Phosphate-dependent regulation of vacuolar trafficking of OsSPX-MFSs is critical for maintaining intracellular phosphate homeostasis in rice  

作　　者：Runze Guo Qi Zhang Kun Qian Yinghui Ying Wenying Liao Lening Gan Chuanzao Mao Yong Wang James Whelan Huixia Shou 

机构地区：[1]State Key Laboratory of Piant Physiology and Biochemistry,Cllege of Life Sciences,Zhejiang University,Hangzhou,Zhejang 310058,P.R.China [2]Hainan Institute,Zhejiang University,Sanya 572025,China [3]The Provincial International Science and Technology Cooperation Base on Engineering Biology,International Campus of Zhejiang University,Haining,Zhejang 314400,China [4]Zhijiang lab,Hangzhou 310012,China

出　　处：《Molecular Plant》2023年第8期1304-1320,共17页分子植物（英文版）

基　　金：supported by the Ministry of Science and Technology of China(2021YFF1000400,2021YFF1001204);the National Natural Science Foundation of China(317723817 qw4111 Project B14027).

摘　　要：Vacuolar storage of inorganic phosphate(Pi)is essential for Pi homeostasis in plants.The SPX-MFS family proteins have been demonstrated to be vacuolar Pi transporters in many plant species.Transcriptional regulation of the predominant transporter among rice SPX-MFSs,OsSPX-MFS3,was only moderately suppressed by Pi starvation.Thus,post-transcriptional mechanisms were hypothesized to regulate the activity of OsSPX-MFS3.In this study,we found that the tonoplast localization of OsSPX-MFSs is inhibited under Pi-depleted conditions,resulting in their retention in the pre-vacuolar compartments(PVCs).A yeast two-hybrid screen identified that two SNARE proteins,OsSYP21 and OsSYP22,interact with the MFS domain of OsSPX-MFS3.Further genetic and cytological analyses indicate that OsSYP21 and OsSYP22 facilitate trafficking of OsSPX-MFS3 from PVCs to the tonoplast.Although a homozygous frameshift mutation in OsSYP22 appeared to be lethal,tonoplast localization of OsSPX-MFS3 was significantly inhibited in transgenic plants expressing a negative-dominant form of OsSYP22(OsSYP22-ND),resulting in reduced vacuolar Pi concentrations in OsSYP22-ND plants.Under Pi-depleted conditions,the interaction between OsSYP22 and OsSPX-MFS3 was disrupted,and this process depended on the presence of the SPX domain.Deleting the SPX domains of OsSPX-MFSs resulted in their tonoplast localization under both Pi-depleted and Pi-replete conditions.Complementation of the osspx-mfs1/2/3 triple mutants with the MFS domain or the SPX domain of OsSPX-MFS3 confirmed that the MFS and SPX domains are responsive to Pi transport activity and Pi-dependent regulation,respectively.These data indicated that the SPX domains of OsSPX-MFSs sense cellular Pi(InsP)levels and,under Pi-depleted conditions,inhibit the interaction between OsSPX-MFSs and OsSYP21/22 and subsequent trafficking of OsSPX-MFSs from PVCs to the tonoplast.

关 键 词：FIR HOMEOSTASIS inhibited 

分 类 号：S511[农业科学—作物学]