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Chilling stress during the growing season could cause a series of changes in wucai (Brassica campestris L.). WS-1 (chilling-tolerant genotype) and Ta2 (chilling-sensitive genotype) were sampled in present study to explore the chilling tolerance mechanisms. Our results indicated that photosynthetic parameters exhibited lower level in Ta2 than in WS-1 under chilling stress. The rapid chlorophyll fluorescence dynamics curve showed that chilling resulted in a greater inactivation of photosystem II reaction center in Ta2. Reactive oxygen species and malondialdehyde content of chloroplast in Ta2 were higher than WS-1. The ascorbate–glutathione cycle in chloroplast of WS-1 played a more crucial role than Ta2, which was confirmed by higher activities of antioxidant enzymes including Ascorbate peroxidase, Glutathione reductase, Monodehydroascorbate reductase and Dehydroascorbate reductase and higher content of AsA and GSH. In addition, the ultrastructure of chloroplasts in Ta2 was more severely damaged. After low temperature stress, the shape of starch granules in Ta2 changed from elliptical to round and the volume became larger than that of WS-1. The thylakoid structure of Ta2 also became dispersed from the original tight arrangement. Combined with our previous study under heat stress, WS-1 can tolerant both chilling stress and heat stress, which was partly due to a stable photosynthetic system and the higher active antioxidant system in plants, in comparison to Ta2.

Background Chlorophyll (Chl) is a vital photosynthetic pigment involved in capturing light energy and energy conversion. In this study, the color conversion of inner-leaves from green to yellow in the new wucai (Brassica campestris L.) cultivar W7–2 was detected under low temperature. The W7–2 displayed a normal green leaf phenotype at the seedling stage, but the inner leaves gradually turned yellow when the temperature was decreased to 10 °C/2 °C (day/night), This study facilitates us to understand the physiological and molecular mechanisms underlying leaf color changes in response to low temperature. Results A comparative leaf transcriptome analysis of W7–2 under low temperature treatment was performed on three stages (before, during and after leaf color change) with leaves that did not change color under normal temperature at the same period as a control. A total of 67,826 differentially expressed genes (DEGs) were identified. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway and Gene Ontology (GO) analysis revealed that the DEGs were mainly enriched in porphyrin and Chl metabolism, carotenoids metabolism, photosynthesis, and circadian rhythm. In the porphyrin and chlorophyll metabolic pathways, the expression of several genes was reduced [i.e. magnesium chelatase subunit H (CHLH)] under low temperature. Almost all genes [i.e. phytoene synthase (PSY)] in the carotenoids (Car) biosynthesis pathway were downregulated under low temperature. The genes associated with photosynthesis [i.e. photosystem II oxygen-evolving enhancer protein 1 (PsbO)] were also downregulated under LT. Our study also showed that elongated hypocotyl5 (HY5), which participates in circadian rhythm, and the metabolism of Chl and Car, is responsible for the regulation of leaf color change and cold tolerance in W7–2. Conclusions The color of inner-leaves was changed from green to yellow under low temperature in temperature-sensitive mutant W7–2. Physiological, biochemical and transcriptomic studies showed that HY5 transcription factor and the downstream genes such as CHLH and PSY, which regulate the accumulation of different pigments, are required for the modulation of leaf color change in wucai under low temperature.

Background The discovery of male sterile materials is of great significance for the development of plant fertility research. Wucai (Brassica campestris L. ssp. chinensis var. rosularis Tsen) is a variety of non-heading Chinese cabbage. There are few studies on the male sterility of wucai, and the mechanism of male sterility is not clear. In this study, the male sterile mutant MS7–2 and the wild-type fertile plant MF7–2 were studied. Results Phenotypic characteristics and cytological analysis showed that MS7–2 abortion occurred at the tetrad period. The content of related sugars in the flower buds of MS7–2 was significantly lower than that of MF7–2, and a large amount of reactive oxygen species (ROS) was accumulated. Through transcriptome sequencing of MS7–2 and MF7–2 flower buds at three different developmental stages (a–c), 2865, 3847, and 4981 differentially expressed genes were identified in MS7–2 at the flower bud development stage, stage c, and stage e, respectively, compared with MF7–2. Many of these genes were enriched in carbohydrate metabolism, phenylpropanoid metabolism, and oxidative phosphorylation, and most of them were down-regulated in MS7–2. The down-regulation of genes involved in carbohydrate and secondary metabolite synthesis as well as the accumulation of ROS in MS7–2 led to pollen abortion in MS7–2. Conclusions This study helps elucidate the mechanism of anther abortion in wucai, providing a basis for further research on the molecular regulatory mechanisms of male sterility and the screening and cloning of key genes in wucai.

