镉胁迫对小白菜(Brassica campestris L.)抗氧化机理的影响

采用水培的方法,研究了不同Cd2+水平(0、1、2.5、5、10、15mg·L-1)对小白菜(Brassica campestris L.)抗氧化酶(SOD、POD、CAT)活性、非酶物质(SH、GSH、PCs)含量以及生长的影响。结果表明,小白菜叶片和根系SOD活性随Cd处理质量浓度的增加呈降低的变化趋势,POD、CAT活性以及MDA含量随Cd处理质量浓度的增加而增加。小白菜的生物量、根长、株高、叶绿素质量分数随Cd处理质量浓度的增加显著降低(P<0.05),表明Cd抑制了小白菜的生长,破坏了叶绿素的合成。小白菜地上、地下部镉质量分数均随Cd处理质量浓度的增加而显著增加(P<0.05)。当Cd处理质量浓度为15mg·L-1,小白菜地上、地下部镉质量分数分别达到637.5、1663.0mg·kg-1,表明小白菜对Cd有良好的富集效果。小白菜根系与叶片中SH、GSH和PCs含量均随Cd处理质量浓度增加而增加的变化趋势,表明SH、GSH和PCs在解毒小白菜Cd毒害中起着重要作用。

Role of nitrification inhibitor DMPP(3,4-dimethylpyrazole phosphate) in NO^-_3-N accumulation in greengrocery( Brassica campestris L. ssp. chinensis ) and vegetable soil

The influence of nitrification inhibitor(NI) 3,4 dimethylpyrazole phosphate(DMPP) on nitrate accumulation in greengrocery( Brassica campestris L. ssp. chinensis ) and vegetable soil at surface layer were investigated in field experiments in 2002 and 2003 Results showed that NI DMPP took no significant effect on yields of edible parts of greengrocery, but it could significantly decrease NO - 3 N concentration in greengrocery and in vegetable soil at surface layer. In addition, NI DMPP could reduce the NO - 3 N concentration during the prophase stage of storage.

Effect of Nitrogen and Sulfur Supply on Glucosinolates in Brassica campestris ssp.chinensis

Glucosinolates （GSs） are a group of plant secondary metabolites containing abundant nitrogen （N） and sulfur （S） mainly in Brassica and have the beneficial effects on human health including anti-carcinogenic, cholesterol-reducing and other pharmacological effects. The objective of this study was to investigate the effect of different concentrations of N （5, 10, and 20 mmol L-a, denoted by N5, N10 and N20） and S （0,5, 1, and 2 mmol L^-1, denoted by S0.5, S1 and S2） on the yield and GSs in pakchoi （Brassica campestris L. ssp. chinensis var. communis） in hydroponics. Results showed that N10 and N20 significantly enhanced the yield compared with N5, however, N20 had a negative effect relative to N10. Only with N10 and N20 low S supply （S0.5） reduced the yield. The concentrations of aliphatic GSs, aromatic GS and total GSs were enhanced by N5 and indolyl GSs were enhanced by N20. S2 enhanced the concentration of individual GS and total GSs. The concentrations of indolyl GSs were maximized in N20S2 treatment, whereas the highest concentrations of aliphatic GSs, aromatic GS and total GSs were found in N5S2 treatment. Effects of N and S on aliphatic GSs were higher than on indolyl GSs. The results suggest that the accumulation of aliphatic GSs and aromatic GS could be enhanced by low N and high S and restricted by high N while that of indolyl GSs could be enhanced by high N and high S.

A Genetic Linkage Map of Brassica campestris L.ssp. pekinensis (syn. B. rapa L. ssp. pekinensis)

A molecular genetic map of Chinese cabbage was constructed with a 102 recombinant inbred (RI) population from a cross of two cultivated Chinese cabbage lines 177 and 276, using AFLP and RAPD markers. 352 markers including 265 AFLP markers and 87 RAPD markers were integrated into 17 linkage groups. It covered a total of 2 665. 7 cM with an average interval of 7. 6 cM. AFLP marker is efficient for map construction while it easily forms clusters to cause big gaps in map. A total of 13.92 % abnormal segregation markers distributed in the map. The molecular genetic map is fundamental for gene localization, comparative genomics, and QTL mapping of important agronomic traits.

