The effect of vernalization and two growth regulators Fascination^TM and Pro-Gibb^R on the growth, inflorescence development and flowering of Omithogalurrt Chesapeake Snowflake＇ was studied. Regardless of growth regu...The effect of vernalization and two growth regulators Fascination^TM and Pro-Gibb^R on the growth, inflorescence development and flowering of Omithogalurrt Chesapeake Snowflake＇ was studied. Regardless of growth regulator treatment, chilling bulbs for 3 weeks at 10℃ before planting accelerated flowering of the first inflorescence by 5 to 6 days, elongated floral stem length by 1.5 to 2 cm and shortened leaf length by 4 to 5 cm as compared with non-chilled bulbs. When bulbs were chilled 3 weeks at 10℃ before planting, Fascination 2% and Pro-Gibb accelerated flowering of the first inflorescence by 2 to 6 days respectively as compared with the control. When bulbs were not chilled before planting, Fascination 2% and Pro-Gibb accelerated flowering of the first inflorescence by 6 to12 days respectively as compared with the control. The lengths of the leaves and the inflorescences were not affected by PGR treatment. Higher rates of Pro-Gibb （100 mg.L^-1 and 200 mg.L^-1） and more amount of Fascination 2%（100 μL and 200 μL） can cause abortion of inflorescence.展开更多
The turnip(Brassica rapa var. rapa) is a biennial crop that is planted in late summer/early fall and forms fleshy tubers for food in temperate regions. The harvested tubers then overwinter and are planted again the ne...The turnip(Brassica rapa var. rapa) is a biennial crop that is planted in late summer/early fall and forms fleshy tubers for food in temperate regions. The harvested tubers then overwinter and are planted again the next spring for flowering and seeds. FLOWERING LOCUS C(FLC) is a MADS-box transcription factor that acts as a major repressor of floral transition by suppressing the flowering promoters FT and SOC1. Here we show that vernalization effectively represses tuber formation and promotes flowering in Tibetan turnip. We functionally characterized four FLC homologues(BrrFLC1,FLC2, FLC3, and FLC5), and found that BrrFLC2 and BrrFLC1 play a major role in repressing flowering in turnip and in transgenic Arabidopsis. In contrast, tuber formation was correlated with BrrFLC1 expression in the hypocotyl and was repressed under cold treatment following the quantitative downregulation of BrrFLC1. Grafting experiments of non-vernalized and vernalized turnips revealed that vernalization independently suppressed tuberization in the tuber or hypocotyl of the rootstock or scion, which occurred in parallel with the reduction in BrrFLC1 activity. Together, our results demonstrate that the Tibetan turnip is highly responsive to cold exposure, which is associated with the expression levels of BrrFLC genes.展开更多
The relationship between vernalization requirement and quantitative and qualitative changes in total leaf soluble proteins were determined in one spring （cv. Kohdasht） and two winter （cvs. Sardari and Norstar） cul...The relationship between vernalization requirement and quantitative and qualitative changes in total leaf soluble proteins were determined in one spring （cv. Kohdasht） and two winter （cvs. Sardari and Norstar） cultivars of wheat （Triticum aestivum L.） exposed to 4℃. Plants were sampled on days 2, 14, 21 and 35 of exposure to 4℃. The final leaf number （FLN） was determined throughout the vernalization periods （0, 7, 14, 24, and 35 d） at 4℃. The final leaf number decreased until days 24 and 35 in Sardari and Norstar eultivars, respectively, indicating the vernalization saturation at these times. No clear changes were detected in the final leaf number of Kohdash cultivar, verifying no vernalization requirement for this spring wheat cultivar. Comparing with control, clear cold-induced 2-fold increases in proteins quantity occurred after 48 h following the 4℃-treatment in the leaves of the both winter wheat cultivars but, such response was not detected in the spring cultivar. However, the electrophoretic protein patterns showed between-cultivar and between-temperature treatment differences. With increasing exposure time to 4℃, the winter cultivars tended to produce more HMW polypeptides than the spring cultivar. Similar proteins were induced in both Sardari and Norstar winter wheat cultivars, however, the long vernalization requirement in Norstar resulted in high level and longer duration of expression of cold-induced proteins compared to Sardari with a short vernalization requirement. These observations indicate that vernalization response regulates the expression of low temperature （LT） tolerance proteins and determines the duration of expression of LT- induced proteins.展开更多