The novel male sterility line 12-14A of Wucai (Brassica campestris) was generated by backcrossing. In this study, morphological, molecular, and cytological analyses were performed to characterize this line. The phenotypes of flower organs of 12-14A were different from those of its maintainer line 12-14B, as the flowers of 12-14A were completely infertile. Molecular analysis confirmed that the male sterility line 12-14A was classified as the ogu CMS type. An analysis of anther development in the CMS line demonstrated that two types of abortion occur simultaneously: pollen mother cell abortion and tetrad-to-mononuclear microspore abortion. In addition, the mature anthers of 12-14A showed typical abortive features, such as appearing dry, shrunken, and scaly. A heterosis test of hybrids from CMS 12-14A and four inbred lines was carried out, and the F1 hybrids exhibited clear heterosis in plant weight, as well as in the protein, soluble sugar, and vitamin C content, suggesting high yields and high quality potential. These results indicate that this novel CMS line may have powerful potential in Wucai hybrid breeding.

We developed a novel Agrobacterium-mediated anther transformation for Wucai in planta, and in this procedure, the male germ line was the predominant target. Wucai (Brassica campestris L.), a variant of non-heading Chinese cabbage, is widely cultured in China and only improved by classic breeding methods. Here, a novel and efficient in planta Agrobacterium-mediated anther transformation method is developed based on the optimization of several factors that affect anther transformation. After optimization, transformation with the manual pollination application led to increased transient GUS expression in anthers (reaching 91.59%) and the transformation efficacies in planta (0.59–1.56% for four commercial cultivars). The stable integration and inheritance of the transgenes were further examined by molecular and genetic analyses. Three T2 transgenic lines presented a segregation ratio of 3:1, which was consistent with the Mendelian feature of a single dominant gene. In addition, the GUS histochemical assay and genetic crossing analysis revealed that the male germ line was the predominant target in this transformation. This optimized transformation system could provide a useful tool for both the improvement of cultivar qualities and investigation of functional genes in Wucai.

Background Leaf color mutants are the ideal materials to explore the pathways of chlorophyll (Chl) metabolism, chloroplast development, and photosynthesis system. In this study, a spontaneous yellow-green leaf wucai (Brassica campestris L.) mutant “WY16–13” was identified, which exhibited yellow-green leaf color during its entire growth period. However, current understanding of the molecular mechanism underlying Chl metabolism and chloroplast development of “WY16–13” is limited. Results Total Chl and carotenoid content in WY16–13 was reduced by 60.92 and 58.82%, respectively, as compared with its wild type parental line W16–13. Electron microscopic investigation revealed fewer chloroplasts per cell and looser stroma lamellae in WY16–13 than in W16–13. A comparative transcriptome profiling was performed using leaves from the yellow-green leaf type (WY16–13) and normal green-leaf type (W16–13). A total of 54.12 million (M) (WY16–13) and 56.17 M (W16–13) reads were generated. A total of 40,578 genes were identified from the mapped libraries. We identified 3882 differentially expressed genes (DEGs) in WY16–13 compared with W16–13 (i.e., 1603 upregulated genes and 2279 downregulated genes). According to the Gene Ontology (GO) term and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses, these DEGs are involved in porphyrin and Chl metabolism [i.e., chlorophyllase (CLH), heme oxygenase (HO), chlorophyll (ide) b reductase (NYC), and protochlorophyllide oxidoreductase (POR) genes], carbohydrate metabolism, photosynthesis, and carbon fixation in photosynthetic organisms. Moreover, deficiency in Chl biosynthetic intermediates in WY16–13 revealed that the formation of the yellow-green phenotype was related to the disorder of heme metabolism. Conclusions Our results provide valuable insights into Chl deficiency in the yellow-green leaf mutant and a bioinformatics resource for further functional identification of key allelic genes responsible for differences in Chl content.

