重金属镉是自然界广泛存在的一种环境污染物.镉离子可对动植物产生巨大的毒害作用,它通过食物链在人体内富集,最终严重威胁人类健康.在植物中,多药及毒素化合物外排蛋白(Multidrug and Toxic Compound Extrusion,MATE)可能参与包括铁(Fe...重金属镉是自然界广泛存在的一种环境污染物.镉离子可对动植物产生巨大的毒害作用,它通过食物链在人体内富集,最终严重威胁人类健康.在植物中,多药及毒素化合物外排蛋白(Multidrug and Toxic Compound Extrusion,MATE)可能参与包括铁(Fe^2+)、锌(Zn^2+)、铝(Al^3+)以及镉(Cd^2+)在内的金属离子的运输.实验室利用反向遗传学手段研究发现,拟南芥MATE转运蛋白DTX6(Detoxification 6)具有转运镉离子的能力,基因敲除突变体表现出对镉离子的抗性,在酵母中过表达DTX6使得酵母对镉离子极为敏感,而在拟南芥中过表达DTX6则抗镉表型不明显.进一步发现DTX6主要在根和下胚轴中表达,在酵母和拟南芥原生质体中,DTX6蛋白均定位于点状的囊泡结构中,与高尔基体存在共定位,据此我们推断DTX6可能参与镉离子在胞内的运输.展开更多
Paraquat is one of the most widely used nonselective herbicides and has elicited the emergence of para-quat-resistant weeds.However,the molecular mechanisms of paraquat resistance are not completely un-derstood.Here w...Paraquat is one of the most widely used nonselective herbicides and has elicited the emergence of para-quat-resistant weeds.However,the molecular mechanisms of paraquat resistance are not completely un-derstood.Here we report the Arabidopsis gain-of-function mutant pqt15-D with significantly enhanced resistance to paraquat and the corresponding gene PQT15,which encodes the Multidrug and Toxic Extru-sion(MATE)transporter DTX6.A point mutation at+932 bp in DTX6 causes a G311E amino acid substitution,enhancing the paraquat resistance ofpqt15-D,and overexpression of DTX6/PQT15 in the wild-type plants also results in strong paraquat resistance.Moreover,heterologous expression of DTX6 and DTX6-D in Es-cherichia coil significantly enhances bacterial resistance to paraquat.Importantly,overexpression of DTX6-D enables Arabidopsis plants to tolerate 4 mM paraquat,a near-commercial application level.DTX6/PQT15 is localized in the plasma membrane and endomembrane,and functions as a paraquat efflux transporter as demonstrated by paraquat efflux assays with isolated protoplasts and bacterial cells.Taken together,our results demonstrate that DTX6/PQT15 is an efflux transporter that confers paraquat resis-tance by exporting paraquat out of the cytosol.These findings reveal a molecular mechanism of paraquat resistance in higher plants and provide a promising candidate gene for engineering paraquat-resistant crops.展开更多
In modern agriculture,frequent application of herbicides may induce the evolution of resistance in plants,but the mechanisms underlying herbicide resistance remain largely unexplored.Here,we report the char-acterizati...In modern agriculture,frequent application of herbicides may induce the evolution of resistance in plants,but the mechanisms underlying herbicide resistance remain largely unexplored.Here,we report the char-acterization of rtp 1(resistant to paraquat 1),an Arabidopsis mutant showing strong resistance to the widely used herbicides paraquat and diquat.The rtp1 mutant is semi-dominant and carries a point mutation in the gene encoding the multidrug and toxic compound extrusion family protein DTX6,leading to the change of glycine to glutamic acid at residue 311(G311E).The wild-type DTX6 with glycine 311 conferred weak para-quat and diquat resistance when overexpressed,while mutation of glycine 311 to a negatively charged amino acid(G311E or G311D)markedly increased the paraquat and diquat resistance of plants,whereas mutation to a positively charged amino acid(G311R or G311K)compromised the resistance,suggesting that the charge property of residue 311 of DTX6 is critical for the paraquat and diquat resistance of Arabi-dopsis plants.DTX6 is localized in the endomembrane trafficking system and may undergo the endosomal sorting to localize to the vacuole and plasma membrane.Treatment with the V-ATPase inhibitor ConA reduced the paraquat resistance of the rtp1 mutant.Paraquat release and uptake assays demonstrated that DTX6 is involved in both exocytosis and vacuolar sequestration of paraquat.DTX6 and DTX5 show functional redundancy as the dtx5 dtx6 double mutant but not the dtx6 single mutant plants were more sen-sitive to paraquat and diquat than the wild-type plants.Collectively,our work reveals a potential mecha-nism for the evolution of herbicide resistance in weeds and provides a promising gene for the manipulation of plant herbicide resistance.展开更多
基金supported by grants from the National Natural Science Foundation of China(grant no.31770273).
