title: Overexpression of Nelumbo nucifera metallothioneins 2a and 3 enhances seed germination vigor in Arabidopsis.
abstract: Metallothioneins (MTs) are small, cysteine-rich and metal-binding proteins which are involved in metal homeostasis and scavenging of reactive oxygen species. Although plant MTs have been intensively studied, their roles in seeds remain to be clearly established. Here, we report the isolation and characterization of NnMT2a, NnMT2b and NnMT3 from sacred lotus (Nelumbo nucifera Gaertn.) and their roles in seed germination vigor. The transcripts of NnMT2a, NnMT2b and NnMT3 were highly expressed in developing and germinating sacred lotus seeds, and were dramatically up-regulated in response to high salinity, oxidative stresses and heavy metals. Analysis of transformed Arabidopsis protoplasts showed that NnMT2a-YFP and NnMT3-YFP were localized in cytoplasm and nucleoplasm. Transgenic Arabidopsis seeds overexpressing NnMT2a and NnMT3 displayed improved resistance to accelerated aging (AA) treatment, indicating their significant roles in seed germination vigor. These transgenic seeds also exhibited higher superoxide dismutase activity compared to wild-type seeds after AA treatment. In addition, we showed that NnMT2a and NnMT3 conferred improved germination ability to NaCl and methyl viologen on transgenic Arabidopsis seeds. Taken together, these data demonstrate that overexpression of NnMT2a and NnMT3 in Arabidopsis significantly enhances seed germination vigor after AA treatment and under abiotic stresses.
authors.affiliation: Guangdong Provincial Key Laboratory of Plant Resource, School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, China.
authors.forename: Yuliang
authors.initials: Y
authors.lastname: Zhou
authors.forename: Pu
authors.initials: P
authors.lastname: Chu
authors.forename: Huhui
authors.initials: H
authors.lastname: Chen
authors.forename: Yin
authors.initials: Y
authors.lastname: Li
authors.forename: Jun
authors.initials: J
authors.lastname: Liu
authors.forename: Yu
authors.initials: Y
authors.lastname: Ding
authors.forename: Edward W T
authors.initials: EW
authors.lastname: Tsang
authors.forename: Liwen
authors.initials: L
authors.lastname: Jiang
authors.forename: Keqiang
authors.initials: K
authors.lastname: Wu
authors.forename: Shangzhi
authors.initials: S
authors.lastname: Huang
mesh_terms: D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000378:metabolism* / Q000502:physiology*; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D018525:Germination / Q000235:genetics / Q000502:physiology*; D008668:Metallothionein / Q000235:genetics / Q000378:metabolism; D031653:Nelumbo / Q000235:genetics / Q000378:metabolism*; D018384:Oxidative Stress / Q000187:drug effects; D030821:Plants, Genetically Modified / Q000187:drug effects / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D012639:Seeds / Q000235:genetics / Q000378:metabolism* / Q000502:physiology*; D012965:Sodium Chloride / Q000494:pharmacology
chemical_list: D012965:Sodium Chloride; D008668:Metallothionein