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.

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.

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.

油菜(B.napus L.)硼素营养与结实性的研究

硼营养不足,油菜植株各器官含硼量均下降,下降幅度因器官而异,而以花器官下降幅度最大。缺硼时,花器发育异常,雄蕊在解剖生理上的异常现象尤为突出,严重时花粉败育,花蕾脱落,甚至出现颗粒无收的现象。花粉败育表现为花粉囊空瘪,核质解体,无孢原组织分化,绒毡层发育异常,小孢子原生质团溢出药壁外等现象。硼营养不足降低了花药中可溶性糖、淀粉、游离脯氨酸和可溶性蛋白质含量。同时花粉活力和呼吸强度也降低。研究还表明油菜品种对硼营养反应存在基因型差异。宁油8号比宁油7号对缺硼反应更为敏感。缺硼条件下,改善硼营养后,油菜各器官含硼量提高最多的是花器,并使有效分枝数、有效角果数和每角平均实粒数增加,从而提高油菜籽粒产量。

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.

Regional Evaluation of Winter Rapeseed Response to K Fertilization, K Use Efficiency, and Critical Level of Soil K in the Yangtze River Valley

The investigation was carried out to study the response of winter rapeseed to potassium （K） feritlization and the critical soil available K level for current winter rapeseed production in the Yangtze River Valley （YRV） of China. A total of 132 field experiments were conducted in fields of farmers in the major winter rapeseed growing areas in YRV in 2000/2001 and 2004/2005 to 2006/2007 during growing season. Results of these field experiments showed that the average rapeseed yield increment resulting from 100 kg K ha-1 application was 358 kg ha-1, an increase over the control CK （no K） of 18.0% in 2005/2006 and 2006/2007. The average internal use efficiency （IE） of K was higher in the CK treatment （21.9 kg grain, kg-1 K uptake） than in the ＋K （100 kg K ha-1） treatment （17.7 kg grain, kg-1 K uptake）. Winter rapeseed required 68.1 kg of K to produce 1 000 kg seed. The recovery efficiency of K fertilizer in rapeseed production averaged 39.3%. The K balance was negative, with an average net removal of 117.6 kg K ha-1 in the CK treatment annually, and 56.8 kg K ha-1 in the ＋K treatment. The results indicated that there was a significant negative relationship between yield increments by K application and soil available K content. Based on the relative yield of CK/＋K at 90% level, the critical level of soil available K （NH4OAc-extractable K） was 135 mg kg-1.

Comparison of transcriptomes undergoing waterlogging at the seedling stage between tolerant and sensitive varieties of Brassica napus L.

RNA sequencing of the sensitive GH01 variety of Brassica napus L. seedling roots under 12 h of waterlogging was compared with previously published data of the ZS9 tolerant variety to unravel genetic mechanisms of waterlogging tolerance beyond natural variation. A total of 2 977 genes with similar expression patterns and 17 genes with opposite expression patterns were identiifed in the transcription proifles of ZS9 and GH01. An additional 1 438 genes in ZS9 and 1 861 genes in GH01 showed strain speciifc regulation. Analysis of the overlapped genes between ZS9 and GH01 revealed that waterlogging tolerance is determined by ability to regulate genes with similar expression patterns. Moreover, differences in both gene expression proifles and abscisic acid (ABA) contents between the two varieties suggest that ABA may play some role in waterlogging tolerance. This study identiifes a subset of candidate genes for further functional analysis.

油蔬两用油菜品种的品质与产量评价

为促进油菜油蔬两用技术的推广,对18个油蔬两用油菜品种的菜薹产量、不摘薹和摘薹后菜籽产量等性状,以及菜薹的粗纤维、可溶性糖、维生素C、钙、铁、锌、硒质量分数和食味得分等品质性状进行统计,开展主成分分析和聚类分析,并计算各品种的综合产值.结果表明:11个性状可综合为6个主成分,18个品种可划分为3个类群;基于产量和品质特征确定了3个总产值高的品种赣油杂8号、邡油777和沣油958以及1个优质高产品种渝南油683,结果可为重庆地区油菜油蔬两用技术的推广提供种质基础和数据支撑.

