Study On The Developmental Mechanism Of Ginkgo Biloba L.Basal Chichi Based On Hormones And Multi-Omics

Ginkgo biloba L.is an ancient relict tree species known as the"living fossil".Because of its long life span,wide adaptability,strong stress resistance,few pests and diseases,and strong ornamental,it has important economic,ecological and scientific research value.Chichi is a unique biological phenomenon of G.biloba.It usually grows on tree trunks,branches or root collars.It is an inverted cone or cylinder with a wide base and a blunt tip.More than a century has passed since the discovery and naming of chichi,but its developmental mechanism is still divergent.With the development of biotechnology,multi-omics technology is increasingly used to explain various biological phenomena.The completion of G.biloba genome sequencing has provided strong support for explaining its developmental mechanism through parametric transcriptome sequencing technology.In this study,G.biloba basal chichi was used as the research object,and RNA-seq and LC-MS/MS were used to compare the differences in transcription and metabolism between the roots(R),stems(S)tissues and chichi(C).We screened differentially expressed genes(DEGs),differentially accumulated metabolites(DAMs)and plant hormones in chichi development,constructed hormone signal transduction and regulation pathways,and screened the key enzymes and regulatory genes.The aim is to explore the regulation mechanism of chichi,explain the specificity of chichi and its possible role in the process of G.biloba adapting to the environment,and provide ideas for research on the function of G.biloba genes and explaining the ability of G.biloba to adapt to the environment.The main results of this study are as follows.(1)A total of 21 compounds of 7 types of plant hormones were detected in the tissues of basal chichi,roots and stems.Cytokinin compounds(c Z,t Z,IP),jasmonic acid compounds(MEJA),abscisic acid(ABA),and salicylic acid(SA)are the highest in chichi,and they are all significantly higher than stems and roots.Auxin compounds(IAA,ME-IAA,ICAld,ICA),gibberellin(GA₆),jasmonic acid(JA,H2JA,JA-ILE)and ethylene precursor ACC have the highest content in roots.Except for ICAld,the content of other compounds in roots was significantly higher than that in stems and chichi.The content of IAA and ME-IAA showed a trend of roots>chichi>stems.Among the 7 detected gibberellin compounds(GA₃,GA₄,GA₆,GA₇,GA₁₅,GA₂₀and GA₅₁),the content of GA₃is far higher than other compounds,and the content in chichi and roots is higher,which is significantly higher than that in stems.Among the content ratios of plant hormones,the ratio of AUX/GA was the highest in roots,which was significantly higher than that of stems and chichi;the ratio of AUX/CTK showed a trend of root>stem>chichi.(2)A total of 414 metabolites were detected in the three tissues,which belonged to 11primary classifications and 32 secondary classifications.The metabolites with the most relative content are amino acids and their derivatives(30.41%),lipids(17.76%),phenolic acids(9.62%),organic acids(7.89%),and flavonoids(7.60%).The roots and stems were used as the control group and compared with the chichi.The S vs C and R vs C Comparison groups obtained 119 DAMs and 156 DAMs respectively.There were 69 common DAMs between the two groups,68 of which had the same trend.The 20 common up-regulated DAMs are mainly concentrated in amino acids and their derivatives(7 DAMs)and nucleotides and their derivatives(7 DAMs);the 48 common down-regulated DAMs are mainly concentrated in flavonoids(15 DAMs),phenolic acids(14 DAMs),lignans and coumarins(8 DAMs)and lipids(4 DAMs).In the S vs C comparison group,55 DAMs were enriched in 63 KEGG pathways;in the R vs C comparison group,53 DAMs were enriched in 51 KEGG pathways.(3)A total of 74.95 Gb Clean Data was obtained from 9 plant samples.A total of505,378,738 Raw Reads were obtained,and 487,175,244 Clean Reads were obtained after filtration.The ratio of the transcriptome sequence alignment of each sample to the reference genome is over 83%.The roots and stems were used as the control group and compared with the chichi.The Comparison group of S vs C and R vs C obtained 2655 DEGs and 5259DEGs respectively.There were 1124 common DEGs between the two groups,and 826 of them had the same expression trend.In the S vs C comparison group,843 DEGs were enriched in 127 KEGG pathways;in the R vs C comparison group,1605 DEGs were enriched in 129 KEGG pathways.(4)There is a strong correlation(r>0.8)between 1753 DEGs and 118 DAMs in the S vs C comparison group;3740 DEGs and 146 DAMs in the R vs C comparison group have a strong correlation.The two comparative combinations of DAMs with strong correlation are mainly concentrated in the classification of phenolic acids,flavonoids,amino acids and their derivatives,nucleotides and their derivatives,lignans and coumarins,and lipids.There is a strong correlation between 949 common DEGs and 8 phytohormones.Among them,the DEGs with a strong correlation with t Z are the most,reaching 538,followed by MEJA(343DEGs),IAA(297 DEGs),ACC(268 DEGs),SA(222 DEGs),JA(127 DEGs),ABA(118DEGs),GA₃(53 DEGs).A total of 27 DEGs that are strongly related to the corresponding hormone compounds are enriched in the KEGG pathway related to plant hormone synthesis and signal transduction,of which 15 DEGs are strongly correlated with two or more hormone compounds.(5)The development of basal chichi is closely related to the synthesis of phenylpropane,flavonoids,amino acids,nucleotides,as well as the synthesis of plant hormones and signal transduction.We speculate that the root system initiates a response response after receiving a stress stimulus,and induces the development of basal chich through signal transduction.Cytokinins play a major role in the morphogenesis of basal chichi.Basal chichi is involved in the stress response of plants through the regulatory network of plant hormones such as abscisic acid,jasmonic acid,salicylic acid and ethylene.We screened out the following key enzymes and genes that may be involved in the development and stress regulation of G.biloba basal chichi:caffeoyl-Co A O-methyltransferase(Gb?12660)and shikimate O-hydroxycinnamoyltransferase(Gb?09387)related to phenylpropane biosynthesis,acyl-Co A oxidase(ACX,Gb?13280)related to jasmonic acid synthesis,UDP-glucosyl transferase 73C(UGT73C,Gb?19257)related to cytokinin synthesis,auxin response factor(ARF,Gb?17830),auxin responsive GH3 family(Gb?40050),cytokinin two-component response regulator ARR-A family(Gb?33947)and ARR-B family(Gb?37200),jasmonic acid transcription factor MYC2(Gb?15096).