BnaWRKY75 positively regulates the resistance against Sclerotinia sclerotiorum in ornamental Brassica napus

With the development of tourism at home and abroad,Rapeseed(Brassica napus)has become an important ornamental plant.However,its ornamental value at the inflorescence stage is greatly reduced by Sclerotinia sclerotiorum.Identification of important genes in the defense responses is critical for molecular breeding,which is an important strategy for controlling the disease.In this study,we isolated a B.napus WRKY transcription factor gene,BnaWRKY75.BnaWRKY75 was found to encode a nucleus-localized protein and exhibited relatively high expression in the stems.Arabidopsis thaliana transgenic plants expressing BnaWRKY75 showed enhanced resistance to S.sclerotiorum,and both ProBnaWRKY75:GUS and gene expression analyses showed that BnaWRKY75 was highly responsive to S.sclerotiorum infection,indicating the involvement of BnaWRKY75 in response to this infection.Furthermore,overexpression(OE)of BnaWRKY75 in B.napus significantly enhanced the resistance to S.sclerotiorum,whereas the resistance was reduced in RNAi transgenic B.napus plants.Moreover,the BnaWRKY75-OE B.napus plants exhibited constitutive activation of salicylic acid-,jasmonic acid-,and ethylene-mediated defense responses and the inhibition of both H_(2)O_(2)and O_(2)·^(-)accumulation in response to this pathogen.By contrast,BnaWRKY75-RNAi plants showed a reverse pattern,suggesting that BnaWRKY75 is involved in hormonal signaling pathways and in the control of reactive oxygen species accumulation.In conclusion,these data indicate that BnaWRKY75,a regulator of multiple defense responses,positively regulates resistance against S.sclerotiorum,which may guide the improvement of resistance in rapeseed.

Heterogeneous expression of stearoyl-acyl carrier protein desaturase genes SAD1 and SAD2 from Linum usitatissimum enhances seed oleic acid accumulation and seedling cold and drought tolerance in Brassica napus

Flax(Linum usitatissimum L.)is a versatile crop and its seeds are a major source of unsaturated fatty acids.Stearoyl-acyl carrier protein desaturase(SAD)is a dehydrogenase enzyme that plays a key role in oleic acid biosynthesis as well as responses to biotic and abiotic stresses.However,the function of SAD orthologs from L.usitatissimum has not been assessed.Here,we found that two LuSAD genes,LuSAD1 and LuSAD2,are present in the genome of L.usitatissimum cultivar‘Longya 10’.Heterogeneous expression of either LuSAD1 or LuSAD2 in Arabidopsis thaliana resulted in higher contents of total fatty acids and oleic acid in the seeds.Interestingly,ectopic expression of LuSAD2 in A.thaliana caused altered plant architecture.Similarly,the overexpression of either LuSAD1 or LuSAD2 in Brassica napus also resulted in increased contents of total fatty acids and oleic acid in the seeds.Furthermore,we demonstrated that either LuSAD1 or LuSAD2 enhances seedling resistance to cold and drought stresses by improving antioxidant enzyme activity and nonenzymatic antioxidant levels,as well as reducing membrane damage.These findings not only broaden our knowledge of the LuSAD functions in plants,but also offer promising targets for improving the quantity and quality of oil,and the abiotic stress tolerance of oil-producing crops,through molecular manipulation.

Knock-out of BnHva22c reduces the susceptibility of Brassica napus to infection with the fungal pathogen Verticillium longisporum

