title: Identification and functional characterization of HbOsmotin from Hevea brasiliensis.
abstract: Latex in the laticiferous cell network of Hevea brasiliensis tree is composed of cytoplasm that synthesizes natural rubber. Ethylene stimulation of the tree bark enhances latex production partly by prolonging the duration of latex flow during the tapping process. Here, we identified an osmotin-like cDNA sequence (HbOsmotin) from H. brasiliensis that belongs to the pathogenesis-related 5 (PR-5) gene family. The HbOsmotin protein is present in the lutoids of latex in H. brasiliensis, whereas in onion epidermal cells, this protein is predominantly distributed around the cell wall, suggesting that it may be secreted from the cytoplasm. We investigated the effects of exogenous ethylene on HbOsmotin transcription and protein accumulation in rubber latex, and further determined the protein function after osmotic stress in Arabidopsis. In regularly tapped trees, HbOsmotin expression was drastically inhibited in rubber latex after tapping, although the expression was subsequently recovered by ethylene stimulation. However, in virgin plants that had never been tapped, exogenous ethylene application slightly decreased HbOsmotin expression. HbOsmotin overexpression in Arabidopsis showed that HbOsmotin reduced the osmotic stress tolerance of the plant, which likely occurred by raising the water potential. These data indicated that HbOsmotin may contribute to osmotic regulation in laticiferous cells.
authors.affiliation: Institute of Tropical Biosciences and Biotechnology, Chinese Academy of Tropical Agricultural Sciences, Haikou, Hainan 571101, China.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Tong
authors.affiliation: Institute of Tropical Biosciences and Biotechnology, Chinese Academy of Tropical Agricultural Sciences, Haikou, Hainan 571101, China.
authors.forename: Yong
authors.initials: Y
authors.lastname: Sun
authors.affiliation: Institute of Tropical Biosciences and Biotechnology, Chinese Academy of Tropical Agricultural Sciences, Haikou, Hainan 571101, China.
authors.forename: Dan
authors.initials: D
authors.lastname: Wang
authors.affiliation: Institute of Tropical Biosciences and Biotechnology, Chinese Academy of Tropical Agricultural Sciences, Haikou, Hainan 571101, China.
authors.forename: Limin
authors.initials: L
authors.lastname: Wang
authors.affiliation: Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA 50011, USA.
authors.forename: Ling
authors.initials: L
authors.lastname: Li
authors.affiliation: Institute of Tropical Biosciences and Biotechnology, Chinese Academy of Tropical Agricultural Sciences, Haikou, Hainan 571101, China.
authors.forename: Xueru
authors.initials: X
authors.lastname: Meng
authors.affiliation: Institute of Tropical Biosciences and Biotechnology, Chinese Academy of Tropical Agricultural Sciences, Haikou, Hainan 571101, China; College of Agriculture, Hainan University, Haikou, Hainan 570228, China.
authors.forename: Weiqiang
authors.initials: W
authors.lastname: Feng
authors.affiliation: Center for Metabolic Biology, Iowa State University, Ames, IA 50011, USA.
authors.forename: Eve Syrkin
authors.initials: ES
authors.lastname: Wurtele
authors.affiliation: Institute of Tropical Biosciences and Biotechnology, Chinese Academy of Tropical Agricultural Sciences, Haikou, Hainan 571101, China; College of Agriculture, Hainan University, Haikou, Hainan 570228, China; Department of Genetics, Development and Cell Biology, Iowa State University, Ames, IA 50011, USA. Electronic address: xchwanghainan@163.com.
authors.forename: Xuchu
authors.initials: X
authors.lastname: Wang
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism; D015153:Blotting, Western; D003001:Cloning, Molecular; D005030:Ethylenes / Q000494:pharmacology; D018506:Gene Expression Regulation, Plant / Q000187:drug effects / Q000235:genetics*; D028482:Hevea / Q000235:genetics* / Q000378:metabolism; D018613:Microscopy, Confocal; D009997:Osmotic Pressure; D010802:Phylogeny; D010937:Plant Growth Regulators / Q000494:pharmacology; D010940:Plant Proteins / Q000145:classification / Q000235:genetics* / Q000378:metabolism; D030821:Plants, Genetically Modified; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012408:Rubber / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D014158:Transcription, Genetic / Q000187:drug effects / Q000235:genetics*
chemical_list: D005030:Ethylenes; D010937:Plant Growth Regulators; D010940:Plant Proteins; D012408:Rubber; C036216:ethylene
keywords: Ethylene; Hevea brasiliensis; Laticifer cell; Osmotic regulation; Osmotin; Rubber latex