Differential Expression Analysis of Genic Male Sterility A／B Lines in Chinese Cabbage—Pak—Choi（Brassica campestris ssp.chinensis Makino）

To determine differential expression of genie male sterility A/B lines in Chinese cabbage-pak-choi (Brassica campestris ssp. chinensis Makino var. communis Tsen et Lee), we used the RNA fingerprinting technique, cDNA-AFLP analysis, in different developmental stages and different tissues. While no obvious differential expressions were observed in rosette leaves, florescence leaves, and scapes, some differential expressions were found in alabstrums of A/B lines and among leaves, scapes and alabstrums. We analyzed the al-abstrums collected in different developmental stages with 10 primer combinations. We got a unique band between middle size alabstrums and large alabstrums in B line in one of the ten pair primers, and in another one pair, one band reflecting a higher gene-expression level in A line than that in B line was obtained. No unique bands were found with the other primer combinations. The bands reflecting different gene-expression level were confirmed by Northern hybridization. The results indicated that cDNA-AFLP was a suitable tool for studying differential expression of genie male sterility in plants. SDS-polyacrylamide gel electrophoresis patterns of soluble proteins further verified the difference in A/B lines.

Exogenous application of a low concentration of melatonin enhances salt tolerance in rapeseed(Brassica napus L.) seedlings

Melatonin is a naturally occurring compound in plants. Here, we tested the effect of exogenous melatonin on rapeseed（Brassica napus L.） grown under salt stress. Application of 30 μmol L^-1 melatonin alleviated salt-induced growth inhibition, and the shoot fresh weight, the shoot dry weight, the root fresh weight, and the root dry weight of seedlings treated with exogenous melatonin increased by 128.2, 142.9, 122.2, and 124.2%, respectively, compared to those under salt stress. In addition, several physiological parameters were evaluated. The activities of antioxidant enzymes including peroxidase（POD）, catalase（CAT） and ascorbate peroxidase（APX） were enhanced by 16.5, 19.3, and 14.2% compared to their activities in plants without exogenous melatonin application under salt stress, while the H2O2 content was decreased by 11.2% by exogenous melatonin. Furthermore, melatonin treatment promoted solute accumulation by increasing the contents of proline（26.8%）, soluble sugars（15.1%） and proteins（58.8%）. The results also suggested that higher concentrations（〉50 μmol L^-1） of melatonin could attenuate or even prevent the beneficial effects on seedling development. In conclusion, application of a low concentration of exogenous melatonin to rapeseed plants under salt stress can improve the H2O2-scavenging capacity by enhancing the activities of antioxidant enzymes such as POD, CAT and APX, and can also alleviate osmotic stress by promoting the accumulation of osmoregulatory substances such as soluble proteins, proline, and water soluble glucan. Ultimately, exogenous melatonin facilitates root development and improves the biomass of rapeseed seedlings grown under salt stress, thereby effectively alleviating the damage of salt stress in rapeseed seedlings.

Nitrogen Dioxide-Induced Responses in Brassica campestris Seedlings: The Role of Hydrogen Peroxide in the Modulation of Antioxidative Level and Induced Resistance

