Synergistic effects of carbon cycle metabolism and photosynthesis in Chinese cabbage under salt stress

Chinese cabbage(Brassica rapa ssp. pekinensis) has a long cultivation history and is one of the vegetable crops with the largest cultivation area in China. However, salt stress severely damages photosynthesis and hormone metabolism, nutritional balances, and results in ion toxicity in plants. To better understand the mechanisms of salt-induced growth inhibition in Chinese cabbage, RNA-seq and physiological index determination were conducted to explore the impacts of salt stress on carbon cycle metabolism and photosynthesis in Chinese cabbage. Here, we found that the number of thylakoids and grana lamellae and the content of starch granules and chlorophyll in the leaves of Chinese cabbage under salt stress showed a time-dependent response, first increasing and then decreasing. Chinese cabbage increased the transcript levels of genes related to the photosynthetic apparatus and carbon metabolism under salt stress, probably in an attempt to alleviate damage to the photosynthetic system and enhance CO_(2) fixation and energy metabolism. The transcription of genes related to starch and sucrose synthesis and degradation were also enhanced;this might have been an attempt to maintain intracellular osmotic pressure by increasing soluble sugar concentrations. Soluble sugars could also be used as potential reactive oxygen species(ROS) scavengers, in concert with peroxidase(POD)enzymes, to eliminate ROS that accumulate during metabolic processes. Our study characterizes the synergistic response network of carbon metabolism and photosynthesis under salt stress.

Fine mapping and cloning of the sterility gene Bra2Ms in nonheading Chinese cabbage(Brassica rapa ssp.chinensis)

The application of a male-sterile line is an ideal approach for hybrid seed production in non-heading Chinese cabbage(Brassica rapa ssp.chinensis).However,the molecular mechanisms underlying male sterility in B.rapa are still largely unclear.We previously obtained the natural male sterile line WS24-3 of non-heading Chinese cabbage and located the male sterile locus,Bra2Ms,on the A2 chromosome.Cytological observations revealed that the male sterility of WS24-3 resulted from disruption of the meiosis process during pollen formation.Fine mapping of Bra2Ms delimited the locus within a physical distance of about 129 kb on the A2 chromosome of B.rapa.The Bra039753 gene encodes a plant homeodomain(PHD)-finger protein and is considered a potential candidate gene for Bra2Ms.Bra039753 was significantly downregulated in sterile line WS24-3 compared to the fertile line at the meiotic anther stage.Sequence analysis of Bra039753 identified a 369 bp fragment insertion in the first exon in male sterile plants,which led to an amino acid insertion in the Bra039753 protein.In addition,the 369 bp fragment insertion was found to cosegregate with the male sterility trait.This study identified a novel locus related to male sterility in non-heading Chinese cabbage,and the molecular marker obtained in this study will be beneficial for the marker-assisted selection of excellent sterile lines in non-heading Chinese cabbage and other Brassica crops.

Fast,simple,efficient Agrobacterium rhizogenes-mediated transformation system to non-heading Chinese cabbage with transgenic roots

Non-heading Chinese cabbage, a variety of Brassica campestris, is an important vegetable crop in the Yangtze River Basin of China. However,the immaturity of its stable transformation system and its low transformation efficiency limit gene function research on non-heading Chinese cabbage. Agrobacterium rhizogenes-mediated(ARM) transgenic technology is a rapid and effective transformation method that has not yet been established for non-heading Chinese cabbage plants. Here, we optimized conventional ARM approaches(one-step and two-step transformation methods) suitable for living non-heading Chinese cabbage plants in nonsterile environments. Transgenic roots in composite non-heading Chinese cabbage plants were identified using phenotypic detection, fluorescence observation, and PCR analysis. The transformation efficiency of a two-step method on four five-day-old non-heading Chinese cabbage seedlings(Suzhouqing, Huangmeigui, Wuyueman, and Sijiu Caixin) was 43.33%-51.09%, whereas using the stout hypocotyl resulted in a transformation efficiency of 54.88% for the 30-day-old Sijiu Caixin.The one-step method outperformed the two-step method;the transformation efficiency of different varieties was above 60%, and both methods can be used to obtain transgenic roots for functional studies within one month. Finally, optimized ARM transformation methods can easily,quickly, and effectively produce composite non-heading Chinese cabbage plants with transgenic roots, providing a reliable foundation for gene function research and non-heading Chinese cabbage genetic improvement breeding.

