phosphorylation of Akt (P-Akt) were quantified by Western blot. RESULTS: At 24 and 48 h after transplantation, both the apoptotic cells and caspase3 protein expression in MSCs group were less than those in LY group and HIBD group (P<0. 05), while the expression of P-Akt was higher than those in LY group and HIBD group (P<0.05), and with the passage of time after transplantation, the expression of each index showed a downward trend. CONCLUSION: The apoptotic cells of brain and the expression of caspase3 protein decrease, while the expression of P-Akt increase. PI3K/Akt signaling pathway may be an important mechanism for UC-MSCs transplantation in HIBD rats.

Crossover rate between homologous chromosomes and interference are regulated by the addition of specific unpaired chromosomes in Brassica.

Recombination is a major mechanism generating genetic diversity, but the control of the crossover rate remains a key question. In Brassica napus (AACC, 2n = 38), we can increase the homologous recombination between A genomes in AAC hybrids. Hypotheses for this effect include the number of C univalent chromosomes, the ratio between univalents and bivalents and, finally, which of the chromosomes are univalents. To test these hypotheses, we produced AA hybrids with zero, one, three, six or nine additional C chromosomes and four different hybrids carrying 2n = 32 and 2n = 35 chromosomes. The genetic map lengths for each hybrid were established to compare their recombination rates. The rates were 1.4 and 2.7 times higher in the hybrids having C6 or C9 alone than in the control (0C). This enhancement reached 3.1 and 4.1 times in hybrids carrying six and nine C chromosomes, and it was also higher for each pair of hybrids carrying 2n = 32 or 2n = 35 chromosomes, with a dependence on which chromosomes remained as univalents. We have shown, for the first time, that the presence of one chromosome, C9 , affects significantly the recombination rate and reduces crossover interference. This result will have fundamental implications on the regulation of crossover frequency.

[Intracerebral transplantation of human umbilical cord-derived mesenchymal stem cells in neonatal rat model of hypoxic-ischemic brain damage: protective effect to injured brain].

OBJECTIVE: To study the brain protection and the possible mechanism of human umbilical cord-derived mesenchymal stem cells (hUC-MSCs) in neonatal rat model of hypoxic-ischemic brain damage (HIBD). METHODS: Successfully establishing a neonatal rat model of HIBD, hUC-MSCs labeled with BrdU were transplanted into the lateral ventricle 24 hours after HIBD. The number of apoptotic cells and the expression of Caspase-3 were detected by TUNEL and Western blot respectively at 24 and 48 hours after transplantation. The neurological functions of HIBD rats were evaluated by Longa score, and the survival, differentiation and pro-differentiation effects of hUC-MSCs were identified by immunofluorescence at 1 to 3 weeks after transplantation. RESULTS: At 24 and 48 hours after transplantation, apoptotic cells and Caspase-3 expression in the MSCs group were less than in the HIBD group (P<0.05). At 2 and 3 weeks after transplantation, the Longa score in the MSCs group was lower than in the HIBD group (P<0.05). After transplantation, positive cells labeled with BrdU were seen in the brain tissue. The expression levels of glial fibrillary acidic protein (GFAP) and neuron specific esterase (NSE) in the MSCs group were higher than in the HIBD and sham-operated control groups (P<0.05), and increased gradually with the transplantation time (P<0.05). CONCLUSIONS: hUC-MSCs transplantation in HIBD rats can inhibit Caspase-3 expression and reduce apoptotic cells in the early stage, and in the later period, the survival hUC-MSCs can differentiate into neural-like cells and promote the differentiation of endogenous neural-like cells, providing protective effects to brain.

Understanding how methyltransferase-like 3 functions in lung diseases: From pathogenesis to clinical application.

Lung diseases have complex pathogenesis and treatment challenges, showing an obvious increase in the rate of diagnosis and death every year. Therefore, elucidating the mechanism for their pathogenesis and treatment ineffective from novel views is essential and urgent. Methyltransferase-like 3 (METTL3) is a novel post-transcriptional regulator for gene expression that has been implicated in regulating lung diseases, including that observed in chronic conditions such as pulmonary fibrosis (PF), pulmonary arterial hypertension (PAH), and chronic obstructive pulmonary disease (COPD), as well as acute conditions such as pneumonia, severe acute respiratory syndrome coronavirus 2 infection, and sepsis-induced acute respiratory distress syndrome. Notably, a comprehensive summary and analysis of findings from these studies might help understand lung diseases from the novel view of METTL3-regulated mechanism, however, such a review is still lacking. Therefore, this review aims to bridge such shortage by summarising the roles of METTL3 in lung diseases, establishing their interrelationships, and elucidating the potential applications of METTL3 regarding diagnosis, treatment, and prognosis. The analysis collectively suggests METTL3 is contributable to the onset and progression of these lung diseases, thereby prospecting METTL3 as a valuable biomarker for their diagnosis, treatment, and prognosis. In conclusion, this review offers elucidation into the correlation between METTL3 and lung diseases in both research and clinical settings and highlights potential avenues for exploring the roles of METTL3 in the respiratory system.

Temperature-dependent jumonji demethylase modulates flowering time by targeting H3K36me2/3 in Brassica rapa.

