The Effect And Mechanism Of Selenium In Reducing The Absorption Of Absorption Of Heavy Metal Antimony In Root System

China is the second largest producer of rice in the world,rice sowing area accounts for 1/4 of the country's food crops,and the output accounts for more than half.And now in some provinces and cities in south China where people use rice as the main food crop,But there is a problem of Sb contamination in rice.The high level of Sb in the environment can significantly affect the normal growth and yield of local crops,and at the same time lead to excessive Sb content of crops,then accumulates in the body through the food chain.Selenium is an essential nutrient element for humans,and an low amount of Se is also beneficial for plant growth.Studies have shown that a low doses of Se can reduce the content of heavy metals in plants.However,the mechanisms on why and how the addition of Se can reduce the uptake of so many heavy metals?metalloids?in different plants are unclear.Therefore,this study uses rice?Yexiangyou No.3?as the experimental material,trying to study the interaction between Se of different valence states and Sb of different forms:1)Changes in the growth and development of rice,especially the development of root system;2)Changes in the content of root cell wall components;3)Changes in the cell wall related enzyme activity of the root system;4)Changes in related antioxidant enzyme activities;5)Changes in the content of related endogenous hormones;6)Changes in element absorption.The mechanism of Se inhibiting the absorption of Sb in rice was studied from the angle of root system response.The main results obtained are as follows:?1?The effects about Se of different valence states and Sb of different forms were studied on Sb absorption and root morphological changes.In this study,under 10 mg·^L-1Sb???treatment,an additional 0.2 mg·^L-1Se???treatment reduced the number of root tips.The addition of 0.2 mg·^L-1Se???significantly redLuced root length,root area,root tips and root forks.In addition,under the above treatment,Se significantly reduced the content of Sb in rice roots,indicating that changes in rice root tip,root area and other indicators played a role in the absorption of Sb.?2?The response of endogenous hormones in the roots of rice were studied under the Se of different valence states and Sb of different forms.The result has shown that Gibberellin only plays a role in specific Se,Sb morphology.The study also found that when rice was exposed to 10 mg·L"'Sb???treatment,additional 0.8 mg·^L-1Se???treatment significantly reduced the roots content of jasmine.At the same time,the root number,root fraction,root length,and root area of rice are also reduced.We speculate that jasmine has a certain correlation with the above root index changes,which requires further experimental verification.?3?The response of cell wall components and cell-related enzyme activities in the roots of rice were studied under the under the Se of different valence states and Sb of different forms.The result has shown that different forms of Sb significantly increased the content of hemicellulose I,especially under Sb???treatment,the addition of Se in most cases significantly increased the content of pectin.At the same time,under the treatment with different valence states of Se and Sb,PME,?-gal,PG play different roles in the degradation of pectin.In most cases,the content of hemicellulose I in rice root cell walls was consistent with the inhibition of ?-gal enzyme activity.Under the different forms of Sb treatment,the addition of Se inhibited the activity of XTH in most cases.At this time,the related indicators of rice root system generally showed a tendency to be suppressed,the results indicated that the addition of Se may elongate the root cell wall and thus change the morphological characteristics of the root system.