MicroRNA396(miR396)has been demonstrated to regulate flower development by targeting growth-regulating factors(GRFs)in annual species.However,its role in perennial grasses and its potential involvement in flowering ti...MicroRNA396(miR396)has been demonstrated to regulate flower development by targeting growth-regulating factors(GRFs)in annual species.However,its role in perennial grasses and its potential involvement in flowering time control remain unexplored.Here we report that overexpression of miR396 in a perennial species,creeping bentgrass(Agrostis stolonifera L.),alters flower development.Most significantly,transgenic(TG)plants bypass the vernalization requirement for flowering.Gene expression analysis reveals that miR396 is induced by long-day(LD)photoperiod and vernalization.Further study identifies VRN1,VRN2,and VRN3 homologs whose expression patterns in wild-type(WT)plants are similar to those observed in wheat and barley during transition from short-day(SD)to LD,and SD to cold conditions.However,compared to WT controls,TG plants overexpressing miR396 exhibit significantly enhanced VRN1 and VRN3 expression,but repressed VRN2 expression under SD to LD conditions without vernalization,which might be associated with modified expression of methyltransferase genes.Collectively,our results unveil a potentially novel mechanism by which miR396 suppresses the vernalization requirement for flowering which might be related to the epigenetic regulation of VRN genes and provide important new insight into critical roles of a miRNA in regulating vernalization-mediated transition from vegetative to reproductive growth in monocots.展开更多
Vernalization is necessary for winter wheat to flower.However,it is unclear whether vernalization is also required for spring wheat,which is frequently sown in fall,and what molecular mechanisms underlie the vernaliza...Vernalization is necessary for winter wheat to flower.However,it is unclear whether vernalization is also required for spring wheat,which is frequently sown in fall,and what molecular mechanisms underlie the vernalization response in wheat varieties.In this study,we examined the molecular mechanisms that regulate vernalization response in winter and spring wheat varieties.For this purpose,we determined how major vernalization genes(VRN1,VRN2,and VRN3)respond to vernalization in these varieties and whether modifications to histones play a role in changes in gene expression.We also identified genes that are differentially regulated in response to vernalization in winter and spring wheat varieties.We found that in winter wheat,but not in spring wheat,VRN1 expression decreases when returned to warm temperature following vernalization.This finding may be associated with differences between spring and winter wheat in the levels of tri-methylation of lysine 27 on histone H3(H3K27me3)and tri-methylation of lysine 4 on histone H3(H3K4me3)at the VRN1 gene.Analysis of winter wheat transcriptomes before and after vernalization revealed that vernalization influences the expression of several genes,including those involved in leucine catabolism,cysteine biosynthesis,and flavonoid biosynthesis.These findings provide new candidates for further study on the mechanism of vernalization regulation in wheat.展开更多