Global warming has a severe impact on the flowering time and yield of crops. Histone modifications have been well-documented for their roles in enabling plant plasticity in ambient temperature. However, the factor modulating histone modifications and their involvement in habitat adaptation have remained elusive. In this study, through genome-wide pattern analysis and quantitative-trait-locus (QTL) mapping, we reveal that BrJMJ18 is a candidate gene for a QTL regulating thermotolerance in thermotolerant B. rapa subsp. chinensis var. parachinensis (or Caixin, abbreviated to Par). BrJMJ18 encodes an H3K36me2/3 Jumonji demethylase that remodels H3K36 methylation across the genome. We demonstrate that the BrJMJ18 allele from Par (BrJMJ18Par) influences flowering time and plant growth in a temperature-dependent manner via characterizing overexpression and CRISPR/Cas9 mutant plants. We further show that overexpression of BrJMJ18Par can modulate the expression of BrFLC3, one of the five BrFLC orthologs. Furthermore, ChIP-seq and transcriptome data reveal that BrJMJ18Par can regulate chlorophyll biosynthesis under high temperatures. We also demonstrate that three amino acid mutations may account for function differences in BrJMJ18 between subspecies. Based on these findings, we propose a working model in which an H3K36me2/3 demethylase, while not affecting agronomic traits under normal conditions, can enhance resilience under heat stress in Brassica rapa.

A graph-based pan-genome of Brassica oleracea provides new insights into its domestication and morphotype diversification.

The domestication of Brassica oleracea has resulted in diverse morphological types with distinct patterns of organ development. Here we report a graph-based pan-genome of B. oleracea constructed from high-quality genome assemblies of different morphotypes. The pan-genome harbors over 200 structural variant hotspot regions enriched in auxin- and flowering-related genes. Population genomic analyses revealed that early domestication of B. oleracea focused on leaf or stem development. Gene flows resulting from agricultural practices and variety improvement were detected among different morphotypes. Selective-sweep and pan-genome analyses identified an auxin-responsive small auxin up-regulated RNA gene and a CLAVATA3/ESR-RELATED family gene as crucial players in leaf-stem differentiation during the early stage of B. oleracea domestication and the BoKAN1 gene as instrumental in shaping the leafy heads of cabbage and Brussels sprouts. Our pan-genome and functional analyses further revealed that variations in the BoFLC2 gene play key roles in the divergence of vernalization and flowering characteristics among different morphotypes, and variations in the first intron of BoFLC3 are involved in fine-tuning the flowering process in cauliflower. This study provides a comprehensive understanding of the pan-genome of B. oleracea and sheds light on the domestication and differential organ development of this globally important crop species.

[The risk factors of ventilator-associated pneumonia in newborn and the changes of isolated pathogens].

OBJECTIVE: To study the risk factors of ventilator-associated pneumonia (VAP) in newborn and the profiles of isolated pathogens. METHODS: The clinical data of 179 neonates in the previous group (from December 2005 to December 2008) and 331 neonates in the present group (from January 2009 to January 2012) admitted into the neonatal intensive care unit (NICU) and received mechanical ventilation for equal or longer than 48 hours were respectively reviewed and analyzed,and their isolated pathogen profile and drug sensitivity were also compared in two groups. RESULTS: The incidence of VAP in the previous group and the present group were 22.35% and 20.24% respectively, no significant difference between two groups (P > 0.05) was observed. Gram-negative bacteria was the main pathogens (93.40%), the first 5 common pathogens in the previous group were Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Escherichia coli and Enterobacter aerogenes. However, the first 5 of isolated gram-negative pathogens in the present group were somewhat different from the previous group, which were Klebsiella pneumoniae, Acinetobacter baumannii, Enterobacter cloacae, Escherichia coli and Enterobacter aerogenes. The drug sensitivity test showed that these pathogens had a general decline in sensitivities to commonly used antibiotics, of which the carbapenem antibiotic drug sensitivity decreased significantly, there was statistically significant difference between the previous group and the present group (P < 0.05). The risk factors of VAP include the duration of mechanical ventilation (OR = 5.680, 95% CI: 2.867-11.253), the frequency of tracheal intubation (OR = 2.219, 95% CI: 1.037- 4.748), birth weight (OR = 2. 127, 95% CI: 1.067-4.238) and neonatal asphyxia (OR = 2.025, 95% CI: 1.079-3.799) as well as the duration of hospital stay (OR = 2.012, 95% CI: 1.215-3.967). CONCLUSIONS: According to the data in our hospital, the main pathogenic bacteria of VAP were gram-negative pathogens, which showed a general decline in sensitivities to commonly used antibiotics. The incidence of VAP was closely related to the duration of mechanical ventilation, the frequency of intubation, birth weight and the hospitalization as well as the neonatal asphyxia.

[Pathogens and risk factors for ventilator-associated pneumonia in neonates].

OBJECTIVE: To study the pathogens, drug sensitivity and risk factors for ventilator-associated pneumonia (VAP) in neonates. METHODS: Retrospective analysis was performed on the clinical data of 401 neonates who were admitted to the neonatal intensive care unit and received mechanical ventilation for 48 hours or longer from January 2008 to February 2012. Eighty-five of the 401 neonates suffered VAP. RESULTS: The main pathogens for VAP were Gram-negative bacteria (97%), including Klebsiella pneumoniae (51%), Acinetobacter baumannii (17%) and Escherichia coli (12%) as the three most frequent ones. The drug sensitivity test showed that these pathogens developed resistance to amoxicillin, amoxicillin/clavulanic acid, piperacillin, ceftazidime, cefazolin, and cefotaxime, with a susceptibility rate of below 15%, and demonstrated decreased sensitivity to imipenem and meropenem, with a susceptibility rate of below 75%. The independent risk factors for neonatal VAP included birth weight (OR=1.399, P<0.05), duration of mechanical ventilation (OR=1.966, P<0.01), length of hospital stay (OR=1.812, P<0.01), times of tracheal intubation (OR=2.056, P<0.01), and 1 min Apgar score (OR=2.146, P<0.01). CONCLUSIONS: The incidence of neonatal VAP is influenced by many factors. The main pathogens for neonatal VAP are Gram-negative bacteria and antibacterial agents should be properly used according to drug sensitivity test results. Comprehensive prevention and control measures should be taken to reduce the incidence of VAP.