title: The PSI family of nuclear proteins is required for growth in arabidopsis.
abstract: PSI1 was identified as a gene that is co-expressed with the phytosulfokine (PSK) receptor genes PSKR1 and PSKR2 in Arabidopsis thaliana. It represents a plant-specific protein family of unknown function with six members in two clades. Clade 1 members PSI1, PSI2 and PSI3 were characterized in this study. All three are nuclear localized. A predicted N-terminal myristoylation site was functionally analyzed. psi1-1 seedlings have shorter roots and hypocotyls. This growth-retarded phenotype was restored by expression of either wildtype PSI1 or PSI1 G2A with a mutated myristate attachment site in the psi1-1 background suggesting that myristate attachment was not essential for PSI1 function. psi2-1 and psi3-1 seedlings have a wildtype phenotype but overexpression of PSI1 or PSI2 promoted seedling growth. PSI2 activity appears to be linked to PSK signaling as psi2-1 and psi2-1 psi3-1 roots are unresponsive to PSK. PSI3 functions in vegetative plant growth synergistic with PSI2. psi3-1 and particularly psi2-1 psi3-1 rosettes are small. Overexpression of PSI3 promoted plant growth indicating that PSI3 is limiting at the vegetative stage. Severe dwarfism of psi2-1 psi3-1 plants results from reduced cell growth and proliferation and premature leaf growth arrest. Plants further display reduced fertility and premature senescence revealing a crucial function of PSI proteins in vegetative growth and reproduction. Psi single and double knock-out plants have less and PSI3ox plants have more starch compared to wt and growth retardation is partially rescued by sucrose. Our studies reveal a crucial function of the nuclear-localized PSI proteins in growth possibly through metabolic control.
authors: Plant Developmental Biology and Plant Physiology, University of Kiel, Am Botanischen Garten 5, 24118, Kiel, Germany.
authors: Nils
authors: N
authors: Stührwohldt
authors: Jens
authors: J
authors: Hartmann
authors: Renate I
authors: RI
authors: Dahlke
authors: Claudia
authors: C
authors: Oecking
authors: Margret
authors: M
authors: Sauter
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D002467:Cell Nucleus / Q000378:metabolism; D003001:Cloning, Molecular; D004843:Epistasis, Genetic; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D055786:Gene Knockout Techniques; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D015398:Signal Transduction; D013045:Species Specificity; D013213:Starch / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D009687:Nuclear Proteins; D013213:Starch