Physiological and transcriptome analyses of Chinese cabbage in response to drought stress

Chinese cabbage is an important leafy vegetable crop with high water demand and susceptibility to drought stress.To explore the molecular mechanisms underlying the response to drought,we performed a transcriptome analysis of drought-tolerant and-sensitive Chinese cabbage genotypes under drought stress,and uncovered core drought-responsive genes and key signaling pathways.A co-expression network was constructed by a weighted gene coexpression network analysis(WGCNA)and candidate hub genes involved in drought tolerance were identified.Furthermore,abscisic acid(ABA)biosynthesis and signaling pathways and their drought responses in Chinese cabbage leaves were systemically explored.We also found that drought treatment increased the antioxidant enzyme activities and glucosinolate contents significantly.These results substantially enhance our understanding of the molecular mechanisms underlying drought responses in Chinese cabbage.

DIA-based proteome profiling with PRM verification reveals the involvement of ER-associated protein processing in pollen abortion in Ogura CMS cabbage

Ogura cytoplasmic male sterility(Ogura CMS)is extensively applied in hybrid seed production in cruciferous crops.However,the posttranscriptional molecular basis of Ogura CMS in cruciferous crops remains elusive.Here,a data-independent acquisition-based proteomic approach coupled with a parallel reaction monitoring-based targeted proteomic assay was used to analyze the proteome dynamics of Ogura CMS cabbage line RM and its maintainer line RF during floral bud development to obtain insights into the mechanism underlying Ogura CMS in cruciferous crops.A total of 9162 proteins corresponding to 61464 peptides were identified in RM and RF floral buds.The proteomic fluctuation of RM was weaker than that of RF.Differences in protein expression between RM and RF gradually enlarged with floral bud development.Fifteen continually up-regulated and eight continually down-regulated proteins were found in RM relative to RF throughout floral bud development.Differentially expressed proteins between RM and RF during floral bud development were implicated in the endoplasmic reticulum(ER)-associated protein processing pathway,in which most of them exhibited down-regulated expression in RM.These data suggest that ER-associated protein processing may be involved in pollen abortion in Ogura CMS cabbage by inhibiting the expression of critical factors.Our findings not only deepen the understanding of the molecular mechanisms of Ogura CMS in cruciferous crops but also provide better guidance for applying Ogura CMS in the hybrid breeding of cruciferous crops.

Dissection of two QTL clusters underlying yield-related heterosis in the cabbage founder parent 01–20

Cabbage has significant heterosis and most commercial cultivars are hybrids.To explore genetic basis of cabbage heterosis and promote cabbage heterosis utilization,we constructed two populations by crossing 100 DH lines derived from a cabbage hybrid 01–20×96–100 with two female parents.Hybrids exhibited different extents of heterosis,the mean value of economic yield was 2.6 times bigger than parents.We identified 66 and 73 QTLs associated with mid-parent heterosis and transgressive heterosis of twelve yield-related traits,respectively.Some QTLs could be detected under the two-year experiment existed in two populations with different testers,showing relatively high phenotypic contribution rate(15.8%–20.0%).Heterosis QTLs exhibited clustered distribution in several cabbage chromosome regions.Two dominant genetic regions,mk300–316 and mk258–268,originated from the elite parent 01–20,exhibited significant genetic effects for yield-related heterosis,which were first identified.Three elite DH lines(D22,D46,D83)harboring these two dominant regions were selected as having strong heterosis in cabbage production.Candidate gene analysis revealed that some genes participating in biosynthetic processes of carbohydrates and some responses to auxin might affect cabbage yield heterosis.QTL identification and genetic dissection of yield-related traits provide new insights into the genetic effects of cabbage heterosis.

