Effect Of The Alternating Magnetic Field On Physiology And Biochemical Characteristics In Cynanchum Thesioides(Freyn)K. Schum

Cynanchum thesioides(Freyn)K.Schum is an upright semi-shrub plant belonging to the genus Cynanchum in the family Metaplexis.It is common in Heilongjiang,Jilin,Liaoning,Inner Mongolia,Hebei,Henan,Shandong,Shanxi,Shaanxi,Gansu,Xinjiang and Jiangsu provinces in China.Triterpenes and flavonoids are the main bioactive constituents of Cynanchum thesioides(Freyn)K.Schum.The whole grass and fruit can be used as precious Mongolian medicine which has remarkable effect on clearing away the deficiency of fire,benefiting Qi,producing saliva and tonifying breast.The ripening period of Cynanchum thesioides(Freyn)K.Schum is from June to August.Due to the vigorous field heat and respiration after harvest,the fruit had tissue fibrosis which seriously affects its shelf life and edible value.At present,physical,chemical and biological fresh-keeping methods of other fruits and vegetables have been developed in endlessly,but few researches have been made on the fresh-keeping methods of Cynanchum thesioides(Freyn)K.Schum.Therefore,it is imperative to study the fresh-keeping methods of Cynanchum thesioides(Freyn)K.Schum.As a branch of biophysics,biomagnetism is an interdisciplinary subject that studies the relationship among the magnetism of living matter,the phenomenon of biomagnetism,the structure and function in the process of life activities,and the influence of external magnetic field on the magnetism of living organisms.Magnetic fresh-keeping has the advantages of simple operation,economic and practical function,no chemical and biological pollution and so on.It is broad for the application prospect of magnetic fresh-keeping market.Cell wall degradation is one of the main causes of fruit softening.?-glucosidase(BG)and polygalacturonidase(PG)are vital in cell wall degradation.BG is an enzyme that catalyzes the final biochemical reaction of cellulose hydrolysis to glucose in cell wall.PG,can lyse cell walls and catalyze the cleavage of pectin to producegalacturonic acid and oligomeric galacturonic acid,eventually leading to fruit softening.In this study,the alternating magnetic field with different intensity and time was used to treat the Cynanchum thesioides(Freyn)K.Schum,and the relevant physiological and biochemical indexes were measured to determine the optimal intensity and time of the magnetic field treatment,so as to provide certain theoretical basis for the application in other fruits and vegetables preservation.At the same time,combine transcriptome sequencing analysis,the cloning of the cell wall degrading enzyme BG and PG genes,and the fluorescence quantitative PCR technology,the changes in the relative expression levels of BG and PG genes after the optimal magnetic field treatment were measured.The preservation mechanism of the magnetic field treatment was explored from the perspective of molecular biology.The main conclusions were as follows:(1)Different intensity alternating magnetic field was used to treat Cynanchum thesioides(Freyn)k.Schum.The results showed that the best intensity of magnetic field value was 1.28 mT.It could delay the decrease of titratable acid content and soluble solid content,so that it can maintain Cynanchum thesioides(Freyn)k.Schum taste more stable.It also could maintain low level of the respiration intensity,and membrane permeability,which make the appearance quality the best.(2)Different time alternating magnetic field was used to treat Cynanchum thesioides(Freyn)k.Schum.The results showed that the best magnetic field processing time is 15 min,which can keep the titratable acid content and soluble solid content stable.At the same time,it could reduce the respiration intensity,hardness and film permeability,and also slow down the softening speed of the Cynanchum thesioides(Freyn)k.Schum.As a result,it made the appearance quality the best.(3)Transcriptome sequencing technology was used to screen out the full-length sequences of the different expressed genes of cell wall degrading enzymes BG and PG and eventually design specific primers.Then,the cDNA of Cynanchum thesioides(Freyn)k.Schum was used as the template for RT-PCR amplification.After theamplification products were sequenced,the gene sequences of BG and PG were obtained with lengths of 1311 bp and 1434 bp,respectively.The Blast analysis results showed that the full-length cDNA of BG and PG genes was successfully cloned in this study.Then,the fluorescence quantitative PCR technology was used to conclude that when the magnetic field intensity and treatment time were 1.28 mT and 15 min,the relative expression levels of BG and PG genes could be reduced,and the preservation effect was the best.