The ability of wheat to adapt to a wide range of environmental conditions is determined mostly by allelic diversity among genes regulating vernalization requirement.Vrn-1 is a major regulator of this requirement.In th...The ability of wheat to adapt to a wide range of environmental conditions is determined mostly by allelic diversity among genes regulating vernalization requirement.Vrn-1 is a major regulator of this requirement.In this study,two novel alleles of Vrn-A1 were discovered in Chinese cultivars:vrn-A1n was identified in two landraces,Jiunong 2 and Ganchun 16,and Vrn-A1o was detected in Duanhongmangmai.Both novel alleles showed a linked duplication in the promoter region.The common copy of these two alleles was identical to the recessive allele vrn-A1.Compared with the recessive allele vrn-A1,the other copy of vrn-A1n contained a 54-bp deletion in the promoter region and the distinct copy of Vrn-A1o contained an11-bp deletion in the promoter region.In segregating populations in the greenhouse under nonvernalizing(20–25°C)and long-day(16 h light)conditions,plants with the novel vrn-A1n allele did not head earlier than those with the recessive vrn-A1 allele.However,plants that were either homozygous or heterozygous for the novel Vrn-A1o allele headed earlier than those with the recessive vrn-A1 allele.To identify the novel allele with the small-sized product and facilitate screening,a DNA marker for the novel dominant allele Vrn-A1o was designed.Analysis of the novel-allele distribution showed that two cultivars carrying the vrn-A1n allele were dispersed in the northwestern spring wheat zone,and 12 cultivars carrying the dominant Vrn-A1o allele were widely distributed in the northwestern spring wheat zone,Xinjiang winter and spring wheat zone,Yellow and Huai River valley winter wheat zone,and Qinghai-Tibetan Plateau spring and winter wheat zone.Our study identifies useful germplasm and a DNA marker for wheat breeding.展开更多
Spring wheat (cv. 7742) and winter wheat (cv. Nongda 015) were vernalized by seed chilling, and the changes of GAs, ABA content and GAs / ABA ratio in embryo were investigated. The differences between cultivars, treat...Spring wheat (cv. 7742) and winter wheat (cv. Nongda 015) were vernalized by seed chilling, and the changes of GAs, ABA content and GAs / ABA ratio in embryo were investigated. The differences between cultivars, treatments and variety-treatment interactions were significant for both GAs and ABA. The level of GAs and ABA as well as GAs / ABA ratio were hardly changed by seed chilling in spriug wheat However, in winter wheat, the GAs content decreased much less compared with ABA that reduced sharply after chilling. It showed that the GAs / ABA ratio in winter wheat was increased remarkably (4.55 times) than in spring wheat. It was suggested that the absolute GAs level was independent of the vernalization effect because there was a higher GAs level before and after seed chilling in winter wheat when compared with spring wheat, One of the vemalization effects was the decline of ABA level that led to the increase of GAs / ABA ratio.展开更多
Angelica sinensis(Oliv.)Diels is a valuable herbal plant.In production,its premature bolting,caused by vernalization,seriously affects its root yield.In this stuty,thermal treatments of 5,0 and?5°C,as well as tre...Angelica sinensis(Oliv.)Diels is a valuable herbal plant.In production,its premature bolting,caused by vernalization,seriously affects its root yield.In this stuty,thermal treatments of 5,0 and?5°C,as well as treatments with shifts between these temperatures,were performed in its overwintering storage to investigate the chilling effect on the early bolting of Angelica sinensis and analyze the vernalization response to different temperatures.The results indicated that the 0°C treatment rendered the highest bolting rate,and the-5°C resulted in the lowest bolting rate.The initial short-term treatment at-5°C could promote the early bolting of A.sinensis,and the treatment at 5°C prior to planting could hasten its seedling bud growth.At the appropriate temperature,the early bolting rate of Angelica was positively related to the number of treatment days.So the frozen storage at-5°C could inhibit the vernalization of Angelica seedlings and the early bolting.The vernalization of Angelica could be a continuous process related to the number of treatment days.This study would serve as reference for the overwintering storage and cultivation of Angelica.展开更多