Fast tracking alien gene discovery by molecular markers in a late flowering Chinese cabbage-cabbage translocation line‘AT7–4'

Flowering time is an important agronomic trait of Chinese cabbage with late flowering being a primary breeding objective.In our previous work,we obtained Chinese cabbage-cabbage translocation lines that contained several beneficial cabbage genes.Cabbage-specific molecular markers show that these genes were coming from chromosome C01 of cabbage.In this study,we investigated the inheritance of flowering time in a couple of translocation lines and analyzed the transmission rate of molecular markers in the offspring.Consequently,we obtained the late flowering Chinese cabbage-cabbage translocation line‘AT7–4’in which the flowering time was later than that of‘85–1’by about 7 days under 4-week vernalization.Based on previous studies of the genomes of Chinese cabbage and cabbage,we located the cabbage-specific molecular markers that were closely linked at the top of the chromosome A01 in the F2mapping population generated by self-crossing F1s derived from a cross between the translocation line‘AT7–4’and Chinese cabbage‘14–36’.Five flowering-related genes in the alien fragment were found by functional annotation and their molecular markers were developed.This study lays the foundation for the future improvement of Chinese cabbage varieties using A-C translocation lines.

Comprehensive analysis of the full-length transcripts and alternative splicing involved in clubroot resistance in Chinese cabbage

Chinese cabbage is an economically important Brassica vegetable worldwide, and clubroot, which is caused by the soilborne protist plant pathogen Plasmodiophora brassicae is regarded as a destructive disease to Brassica crops. Previous studies on the gene transcripts related to Chinese cabbage resistance to clubroot mainly employed RNA-seq technology,although it cannot provide accurate transcript assembly and structural information. In this study, PacBio RS II SMRT sequencing was used to generate full-length transcriptomes of mixed roots at 0, 2, 5, 8, 13, and 22 days after P. brassicae infection in the clubroot-resistant line DH40R. Overall, 39 376 high-quality isoforms and 26 270 open reading frames(ORFs) were identified from the SMRT sequencing data. Additionally, 426 annotated long noncoding RNAs(lncRNAs),56 transcription factor(TF) families, 1 883 genes with poly(A) sites and 1 691 alternative splicing(AS) events were identified. Furthermore, 1 201 of the genes had at least one AS event in DH40R. A comparison with RNA-seq data revealed six differentially expressed AS genes(one for disease resistance and five for defensive response) that are potentially involved in P. brassicae resistance. The results of this study provide valuable resources for basic research on clubroot resistance in Chinese cabbage.

Blue light induces leaf color change by modulating carotenoid metabolites in orange-head Chinese cabbage(Brassica rapa L.ssp. pekinensis)

Carotenoids are involved in the formation of plant leaf color as well as photosystem photoprotection. This study showed that blue light significantly induced up-regulation of the total carotenoid content in the inner leaves of orange-head Chinese cabbage(OHCC). Furthermore, the transcriptomic analysis revealed that blue light treatment induced upregulation of genes in photosynthesis(BrHY5-2, BrCOP1 and BrDET1) and the methylerythritol 4-phosphate pathways(BrGGPS, BrDXS and BrHDR) upstream of the carotenoid metabolic pathway. Carotenoid metabolomic analysis revealed that the accumulation of several orange and red carotenoids(lycopene, zeaxanthin, β-carotene, lutein, and β-cryptoxanthin) after blue light treatment contributed to the deepening of the leaf coloration, suggesting that short-term blue light treatment could be used to boost nutritional quality. The light signal gene BrHY5-2 participated in the blue light-induced transcriptional regulation of carotenoid biosynthesis in OHCC. Overexpression of BrHY5-2 in Arabidopsis significantly increased the total carotenoid content and the sensitivity to blue light. The above findings revealed new insights about blue-light-induced carotenoid synthesis and accumulation in OHCC lines. They suggested a new engineering approach to increase the nutritional value of vegetables.

