Accumulation Capacity And Tolerance Mechanism Of Different Species Of Solanum Nigrum L.Exposed To Cadmium

Cadmium is one of the most toxic heavy metals in the environment.Once it enters the human body through the food chain,it will cause serious irreversible damage.Phytoremediation is simple and easy to operate,and the cost is low,which is conducive to maintaining the soil's ecological environment system.Solanum nigrum L.is a discovered cadmium-tolerant plant.However,the physiological and biochemical properties of different species of Solanum nigrum L.are different,and its ability to repair cadmium pollution needs further research.We explored the tolerance and enrichment characteristics of Solanum nigrum L.through hydroponic experiments.The findings are as follows:Tolerance to Cd stress of the three Solanum nigrum L.decreased with the increase of Cd concentration and the increase of Cd treatment time.Tolerance of Solanum nigrum L.under 14 days Cd treatment was HZ>JL>GD.Chlorophyll content of three Solanum nigrum L.decreased with the increase of Cd concentration,and chlorophyll content affected by Cd showed that GD>JL>HZ.Under different Cd treatments,the SOD activities of the roots and leaves of the three Solanum nigrum L.were HZ>JL>GD,the POD activities in the roots were HZ>GD>JL,and the POD activities in the leaves were GD>HZ>JL.CAT activities in roots were JL>HZ>GD,and CAT activities in leaves were HZ>JL>GD.The strength of the membrane lipid peroxidation under Low-level cadmium stress(<10 mg·L-1)of three Solanum nigrum L.were JL>HZ>GD,and under high-level cadmium stress(>50 mg·L-1)were JL>GD>HZ.From the perspective of biomass index,chlorophyll content,antioxidant enzyme activity,and MDA content,HZ is more resistant to cadmium.Under different Cd treatments,the Cd content in different parts of different Solanum nigrum L.increased with the increase of Cd concentration and time(except for individual data of leaves).Under the same Cd treatment,Cd contents in roots,stems,leaves and fruits of Solanum nigrum L.were root>stem>leaf>fruit.Among them,14 days of Cd stress,Cd contents of the roots,stems,and leaves of Solanum nigrum L.reached their maximum values when the Cd treatment concentration was 100 mg·L-q(20 mg·L-1 of JL leaves):16417.86 mg·kg-1,5102.10 mg·kg-1 and 1311.81 mg·kg-1 for JL,20537.35 mg·kg-1,10856.63 mg·kg-1 and 3909.98 mg·kg-1 for HZ,and 7037.86 mg·kg-1,2892.09 mg·kg-1 and 495.74 mg·kg-1 for GD.With the increase of Cd treatment concentration and time,Above-ground and below-ground Cd accumulation(except for individual data)basically showed a rising trend.The above-ground and below-ground Cd accumulation reached the maximum when the Cd treatment concentration was 100 mg·L-1:521.49 ?g and 1181.22 ?g for JL,1640.59 ?g and 710.50 ?g for HZ,and 284.34 ?g and 258.87 ?g for GD.When Cd treatment performed for 14 days,the response of Solanum nigrum L.to heavy metals changed steadily.The above-ground enrichment capacity of JL continued to decrease with the increase in Cd concentration.When Cd treatment was 5 mg·L-1,the enrichment coefficient was 78.95,when the Cd treatment was 100 mg·L-1,the enrichment coefficient is 13.08,and the above-ground enrichment coefficient of HZ was higher than JL,and the maximum was 131.47 of 5 mg·L-1.Although the enrichment coefficient has been decreasing,it was still higher than that of JL at high concentrations.When the Cd treatment was 100 mg·L-1,the enrichment coefficient was 42.99.Compared with JL and HZ,the enrichment coefficient of GD has always been low,while the concentration transfer coefficients of HZ and JL are also higher than that of GD,and it was clearly found that the total transfer coefficient of HZ is much larger than that of JL and GD.In summary,the enrichment ability and transferability of Solanum nigrum L.treated with Cd for 14 days were HZ>JL>GD.The subcellular components were separated by differential centrifugation,and it was found that the distribution ratio of Cd in the three types of Solanum nigrum L.subcells was different.When the concentration was high,the distribution ratio of Cd in the organelles of HZ was the smallest.Organic acids were analyzed by reversed-phase high-performance liquid chromatography,and the contents of 5 organic acids in 3 kinds of Solanum nigrum L.were basically stable,namely citric acid>tartaric acid>acetic acid>malic acid>oxalic acid.Under each cadmium stress,the content of citric acid in the leaves of JL,the content of tartaric acid in HZ and the content of citric acid in GD were significantly induced.Using the NMT technique to measure the cadmium flux in meristematic zone of the root of Solanum nigrum L..,it was found that at the same Cd treatment concentration the Cd flux of different varieties of Solanum nigrum L.is different,the basic law is HZ>JL>GD,and as the concentration of Cd treatment increased,the Cd flux of the same Solanum nigrum L.increased first and then decreased.In general,HZ seedlings absorbed cadmium better than the other two Solanum nigrum L..