An F2 population, derived from a cross between the vernalization independent genotype ＇ RcBr＇ and the vernalization dependent genotype＇08A061 ＇ , was developed to eonstruet a linkage map with 165 SSR and InDel mar...An F2 population, derived from a cross between the vernalization independent genotype ＇ RcBr＇ and the vernalization dependent genotype＇08A061 ＇ , was developed to eonstruet a linkage map with 165 SSR and InDel markers. QTL analysis was performed by two phenotypie evaluation （ days to 5 em elongate stalk and flowering time） based on the difference in F2：3 families under vernalization and no vernalization. The results showed that the vernalization requirement was reeessive in Brassica rapa. Seven QTLs that controlled vernalization requirement were detected on A02 and A06 linkage groups, which explained phenotypic variation ranging from 0.08% to 22.52%. Two QTLs （ VR-DE01, VR-b391 ） were detected on the top of A02, which explained 22.52% and 14. 54% of the phenotypic variation, respectively, and closely linked with BrFLC2 gene. Two QTLs （VR-DE03, VR-DE04） were deteeted on A06 with 13.30% and 13.64% of phenotypie variation. These detected QTLs will provide useful information on understanding the genetic basis between vernalization requirement and bolting, and that will be useful for marker-assisted selection （MAS） in a breeding program for bolting resistant eultivars.展开更多
该研究通过控制伴矿景天(Sedum plumbizincicola X.H.Guo et S.B.Zhou ex L.H.Wu)生长时的温度及其持续时间,探明伴矿景天的春化临界条件及生理响应特征。本研究采用盆栽试验,将伴矿景天健壮种苗各8株进行以下处理:分别置于4、8和12℃...该研究通过控制伴矿景天(Sedum plumbizincicola X.H.Guo et S.B.Zhou ex L.H.Wu)生长时的温度及其持续时间,探明伴矿景天的春化临界条件及生理响应特征。本研究采用盆栽试验,将伴矿景天健壮种苗各8株进行以下处理:分别置于4、8和12℃恒温光照生长箱中进行14、21、28、35、42、49和56 d的低温预处理后移至23℃恒温光照生长箱中继续培养处理;恒温光照生长箱中始终23℃处理;4℃低温预处理123 d后移至室外自然环境处理;始终室外自然环境处理。结果表明,4℃低温预处理可促进伴矿景天开花,且随着低温预处理时间的延长,其首花日期提前,开花率提高。伴矿景天春化临界温度为4~8℃,其中4℃条件下其所需春化时间为35 d,49 d后其可完全春化。随着4℃低温预处理时间的增加(14~56 d),伴矿景天的茎粗和株高均显著增长,但其地上部生物量无显著差异。4℃低温预处理49 d后移至23℃恒温光照生长箱中继续培养,完全春化的伴矿景天在收获期的茎粗和株高均显著高于恒温光照生长箱中始终23℃处理,但地上部生物量无显著差异。与恒温光照生长箱中始终23℃处理相比,4℃低温预处理56 d后移至23℃恒温光照生长箱中继续培养可显著降低伴矿景天盛花期叶片的叶绿素和全氮含量,但可增加叶片的可溶性糖、淀粉和可溶性蛋白含量并提高碳氮比(C/N)值。本研究认为提高伴矿景天生长期间的环境温度可以有效抑制其春化过程,调控伴矿景天开花期,实现少开花甚至不开花,以实现持续生长和刈割,从而提高超积累植物对污染土壤中镉的吸取率。展开更多
文摘The effect of vernalization and two growth regulators Fascination^TM and Pro-Gibb^R on the growth, inflorescence development and flowering of Omithogalurrt Chesapeake Snowflake＇ was studied. Regardless of growth regulator treatment, chilling bulbs for 3 weeks at 10℃ before planting accelerated flowering of the first inflorescence by 5 to 6 days, elongated floral stem length by 1.5 to 2 cm and shortened leaf length by 4 to 5 cm as compared with non-chilled bulbs. When bulbs were chilled 3 weeks at 10℃ before planting, Fascination 2% and Pro-Gibb accelerated flowering of the first inflorescence by 2 to 6 days respectively as compared with the control. When bulbs were not chilled before planting, Fascination 2% and Pro-Gibb accelerated flowering of the first inflorescence by 6 to12 days respectively as compared with the control. The lengths of the leaves and the inflorescences were not affected by PGR treatment. Higher rates of Pro-Gibb （100 mg.L^-1 and 200 mg.L^-1） and more amount of Fascination 2%（100 μL and 200 μL） can cause abortion of inflorescence.
基金supported by the National Science Foundation of China(No.31500221,31590823 and 31601999)the West Light Foundation of the Chinese Academy of Sciences by XXK
文摘The turnip(Brassica rapa var. rapa) is a biennial crop that is planted in late summer/early fall and forms fleshy tubers for food in temperate regions. The harvested tubers then overwinter and are planted again the next spring for flowering and seeds. FLOWERING LOCUS C(FLC) is a MADS-box transcription factor that acts as a major repressor of floral transition by suppressing the flowering promoters FT and SOC1. Here we show that vernalization effectively represses tuber formation and promotes flowering in Tibetan turnip. We functionally characterized four FLC homologues(BrrFLC1,FLC2, FLC3, and FLC5), and found that BrrFLC2 and BrrFLC1 play a major role in repressing flowering in turnip and in transgenic Arabidopsis. In contrast, tuber formation was correlated with BrrFLC1 expression in the hypocotyl and was repressed under cold treatment following the quantitative downregulation of BrrFLC1. Grafting experiments of non-vernalized and vernalized turnips revealed that vernalization independently suppressed tuberization in the tuber or hypocotyl of the rootstock or scion, which occurred in parallel with the reduction in BrrFLC1 activity. Together, our results demonstrate that the Tibetan turnip is highly responsive to cold exposure, which is associated with the expression levels of BrrFLC genes.