Effects of Combined Application of Biochar-based Organic Fertilizer and Reduced Nitrogen Fertilizer on Soil Enzyme Activity and Yield of Purple Cabbage(Brassica oleracea var.capita rubra)in Yuanmou County

[Objectives]In response to the issue of soil improvement in Yuanmou County,the effects of combined application of biochar-based organic fertilizer and reduced nitrogen fertilizer on soil nutrients,soil enzyme activity,and yield of purple cabbage(Brassica oleracea var.capita rubra)were investigated in the field base of Institute of Thermal Zone Ecological Agriculture,Yunnan Academy of Agricultural Sciences in Yuanmou County.[Methods]A total of 13 treatments were set up by applying biochar-based organic fertilizer at three levels of 15,30 and 45 t/hm^(2)(T_(1),T_(2),T_(3)),combined with top application of nitrogen fertilizer(urea)at four levels:375(N_1),300(N_(2)),225(N_(3))and 0 kg/hm^(2),with non-fertilizing treatment as control check(CK),in order to explore the optimal ratio for the combined application of biochar-based organic fertilizer with nitrogen fertilizer.[Results]The application of biochar-based organic fertilizer could significantly improve soil nutrients,enzyme activity,and purple cabbage yield.The improvement effect of combined application with nitrogen fertilizer was higher than that of single application of biochar-based organic fertilizer,and the improvement effect was enhanced with the application amount of biochar-based organic fertilizer increasing.The contents of organic matter and total nitrogen were the highest in treatment T_(3)N_(3),of which the values increased by 81.39%and 56.09%compared with the CK,respectively.The contents of soil hydrolyzable nitrogen,available phosphorus,and available potassium were all the highest under treatment T_(3)N_(2),with increases of 92.76%,171.01%and 235.50%,respectively.There was a significant positive correlation between the activity of soil catalase,urease,and sucrase and organic matter,total nitrogen,and available nutrients.The overall soil enzyme activity was relatively higher in treatment T_(3)N_(2).The yield of purple cabbage treated with biochar-based organic fertilizer combined with nitrogen fertilizer could reach 85750 kg/hm^(2),which was 94.78%higher than that treated with biochar-based organic fertilizer alone.Based on comprehensive analysis,the optimal combination ratio was 45 t/hm^(2)of biochar-based organic fertilizer and 300 kg/hm^(2)of urea(T_(3)N_(2)).[Conclusions]This study provides data support for the promotion of biochar-based organic fertilizers and reduced fertilizer in agricultural soil in the Dam area of Yuanmou County.

Effects of Rice Straw Steam-explosion Spent Liquor on the Growth of Cabbage Seedlings

The direct use of spent liquor from pulping and papermaking engineering,which is abundant in active organic matter,can avoid resource wastage and environmental pollution.In this study,the effects of soaking solution and filtrate from steam-exploded rice straw on seed germination and the early development of cabbage were investigated.The results have shown that soaking solution and filtrate stimulated early cabbage growth at low concentrations.Optimal germination potential and the rate of soaking solution-treated cabbage seeds increased by 8%and 5%,respectively;meanwhile,that of the filtrate-treated cabbage seeds increased by 11%and 5%,respectively.Promotion of root growth by steam-exploded rice straw spent liquor was expressed in lateral root multiplication.The fresh weight of cabbage seedlings treated with the soaking solution/filtrate increased by more than 50%and the dry weight over 20%.Comparatively,the stimulation of filtrate on seed germination and early development of cabbage is superior to that of the soaking solution.Steam-exploded rice straw spent liquor is rich in bioactive lignin and oligosaccharides,which makes it a promising biostimulant for promoting crop growth.

