伴矿景天SpMTP10介导锰积累的机制OA

INTRODUCTION:Manganese(Mn)is an essential micronutrient for plant growth and primarily acts as an enzyme co-factor and participates in the redox processes.However,excessive absorption of Mn by plants can also induce toxicity damage.Therefore,plants need to tightly regulate the uptake,homeostasis,and distribution of Mn to cope with stresses caused by its deficiency or excess.In these processes,cation diffusion facilitator(CDF)family transporters,which in plants are also known as metal tolerance proteins(MTPs),have been shown to be crucial for Mn homeostasis.There-fore,identifying MTP family genes and elucidating their underlying mechanisms for Mn accumulation would provide not only novel insights into basic scientific issues of plant Mn accumulation but also gene resources for crop improvement and Mn pollution bioremediation. RATIONALE:Sedum plumbizincicola is a recently discovered Cd/Zn hyperaccumulator that grows in mining areas.The soil in its natural habitat contains more than 10 000 mg·kg-1 Mn,suggesting that S.plumbizincicola may have efficient Mn transport and detoxification capabilities.Based on the transcriptome sequencing results of S.plumbizincicola obtained previously,a member of the MTP family gene named SpMTP10 was cloned and its role in mediating Mn accumulation was investigated in this study. RESULTS:Phylogenetic analysis with orthologs from Arabidopsis and rice revealed that SpMTP10 belongs to the Mn-CDF subfamily and is most closely related to AtMTP10,AtMTP9 and OsMTP9,with the highest sequence identity of 72％to AtMTP10.SpMTP10 is mainly expressed in the roots of S.plumbizincicola and its expression level is not affected by Mn treatment.Expression of SpMTP10 in yeast can greatly enhance the tolerance of transformants to excessive Mn stress and increase Mn accumulation in transformants.However,under conditions of excessive cadmium(Cd),zinc(Zn),copper(Cu),and iron(Fe)stress,the yeast transformants exhibited no significant changes in tolerance.Subsequent subcellular localization analysis revealed that SpMTP10 was localized to the endoplasmic reticulum(ER)membrane.Compared with wild-type plants,transgenic Arabidopsis overexpressing SpMTP10 demonstrated reduced Mn accumula-tion in roots but increased Mn accumulation in shoots,rendering the plants more sensitive to excessive Mn stress. CONCLUSION:In conclusion,SpMTP10 likely enhances yeast tolerance to excessive Mn toxicity by promoting Mn sequestration in the ER.In plants,Mn transport mediated by SpMTP10 into the ER may facilitate intercellular migration of Mn in the ER lumen via plasmodesmata,thereby promoting Mn movement toward vascular tissues in roots and sub-sequent long-distance transport to shoots.