| Angelica dahurica var.formosana has a variety of usage,and is commonly used as a traditional Chinese medicine.Early-bolting often occurs in its production,which lead to the root lignification,decrease of its medicinal component contents and loss of the medicinal values.Therefore,exploring the occurring process and key factors of A.dahurica var.formosana early-bolting can reveal the reasons of A.dahurica var.formosana early-bolting.It also can provide the foundations for guiding actual production,reducing early-bolting rate in the field and cultivating new varieties of A.dahurica var.formosana with low early-bolting rate.As one of the main plant hormones,IAA plays an important role in plant growth and development and participates in a variety of plant physiological and biochemical processes.However,whether it is involved in A.dahurica var.formosana early bolting and its regulatory mechanism have not been reported yet.In this paper,the morphological development process of early-blotting were observed,the main agronomic traits,photosynthetic characteristics,some other physiological indicators,transcriptome and metabolome of the different tissues of early-bolting and normal A.dahurica var.formosana were measured and analyzed.The main results are as following:(1)A.dahurica var.formosana flower buds begin to differentiate and internodes begin to elongate as the number of compound leaves reach 9-10.At the same time,the ratio of early-bolting root phloem/xylem decreased(0.37),significantly lower than the normal(0.84).The phloem degenerated.Xylem fibrous cell wall became thicker,and the lignin content increased significantly,which showed the root lignification.The previou results indicated that the flower bud differentiation,internode elongation and the root lignification in A.dahurica var.formosana occured synchronously.The lignification of the root of early-blitting A.dahurica var.formosana was related to the beginning of reproductive growth and the acceleration of root xylem differentiation.(2)The plant height,stem diameter and compound leaves number of early-bolting plants were significantly higher than that of the normal plants,which indicated that the development stage of early-bolting plants was early than the normal plants.The physiology and biochemical indexes of early-bolting plants were also significantly different from the normals.The stomatal density,photosynthetic parameters and chlorophyll content of the leaves were significantly lower than the normal,which indicated the early-bolting plants photosynthetic performance significantly reduced.The contents of organic carbon,soluble sugar and sucrose in all tissues of early-bolting plants were lower or significantly lower than that in normal plants,which was consistent with the decrease of photosynthetic performance.In addition,the contents of total nitrogen and soluble protein in leaves and root phloem of early-bolting plants were higher than that in the same tissue of normal plants,which should be related to the fact that leaves and root phloem in early time of early-bolting process need a lot of protein,such as transcription factors,to participate in growth and development,while the content of total nitrogen and soluble protein in root xylem was lower than that in normal plants.Besides,the C/N ratios of the leaves and root phloem of early-bolting plants were lower than that of normal plants,while the C/N ratio in the root xylem was higher than that of normal plants due to the total nitrogen decreasing-rate of the root xylem was lower than that of the organic carbon.The contents of IAA in leaves,stem and root xylem were significantly higher than that in the normal plants,but the content of IAA in degenerated root phloem was lower than that in the normal plants,which was basically consistent with the observed aboveground part elongation of early-bolting plants,the leaves dry matter content significantly increasing,the root xylem rapidly increasing and the root phloem degeneration.In addition,the IAA content of terminal flower seeds with high early-bolting rate was 174.74ng/g,which was significantly higher than that of 117.38 ng/g of primary flower seeds with lower early-bolting rate.Therefore,IAA content was related to the difference in physiological and biochemical indexes of early bolting,which had a certain relationship to the early-bolting in A.dahurica var.formosana.(3)Transcriptome analysis of different tissues(leaves,stems,root phloem and root xylem)of normal and early-bolting plants yielded a total of 110251 unigenes,149 of which were differentially expressed in leaves,stems,root phloem and root xylem of A.dahurica var.formosana.It was found that the expressions of REVEILLE 8(RVE8),SUPPRESSOR OF CONSTANS OVEREXPRESSION 1(SOC1),FRUITFULL(FUL),which were related to flowering,and WALLS ARE THIN 1(WAT1),which was related to the secondary cell wall lignin synthesis and IAA transportation,were up-regulated in leaves,stems and root xylem of early-bolting plants,and down-regulated in root phloem.Moreover,IAA synthesis pathway were also up-regulated in the leaves,stems and root xylem of early-bolting plants,and down-regulated in root phloem,which was consistent with the above gene expression trend.The metabolites were enriched to 582 different metabolites.Of them,the lignin and coumarin-related metabolites were significantly enriched in the root xylem,while the content of tryptophan,the precursor of auxin synthesis,significantly decreased in the root phloem.Through the comprehensive analysis of metabolism and transcriptome,it was suggested that IAA regulates RVE8 and its downstream gene SOC1 and FUL to control flowering time,and also regulates the synthesis pathway of phenylpropanoids and affect the synthesis of secondary cell wall lignin by WAT1.Ad RVE8,Ad SOC1 and Ad WAT1 were cloned and its bioinformatically were analyzed.The q PCR results showed that the variation of expression levels of Ad RVE8,Ad SOC1 and Ad WAT1 in different tissues of early-bolting and normal plants were consistent with the transcriptome results.IAA were sprayed in the seedling stage of A.dahurica var.formosana.The results showed that IAA content in the leaf increased.The expression levels of Ad RVE8,Ad SOC1 and Ad WAT1 also increased,and the expression levles of Ad SOC1 and Ad WAT1 increased significantly,which indicated that proving that the expressions of Ad RVE8,Ad SOC1 and Ad WAT1 were related to IAA to some degree.(4)The SSR loci obtained from the transcriptome data of A.dahurica var.formosana were numerous and abundant.Transcriptome data were used to develop SSR markers for A.dahurica var.formosana,and 114 SSR loci were synthesized and verified,14 of which were specific and polymorphic.Further verification found that 10 of them met the standard.All of the 10 SSR loci are located in UTR region,which may be involved in the regulation of some traits. |
PDF Full Text Request