| High soil salinity threatens plant growth and development,and it is very meaningful to study the mechanism of plant salt tolerance.Chrysanthemum×grandiflora is a ground-grown chrysanthemum cultivar bred by hybridization and spaceflight on the basis of the introduction of Chrysanthemum morifolium and Dendranthema morifolium.At present,there have been reports on the physiology of salt tolerance,but no research on short-term salt stress transcriptome sequencing has been reported.As a chrysanthemum variety with strong resistance,its salt resistance does not depend on a single gene,but is controlled by multiple genes.Therefore,this experiment chose to study the overall expression pattern of C.Grandiflora related genes in response to salt stress at the transcriptome level.In this article,C.Grandiflora ’Niu9717’ seedlings were treated with 200mM NaCl solution for root irrigation for transcriptome sequencing to mine salt tolerance genes.To study the salt resistance function of Arabidopsis overexpressing xyloglucan endotransglycosidase/hydrolase gene(CgXTH23),and to reveal the molecular mechanism of C.Grandiflora response to salt stress and the characteristics of CgXTH23 gene.The main results of this study are as follows:1.After treatment with 200mM NaCl solution,the growth potential of the plants in the treatment group was weaker,and the water content of the leaves gradually decreased with the increase of treatment time,while the growth of C.Grandiflora in the control group was significantly better than that in the control group.processing group.The activities of antioxidant enzymes showed a trend of first increasing and then decreasing with the increase of treatment time.2.For transcriptome sequencing(RNA-Seq),C.Grandiflora seedlings with 11-12 leaves were selected.After 200mM NaCl treatment for 12 h,extracted roots and leaves for sequencing.The m RNA expression of C.Grandiflora with unknown genomic information under salt stress was measured by RNA-seq,and a total of 39,185 Unigenes were obtained.In the Nr database,31,181 Unigenes were annotated,and the Unigene annotations of six species were mainly matched with C.Grandiflora,among which sequences homologous to Artemisia annua were the most,accounting for 79.55% of the total.Under salt stress for 12 h,3,094 differentially expressed genes were identified in roots and 7,880 differentially expressed genes were identified in leaves.There were 1,297 up-regulated expressed genes in roots and 3,125up-regulated expressed genes in leaves.3.Root responses to salt stress focus on the upregulation of genes encoding involved ion transporters,in which the expression of ion transporter genes NHX and HKT is altered,thereby altering osmotic regulation capacity,maintaining high biofilm stability,and ultimately responding to salt stress reaction.In leaves,the responses focused on phenylpropane biosynthesis and phytohormone signaling,and a number of up-regulated genes were identified that play important roles in leaf defense against salt stress.4.16 genes in the plant hormone signaling pathway were selected for q RT-PCR analysis,and the related genes XTH23,XTH22,GLK1,ABI2,PYL1,CEX8,TIFY9 and SCL15 involved in the salt stress response of C.Grandiflora were all down-regulated.BOA,BHLH23,SRK2 E,PIF1,IAA27,CXE15,SAUR36 and SAPK10 were all up-regulated.5.CgXTH23 was cloned by RT-PCR technique.Bioinformatics analysis of CgXTH23 showed that its ORF is 594 bp in length and encodes 197 amino acids.It is an unstable protein and a hydrophilic protein.There is no transmembrane structure,no signal peptide,and it is a non-secreted protein.Random coils and extended chains are the main structures of the protein,with 1 glycosylation site and 36 phosphorylation sites.The CgXTH23 protein is most closely related to Cynara scolymus.Arabidopsis overexpressing the C.Grandiflora CgXTH23 gene was more sensitive to salt stress.Taking the cloning of CgXTH23 gene as an example,the functional role of C.Grandiflora CgXTH23 gene in resistance to salt stress was revealed. |
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