title: Molecular cloning and characterization of three isoprenyl diphosphate synthase genes from alfalfa.
abstract: Isoprenoid is the precursor for the biosynthesis of saponins, abscisic acid, gibberellins, chlorophylls and many other products in plants. Saponins are an important group of bioactive plant natural products. The alfalfa (Medicago sativa L.) saponins are glycosides of different triterpene aglycones and possess many biological activities. We isolated three genes (MsFPPS, MsGPPS and MsGGPPS) encoding isoprenyl diphosphate synthases (IDS) from alfalfa via a homology-based PCR approach. The enzyme activity assay of purified recombined MsFPPS and MsGGPPS expressed in Escherichia coli indicated that they all had IDS activity. Expression analysis of the three genes in different alfalfa tissues using real time PCR displayed that they were expressed in all tissues although they had a different expression patterns. MsFPPS and MsGPS displayed a significant increase in transcript level in response to methyl jasmonate, but the transcript level of MsGGPPS decreased obviously. To elucidate the functions of the three IDSs, their overexpression driven by a constitutive cauliflower mosaic virus-35S promoter in tobacco plants was applied and analyzed. The T(0) transgenic plants of MsFPPS showed high levels of squalene content when compared with control. However, no differences were detected in T(0) transgenic plants of MsGPPS and MsGGPPS. In addition, the overexpression of MsFPPS induced senescence response in transgenic plant leaves. This result may indicate that MsFPPS performs a role not only in phytosterol and triterpene biosynthesis, but also in growth regulation.
authors.affiliation: College of Animal Science and Technology, China Agriculture University, Beijing, 100193, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Sun
authors.forename: Ruicai
authors.initials: R
authors.lastname: Long
authors.forename: Junmei
authors.initials: J
authors.lastname: Kang
authors.forename: Tiejun
authors.initials: T
authors.lastname: Zhang
authors.forename: Ze
authors.initials: Z
authors.lastname: Zhang
authors.forename: He
authors.initials: H
authors.lastname: Zhou
authors.forename: Qingchuan
authors.initials: Q
authors.lastname: Yang
mesh_terms: D000085:Acetates / Q000494:pharmacology; D003517:Cyclopentanes / Q000494:pharmacology; D004926:Escherichia coli; D015870:Gene Expression; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D051228:Geranyltranstransferase / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics*; D000455:Medicago sativa / Q000201:enzymology* / Q000235:genetics; D009928:Organ Specificity; D054883:Oxylipins / Q000494:pharmacology; D010802:Phylogeny; D010937:Plant Growth Regulators / Q000494:pharmacology; D018515:Plant Leaves / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D010940:Plant Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics*; D030821:Plants, Genetically Modified / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D011106:Polyisoprenyl Phosphates / Q000737:chemistry; D060888:Real-Time Polymerase Chain Reaction; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics; D013185:Squalene / Q000378:metabolism; D014026:Nicotiana / Q000235:genetics / Q000254:growth & development / Q000378:metabolism
chemical_list: D000085:Acetates; D003517:Cyclopentanes; D054883:Oxylipins; D010937:Plant Growth Regulators; D010940:Plant Proteins; D011106:Polyisoprenyl Phosphates; D011994:Recombinant Proteins; D013185:Squalene; C072239:methyl jasmonate; D051228:Geranyltranstransferase