Verticillium longisporum(Vl43)is a soilborne hemibiotrophic fungal pathogen causing stem striping on oilseed rape(OSR)and severe yield losses.Breeding for resistant varieties is the most promising approach to control this disease.Here,we report the identification of Hva22c as a novel susceptibility factor and its potential for improving OSR resistance.Hva22c is a member of the Hva22 gene family,originally described for barley(Hordeum vulgare).Several Hva22 members have been located at the endoplasmic reticulum.Hva22c is up-regulated in response to Vl43 in both Arabidopsis and OSR.We demonstrate that knock-out of Hva22c in OSR by CRISPR/Cas9 and its homolog in Arabidopsis by T-DNA insertion reduced plants’susceptibility to Vl43 infection and impaired the development of disease symptoms.To understand the underlying mechanism,we analysed transcriptomic data from infected and non-infected roots of hva22c knock-out and wild type plants.We identified a homozygous mutant with frame-shifts in all four BnHva22c loci displaying a vastly altered transcriptional landscape at 6 dpi.Significantly,a large set of genes was suppressed under mock conditions including genes related to the endomembrane systems.Among the up-regulated genes we found several defense-related and phytohormone-responsive genes when comparing mutant to the wild type.These results demonstrate that Hva22c is functionally required for a fully compatible plant-fungus interaction.Its loss of function reduces plant susceptibility,most likely due to endoplasmatic reticulum and Golgi dysfunction accompanied by additionally activated defense responses.These findings can help improve OSR resistance to V.longisporum infection.

BnaC03.BIN2 regulates plant height by affecting the main inflorescence length and first effective branch height in Brassica napus L.

Rapeseed(Brassica napus L.)is one of the main oil crops in the world,and increasing its yield is of great significance for ensuring the safety of edible oil.Presently,improving rapeseed plant architecture is an effective way to increase rapeseed yield with higher planting density.However,the regulatory mechanism of rapeseed plant architecture is poorly understood.In this study,a dwarf rapeseed mutant dwarf08(df08)is obtained by ethyl methane sulfonate(EMS)-mutagenesis.The decrease in plant height of df08 is mainly caused by the reduction in main inflorescence length and first effective branch height and controlled by a single semi-dominant gene.The hybrid plants(F1)show a semi-dwarf phenotype.Through map-based cloning and transgenic assay,we confirm that the nonsynonymous single nucleotide variant(SNV)(C to T)in BnaC03.BIN2,which is homologous with Arabidopsis(Arabidopsis thaliana)BIN2,is responsible for the dwarfism of df08.BnaC03.BIN2 interacts with BnaBZR1/BES1 and involves in brassinosteroids(BRs)signal transduction.Proline to Leucine substitution in 284(P284L)enhances the protein stability of BnaC03.bin2-D,disrupts BRs signal transduction and affects the expression of genes regulating cell division,leading to dwarfism of df08.This study provides a new insight for the mechanism of rapeseed plant height regulation and creates an elite germplasm that can be used for genetic improvement of rapeseed architecture.

Landscape of Sequence Variations in Homologous Copies of FAD2 and FAD3 in Rapeseed(Brassica napus L.)Germplasm with High/Low Linolenic Acid Trait

Genetic manipulation(either restraint or enhancement)of the biosynthesis pathway ofα-linolenic acid(ALA)in seed oil is an important goal in Brassica napus breeding.B.napus is a tetraploid plant whose genome often har-bors four and six homologous copies,respectively,of the two fatty acid desaturases FAD2 and FAD3,which con-trol the last two steps of ALA biosynthesis during seed oil accumulation.In this study,we compared their promoters,coding sequences,and expression levels in three high-ALA inbred lines 2006L,R8Q10,and YH25005,a low-ALA line A28,a low-ALA/high-oleic-acid accession SW,and the wildtype ZS11.The expression levels of most FAD2 and FAD3 homologs in the three high-ALA accessions were higher than those in ZS11 and much higher than those in A28 and SW.The three high-ALA accessions shared similar sequences with the pro-moters and CDSs of BnFAD3.C4 and BnFAD3.A3.In A28 and SW,substitution of three amino acid residues in BnFAD2.A5 and BnFAD2.C5,an absence of BnFAD2.C1 locus,and a 549 bp long deletion on the BnFAD3.A3 promoter were detected.The profile of BnFAD2 mutation in the two low-ALA accessions A28 and SW is different from that reported in previous studies.The mutations in BnFAD3 in the high-ALA accessions are reported for thefirst time.In identifying the sites of these mutations,we provide detailed information to aid the design of mole-cular markers for accelerated breeding schemes.