This article investigates the responses of Brassica campestris seedlings to an acute level of nitrogen dioxide （NO2） exposure in a plant growth chamber, and examines whether pretreating plants with hydrogen peroxide （H2O2） will alleviate NO2-caused injury. Twenty-eight-day-old B. campestris plants sprayed with 10 mmol L^-1 H2O2 aqueous solution （corresponding to approximate 1.0 mg H2O2 per single plant） were exposed to different concentrations of NO2 （0.25, 0.5, 1.0, and 2.0 μL L^-1, respectively） for 24 h under controlled environment. To measure the plant biomass, the plants were fumigated with the same NO2 concentrations as mentioned above for 7 h per day （8.00-15.00） for 7 days. As a control, charcoal filtered air alone was applied. Data were collected on plant biomass, total chlorophyll, photosynthetic rate, stomatal conductance, nitrate and nitrate reductase （NR）, antioxidative enzymes, ascorbate （ASA）, and malondialdehyde （MDA）, immediately after exposure. The results showed that exposure to a moderate dose of NO2 （e.g., 0.25 μL L^-1） had a favorable effect on plants, and the dry weight of the above-ground part increased, whereas the exposure to high NO2 concentrations （e.g., 0.5 μL L^-1 or higher） caused a reduction in the plant biomass and the total chlorophyll, when compared with the control. In addition, at 0.5 μL L^-1 or higher NO2 concentrations, prominent increases in the MDA level and superoxide dismutase （SOD） and NR activities were observed. Exposure to 1 μL L^-1 and higher NO2 resulted in necroses appearing on older leaves, and an increase in catalase （CAT） activity, decrease in ASA content, increased accumulation of NO3^-, and reduction in photosynthesis, when compared with the controls. No changes were detected in stomatal conductance under NO2 fumigation. The pretreatment with 10 mmol L^-1 H2O2 alleviated significantly NO2- caused biomass decrease and photosynthetic inhibition when compared with H2O2-untreated plants. Under NO2 fumigation, further induction in SOD and CAT activities occurred in H2O2 treated plants when compared with H2O2- untreated plants. The effect of NO2 on the ASA and MDA contents was also absent in H2O2-treated plants. However, the H2O2 treatment did not alter the nitrate content and NR activity in plants under NO2 fumigation. The H2O2 treatment caused a lower rate of stomatal conductance. Taken together, these data suggest that fumigation with an acute level of NO2 causes oxidative damage to B. campestris seedlings. The H2O2 pretreatment markedly protects plants against NO2 stress and this may be associated with inducible antioxidative level. NO2 fumigation contributes, at least in part, to the enhanced levels of nitrate in B. campestris leaves.

Genetic linkage map of Brassica campestris L.using AFLP and RAPD markers

A genetic linkage map comprised of 131 loci was constructed with an F2 population derived from an inter-subspecific cross between Brassica campestris L.ssp.chinensis cv.aijiaohang” and ssp.rapifera cv.,”'isihai”.The genetic map included 93 RAPD loci,36 AFLP loci and 2 morphological loci organized into 10 main linkage groups(LGs) and 2 small groups,covering 1810.9cM with average distance between adjacent markers being approximately 13.8cM.The map is suitable for identification of molecular markers linked to important agronomic traits.QTL analysis,and even for marker-assisted selection in breeding programs of Chinese cabbage and turnip.

Effect of the Antisense BcMF12 Driven by the BcA9 Promoter on Gene Silencing in Brassica campestris L.ssp.chinensis

The study analyzed the silencing of BcMF12 gene regulated by BcA9 promoter in the transgenic pakchoi and confirmed the effect of antisense BcMF12 gene on the pollen development. A conserved BcMF12 gene fragment was amplified from the cDNA of flower buds in pakchoi （Brassica campestris L. ssp. chinensis, syn. B. rapa L. ssp. chinensis） and was fused to the anther specific BcA9 promoter. The plant antisense expression vector was constructed and then introduced into pakchoi via Agrobacterium-mediated transformation. The transgenic plants were screened by antibiotics and molecular analysis. PCR and Southern blot revealed that the antisense BcMF12-GUS fusion gene regulated by BcA9 promoter was integrated into transgenic plants. Northern blot suggested that the expression of BcMF12 gene was down-regulated significantly. The pollen germination rate of transgenic plants with antisense BcMF12 gene decreased as compared with that of the control plants. The expression of the gene BcMF12 related to the pollen development was inhibited by the antisense BcMF12 driven by BcA9 promoter, which consequently affected the pollen development in pakchoi.

Genetic Diversity of Testa Pigments and RAPD Marker of Yellow-Seeded Rapeseed (Brassica napus L.)

