title: Knock-down of transcript abundance of a family of Kunitz proteinase inhibitor genes in white clover (Trifolium repens) reveals a redundancy and diversity of gene function.
abstract: The transcriptional regulation of four phylogenetically distinct members of a family of Kunitz proteinase inhibitor (KPI) genes isolated from white clover (Trifolium repens; designated Tr-KPI1, Tr-KPI2, Tr-KPI4 and Tr-KPI5) has been investigated to determine their wider functional role. The four genes displayed differential transcription during seed germination, and in different tissues of the mature plant, and transcription was also ontogenetically regulated. Heterologous over-expression of Tr-KPI1, Tr-KPI2, Tr-KPI4 and Tr-KPI5 in Nicotiana tabacum retarded larval growth of the herbivore Spodoptera litura, and an increase in the transcription of the pathogenesis-related genes PR1 and PR4 was observed in the Tr-KPI1 and Tr-KPI4 over-expressing lines. RNA interference (RNAi) knock-down lines in white clover displayed significantly altered vegetative growth phenotypes with inhibition of shoot growth and a stimulation of root growth, while knock-down of Tr-KPI1, Tr-KPI2 and Tr-KPI5 transcript abundance also retarded larval growth of S. litura. Examination of these RNAi lines revealed constitutive stress-associated phenotypes as well as altered transcription of cellular signalling genes. These results reveal a functional redundancy across members of the KPI gene family. Further, the regulation of transcription of at least one member of the family, Tr-KPI2, may occupy a central role in the maintenance of a cellular homeostasis.
authors.affiliation: Institute of Fundamental Sciences, Massey University, Private Bag 11-222, Palmerston North, New Zealand.
authors.forename: Afsana
authors.initials: A
authors.lastname: Islam
authors.affiliation: Institute of Fundamental Sciences, Massey University, Private Bag 11-222, Palmerston North, New Zealand.
authors.forename: Susanna
authors.initials: S
authors.lastname: Leung
authors.affiliation: Plant & Food Research, Private Bag 92169, Auckland, 1142, New Zealand.
authors.forename: Elisabeth P J
authors.initials: EP
authors.lastname: Burgess
authors.affiliation: Plant & Food Research, Private Bag 92169, Auckland, 1142, New Zealand.
authors.forename: William A
authors.initials: WA
authors.lastname: Laing
authors.affiliation: AgResearch Grasslands, Private Bag 11-008, Palmerston North, New Zealand.
authors.forename: Kim A
authors.initials: KA
authors.lastname: Richardson
authors.affiliation: Faculty of Agriculture and Life Sciences, Lincoln University, PO Box 85084, Lincoln, 7647, New Zealand.
authors.forename: Rainer W
authors.initials: RW
authors.lastname: Hofmann
authors.affiliation: Institute of Fundamental Sciences, Massey University, Private Bag 11-222, Palmerston North, New Zealand.
authors.forename: Paul P
authors.initials: PP
authors.lastname: Dijkwel
authors.affiliation: Institute of Fundamental Sciences, Massey University, Private Bag 11-222, Palmerston North, New Zealand.
authors.forename: Michael T
authors.initials: MT
authors.lastname: McManus
mesh_terms: D000595:Amino Acid Sequence; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D008969:Molecular Sequence Data; D005810:Multigene Family; D010447:Peptide Hydrolases / Q000378:metabolism*; D010455:Peptides / Q000235:genetics* / Q000378:metabolism; D010641:Phenotype; D010802:Phylogeny; D010935:Plant Diseases / Q000235:genetics; D018515:Plant Leaves; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D018517:Plant Roots; D034622:RNA Interference; D015398:Signal Transduction; D013312:Stress, Physiological; D014026:Nicotiana / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic; D029921:Trifolium / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism
chemical_list: C053865:Kunitz-type protease inhibitor, plant; D010455:Peptides; D010940:Plant Proteins; D010447:Peptide Hydrolases
keywords: Kunitz proteinase inhibitor (KPI); RNAi gene silencing; Trifolium repens; insect herbivory; plant development; white clover