The heat transfer of methane at supercritical pressure in a helically coiled tube was numerically investigated using the Reynolds Stress Model under constant wall temperature. The effects of mass flux (G), inlet pressure (Pin) and buoyancy force on the heat transfer behaviors were discussed in detail. Results show that the light fluid with higher temperature appears near the inner wall of the helically coiled tube. When the bulk temperature is less than or approach to the pseudocritical temperature (T pc ), the combined effects of buoyancy force and centrifugal force make heavy fluid with lower temperature appear near the outer-right of the helically coiled tube. Beyond the T pc , the heavy fluid with lower temperature moves from the outer-right region to the outer region owing to the centrifugal force. The buoyancy force caused by density variation, which can be characterized by Gr/Re2 and Gr/Re2.7, enhances the heat transfer coefficient (h) when the bulk temperature is less than or near the T pc , and the h experiences oscillation due to the buoyancy force. The oscillation is reduced progressively with the increase of G. Moreover, h reaches its peak value near the T pc . Higher G could improve the heat transfer performance in the whole temperature range. The peak value of h depends on Pin. A new correlation was proposed for methane at supercritical pressure convective heat transfer in the helical tube, which shows a good agreement with the present simulated results.

The hot climate of southern China from late summer to early fall is one of the major factors limiting the yield and quality of wucai (Brassica campestris L.). To study the effects of high temperature on the growth and development of wucai, two cultivars (heat-sensitive ‘WS-6’ and heat-tolerant ‘WS-1’) were subjected to three heat stress treatments for 5 days. The two cultivars were evaluated for plant growth, photosynthetic characteristics, oxidative damage, and activities of antioxidant enzymes, including superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT). Heat stress treatments higher than 30 °C resulted in significant changes for both cultivars in plant growth (plant height, stem diameter, and single plant weight) and photosynthetic performance [net photosynthetic rate (P N), stomatal conductance (g s), intercellular CO2 concentration (C i), and leaf transpiration rate (E)]. The chlorophyll (Chl) content was markedly reduced by heat stress, inhibiting photochemical activity. However, larger decreases in growth and photosynthetic parameters occurred under heat stress in WS-6, compared with WS-1. Furthermore, microscopy also revealed greater severity of damage to the photosynthetic apparatus and membrane system of WS-6 under heat stress, compared with WS-1. These effects were probably due to a greater accumulation of reactive oxygen species (ROS) and malondialdehyde (MDA) in WS-6, relative to WS-1. Moreover, higher photochemical efficiency of photosystem II (PSII) and greater activities of antioxidant enzymes were present in WS-1, compared with WS-6. Our results indicated that the extent of heat stress damage in wucai was cultivar dependent. The heat-tolerant cultivar WS-1 had a greater capacity for self-protection and self-regulation under heat stress.

The effects on root growth, root antioxidant capacity, and cellular ultrastructure were investigated using two wucai genotypes (heat-tolerant WS-1 and heat-sensitive WS-6) under heat stress (40/30 °C) for 5 days. Heat stress caused decreases in root biomass, relative water content (RWC), root vigor, and root traits of two wucai genotypes. In addition, it resulted in reactive oxygen species (ROS) accumulation and increased hydrogen peroxide (H2O2) content, superoxide anion (O2 −) formation rate, and malondialdehyde (MDA) content, but the activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) were inhibited to different extents in two genotype wucai roots. However, these data indicated that the decline extent of WS-1 (heat tolerant) in root growth and antioxidant capacity was significantly lower than that of WS-6 (Heat sensitive). Microscopic analyses revealed that WS-1 (heat tolerant) showed a better cellular shape than WS-6 under heat stress and slightly oxidative damage; nuclear and mitochondria in WS-1 were of a better intact shape and clear bilayer membrane. Most importantly, the thicker root cell wall in heat-tolerant wucai genotype responding to heat stress was first reported. These results suggested that the ability of heat-tolerant wucai genotype to minimize the heat stress depended upon the higher self-regulation capacity and effectiveness of the antioxidant metabolism.

This article mainly introduces the contemporary changes in Chinese family and especially analyses the transformation of family structure and type, family housing conditions, family relationship network, the relationship between husband and wife and parenthood. In addition, it discusses the influence of family changes in the socialization of children. Then it expounds the new transformation in children’s socialization because of family, school, mass media, etc. Finally, it discusses its challenge and reflection to family and pedagogue.

A new densification method of chemical manganese dioxide (CMD)-NaMnO4 densification has been developed. This MnO2 produced by NaMnO4 oxidation possessed γ-type structure. After the crude MnO2 was densified, the tap density of the MnO2 powder could be increased from 1.2 to 2.0 g/cm3. The discharge capacity is higher than that densified by other oxidizers.