Effect Of Exogenous Salicylic Acid On Copper Tolerance Of Yunma No.1

Industrial hemp is one of the important natural fiber crops in my country.Heilongjiang,Yunnan,Shanxi,Anhui,etc.are the main planting areas of industrial hemp.These provinces are rich in copper mines,and there is a risk of copper tailings pollution in the cultivated soil;industrial hemp has strong resistance to Copper and higher biomass can replace food crops on copper-contaminated soils,but high concentrations of copper affect the growth and development of industrial hemp.It is of great significance to explore how to enhance copper tolerance.Salicylic acid（SA）can improve the stress resistance of crops.In this study,the copper-sensitive variety Yunma No.1（the first industrial hemp variety bred in my country）was used to explore the effects of exogenous SA seed soaking on the germination of industrial hemp seeds under copper stress,and the effects of exogenous SA spraying on the seedling and full growth stages of industrial hemp.The effects of growth and copper enrichment;determination of germination-related indicators,photosynthesis indicators,antioxidant enzyme activities,copper content in various parts,etc.to analyze the physiological and molecular mechanisms of copper tolerance in industrial hemp under copper stress and the effect of SA treatment on alleviating copper stress,conducted transcriptomic and resistance gene screening,selected and cloned the related genes of copper tolerance in industrial hemp,and provided a theoretical basis for the cultivation and breeding of industrial hemp to improve copper tolerance under copper stress.The main findings are as follows:1.Copper stress has obvious toxic effects on various growth stages of industrial hemp.Copper stress impairs the normal nutrient absorption function through root toxicity,causing slow growth of the whole plant and destroying the normal reactive oxygen species scavenging system of industrial hemp;transcriptome sequencing shows that copper Under stress,the pyrophosphatase activity of industrial hemp decreased,inhibiting the transport and metabolism of phosphorus;industrial hemp resisted copper stress by changing the content and composition of lignin,affecting the solidification and transport of Cu²⁺.2.Exogenous SA can alleviate the toxicity of copper（the optimal concentration is 300μmol/L）.Exogenous SA can significantly improve the metabolism of hemicellulose and xyloglucan and the activity of glucosidase in industrial hemp under copper stress,and regulate the cell wall polysaccharide.The content enhanced the absorption and fixation of Cu²⁺by the cell wall;exogenous SA significantly affected the fructose bisphosphate aldolase activity,carbon fixation in photosynthesis,and carotenoid biosynthesis pathway of industrial hemp under copper stress;transcriptome sequencing showed that exogenous SA significantly enhanced the oxidoreductase activity of industrial hemp under copper stress,regulated the absorption and transport of Cu²⁺,enhanced the detoxification of Cu²⁺,and inhibited the toxicity of copper.3.In the rapid growth period of industrial hemp,foliar spraying of 300μmol/L SA can significantly alleviate copper toxicity,and the enrichment of copper in crops is the best.Exogenous SA treatment inhibits the transport of Cu²⁺from underground to shoot to a certain extent and enhances the absorption and fixation capacity of roots to copper in the soil.Spraying SA in the rapid growth period brings greater biomass to industrial hemp.Under this treatment,The copper accumulation amount was the largest（653.11μg/plant）,and the enrichment ability was the strongest;in addition,the fiber copper content of the fibers treated with SA spraying in the rapid growth period was the lowest.4.The Cs CIPK25,Cs PGIP,Cs WRKY32（Gen Bank accession:ON045129）genes of industrial hemp were cloned,and exogenous SA administration under copper stress can specifically induce the expression of Cs CIPK25 and Cs WRKY32,and regulate ion transport,copper absorption,and immobilization,metal chelate synthesis,and other pathways Enhanced copper tolerance;Cs PGIP did not show the ability to enhance tolerance,but the gene was sensitive to Cu²⁺in the environment.As a copper-sensitive response gene,the expression level indicated the degree of copper stress.