The influence of Lactobacillus plantarum fermentation in selenium-enriched Brassica napus L.:changes in the nutritional constituents,bioactivities and bioaccessibility

Selenium(Se)-enriched Brassica napus L.is a valuable organic Se supplement.In this study,the fermentation broth enriched with organic Se(FFS)was prepared using Lactobacillus plantarum to ferment the substrate of Se-enriched Brassica napus L.Significant increases were observed after fermentation in total sugars,reducing sugars,soluble proteins,total phenolic content(TPC),and total flavonoid content(TFC).The organic Se was retained at a concentration of 54.75 mg/g in the freeze-dried sample.Principal component analysis and cluster analysis showed good separation between the FFS and unfermented(FS)groups.Fragrant 2-ethyloxetane had the highest content among all volatiles,while sinapine had the highest content among all phenolic compounds.The fermentation process showed remarkable improvement in the abundance and concentration of volatile compounds and phenolic contents,making FFS exhibit strong antioxidant activity and inhibitory capacity againstα-glucosidase activity.The bioaccessibility of phenolic compounds was significantly greater in FFS compared to FS.ADMET analysis revealed that the majority of phenolic compounds contained in FFS did not exhibit mutagenicity toxicity,hepatotoxicity,skin sensitization,or blood-brain barrier penetration,indicating a favorable level of biosafety.Overall,our study provides a new insight into the further utilization of Se-enriched Brassica napus L.in foods.

Growing Development and Physiological Characteristics of Seeds Harvested Different Days after Pollination and Their 7-day Seedlings of Two Yellow-Seeded Cultivars of Brassica napus L.

This study aimed to understand the growing development and physiological characteristics of seeds harvested different days after pollination and the seedlings emerged from the seeds of yellow-seeded Brassica napus L..Two yellow-seeded cultivars‘Hongyuan 558’and‘Qinyou 806’were selected in this study,and 50 seeds were collected 30,35,and 40 d after pollination,respectively.The seeds were weighed and placed on filter paper for hydroponic experiments.The seed germination rate was determined 3-5 d later.The physiological indicators including superoxide dismutase(SOD),peroxidase(POD),and catalase(CAT)activities and malondialdehyde(MDA)content were measured for the seeds harvested different days after pollination and the 7-day-seedlings emerged from the seeds.The results showed that the seed dry weights and germination rates of both‘Qinyou 806’and‘Hongyuan 558’increased as the days after pollination increased,especially 30-35 d after pollination.The germination rate and dry and fresh weights of the seeds showed no significant differences between the two cultivars,and almost all the seeds germinated 40 d after pollination.As the days after pollination increased,the SOD activities in the seeds of both cultivars first increased and then decreased,reaching their peaks 35 d after pollination,which may be related to encountering adverse stress.The POD activity in the seeds of‘Qinyou 806’kept declining,and that of‘Hongyuan 558’first increased and then decreased,which may be related to the antioxidant mechanism and adaptive regulation.The CAT activities in the seeds of both cultivars first decreased and then increased.The MDA content in the seeds of‘Qinyou 806’first decreased and then increased,while that of‘Hongyuan 558’kept reducing and was the highest in the seeds 30 d after pollination,which indicated‘Hongyuan 558’was mildly affected by the environment and had strong resistance.The activities of SOD and POD in the seedlings of two cultivars that were emerged from the seeds 35-40 d after pollination became weakened,which may be related to their exposure to stress.The CAT activity in the seedlings of‘Hongyuan 558’was generally higher than that of‘Qinyou 806’,indicating that‘Hongyuan 558’had stronger stress resistance.The MDA content in the seedlings emerged from the seeds 35-40 d after pollination showed a decreasing trend,indicating that the seedlings emerged from the seeds harvested at this stage had mild cell membrane damage and enhanced stress resistance.In conclusion,‘Hongyuan 558’had strong environmental adaptability and stress resistance.

Effect of Foliar Fertilizer Spraying at Seedling Stage on the Growth Physiological Characteristics and Yield of Brassica napus L.