油菜抗咪唑啉酮类除草剂基因BnALS1R等位基因特异PCR标记的开发与应用

油菜抗咪唑啉酮类除草剂基因BnALS1R是从抗性突变体M9中克隆获得,抗性基因BnALS1R与野生型基因BnALS1存在1处SNP,即乙酰乳酸合酶第638位丝氨酸残基被天冬酰胺酸替代。为获得油菜抗除草剂基因BnALS1R的分子标记,根据该处点突变,结合获得的BnALS3与BnALS1序列,开发30条等位基因特异PCR(allele-specific PCR,AS-PCR)引物,采用筛选出的3条AS-PCR引物在F2、BC1和BC2群体中进行PCR扩增。结果表明,该标记有效检测出群体中存在的3种基因型,其分离比分别为1∶2∶1、1∶1、1∶1,均遵循单基因遗传规律。应用该标记对获得的抗性恢复系进行PCR扩增,结果发现所有抗性恢复系均能扩增出抗性基因BnALS1R目的条带,表明3条标记引物可应用于抗性基因的检测。AS-PCR标记的获得将促进以抗性基因进行油菜抗除草剂分子标记辅助选择育种。

播种期降水偏多对油菜重要农艺性状和产量的影响

为了解播种期降水偏多对油菜产量的影响,选用10个国家区试高产优质油菜新品种,分析正常年份(2019/2020)与降水偏多年份(2020/2021)在长江中游11个生态点的重要农艺性状、产量、品质和抗性,评估2020/2021年减产原因。通过正常年份与渍害年份逐月降雨量、温度等气象数据变化与产量与农艺性状变化进行相关和回归分析,结果发现,即使在正常排灌情况下,灾害年份油菜产量显著下降,播种期平均推迟11.5 d,生育期缩短11.2 d,产量和产油量分别极显著下降21.8%和23.2%。其中油菜株高、单株有效角果数和收获密度分别下降9.2%、21.1%和6%,均达到显著或极显著水平,而含油量、芥酸、硫苷、千粒重、角粒数、菌核病病指等性状变化不显著。回归分析表明,10月降雨大幅增加、形成渍害是减产的直接原因,而次生灾害如降雨导致播期推迟、秋季气温偏低和冬季降水减少导致的间接影响更大,对减产的贡献分别达到25.4%、50.5%和33%。对10个品种的产量和产油量分析,耐渍品种的选择应综合考虑正常年份产量、耐渍指数和含油量等指标,其中H1951、越优577、9zyYP12等品种正常年份产油量比对照增产11%~16.5%,灾害年份比对照增产5.4%~18.4%,生产上在做好开沟降渍的同时,抢播早播并增加密度可有效提高产量,有利于最大程度减轻灾害损失。

油菜乙酰乳酸合酶突变体S638N的酶学特性及其对ALS类除草剂的抗性

在对油菜抗咪唑啉酮类除草剂基因Bn ALS1R克隆与功能验证基础上,为比较抗性基因编码的乙酰乳酸合酶突变体S638N酶学特性及其对ALS类除草剂抗性与野生型的差异,构建基因原核表达载体,在大肠杆菌中表达S638N和野生型的重组融合蛋白。SDS-PAGE和Western blot分析表明,S638N和野生型均能表达出约74 k D的特异性重组蛋白。纯化目的蛋白,在不同温度和pH条件下,测定S638N和野生型的酶活性。结果显示,温度和pH对突变酶活性的影响与野生型相同,表现为先升后降,在37℃、pH 7.0条件下催化活性均最高。同时,该突变酶的酶学动力学参数Km和Vmax与野生型没有显著差异,其对3个辅助因子的响应曲线也与野生型类似,缺少其中任何一个辅助因子均使突变酶S638N基本都没有活性。然而,突变酶S638N对IMI类除草剂抗性显著高于野生型,而对Su类除草剂敏感性和野生型相同。因此,突变酶S638N具有对IMI类除草剂的专一抗性,但未改变酶学反应特征。

甘蓝型油菜木质素合成关键基因F5H、4CL和COMT的定量表达

以甘蓝型油菜(Brassica napus L.)抗倒伏品种浙平1号和易倒伏品种高芥1号为材料,采用荧光定量PCR方法对木质素合成关键基因F5H(阿魏酸-5-羟基化酶)、4CL(4-香豆酸CoA连接酶)和COMT(咖啡酸/5-羟基阿魏酸-O-甲基转移酶)在薹期和角果期根颈部、茎部的相对表达量进行了分析。结果显示,F5H在薹期和角果期根颈部的相对表达量,易倒伏材料高于抗倒伏材料;茎部的相对表达量,抗倒伏材料高于易倒伏材料。4CL和COMT基因在薹期根颈部、茎部和角果期根颈部的相对表达量,易倒伏材料高于抗倒伏材料;角果期茎部的相对表达量,抗倒伏材料显著(P<0.05)高于易倒伏材料。结果表明,油菜角果期茎部木质素合成关键基因F5H、4CL和COMT的相对高量表达可能有助于增强植株的抗倒伏能力。

