The Origin And Evolution Of NTR1 Gene In Terrestrial Plants And Its Functional Analysis In Arabidopsis And Rice

2,4,6-trinitrotoluene(TNT)is an organic compound with benzene ring,which can combine with humus of soil closely and reduce the ability of plants to absorb nutrients.It is listed as an important pollutant in soil.In addition,TNT has strong toxicity and is listed as an important carcinogen by Environmental Protection Agency(EPA).The most effective way to control TNT in soil is phytoremediation.However,at present,phytoremediation of TNT is limited to cloning the nitroreductase gene of bacteria into plants for heterologous expression.In this paper,we found that there is also a nitroreductase gene NTR1 in plants.However,the origin and evolution model of NTR1 gene in plants are not clear,and its role in plants is not clear.In this study,we used the methods of bioinformatics and experimental biology to analyze the origin and evolution of nitroreductase gene(NTR1)in terrestrial plants,the tissue expression and abiotic stress expression patterns of NTR1 gene in Rice and Arabidopsis,and further constructed transgenic plants of Rice and Arabidopsis,which regulated the tolerance of Rice and Arabidopsis to TNT It is analyzed.The main results are as follows:(1)NTR1 gene widely exists in terrestrial plants,but there is no highly homologous gene in the ancestral species of terrestrial plants,green algae and other eukaryotes.Phylogenetic analysis shows that NTR1 gene is the ancestral species of terrestrial plants through a horizontal gene transfer The transfer(HGT)event was obtained from bacteria,and its potential donor was verruco microbia.(2)Adaptive evolution analysis showed that the NTR1 gene of terrestrial plants experienced significant positive selection pressure in the initial stage after the horizontal transfer event;and after the differentiation of major terrestrial plants,the main selection pressure was purification selection,which indicated that the NTR1 gene of terrestrial plants experienced functional adaptive evolution after horizontal transfer.(3)The results of expression pattern analysis showed that the gene was induced by abiotic stresses such as high temperature,low temperature,drought and salt damage in Rice and Arabidopsis,and was induced by plant hormones ABA and GA,indicating that the NTR1 gene of terrestrial plants might be related to stress.(4)Through the TNT tolerance analysis of Arabidopsis and Rice transgenic materials,it was found that compared with wild type,the root length and leaf surface area of Arabidopsis overexpression materials were significantly increased,while the root length and leaf surface area of RNAi materials were significantly reduced;the root length of rice overexpression materials was significantly longer than the control,while the mutant materials were significantly lower than the control,indicating that the gene was related to TNT toleranceIn this paper,the origin and evolution model of nitroreductase gene NTR1 in terrestrial plants were explained,and it was found that NTR1 gene was related to TNT tolerance in Arabidopsis and Rice,respectively.The results not only have important theoretical value to reveal the genetic basis of the origin of stress resistance of terrestrial plants,but also have guiding significance for the purpose of using plant genes for soil phytoremediation.