14 yellow-seeded rapeseed lines (Brassia napus L.) from different genetic sources were used to analyze diversity of testa pigments content, oil and protein content, and RAPD markers. The results showed that the anthocyanin and melanin were the most important pigments in testa and their content were responsible for the variation in seed color ranging from orange to black yellow, 14 yellow-seeded lines could be classified into 3 groups: high anthocyanin content group with anthocyanin content over 2. 54 mg g-1 DW, the seed color was light yellow or orange; low pigments content group with low content of anthocyanin and melanin, the testa was transparent and the seed color was light yellow, greenish yellow or twany; high melanin content group with melanin content over 178. 4U(A290nm) , the testa was black, the seed color was black yellow. Oil content changed from 36.2% to 45. 5%, protein content from 21.1% to 27.7% , and the correlation analysis revealed that the oil content is highly significantly negatively correlated with the protein content. The cluster analysis showed that the extensive genetic variation existed among 14 yellow-seeded lines by using unweighted paired group method with arithmetic average (UPGMA) based on RAPD markers which were amplified with decamer primers, the genetic similarity among them ranged from 0. 25 to 0.909, and 14 yellow-seeded lines could put into 2 clusters corresponding to genome difference.

Identification of suitable reference genes in leaves and roots of rapeseed (Brassica napus L.) under different nutrient deficiencies

Nutrient deficiency stresses often occur simultaneously in soil. Thus, it＇s necessary to investigate the mechanisms underlying plant responses to multiple stresses through identification of some key stress-responsive genes. Quantitative real-time PCR （qRT-PCR） is essential for detecting the expression of the interested genes, of which the selection of suitable reference genes is a crucial step before qRT-PCR. To date, reliable reference genes to normalize qRT-PCR data under different nutrient deficiencies have not been reported in plants. In this study, expression of ten candidate reference genes was detected in leaves and roots of rapeseed （Brassica napus L.） after implementing different nutrient deficiencies for 14 days. These candidate genes, included two traditionally used reference genes and eight genes selected from an RNA- Seq dataset. Two software packages （GeNorm, NormFinder） were employed to evaluate candidate gene stability. Results showed that VHA-E1 was the highest-ranked gene in leaves of nutrient-deficient rapeseed, while VHA-G1 and UBC21 were most stable in nutrient-deficient roots. When rapeseed leaves and roots were combined, UBC21, HTB1, VHA-G1 and A CT7 were most stable among all samples. To evaluate the stabilities of the highest-ranked genes, the relative expression of two target genes, BnTrxl;1 and BnPhtl;3 Were further determined. The results showed that the relative expression of BnTrxl;1 depended on reference gene selection, suggesting that it＇s necessary to evaluate the stability of reference gene prior to qRT-PCR. This study provides suitable reference genes for gene expression analysis of rapeseed responses to different nutrient deficiencies, which is essential for elucidation of mechanisms underlying rapeseed responses to multiple nutrient deficiency stresses

Foliar K application delays leaf senescence of winter rapeseed(Brassica napus L.) under waterlogging

To better understand waterlogging effect on leaf senescence in winter rapseed (Brassica napus L.) during flowering stage, experiments were designed to explore foliar K application influences on adverse effects of waterlogging stress. Winter rapeseed was sprayed with K after waterlogging at initial flowering stage. Results indicated that waterlogging significantly decreased leaf net photosynthetic rate (Pn), stomatal conductance (Gs), intercellular CO2 concentration (Ci) and transpiration rate (Tr). It also declined maximum quantum yield of PS II (Fv/Fm), quantum yield of electron transport (ΦPS II) and photochemical quenching (qP), but increased leaf non-photochemical quenching (NPQ) and minimal fluorescence (Fo). Interestingly, exogenous application of K significantly alleviated waterlogging-induced photosynthesis inhibition. Foliar K application increased RuBisCO activation, chlorophyll and soluble protein contents, while significantly decreased MDA content under waterlogging stress. Moreover, K supplementation improved accumulation of K+, Ca2+, Mg2+, N, Zn2+, Mn2+, Fe2+ in leaves. In general, foliar K application is effective inalleviating deleterious effects of waterlogging stress and delays leaf senescence of winter rapeseed.

Recent Advances,Problems and Outlooks in Rapeseed(Brassica napus L.)Breeding in China

As a big rapeseed(Brassica napus L.) producing and consuming country, China provides more and more rapeseed oil year by year. With the development of demand for rapeseed and import of edible oil, rapeseed breeding and production is facing a great challenge. New situation has proposed higher requirements to yield, oil quality and safety, etc. In the review, some aspects about rapeseed breeding in China were reported, including breeding of high-oil content rapeseed, breeding of extremely early-maturing rapeseed, development of mechanization and development of chemical emasculation. Some prospects and expectations were also proposed.