甘蓝型油菜CMS不育系L160A的遗传分析

对新近选育的甘蓝型油菜CMS不育系L16 0A育性的遗传特点、L16 0A与pol细胞质不育系和陕 2A不育系的关系以及L16 0A的恢复系L16 0R - 1与恢复系L17C、湖南花叶恢、垦C1恢复基因的等位性进行了分析。结果表明 ,L16 0A不育性的遗传由一对隐性基因控制 ,同时受到其他微效基因的修饰 ;其恢保关系与pol细胞质不育系L17A、湘矮A和不育系陕 2A是一致的。L16 0A的恢复系L16 0R - 1与L17A的恢复系L17C和湘矮A的恢复系湖南花叶恢的恢复基因是等位的 ,而与陕 2A的恢复系垦C1的恢复基因是否具有等位性 。

甘蓝型油菜不同发育时期株高QTL的动态分析

利用新版SG遗传图谱和282个SG-DH株系在中国西安、中国杭州和德国哥廷根3个生长环境下8个发育时期测定的株高数据,运用WinQTLCart2.5复合区间作图法以及结合条件遗传分析方法对其进行静态和动态QTL分析。结果显示,来自品种Gaoyou等位基因在PHA3和PHC6两个QTL上同时存在时,可降低株高约20cm;而当植株整合来自冬性品种Sollux的PHA9、PHC1和来自半冬性品种Gaoyou的PHA1、PHA3、PHC6时,株高可相应下降40cm;环境对株高QTL的作用机制影响不大,但不同QTL的基因表达模式不同,存在来自双亲之一的等位基因控制株高和双亲等位基因在不同生长时期交替控制株高2种情况;通常株高QTL在中后期才能被检测到,但基因多在生长最为旺盛的短时期内表达,符合基因表达在先,性状表现在后的规律。解析株高性状在不同发育时期基因的累加效应和特定时段内的净表达效应,对克隆油菜株高基因和指导生产实践均有指导意义。

油菜开花期QTL定位和候选基因分析

为辅助选育早熟油菜品种、克隆油菜开花期基因及开发花期分子标记,以已测序的油菜品种中双11(Z)和重测序的油菜品系No.73290(N)为亲本构建的含184个单株的BnaZNF2群体为材料,通过分析该群体的基因型数据和F2:3家系连续三年(2010-2012)在武汉的表型数据,对开花期QTL进行检测和整合,定位到分布在11个连锁群上的14个开花期QTL。其中只有5个QTL能在3年中重复检测到,分别是qDtF.A2-1、qDtF.A6-2、qDtF.C2-1、qDtF.C2-2和qDtF.C3-1,贡献率在7.1%~21.1%之间。通过查阅文献和在拟南芥、水稻等作物网站上搜索,搜集到442个与植物开花期有关的基因。基于油菜基因组物理图谱,通过生物信息学分析,在本研究定位的QTL区间上筛选到54个可能的候选基因,可以用于开花期基因的克隆。在5个主要QTL区间内分别定位到8、5、4、2和4个候选基因,其中有15个在双亲中存在序列差异,可以开发开花期的功能标记用于分子标记辅助选择育种。

冬灌处理对河北冬油菜关键性状的影响

为指导河北等地冬油菜的水分管理,明确冬前灌溉对河北冬油菜产量形成的影响,选用12个白菜型冬油菜及9个甘蓝型冬油菜品种(品系),进行冬灌处理,统计越冬率,测定叶片及角果的氮、磷、钾含量,考察产量及产量构成等指标。试验结果表明:冬灌可以有效预防油菜冻害、提高越冬率,有利于油菜返青后的生长、农艺性状的改善及产量的形成。与对照(不进行冬灌)相比,冬灌处理对冬油菜生育期无明显影响;但供试油菜品种的越冬率均可达90%以上,显著高于对照;且分枝部位高度、株高等农艺性状及产量均显著提高,分别较对照增加33%、90.3%、14.5%;6个供试冬油菜叶片中的氮、磷含量与果皮中的钾含量均高于其它器官。