Arabidopsis Synaptotagmin 2 Participates in Pollen Germination and Tube Growth and Is Delivered to Plasma Membrane via Conventional Secretion  

作　　者：Hui Wang Shengcheng Han Wei Siao Chunqing Song Yun Xiang Xiaorong Wu Pengyu Cheng Hongjuan Li JAn Jasik Karol Micieta JAn Turna Boris Voigtt Frantisek Baluska Jin Liu Yingdian Wang Heping Zhao 

机构地区：[1]Beijing Key Laboratory of Gene Resource and Molecular Development, College of Life Science, Beijing Normal University, Beijing 100875, China [2]Department of Plant Cell Biology, IZMB, University of Bonn, Kirschallee 1,53115 Bonn, Germany [3]School of Life Science, Lanzhou University, Lanzhou 730000, China [4]Comenius University Science Park, Comenius University, Bratislava, Mlynska dolina, 842 15 Bratislava 4, Slovakia [5]Department of Botany, Faculty of Natural Sciences, Comenius University, Revova 39, 811 02 Bratislava 1, SIovakia [6]Department of Botany, Faculty of Natural Sciences, Comenius University, Revova 39, 811 02 Bratislava 1, Slovakia [7]Institute of Botany, Slovak Academy of Sciences, Dubravska cesta 9, SK-84523 Bratislava, Slovak Republic [8]These authors contributed equally to this article. [9]present address: Office of Teaching Affairs, Handan University, Handan 056005, China

出　　处：《Molecular Plant》2015年第12期1737-1750,共14页分子植物（英文版）

摘　　要：Arabidopsis synaptotagmin 2 （SYT2） has been reported to participate in an unconventional secretory pathway in somatic cells. Our results showed that SYT2 was expressed mainly in the pollen ofArabidopsis thaliana. The pollen of syt2 T-DNA and RNA interference mutant lines exhibited reduced total germination and impeded pollen tube growth. Analysis of the expression of SYT2-GFP fusion protein in the pollen tube indicates that SYT2 was localized to distinct, patchy compartments but could co-localize with the Golgi markers, BODIPY TR C5 ceramide and GmManl-mCherry. However, SYT2-DsRed-E5 was localized to the plasma membrane in Arabidopsis suspension cells, in addition to the Golgi apparatus. The localization of SYT2 at the plasma membrane was further supported by immunofluorescence staining in pollen tubes. Moreover, brefeldin A treatment inhibited the transport of SYT2 to the plasma membrane and caused SYT2 to aggregate and form enlarged compartments. Truncation of the SYT2-C2AB domains also resulted in retention of SYT2 in the Golgi apparatus. An in vitro phospholipid-binding assay showed that SYT2-C2AB domains bind to the phospholipid membrane in a calcium-dependent manner. Take together, our results indicated that SYT2 was required for pollen germination and pollen tube growth, and was involved in conventional exocytosis.Arabidopsis synaptotagmin 2 （SYT2） has been reported to participate in an unconventional secretory pathway in somatic cells. Our results showed that SYT2 was expressed mainly in the pollen ofArabidopsis thaliana. The pollen of syt2 T-DNA and RNA interference mutant lines exhibited reduced total germination and impeded pollen tube growth. Analysis of the expression of SYT2-GFP fusion protein in the pollen tube indicates that SYT2 was localized to distinct, patchy compartments but could co-localize with the Golgi markers, BODIPY TR C5 ceramide and GmManl-mCherry. However, SYT2-DsRed-E5 was localized to the plasma membrane in Arabidopsis suspension cells, in addition to the Golgi apparatus. The localization of SYT2 at the plasma membrane was further supported by immunofluorescence staining in pollen tubes. Moreover, brefeldin A treatment inhibited the transport of SYT2 to the plasma membrane and caused SYT2 to aggregate and form enlarged compartments. Truncation of the SYT2-C2AB domains also resulted in retention of SYT2 in the Golgi apparatus. An in vitro phospholipid-binding assay showed that SYT2-C2AB domains bind to the phospholipid membrane in a calcium-dependent manner. Take together, our results indicated that SYT2 was required for pollen germination and pollen tube growth, and was involved in conventional exocytosis.

关 键 词：SYNAPTOTAGMINS pollen germination calcium-dependent phospholipid binding C2 domains conventional secretion 

分 类 号：U469.11[机械工程—车辆工程] X53[交通运输工程—载运工具运用工程]