基金financially supported by a grant from Tarbiat Modares University,Tehran,Iran
文摘The relationship between vernalization requirement and quantitative and qualitative changes in total leaf soluble proteins were determined in one spring （cv. Kohdasht） and two winter （cvs. Sardari and Norstar） cultivars of wheat （Triticum aestivum L.） exposed to 4℃. Plants were sampled on days 2, 14, 21 and 35 of exposure to 4℃. The final leaf number （FLN） was determined throughout the vernalization periods （0, 7, 14, 24, and 35 d） at 4℃. The final leaf number decreased until days 24 and 35 in Sardari and Norstar eultivars, respectively, indicating the vernalization saturation at these times. No clear changes were detected in the final leaf number of Kohdash cultivar, verifying no vernalization requirement for this spring wheat cultivar. Comparing with control, clear cold-induced 2-fold increases in proteins quantity occurred after 48 h following the 4℃-treatment in the leaves of the both winter wheat cultivars but, such response was not detected in the spring cultivar. However, the electrophoretic protein patterns showed between-cultivar and between-temperature treatment differences. With increasing exposure time to 4℃, the winter cultivars tended to produce more HMW polypeptides than the spring cultivar. Similar proteins were induced in both Sardari and Norstar winter wheat cultivars, however, the long vernalization requirement in Norstar resulted in high level and longer duration of expression of cold-induced proteins compared to Sardari with a short vernalization requirement. These observations indicate that vernalization response regulates the expression of low temperature （LT） tolerance proteins and determines the duration of expression of LT- induced proteins.
基金supported in part by Biotechnology Risk Assessment Grant Program competitive grant no.2019-33522-30102 from the USDA and National Institute of Food and Agriculture and the United States Golf Association,Inc.grant no.2016-25-575 as well as the Sichuan Science and Technology Program grant no.2019YFH0064.
文摘MicroRNA396(miR396)has been demonstrated to regulate flower development by targeting growth-regulating factors(GRFs)in annual species.However,its role in perennial grasses and its potential involvement in flowering time control remain unexplored.Here we report that overexpression of miR396 in a perennial species,creeping bentgrass(Agrostis stolonifera L.),alters flower development.Most significantly,transgenic(TG)plants bypass the vernalization requirement for flowering.Gene expression analysis reveals that miR396 is induced by long-day(LD)photoperiod and vernalization.Further study identifies VRN1,VRN2,and VRN3 homologs whose expression patterns in wild-type(WT)plants are similar to those observed in wheat and barley during transition from short-day(SD)to LD,and SD to cold conditions.However,compared to WT controls,TG plants overexpressing miR396 exhibit significantly enhanced VRN1 and VRN3 expression,but repressed VRN2 expression under SD to LD conditions without vernalization,which might be associated with modified expression of methyltransferase genes.Collectively,our results unveil a potentially novel mechanism by which miR396 suppresses the vernalization requirement for flowering which might be related to the epigenetic regulation of VRN genes and provide important new insight into critical roles of a miRNA in regulating vernalization-mediated transition from vegetative to reproductive growth in monocots.
基金supported by Project 2662020ZKPY002 supported by the Fundamental Research Funds for the Central Universities.
文摘Vernalization is necessary for winter wheat to flower.However,it is unclear whether vernalization is also required for spring wheat,which is frequently sown in fall,and what molecular mechanisms underlie the vernalization response in wheat varieties.In this study,we examined the molecular mechanisms that regulate vernalization response in winter and spring wheat varieties.For this purpose,we determined how major vernalization genes(VRN1,VRN2,and VRN3)respond to vernalization in these varieties and whether modifications to histones play a role in changes in gene expression.We also identified genes that are differentially regulated in response to vernalization in winter and spring wheat varieties.We found that in winter wheat,but not in spring wheat,VRN1 expression decreases when returned to warm temperature following vernalization.This finding may be associated with differences between spring and winter wheat in the levels of tri-methylation of lysine 27 on histone H3(H3K27me3)and tri-methylation of lysine 4 on histone H3(H3K4me3)at the VRN1 gene.Analysis of winter wheat transcriptomes before and after vernalization revealed that vernalization influences the expression of several genes,including those involved in leucine catabolism,cysteine biosynthesis,and flavonoid biosynthesis.These findings provide new candidates for further study on the mechanism of vernalization regulation in wheat.