In order to select a suitable foliar fertilizer for Brassica napus L.at the seedling stage,using‘Fengyou 958’as the material,different foliar fertilizers including BR,Se,Si,BR+Si,BR+Se,Se+Si and BR+Se+Si were sprayed at the seedling stage to study their effect on the physiological characteristics,growth and yield of Brassica napus L..The results showed that the growth,chlorophyll content,soluble sugar content,soluble protein content,and yield of different treatments at the budding stage improved compared with the control.The effect of the Si+Se treatment was the best,followed by the Se and Si treatments.The chlorophyll content of the flower decreased continuously during the whole flowering period,and the chlorophyll content of the mature silique peel was higher than that of the seed.The content of soluble sugar in flowers was the highest in the early flowering stage,and the content of soluble sugar in leaves at the flowering stage was higher than that at the budding stage.The soluble sugar content in the harvested silique peel decreased gradually with the increase of time,and that in the silique peel and seed was similar at 35 d after pollination.The soluble protein content in the silique peel and seed decreased gradually at the mature stage,and the soluble protein content in the silique peel was higher than that in the seed at the same stage.Si+Se foliar fertilizer spraying at the seedling stage can promote the growth and yield of Brassica napus L.and can be applied in Brassica napus L.production.

Development of a KASP Marker on Chromosome A05 for Seed Oil Content of Brassica napus

In order to identify the molecular markers that can be widely used in the breeding of Brassica napus L.varieties with high seed oil content under different genetic backgrounds,we developed a Kompetitive Allele Specific PCR(KASP)marker for seed oil content on the basis of the results from available studies.The verification in the F_(2) population showed that the marker was closely linked to the quantitative trait locus(QTL)for oil content on chromosome A05.The findings helped to breed the‘Fengyou’varieties with high seed oil content in the middle reaches of the Yangtze River.

Phytogenetic Studies on Intergeneric Hybridization Between Brassica napus and Matthiola incana

The intergeneric hybridization between Brassica napus L. cv. oro and Matthiola incana (L.) R. Br. was carried out to study the phytogenetic peculiarities of the hybrid plants. In order to improve the oil quality of rape seed, ovaries of B. napus pollinated with pollen of M. incana, were cut off and inoculated onto MS media supplemented with various plant hormones at the 7th day after pollination. Two mature embryos were obtained from 750 pollinated ovaries cultured in vitro. The percentage of seed set was 0.26%. The mature embryos were transferred onto the MS media supplemented with 2.0 mg/L 6-BA + 0.1 mg/L NAA, and a compound bud was produced later. The compound bud was then cut into a number of single buds, which were transferred onto fresh media. Twenty-two plantlets in vitro were developed from the above single buds. The hybrid plants (F-1) were basically intermediate between the two parents in many,characters with a few showing hybrid vigor. The fertility of hybrid plants (F-1) was poor. Cytological studies revealed that the hybrid plants (F-1) were mixoploid. in nature. The chromosome number of many somatic cells was 2n = 26, which was the sum of the chromosome number of the two parents. The chromosome number of other somatic cells was 2n = 38, similar to that of B. napus. The hybrid offspring (F-2) from the selfed hybrid plants (F-1) showed polymorphism. Among the hybrid offspring (F-2) some were nearly matroclinous and fertile, similar to B. napus. some others were intermediate between the two parents and less fertile, and a few were poorly developed and nearly infertile. From the hybrid offspring a few plants with improved seed-oil quality were obtained.

Correlation Analysis of SPAD Value with Chlorophyll Content and Economic Yield Traits of Brassica napus L.

[Objective] The aim was to compare differences of SPAD value, chloro- phyll content, agronomic characters, economic characters and yield traits to analyze correlation of SPAD value with other indices and establish regression functions. [Method] Based on 34 Brassica napus L. varieties, SPAD value, chlorophyll content, agronomic characters, economic characters and yield traits were measured and re- gression functions were established according to correlations. [Result] SPAD value, chlorophyll content, agronomic and economic characters and yield traits all achieved significant level in differences among 34 varieties. Specifically, SPAD value was of extremely significant correlation with chlorophyll a and b, total chlorophyll and carotenoid, and the correlation from high to low was chl-b〉chl-z〉chl-a〉chl-x. SPAD value was of significantly positive correlation with total pod number per plant, plant height, seed number per pod, yield per plant and harvest yield, and of insignificant correlation with branch point height, effective branch number, pod density of main stem, and pod length. [Conclusion] It is simple and rapid to predict chlorophyll con- tent, economic characters and yields of Brassica napus L. with SPAD value and re- gression functions.

