| Potato is an important food crop,and its quality and food safety are seriously affected by heavy metals.Metal tolerance proteins(MTPs)play an important roles in the transport and tolerance of divalent heavy metals in plants.In this study,11 MTP genes were identified and screened from the whole potato genome file,named StMTP1-StMTP11 according to their chromosomal locations.Specific changes in the structure of StMTP8 were found through phylogenetic analysis,gene and protein structure analysis.Then the results of q RT-PCR analysis showed that StMTP8 had root-specific expression in response to Cd stress.The StMTP8-GFP recombinant plasmid was transformed into Agrobacterium,and the tobacco leaves were infected to observe the functional position of the StMTP8.Heterologously expressed in Cd-sensitive yeast and tobacco,and analyzed the function of this gene under Cd stress.It is expected to provide an important reference for the molecular breeding of potato varieties with low Cd accumulation,and provide a two-way selection for soil remediation and environmental management of potato varieties with high Cd accumulation.The main research results are as follows:(1)The promoter of StMTP1-StMTP11 contained Cis-acting elements related to abiotic stress,such as GATA-motif,ARE,Box4,G-box,MBS,TCT-motif,etc.,which indicating that they are closely related to plant stress resistance.This gene family has11 members,which are mainly distributed in the Zn-MTP and Mn-MTP subfamilies.The protein structures of StMTPs were analyzed and the conserved residues HXXXD and DXXXD closely related to heavy metal transport were found.(2)StMTPs showed a positive response to Zn and Cd stress,and the expression levels of some genes showed a trend of leaf> stem> root,of which StMTP8 was specifically expressed in roots under Cd stress(3)The StMTP8 has high homology with At MTP1 and Os MTP1,and these two genes could increase the tolerance of plants and yeast to cadmium stress.In addition,a signal peptide evolved at the N-terminus of the StMTP8 amino acid sequence,and the appearance of this structure may alter changed the localization and function of StMTP8.(4)The StMTP8 is mainly located in the nucleus,indicating that it mainly functions in the nucleus.After the signal peptide was removed,the gene was mainly expressed in the cytoplasm,indicating that the N-terminal signal peptide might be a nuclear localization signal peptide.(5)Overexpression of StMTP8 in yeast improved yeast sensitivity to Cd and increased Cd content in yeast.Similarly,after transgenic tobacco was stressed by Cd,the damage degree of root cells was much lower than that of wild type,while the content of Cd in roots was higher than that of wild type.An analysis of their protective enzyme system found that CAT and POD activities were significantly higher than those of the wild type in transgenic plants after 100 u M Cd stress for 3d.It indicated that transgenic plants could better cope with the sudden increase of ROS caused by cadmium stress and reduce the damage to plants.In conclusion,StMTPs responded positively to heavy metal stress.The StMTP8 was characterized by root-specific expression under cadmium stress,and heterologous expression of this gene in tobacco and yeast enhanced their cadmium tolerance.StMTP8 mainly acts on the nucleus,and the N-terminally evolved signal peptide affects the subcellular localization of the protein. |
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