The Study On Cutting Propagation Technology And Rooting Mechanism Of Cordia Dichotoma Forst.f.

Cordia dichotoma Forst.f.is a perennial deciduous tree of genus Cordia in Boraginaceae.Its fruit is edible and can be used as medicine,with highly economic and ecological value.Meanwhile it is promoted and planted as a species of economic forest in coastal areas of China.Cutting propagation,as one of the techniques of asexual propagation,has the advantages of easy operation,fast seedling formation and large propagation coefficient.At present,there are few studies on the seedling cultivation of C.dichotoma Forst.f.and the systematic research on related cutting propagation has not been reported.In this experiment,the cutting propagation system of C.dichotoma Forst.f.has been established through single factor and orthogonal design experimental method.On the basis of the research,the changes of physiological and biochemical indexes such as nutrients,endogenous hormones and oxidase activity in adventitious root formation of cuttings were studied,and the correlation analysis of related differential proteins in rooting process was carried out by i TRAQ technology,and the rooting mechanism of C.dichotoma Forst.f.cuttings was preliminarily revealed.Findings are as follows:（1）The optimal cutting propagation combination of C.dichotoma Forst.f.is as follows:Using annual lignified hardwood as cuttings,V _perlite:V _peat=2:1 as cuttings matrix,the cuttings were soaked by 4000 mg·L^-1IBA at the base of cuttings for 15 s,and the cuttings survival rate was as high as94.44%in spring.（2）The adventitious root formation of C.dichotoma Forst.f.cutting can be roughly divided into three stages:callus formation（S1,0-20 d）,adventitious root formation（S2,20-40 d）,adventitious root elongation（S3,after 40 d）.There are three types of rooting cuttings:skin rooting,callus rooting and mixed rooting.IBA treatment can accelerate the rooting process of C.dichotoma Forst.f.cuttings and increase the formation of callus rooting cuttings.（3）IBA treatment can promote the metabolic synthesis of soluble sugar and starch in the adventitious root formation stage,stimulate the accumulation of soluble protein in the early stage of adventitious root formation,and improve the utilization efficiency of energy materials in the adventitious root elongation stage,which is conducive to rooting.PPO and POD were closely related to rooting of cuttings,and IBA treatment significantly improved the activity of PPO and POD,which was beneficial to rooting.Treatment with IBA improved SOD activity in callus formation,which was beneficial to the healing of cuttings and the occurrence of adventitious roots.The activity of CAT was inhibited under the treatment of IBA,and the toxic effect of cells was weakened,which was conducive to rooting.IBA treatment increased the content of IAA in cuttings,which was beneficial to induce the formation of advent roots.The change of ABA content had a negative effect on rooting.IBA treatment inhibited the formation of ABA and reduced the effect of ABA on the activity of cuttings.The content of GA3 and ZR showed that relatively low concentration in the early stage was favorable for callus formation,while relatively high concentration in the later stage was favorable for the occurrence of advancedroots.（4）The i TRAQ technique was used to study the differential proteomics of cuttings S1,S2 and S3 at different stages.A total of 2647 rooting related proteins were obtained,among which 343 were trusted.In the early stage of adventitious root formation（S1 VS S2）,182 different proteins were screened,among which 133 were up-regulated and 49 were down-regulated.At the later stage of adventitious root formation（S2 VS S3）,a total of 217 differential proteins were identified,among which 167 were up-regulated and 50 were down-regulated.（5）The results of GO enrichment analysis showed that the differential proteins were mainly enriched in the cell terms of thylakoid,photosynthetic membrane,ribosomes and photosystem,and were involved in cell metabolic processes such as photosynthesis,macromolecule synthesis and peptide biosynthesis.The enrichment analysis of KEGG Pathway showed that the differentially expressed proteins were mainly concentrated in the photopolytic,and ribosomal metabolic pathways.