Screening of Drought-tolerant Brassica napus L.Varieties and Analysis on Their Physiologic and Biochemical Variations under Drought Stress

[Objective] The aim of this study was to screen drought-tolerant Brassica napus L. germplasm resources by analyzing their physiological and biochemical changes under drought stress. [Method] Forty varieties of B. napus varieties were cultured under PEG-6000 osmotic stress and extreme drought stress in pots, re- spectively. Then, the contents of chlorophyll, carotenoid, proline, malondialdehyde （MDA）, soluble sugar, soluble protein, and the activities of superoxide dismutase （SOD）, catalase（CAT）, peroxidase（POD） were measured under drought stress. [Result] Sever- al drought-tolerant varieties of B. napus were screened out： YAU200908, Xiangyou No.15, YAU200903, YAU200907, YAU200906 and YAU200904. Physiological and biochemical analysis showed that, the contents of chlorophyll and carotenoid de- creased with drought stress increasing; the contents of proline, soluble sugar, solu- ble protein, MDA and the activities of SOD,CAT, POD raised with drought stress in- creasing. [Conclusion] In the rapeseed varieties with stronger drought tolerance, the decrease in carotenoid content and the increase in proline content, soluble sugar content, MDA content, SOD activity, CAT activity were more obvious, so all these physiological and biochemical indices can be used to evaluate the drought tolerance of rapeseed.

Effects of ABA on Photosynthetic Characteristics of Pods and Yield of Brassica napus

[Objective] The aim was to evaluate the effects of different concentrations of ABA on photosynthetic characteristics of pods and yield of Brassica napus and analyze the relationships between ABA concentration and yield components, to provide theoretical basis for cultivation of high-yield rapeseed. [Method] At the end of flowering stage, the rape plants were separately sprayed with 1, 2, 100 and 200μmol/L of ABA; photosynthetic parameters, water use efficiency （WUE）, yield and yield components of the rape plants were investigated 0, 5, 10 and 15 d later, respectively. [Result] ABA treatment with different concentrations significantly changed pod photosynthetic parameters and yield components of rapeseed. Low concentra- tions of ABA could improve pod＇s net photosynthetic rate and yield components while high concentrations had the contrary effect. [Conclusion] Whether ABA func- tioned in inhibiting or promoting role might depend on the interaction between endogenous hormone levels and exogenous ABA concentration. Improvement of WUE would be the main reason for yield increasing.

Cloning of Brassica napus EIN3 Gene and Its Expression Induced by Sclerotinia sclerotiorum

[Objective] The study was to investigate roles of Brassica napus EINB in （ BnEIN3 ） resistance to Sclerotinia sclerotiorum. [ Methods] Genomic PCR and RT-PCR were carded out to isolate genomic DNA and cDNA sequences of BnEIN3 from oilseed rape, based on the highly conserved region of EIN3 gene from Arabidopsis thaliana and the homologous sequences of oilseed rape ESTs. Expression levels of BnEIN3 were detected in three varieties of oilseed rape inoculated with S. sclerotiorum by real-time quantitative PCR.[Results] A 1 947 bp DNA fragment was obtained from oilseed rape. The fragment shared 82% identity to A. thaliana EIIV3, encoded 614 amino acids containing an EIN3 domain, and was named as BnEIN3. Real-time PCR results showed that expression patterns of BnEIN3 were drastically different in different varieties. In highly resistant oilseed rape variety D083, BnEIN3 expression level was significantly increased 72 h after S. sclerotiorum inoculation whereas in middle resistant and susceptible varieties Zhongshuang 9 and 84039, BnEIN3 expression was suppressed. [ Conclusion ] BnEIIV3 may play an important role in oilseed rape resistance to S. sclerotiorum.

