| The heavy metal cadmium pollution is currently one of the most serious environmental pollution in my country,and it is paid attention to because of the easy transfer of cadmium ions into the human food chain.Hemp(Cannabis Sativa L.),Cannabis of Cannabaceae,as an annual herbaceous cash crop,plays an important role in textiles,papermaking,medicine,health care,etc.It has a short growth cycle,strong tolerance,large biomass,and is not easy to bring heavy metals into the human food chain,so it is used to repair heavy metal contaminated soil.Our research team found in the early stage that after hemp is subjected to cadmium stress,a large amount of proanthocyanidins are produced inside the plant,which can relieve the cadmium stress of the plant.In this study,by measuring the physiological indicators,antioxidant activity,changes in differential genes and differential metabolites,and the stress resistance of Arabidopsis thaliana after overexpression of key proanthocyanidin genes in different processing environments,to explore how proanthocyanidins can alleviate the cadmium stress of hemp.The main experimental results are as follows:1.Comparing the growth morphology and antioxidant activity of hemp under different treatments,the results showed that the leaves of hemp after cadmium treatment showed obvious yellowing and curling,and the roots became shorter and less.After pretreatment of exogenous proanthocyanidins,the cadmium poisoning of plants has been significantly alleviated.Pretreatment of exogenous proanthocyanidins can also significantly alleviate the decrease in SOD and GSH in hemp leaves.The results show that pretreatment of exogenous proanthocyanidins can effectively alleviate the cadmium toxicity of hemp.The results show that pretreatment of exogenous proanthocyanidins can effectively alleviate the cadmium toxicity of hemp.2.Comparing the distribution of differential genes in the transcriptome of hemp under different treatments,the results show that there are 4341 differential genes in the cadmium treatment group compared to the control group,497 differential genes in the proanthocyanidin treatment group compared to the control group,and 1102 differential genes in the proanthocyanidin pretreatment group compared to the cadmium treatment group.The functional enrichment analysis of the current differential gene functions showed that the three treatments mainly changed the gene expression in the metabolic pathways of hemp glutathione metabolism,phenylpropane organisms and photosynthesis.3.Compare the distribution of different metabolites in the metabolome of hemp under different treatments,the results show that there are 28 differential metabolites in the cadmium treatment group compared to the control group,497 differential genes in the proanthocyanidin treatment group compared to the control group,and 1102 differential genes in the proanthocyanidin pretreatment group compared to the cadmium treatment group.The enrichment analysis of the current differential metabolite function showed that the three treatments mainly changed the metabolite content in the metabolic pathways of hemp phenylalanine,vitamin metabolism and carotenoid synthesis.4.The combined analysis of differential genes and differential metabolites showed that: exogenous proanthocyanidins and cadmium ions will act on the EDS1 gene at the same time,causing plants to produce large amounts of salicylic acid.Plants use proanthocyanidins and salicylic acid to alleviate the effects of cadmium stress on plants through photosynthesis,secondary metabolite synthesis,antioxidant synthesis and other related pathways.5.Constructed Arabidopsis plants overexpressing Cs ANR and Cs LAR,the key genes of hemp proanthocyanidin synthesis,and measured the seed germination rate of different cadmium treatment concentrations,and compared the phenotypic changes of Arabidopsis thaliana under different cadmium concentrations in hydroponic culture.The results showed that the cadmium tolerance of Cs LAR transgenic plants was stronger than that of Cs ANR transgenic plants and wild-type Arabidopsis plants. |
