title: Tobacco NtLTP1, a glandular-specific lipid transfer protein, is required for lipid secretion from glandular trichomes.
abstract: Glandular trichomes are the phytochemical factories of plants, and they secrete a wide range of commercially important natural products such as lipids, terpenes and flavonoids. Herein, we report that the Nicotiana tabacum LTP1 (NtLTP1) gene, which is specifically expressed in long glandular trichomes, plays a role in lipid secretion from trichome heads. NtLTP1 mRNA is abundantly transcribed in trichomes, but NtLTP3, NtLTP4 and NtLTP5 are not. In situ hybridization revealed that NtLTP1 mRNAs accumulate specifically in long trichomes and not in short trichomes or epidermal cells. X-gluc staining of leaves from a transgenic plant expressing the NtLTP1 promoter fused to a GUS gene revealed that NtLTP1 protein accumulated preferentially on the tops of long glandular trichomes. GFP fluorescence from transgenic tobacco plants expressing an NtLTP1-GFP fusion protein was localized at the periphery of cells and in the excreted liquid droplets from the glandular trichome heads. In vitro assays using a fluorescent 2-p-toluidinonaphthalene-6-sulfonate probe indicated that recombinant NtLTP1 had lipid-binding activity. The overexpression of NtLTP1 in transgenic tobacco plants resulted in the increased secretion of trichome exudates, including epicuticular wax. In transgenic NtLTP1-RNAi lines, liquid secretion from trichomes was strongly reduced, but epicuticular wax secretion was not altered. Moreover, transgenic tobacco plants overexpressing NtLTP1 showed increased protection against aphids. Taken together, these data suggest that NtLTP1 is abundantly expressed in long glandular trichomes, and may play a role in lipid secretion from long glandular trichomes.
authors.affiliation: Department of Forest Resources, College of Forest and Environmental Sciences, Kangwon National University, Chunchon 200-701, Korea. yechoi@kangwon.ac.kr
authors.forename: Yong Eui
authors.initials: YE
authors.lastname: Choi
authors.forename: Soon
authors.initials: S
authors.lastname: Lim
authors.forename: Hyun-Jung
authors.initials: HJ
authors.lastname: Kim
authors.forename: Jung Yeon
authors.initials: JY
authors.lastname: Han
authors.forename: Mi-Hyun
authors.initials: MH
authors.lastname: Lee
authors.forename: Yanyan
authors.initials: Y
authors.lastname: Yang
authors.forename: Ji-Ah
authors.initials: JA
authors.lastname: Kim
authors.forename: Yun-Soo
authors.initials: YS
authors.lastname: Kim
mesh_terms: D000818:Animals; D001042:Aphids / Q000502:physiology; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D018076:DNA, Complementary / Q000235:genetics; D060467:Disease Resistance / Q000235:genetics; D018506:Gene Expression Regulation, Plant / Q000235:genetics*; D050356:Lipid Metabolism; D008969:Molecular Sequence Data; D009928:Organ Specificity; D019441:Plant Epidermis / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D053147:Plant Exudates / Q000378:metabolism; D018515:Plant Leaves / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D018520:Plant Shoots / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure; D030821:Plants, Genetically Modified; D011401:Promoter Regions, Genetic / Q000235:genetics; D018749:RNA, Plant / Q000235:genetics; D011993:Recombinant Fusion Proteins; D014026:Nicotiana / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D014885:Waxes / Q000378:metabolism
chemical_list: D002352:Carrier Proteins; D018076:DNA, Complementary; D053147:Plant Exudates; D010940:Plant Proteins; D018749:RNA, Plant; D011993:Recombinant Fusion Proteins; D014885:Waxes; C030363:lipid transfer protein