Impact of Fertilizer Types on Photosynthetic and Biological Effects of Direct-seeded Brassica napus at Flowering Stage

[Objective] The aim was to investigate the effects of fertilizer type on di- rect-seeded rapeseed and to explore effective fertilizing. [Method] Four treatments including different types of fertilizers were set in the test. Growth, photosynthesis and chlorophyll fluorescence parameters at flowering stage such as plant height, stem diameter, shoot and root dry matter, net photosynthesis, light energy conversion effi- ciency （Fv/Fm） and SPAD value, were investigated. The effects of fertilizer treat-ments on the yield of rapeseed were evaluated as well. [Result] Both multi-functional fertilizer and controlled release fertilizer could improve plant height, stem diameter, shoot dry matter, SPAD value, net photosynthesis, non-photochemical quenching （NPQ）, etc., which helped increase yield and stress resistance. [Conclusion] Both multi-functional fertilizer and controlled release fertilizer could improve yield significantly while multi-functional fertilizer （MFF） was better than controlled release fertilizer （CRF）.

Transcriptional Regulation of 10 Mitochondrial Genes in Different Tissues of NCa CMS System in Brassica napus L. and Their Relationship with Sterility

Northern blot analysis was conducted with mitochondrial RNA from seedling leaves, floral buds, and developing seeds of NCa CMS, maintainer line and fertile F1 using ten mitochondrial genes as probes. The results revealed that 9 out of the 10 mitochondrial genes, except for atp6, showed no difference in different tissues of the corresponding materials of NCα CMS system and that they might be constitutively expressed genes. Eight genes, such as orf139, orf222, atpl, cox1, cox2, cob, rm5S, and rm26S, showed no difference among the three tissues of all the materials detected. So the expression of these eight genes was not regulated by nuclear genes and was not tissue-specific. The transcripts of atp9 were identical among different tissues, but diverse among different materials, indicating that transcription of atp9 was neither controlled by nuclear gene nor tissue-specific. Gene atp6 displayed similar transcripts with the same size among different tissues of all the materials but differed in abundance among tissues of corresponding materials and its expression might be tissue-specific under regulation of nuclear gene. Moreover, three transcripts of orf222 were detected in the floral buds of NCa cms and fertile F1, but no transcript was detected in floral buds of the maintainer line.The transcription of orf139 was similar to that of orf222 but only two transcripts of 0.8 kb and 0.6 kb were produced. The atp9 probe detected a single transcript of 0.6 kb in NCa cms and in maintainer line and an additional transcript of 1.2 kb in fertile F1. The relationship of expression of orf222, orf139, and atp9 with NCa sterility was discussed.

Development of New Restorer Materials with Ogu CMS in Brassica napus

[Objective] Ogura cytoplasmic male sterility （Ogu CMS） is an ideal pollina- tion control system for heterosis utilization in Brassica napus. However, fertility-restor- ing （Rf） gene only exists in radish chromosome and is closely linked with glucosino- late gene, making it hardly to be applied directly in production. Thus, the key to apply Ogu CMS in Brassica napus is to introduce the Rf genes and to break its linkage with glucosinolate gene. [Me^od] To overcome the interspecific reproductive barrier, grafting was conducted by using Raphanobrassica （2n=-58） as donor materi- als of Rf genes. The obtained interspecific hybrids were analyzed from the agronom- ic traits, seed-setting rate and fertility restoration rate for screening fertility-restoring materials. [Results] By elaborative selection, a homozygous Ogu CMS fertility-restor- ing B. napus material named CLR650 was selected out, whose somatic chromosome numbers were found to be 2n=38-40. Some abnormal phenomena like anaphase bridges and lagging chromosomes in meiosis were observed, but the abnormalities did not affect the formation of normal pollens. It can restore the male fertility in both progenies of self-pollination and testcross by 100%. Molecular analysis showed that CLR650 harbors Ogu CMS fertility-restoring gene, which is obviously different from that of Ogu CMS restore line Rl13 and RHH1 by detecting the molecular markers closely linked with radish restorer gene （Rf0）. [Conclusion] The CLR650 could be a new restorer for the Ogu CMS in B. napus.