基金funded by the National Key Research and Development Program of China(2016YFD0101802)the Key Research and Development Project of Shaanxi Province(2019ZDLNY04-05)+1 种基金the National Basic Research Program of China(2014CB138102)the National Natural Science Foundation of China(30971770 and 31671693)。
文摘The ability of wheat to adapt to a wide range of environmental conditions is determined mostly by allelic diversity among genes regulating vernalization requirement.Vrn-1 is a major regulator of this requirement.In this study,two novel alleles of Vrn-A1 were discovered in Chinese cultivars:vrn-A1n was identified in two landraces,Jiunong 2 and Ganchun 16,and Vrn-A1o was detected in Duanhongmangmai.Both novel alleles showed a linked duplication in the promoter region.The common copy of these two alleles was identical to the recessive allele vrn-A1.Compared with the recessive allele vrn-A1,the other copy of vrn-A1n contained a 54-bp deletion in the promoter region and the distinct copy of Vrn-A1o contained an11-bp deletion in the promoter region.In segregating populations in the greenhouse under nonvernalizing(20–25°C)and long-day(16 h light)conditions,plants with the novel vrn-A1n allele did not head earlier than those with the recessive vrn-A1 allele.However,plants that were either homozygous or heterozygous for the novel Vrn-A1o allele headed earlier than those with the recessive vrn-A1 allele.To identify the novel allele with the small-sized product and facilitate screening,a DNA marker for the novel dominant allele Vrn-A1o was designed.Analysis of the novel-allele distribution showed that two cultivars carrying the vrn-A1n allele were dispersed in the northwestern spring wheat zone,and 12 cultivars carrying the dominant Vrn-A1o allele were widely distributed in the northwestern spring wheat zone,Xinjiang winter and spring wheat zone,Yellow and Huai River valley winter wheat zone,and Qinghai-Tibetan Plateau spring and winter wheat zone.Our study identifies useful germplasm and a DNA marker for wheat breeding.
文摘Spring wheat (cv. 7742) and winter wheat (cv. Nongda 015) were vernalized by seed chilling, and the changes of GAs, ABA content and GAs / ABA ratio in embryo were investigated. The differences between cultivars, treatments and variety-treatment interactions were significant for both GAs and ABA. The level of GAs and ABA as well as GAs / ABA ratio were hardly changed by seed chilling in spriug wheat However, in winter wheat, the GAs content decreased much less compared with ABA that reduced sharply after chilling. It showed that the GAs / ABA ratio in winter wheat was increased remarkably (4.55 times) than in spring wheat. It was suggested that the absolute GAs level was independent of the vernalization effect because there was a higher GAs level before and after seed chilling in winter wheat when compared with spring wheat, One of the vemalization effects was the decline of ABA level that led to the increase of GAs / ABA ratio.
基金Supported by National Natural Science Foundation of China(31260298,31660565)Science and Technology Planning Project of Gansu Province(18JR3RE243,1308RJZE288)~~
文摘Angelica sinensis(Oliv.)Diels is a valuable herbal plant.In production,its premature bolting,caused by vernalization,seriously affects its root yield.In this stuty,thermal treatments of 5,0 and?5°C,as well as treatments with shifts between these temperatures,were performed in its overwintering storage to investigate the chilling effect on the early bolting of Angelica sinensis and analyze the vernalization response to different temperatures.The results indicated that the 0°C treatment rendered the highest bolting rate,and the-5°C resulted in the lowest bolting rate.The initial short-term treatment at-5°C could promote the early bolting of A.sinensis,and the treatment at 5°C prior to planting could hasten its seedling bud growth.At the appropriate temperature,the early bolting rate of Angelica was positively related to the number of treatment days.So the frozen storage at-5°C could inhibit the vernalization of Angelica seedlings and the early bolting.The vernalization of Angelica could be a continuous process related to the number of treatment days.This study would serve as reference for the overwintering storage and cultivation of Angelica.
基金Supported by the National Natural Science Foundation of China(30900981)the Research Program of the Educational Department of Liaoning Province(L2013255)
文摘An F2 population, derived from a cross between the vernalization independent genotype ＇ RcBr＇ and the vernalization dependent genotype＇08A061 ＇ , was developed to eonstruet a linkage map with 165 SSR and InDel markers. QTL analysis was performed by two phenotypie evaluation （ days to 5 em elongate stalk and flowering time） based on the difference in F2：3 families under vernalization and no vernalization. The results showed that the vernalization requirement was reeessive in Brassica rapa. Seven QTLs that controlled vernalization requirement were detected on A02 and A06 linkage groups, which explained phenotypic variation ranging from 0.08% to 22.52%. Two QTLs （ VR-DE01, VR-b391 ） were detected on the top of A02, which explained 22.52% and 14. 54% of the phenotypic variation, respectively, and closely linked with BrFLC2 gene. Two QTLs （VR-DE03, VR-DE04） were deteeted on A06 with 13.30% and 13.64% of phenotypie variation. These detected QTLs will provide useful information on understanding the genetic basis between vernalization requirement and bolting, and that will be useful for marker-assisted selection （MAS） in a breeding program for bolting resistant eultivars.
