The Screening Of Low-Cd Accumulation Cabbage Cultivars In Yangtze River Delta Region

With the rapid development of modem society,economy,agriculture and industry,various environmental pollution caused by human activities has become a worldwide concern.And soil heavy metal pollution is becoming more and more serious,threatening human survival and health.Cadmium(Cd)is one of the important pollutants in soil heavy metal pollution.Cd is easily accumulated in plants due to the characteristics of easy absorption,low decomposition,and high toxicity.Cd accumulates in the edible parts of plants,eventually causing acute health problems in humans via the food chain.In this paper,we identified low-Cd accumulation cabbage(Brassica oleracea L.)cultivars from 30 cultivars commonly planted in the Yangtze River Delta region by performing field-culture experiments and hydroponic experiment.Then,further comparisons of Cd absorption accumulation,physiological characteristics and geng expressin were made between high-and low-Cd accumulation cultivars.The main results are as follows:(1)In the field experiments,the Cd content of the leaves of three randomly selected cultivars did not exceed the national standard-The Cd content of the new leaf is lower than that of the old leaf.Combined with the growth of cabbage in the field,the sampling position 15 determined as the sixth leaf.(2)In the two field experiments,the Cd content in shoot of the 30 cabbge cultivars was different,but the Cd content did not exceed the standard.the Mn,Fe,Cu,and Zn content among the cultivars also different.So that,we preliminarily identified hanxuezhengchun(D1),the Xifeng(D2)and the Xiyuansihao(D3)as low-Cd accumulation cabbage cultivars,Zhongganshier(G1)and hanlvsanji(G2)as high-Cd accumulation cultivars.(3)In the hydroponicexperiments,the Xifeng(D2)and Xiyuan 4(D3)maintained their low-Cd accumulation characteristics,and the cabbage cultivar Hanlvsanji(G2)maintained high-Cd accumulation characteristics.But the Hanxuezhengchun(D1)and Zhongganshier changed their Cd accumulation characteristics.Therefore,Xifeng and Xiyuansihao are stable low-Cd accumulation cabbage cultivars,and Hanlvsanji are stable Cd-accumulated cabbage cultivars.(4)In the hydroponics experiments,under the condition of low and high Cd concentration concentration,all cultivars had no significant difference in the ability to transport Cd.But at the medium Cd concentration,the TF of high-Cd accumulation cultivars was siginificantly lower than that of low-Cd accumulation cultivars,indicating that the difference of Cd accumulation between high-and low-Cd accumulation cultivars of cabbage was not related to its transport capacity,which may be related to its ability of roots to absorb Cd.(5)In the physiological experiments,Cd affects the growth of cabbage plants,inhibit plant growth even poison plants when the concentration is too high.In addition,Low-Cd accumulation cultivars had higher tolerance and lower sensitivity to Cd,while high-Cd accumulation cultivars were more sensitive to Cd and tolerated.(6)In the gene expression experiment,the expression level of Nramp3 in low-Cd accumulation cultivars was significantly higher than that in other cultivars,but the expression level of NRT1.8 only in certain low-Cd accumulation cultivars was significantly higher than other cultivars.The difference of Cd accumulation between cultivars is related to the expression of Nramp3,and the expression of NRTI.8 is related to the Cd accumulation characteristics of certain cultivars.The above results indicate that the Cd accumulation ability of different cabbage cultivars is related to the genotype and concentration of heavy metal Cd in the environment,and the sensitivity and tolerance of cabbage to Cd is related to its accumulation of Cd.In addition,the differences in Cd accumulation among the cabbage cultivars were related to the expression of genes involved in absorption and transport rather than a root-to-shoot translocation limitation.