A Comparative Study on the Quality Components Between Self Pollinated Seeds and Naturally Pollinated Seeds in Brassica napus L. in Sichuan Ecological Region

[ Objective] This study was to reveal the differences in crude fat and glucosinolates between self pollinated seeds and naturally pollinated seeds in Brassica napus in sichuan ecological region.. [ Method] Near-infrared spectroscopy method （NIRS） was employed to measure the quality components in self pollinated seeds and naturally pollinated seeds of 861 shares of Brassica napus from Sichuan ecological region. And correlation analysis and regression analysis were conducted based on the experimental data via SPSS （statistics package for social science）. [ Result] The contents of crude fat in the self pollinated seeds were commonly a higher than that in the naturally pollinated seeds at 0.01 significant level; while the contents of glucosinolates in the self pollinated seeds and the naturally pollinated seeds were insignificantly different. Both the correlation relationship and linear regression for the crude fat between the self pollinated seeds and naturally pollinated seeds reached the significant level. The regression equations for the contents of crude fat（y1 ） and glucosinolates（ y2 ） in the naturally pollinated seeds and of crude fat（ x1 ） and glucosinolates（ x2 ） in self pollinated seeds were respectively determined to be y1 = 16.844 ＋0.614x1 and y2 = -0.620 ＋ 1.017 x2. [ Conclusion] In Brassica napus breeding, crude fat in naturally pollinated seeds should be emphatically taken into account, meanwhile concurrently considering that in self pollinated seeds; while glucosinolates in both the self pollinated seeds and the naturally pollinated seeds must be simultaneously concerned.

Effects of Enzymes Related to Nitrogen Reuse on Nitrogen Redistribution and Nitrogen Use Efficiency in Brassica napus

[Objective] This assay was to explore the contribution of enzymes ac- counting for nitrogen reutilization in two Brassica napus varieties No.6 （low nitrogen use efficiency） and No.2 （high nitrogen use efficiency）. [Method] We measured the yield, transportation and accumulation of grain nitrogen, loss of leaf nitrogen and ni- trogen use efficiency （NUE） in the two rape varieties, by inhibiting proteolytic en- zyme （PE）, glutamine synthetase （GS） and glutamate synthetase （GOGAT） and la- beling with lSN. [Result] Under GOGAT inhibitor treatment, both of the two varieties presented minimum NUE, yield and nitrogen transportation in grain and maximum ni- trogen loss in leaf. The effect of PE inhibitor was the second greatest, and that of GS inhibitor was the lowest. Moreover, 80% of the nitrogen that had been accumu- lated in leaf was transported out during late growth stage, and 50% to 70% of the grain nitrogen derived from the nitrogen in vegetative organs. The two varieties ex- hibited the same tendency. Rape variety No.2 had higher yield, grain nitrogen accu- mulation and lower nitrogen loss compared with No.6. [Conclusion] GOGAT has the greatest effect on the accumulation of grain nitrogen, yield and nitrogen reutilization in rape. Different enzyme activity may be the major factor resulting in different nitro- gen rautilization in the two rape varieties. Nitrogen stored in leaf during early growth stage is mainly used for nitrogen remobilization. A large proportion of grain nitrogen derives from vegetative tissues.

Heterosis Analysis of Nitrogen Use Efficiency for Grain Production of Brassica napus L.

[Objective]The aim was to study heterosis of N use efficiency for grain production （NUEg） of Brassica napus L. and provide theoretical basis for breeding N-efficient cultivars. [Method]Dry matter production and N content of six B.napus parents （Zheshuang 3,Yangyou 7,ZJ1,Shilijia,Ningyou 14 and Huyou 16） and their F1 combinations from 6 × 6 complete diallel cross in maturity stage under two N levels were measured; heterosis of NUEg,combining ability and heritability size were analyzed and calculated. [Result]The results showed that NUEg has obvious heterosis; combining ability variance analysis indicated that NUEg was mainly controlled by additive,dominant and cytoplasmic effects; genetic variance analysis showed that additive effects and dominance effects were all significant in low nitrogen fertilizer and dominance effects were significant in high nitrogen fertilizer. [Conclusion]NUEg of B.napus has obvious heterosis.