Effect Of Temperature On Gene Expression Ability Of Transcription Factor And Saponin Synthase In Ginseng

Ginseng(Panax ginseng C.A.Meyer)is a valuable plant with high medicinal value.Ginsenoside is a secondary metabolite of ginseng whose synthesis is affected by factors such as the environment,transcription factors,and structural genes related to the synthesis of secondary metabolites.Current research has found that plants mainly use two mechanisms to sense and respond to environmental changes.One mechanism is that plant cells receive signals from changes in the external environment,activate transcription factors through plant hormones,and regulate the expression of multiple enzyme genes in secondary metabolic pathways.It responds to environmental changes by producing secondary metabolites;another mechanism is that the transcription factor itself acts as a receptor protein to sense changes in the external environment to regulate the expression of functional genes in response to environmental stress.Abiotic stress includes temperature stress.There are very few studies on how ginseng responds to temperature changes through transcription factors,saponin synthase genes,and hormone synthase genes.Therefore,this article mainly studies temperature-related ginseng transcription factors under different temperature(different sampling times)culture conditions.Genes(PgbHLH1,PgbHLH2,PgMYB5,PgWRKY2),3-hydroxy-3-methylglutaryl coenzyme A reductase gene(PgHMGR),dammarene diol synthase gene(PgDS)in the ginsenoside synthesis pathway,The protopanaxadiol trihydroxyglucosyltransferase gene(PgUGT-D-3OH-1),the protopanaxadiol trihydroxyglucosyltransferase gene(PgUGT-D-3OH-2)and the key to the biosynthesis of ginseng jasmonic acid The expression of the enzyme gene PgLOX1 and the key enzyme gene PgNCED for ginseng abscisic acid biosynthesis,and the relationship among the 10 genes under different temperature(different sampling time)conditions was analyzed and compared.Because the suitable growth environment of ginseng is not easy to form,and the growth cycle is long.Therefore,this research uses the ginseng hairy roots(tissues induced by Agrobacterium rhizogenes infecting ginseng roots)preserved in our laboratory,which has the characteristics of fast growth,easy culture,and high content of active substances,as experimental materials.The results of the research are as follows:(1)Under different temperature conditions(5℃,15℃,20℃,25℃,30℃),the relative expression of PgbHLH1 is 20℃>25℃>15℃>5℃>30℃,and PgMYB5 is 5℃>30℃>15℃>25℃>20℃.The relative expression of PgWRKY2 and PgbHLH2 has no obvious regularity with the change of temperature;The relative expression of PgHMGR、PgDS、PgUGT-D-3OH-1、PgUGT-D-3OH-2are all 20℃>25℃>15℃>5℃>30℃;The relative expression of PgNCED is5℃>15℃>20℃> 25℃>30℃,and PgLOX1 is 20℃>25℃>15℃>5℃>30℃.(2)At the same temperature and different sampling time(2d,4d,6d,8d),the relative expression of PgbHLH1 and PgMYB5 genes increased first,then decreased,and reached the peak on the 4th day.The relative expression of PgbHLH2 and PgWRKY2 changed irregularly;The relative expression of PgHMGR、PgDS、PgUGT-D-3OH-1 and PgUGT-D-3OH-2 genes increased first,then decreased,and reached their peak on the 4th day;The relative expression of PgNCED and PgLOX1 increased first,then decreased,and reached the peak at the fourth day.(3)With the same sampling time and different temperatures,the four saponin synthase genes are positively correlated with PgbHLH1,the correlation coefficients are all greater than 0.96,and PgMYB5 are weakly negatively correlated,the correlation coefficients are all less than-0.7,and the correlation with PgWRKY2 and PgbHLH2 are poor;The 4 saponin synthase genes are positively correlated with PgLOX1,the correlation coefficients are all greater than 0.86,and the correlation with PgNCED are poor;PgNCED is poorly correlated with PgbHLH1,PgbHLH2,PgMYB5,PgWRKY2,and PgLOX1 is weakly negatively correlated with PgMYB5,and the correlation coefficients are all less than-0.76,it is a positive correlation with PgbHLH1,the correlation coefficients are all greater than 0.87,and the correlation with PgbHLH2,PgWRKY2 is poor.It is inferred from this that PgbHLH1 and PgLOX1 play a positive regulatory role in the ginsenoside synthesis pathway,and PgMYB5 plays a negative regulatory role.