Worldwide rapeseed (Brassica napus L.) research:A bibliometric analysis during 2011–2021

Rapeseed(Brassica napus L.) is the world?s second produced oilseed and accounts for nearly 12% of world major vegetable oil production.For the last 10 years,the production,planting area,and yield of rapeseed have been stable,with improvement of seed quality and especially seed oil content.This paper presented the worldwide rapeseed research by using the bibliometric analysis of papers published during the period 2011–2021.In total,7617 articles and reviews were included in this analysis.Our results showed that the global publication on rapeseed increased substantially in the past 11 years,and the number of publications of China grew significantly in particular.China was the largest contributor to rapeseed research with higher H-index value and number of citations compared to the other countries.China also had the largest number of leading universities and institutions,of which Huazhong Agricultural University was the most productive.The scientific mapping including co-authorship network of countries/regions and authors,and co-occurrence network of author keywords were analyzed using VOSviewer software.The most common rapeseed research topics included oil,rapeseed meal,yield,biodiesel,fatty acids,salt stress,and proteins,while the current research focused on topics such as:abiotic stress,evolution,expression analysis,phylogenetic analysis,heterosis,polyploidy,and transcriptomics.This paper depicts the knowledge structure of current global rapeseed research that may help direct the future studies for relevant researchers.

Identifying Cytoplasmic Male Sterile Types of Chinese Cabbage(Brassica campestris L.)by Molecular Markers

Different sterile cytoplasm types of nine cabbage cytoplasmic male sterile materials were identified by molecular marker in the study, in order to better use molecular marker to conduct the assisted breeding in the future. Genomic DNA was isolated from Chinese cabbage by CTAB method. The design of two pairs of specific primers was performed on conserved flanking region of orf138 gene in the GenBank. PCR was performed with genomic DNA of the nine Chinese cabbage materials. The bands were sequenced. The homologous comparison was conducted in NCBI, and finally, the type of sterile cytoplasm was determined. The results showed that the bands were amplified only in four Chinese cabbage male sterile materials with two pairs of specific primers PUPIl and PIII/PIV, while the other five materials did not obtain the relative bands. The result was consistent with the field sterility identification. And then four molecular markers of Chinese cabbage Ogura cytoplasmic male sterility （CMS） were obtained. After conducting a homologous comparative analysis with BLAST in GenBank, it was found that the homologous degree was 100% in specific segments of tbe tbree sterility materials （L1-CI, L3-CI and L3- F1 ） and Ogu orf138 gene （GenBank accession No. ： HQ149728） of the reported broccoli Ogu CMS. The homologous degree of L1-F1 was 99% with a variation point. The type of cytoplasmic male sterility of the other five materials needed further research. Four materials of the nine were identified as the radish cytoplasmic male sterility materials and four molecular markers were obtained.

Genetic Variation and Correlation Analysis on Seed Oil Content and Protein Content of Brassica campestris L.Germplasm Resources

The content of oil and protein in 84 germplasm materials of Brassica campestris L. from all over the country was tested. In Guiyang environment,the oil content and protein content of these materials showed abundant variation,and were divided into three groups. Correlation analysis showed that there was a significant negative correlation between oil content and protein content of B. campestris L. seeds,and the application and formation mechanism of the negative correlation were also discussed.

Effects of Different Cadmium Levels on Active Oxygen Metabolism and H_2O_2-Scavenging System in Brassica campestris L.ssp.chinensis

The effects of different Cd (Cadmium) levels on generation of active oxygen speceies(AOS) and H2O2-scavenging system in the leaves of Brassica campestris L. ssp. chinensiswere studied. The results showed that generation rate, and H2O2 content were enhancedand malondialdehyde (MDA) content increased with the increase of Cd concentrations inthe growth medium. The activities of ascorbate peroxidase (APX), dehydroascorbatereductase (DR) and glutathione reductase (GR) were promoted by the addition of Cd.Exposed to Cd also increased the contents of ascorbate (AsA) and glutathione (GSH) in theleaves.