文摘Paraquat is one of the most widely used nonselective herbicides and has elicited the emergence of para-quat-resistant weeds.However,the molecular mechanisms of paraquat resistance are not completely un-derstood.Here we report the Arabidopsis gain-of-function mutant pqt15-D with significantly enhanced resistance to paraquat and the corresponding gene PQT15,which encodes the Multidrug and Toxic Extru-sion(MATE)transporter DTX6.A point mutation at+932 bp in DTX6 causes a G311E amino acid substitution,enhancing the paraquat resistance ofpqt15-D,and overexpression of DTX6/PQT15 in the wild-type plants also results in strong paraquat resistance.Moreover,heterologous expression of DTX6 and DTX6-D in Es-cherichia coil significantly enhances bacterial resistance to paraquat.Importantly,overexpression of DTX6-D enables Arabidopsis plants to tolerate 4 mM paraquat,a near-commercial application level.DTX6/PQT15 is localized in the plasma membrane and endomembrane,and functions as a paraquat efflux transporter as demonstrated by paraquat efflux assays with isolated protoplasts and bacterial cells.Taken together,our results demonstrate that DTX6/PQT15 is an efflux transporter that confers paraquat resis-tance by exporting paraquat out of the cytosol.These findings reveal a molecular mechanism of paraquat resistance in higher plants and provide a promising candidate gene for engineering paraquat-resistant crops.
基金supported by the Shanghai Science and Technology Innovation Action Plan 18JC1411800the National Natural Science Foundation of China(grant nos.31770274 and 31970343).
文摘In modern agriculture,frequent application of herbicides may induce the evolution of resistance in plants,but the mechanisms underlying herbicide resistance remain largely unexplored.Here,we report the char-acterization of rtp 1(resistant to paraquat 1),an Arabidopsis mutant showing strong resistance to the widely used herbicides paraquat and diquat.The rtp1 mutant is semi-dominant and carries a point mutation in the gene encoding the multidrug and toxic compound extrusion family protein DTX6,leading to the change of glycine to glutamic acid at residue 311(G311E).The wild-type DTX6 with glycine 311 conferred weak para-quat and diquat resistance when overexpressed,while mutation of glycine 311 to a negatively charged amino acid(G311E or G311D)markedly increased the paraquat and diquat resistance of plants,whereas mutation to a positively charged amino acid(G311R or G311K)compromised the resistance,suggesting that the charge property of residue 311 of DTX6 is critical for the paraquat and diquat resistance of Arabi-dopsis plants.DTX6 is localized in the endomembrane trafficking system and may undergo the endosomal sorting to localize to the vacuole and plasma membrane.Treatment with the V-ATPase inhibitor ConA reduced the paraquat resistance of the rtp1 mutant.Paraquat release and uptake assays demonstrated that DTX6 is involved in both exocytosis and vacuolar sequestration of paraquat.DTX6 and DTX5 show functional redundancy as the dtx5 dtx6 double mutant but not the dtx6 single mutant plants were more sen-sitive to paraquat and diquat than the wild-type plants.Collectively,our work reveals a potential mecha-nism for the evolution of herbicide resistance in weeds and provides a promising gene for the manipulation of plant herbicide resistance.