稀土对大白菜(Chinese cabbage)的效应机理及其应用技术

大白菜施用稀土增产效果达极显著水平,平均增产13.6%。主要原因是促进了根系发育,增加了根重和侧根数,扩大了根系垂直方向和水平方向的分布范围,为养分和水分的吸收和运转奠定了良好的基础,从而促进了大白菜地上部分的生长,增加了叶片数和叶面积。其主要机理是稀土提高了叶片中叶绿素的含量和酶的活性,从而增加了有机物质的合成;增强了对营养元素的吸收;增强了抗逆性,降低了发病率。

也谈Cabbages and Kings的汉译问题

文章从翻译功能论视角对欧·亨利英文短篇小说集名Cabbages and Kings的两种译文进行解读。译文《白菜与皇帝》一定程度上影响了交际功能的实现,却完成了文化传递的功能。《东拉西扯》实现了翻译交际功能,却牺牲了文化传递的功能。因此,两种译文各有得失,无对错之别。另外,随着东西方文化交流逐渐加强,译文《白菜与皇帝》必将被越来越多的读者接受。

Determination and dynamics of difenoconazole residues in Chinese cabbage and soil

An analytical method was developed using a solid phase extraction （SPE） cleanup and gas chromatography for detecting the residues of difenoconazole in Chinese cabbage and soil. The recovery and the relative standard deviation of this method in Chinese cabbage was 87.6-99.0%, 1.71-10.50%, respectively; in soil was 92.4-95.5%, 4.93-10.70%, respectively. Further degradation of difenoconazole residue in Chinese cabbage and soil was studied to evaluate residue behavior and environmental safety of difenoconazole. Degradation rate of difenoconazole in both Chinese cabbage and soil followed the first order kinetics with the half-lives of 6.6-7.8 and 54.2-55.0 days, respectively.

Effects of field application of phosphate fertilizers on the availability and uptake of lead, zinc and cadmium by cabbage (Brassica chinensis L.) in a mining tailing contaminated soil

A field trial was conducted to evaluate the reduction of bioavailability of heavy metals including lead (Pb), zinc (Zn) and cadmium (Cd) in a soil contaminated by mining tailings in Shaoxing, Zhejiang, China. Three commercial phosphate (P) fertilizers including phosphate rock (PR), calcium magnesium phosphate (CMP), and single superphosphate (SSP) were applied to the plot at three P application rates, 50, 300, and 500 g/m2 with 9 treatments and control (CK). Plants, water soluble and exchangeable (WE) extra...

Field demonstration of reduction of lead availability in soil and cabbage (Brassica Chinensis L.) contaminated by mining tailings using phosphorus fertilizers

A field demonstration of reduction of lead availability in a soil and cabbage (Brassica Chinensis L.) contaminated by mining tailings, located in Shaoxing, China was carried out to evaluate the effects of applications of phosphorus fertilizers on Pb fractionation and Pb phytoavailability in the soil. It was found that the addition of all three P fertilizers including single super phosphate (SSP), phosphate rock (PR), and calcium magnesium phosphate (CMP) significantly decreased the percentage of water-soluble and exchangeable (WE) soil Pb and then reduced the uptake of Pb, Cd, and Zn by the cabbage compared to the control (CK). The results showed that the level of 300 g P/m2 soil was the most cost-effective application rate of P fertilizers for reducing Pb availability at the first stage of remediation, and that at this P level, the effect of WE fraction of Pb in the soil de- creased by three phosphorus fertilizers followed the order: CMP (79%)>SSP (41%)>PR (23%); Effectiveness on the reduction of Pb uptake by cabbage was in the order: CMP (53%)>SSP (41%)>PR (30%). Therefore our field trial demonstrated that it was effective and feasible to reduce Pb availability in soil and cabbage contaminated by mining tailings using P fertilizers in China and PR would be a most cost-effective amendment.