Dissecting the genetic architecture of glucosinolate compounds for quality improvement in flowering stalk tissues of Brassica napus

Glucosinolates(GSLs) and their hydrolytic products contribute to the quality traits of rapeseed flowering stalk tissues, such as taste, flavor and anticarcinogenic properties(Glucoraphanin). However, little is known about the genetic mechanisms of GSL accumulation in rapeseed flowering stalks. In this study, the variation and genetic architecture of GSL metabolites in flowering stalk tissues were investigated for the first time among a panel of 107 accessions. All GSL compounds exhibited continuous and wide variations in the present population. Progoitrin,glucobrassicanapin and gluconapin were the most abundant GSL compounds. Five quantitative trait loci(QTL) significantly associated with three GSL compounds were identified by genome-wide association study. GRA_C04 was under selected during modern breeding, in which the ratio of lower GSL haplotype(HAP2) in the accessions bred before 1990(52.56%) was significantly lower than that after 1990(78.95%). Four candidate genes, BnaA01. SOT16, BnaA06. SOT17, Bna A06. MYB51a, and Bna A06. MYB51b, were identified in the GTL_A01 and 4OH_A06 regions.These findings provide new insights into GSL biosynthesis in flowering stalk tissues and facilitate quality improvement in rapeseed flowering stalks.

国五国六柴油车尾气颗粒物对小白菜(Brassica campestris L.)的生态毒性

为研究柴油车尾气颗粒物对植物的毒性效应,本研究以执行国五、国六两种排放标准的柴油车为研究对象,测定其尾气颗粒物中重金属含量,并以小白菜(Brassica campestris L.)为受试植物,分析了两种颗粒物对小白菜的毒性效应.结果表明:(1)国五、国六柴油车尾气颗粒物中13种重金属总含量分别为1.04 g·kg^(-1)和0.47 g·kg^(-1),国五柴油车尾气颗粒物重金属含量高于国六柴油车;(2)在两种颗粒物的高浓度胁迫下,小白菜体内叶绿素以及蛋白质的含量均出现显著降低趋势;(3)随着两种颗粒物浓度的升高,植物体内部分氧化应激的酶指标超氧化物歧化酶(SOD)、过氧化氢酶(CAT)呈先上升后下降的趋势,而过氧化物酶(POD)以及丙二醛(MDA)、谷胱甘肽(GSH)呈上升趋势,颗粒物的污染能对小白菜产生较为显著的氧化胁迫效应.(4)21 d的毒性实验后,国五、国六柴油车尾气颗粒物对小白菜鲜重的半数有效浓度(EC50)值分别为76.27 mg·L^(-1)和104.48 mg·L^(-1).综合来看,国六标准的实施有效控制了颗粒物中重金属的含量,并一定程度地降低了其对小白菜的毒性.

Exogenous strigolactones promote lateral root growth by reducing the endogenous auxin level in rapeseed

Strigolactones(SLs)are newly discovered plant hormones which regulate the normal development of different plant organs,especially root architecture.Lateral root formation of rapeseed seedlings before winter has great effects on the plant growth and seed yield.Here,we treated the seedlings of Zhongshuang 11(ZS11),an elite conventional rapeseed cultivar,with different concentrations of GR24(a synthetic analogue of strigolactones),and found that a low concentration(0.18μmol L–1)of GR24 could significantly increase the lateral root growth,shoot growth,and root/shoot ratio of seedlings.RNA-Seq analysis of lateral roots at 12 h,1 d,4 d,and 7 d after GR24 treatment showed that 2301,4626,1595,and 783 genes were significantly differentially expressed,respectively.Function enrichment analysis revealed that the plant hormone transduction pathway,tryptophan metabolism,and the phenylpropanoid biosynthesis pathway were over-represented.Moreover,transcription factors,including AP2/ERF,AUX/IAA,NAC,MYB,and WRKY,were up-regulated at 1 d after GR24 treatment.Metabolomics profiling further demonstrated that the amounts of various metabolites,such as indole-3-acetic acid(IAA)and cis-zeatin were drastically altered.In particular,the concentrations of endogenous IAA significantly decreased by 52.4 and 75.8%at 12 h and 1 d after GR24 treatment,respectively.Our study indicated that low concentrations of exogenous SLs could promote the lateral root growth of rapeseed through interaction with other phytohormones,which provides useful clues for the effects of SLs on root architecture and crop productivity.