Transformation of Cabbage(Brassica oleracea L.var.capitata) with Bt cry1Ba3 Gene for Control of Diamondback Moth

To obtain transgenic cabbage line with broad insect resistance, a new synthetic Bacillus thuringiensis crylBa3 gene was introduced into white cabbage via Agrobacterium tumefaciens-mediated transformation and 37 transformants were obtained. Polymerase chain reaction （PCR） and Southern blot analyses confirmed that crylBa3 was successfully inserted into the genome of cabbage. Reverse transcription-polymerase chain reaction （RT-PCR） demonstrated that crylBa3 was expressed. Western blot results confirmed the production of insecticidal protein encoded by crylBa3. Insect bioassays showed that transgenic cabbages effectively controlled both susceptible and CrylAc-resistant diamondback moth （DBM） larvae.

Joint effects of cadmium and lead on seedlings of four Chinese cabbage cultivars in northeastern China

In northeastern China, large area of vegetable land has been simultaneously polluted by cadmium （Cd） and lead （Pb）. Joint effects of Cd and Pb on Chinese cabbage （Brassica pekinensis L.） were investigated using the seed germination and sand culture method. Four Chinese cabbage cultivars including Kangbingjinchun （KB）, Dongyangchunxia （DY）, Qinglvwang （QL） and Qiangshi （QS） from Shenyang in northeastern China were adopted in this study. The results showed that there were positive linear relationships between the inhibitory rate of biomass, root and shoot elongation and the concentrations of Cd and Pb. In particular, root elongation was more sensitive to joint stress of Cd and Pb. The activity of superoxide dismutase and the content of malondialdehyde （MDA）, soluble protein （SP） and proline （PRO） changed significantly with increasing exposure concentration of Cd and Pb. The decrement in the activity of antioxidative enzymes, the content of SP and accumulation of MDA were relatively low in KB and QS. PRO played an important role in resisting Cd and Pb stress.

Monosomic Addition Lines of Flowering Chinese Cabbage(B.campestris L.ssp.chinensis var.parachinensis L.H.Bailey)-Chinese Kale(B.oleracea L.var.alboglabra L.H.Bailey)

Interspecific alien addition lines have played significant roles in gene mapping, intergenomic gene transfer and chromosomal homoeological identification between closely related species. Selection of alien addition lines was conducted by karyotype analysis and morphological observation with the reference of parents. Triploid interspecies hybrid （AAC, 2n = 3x = 29） was obtained from Brassica campestris ssp. chinensis var. parachinensis Qinglu 9601 （tetraploid, AAAA, 2n = 4x = 40） x B. oleracea var. alboglabra Baihua 9705 （diploid, CC, 2n = 2x = 18） by immature hybrid embryo culture in vitro. Five different alien monosomic addition lines （AA ＋ C2, AA ＋ C3, AA ＋ C4, AA ＋ C6, AA ＋ C7） were obtained from the backcross progenies of AAC x AA. Each alien monosomic addition line has some specific morphological characters. It is feasible to obtain alien addition lines from the progenies of AAC × AA by karyotype analysis and morphological observation based on the reference of parents

Studies on the Formation and Transmission of n + 1 Gametes of Cabbage Primary Trisomics

The transmission rate of n ＋ 1 gamete is an important parameter for the genetic analysis of trisomics. To correctly use the trisomics of the cabbage to carry out gene orientation and other genetic studies, the n ＋ 1 gamete transmission rates by female parent and by male parent were determined. The results showed that the n ＋ 1 gamete transmission rates were 15.28% for tri-1, 12.68% for tri-2, 12.31% for tri-3, 30.51% for tri-4, 22.81% for tri-5, 7.46% for tri-6, 5.36% for tri-7, 42.37% for tri-8, and 9.23% for tri-9 by female parent, and were 12.12% for tri-1, 12.33% for tri-2, 7.81% for tri-3, 4.76% for tri-4, 8.93% for tri-5, 10.94% for tri-6, 1.54% for tri-7, 2.94% for tri-8, and 13.04% for tri-9 by male parent. The main factors affecting the male n ＋ 1 gamete formation and transmission were the rate of trivalent formation at prophase Ⅰ, the rate of 9-9-10-10 division at anaphase Ⅱ, and the pollen viability.