title: A cytosolic invertase is required for normal growth and cell development in the model legume, Lotus japonicus.
abstract: Neutral/alkaline invertases are a subgroup, confined to plants and cyanobacteria, of a diverse family of enzymes. A family of seven closely-related genes, LjINV1-LjINV7, is described here and their expression in the model legume, Lotus japonicus, is examined. LjINV1 previously identified as encoding a nodule-enhanced isoform is the predominant isoform present in all parts of the plant. Mutants for two isoforms, LjINV1 and LjINV2, were isolated using TILLING. A premature stop codon allele of LjINV2 had no effect on enzyme activity nor did it show a visible phenotype. For LjINV1, premature stop codon and missense mutations were obtained and the phenotype of the mutants examined. Recovery of homozygous mutants was problematic, but their phenotype showed a severe reduction in growth of the root and the shoot, a change in cellular development, and impaired flowering. The cellular organization of both roots and leaves was altered; leaves were smaller and thicker with extra layers of cells and roots showed an extended and broader zone of cell division. Moreover, anthers contained no pollen. Both heterozygotes and homozygous mutants showed decreased amounts of enzyme activity in nodules and shoot tips. Shoot tips also contained up to a 9-fold increased level of sucrose. However, mutants were capable of forming functional root nodules. LjINV1 is therefore crucial to whole plant development, but is clearly not essential for nodule formation or function.
authors.affiliation: Metabolic Biology, John Innes Centre, Norwich Research Park, Colney, Norwich NR4 7UH, UK.
authors.forename: Tracey
authors.initials: T
authors.lastname: Welham
authors.forename: Jodie
authors.initials: J
authors.lastname: Pike
authors.forename: Irmtraud
authors.initials: I
authors.lastname: Horst
authors.forename: Emmanouil
authors.initials: E
authors.lastname: Flemetakis
authors.forename: Panagiotis
authors.initials: P
authors.lastname: Katinakis
authors.forename: Takakazu
authors.initials: T
authors.lastname: Kaneko
authors.forename: Shusei
authors.initials: S
authors.lastname: Sato
authors.forename: Satoshi
authors.initials: S
authors.lastname: Tabata
authors.forename: Jillian
authors.initials: J
authors.lastname: Perry
authors.forename: Martin
authors.initials: M
authors.lastname: Parniske
authors.forename: Trevor L
authors.initials: TL
authors.lastname: Wang
mesh_terms: D003600:Cytosol / Q000201:enzymology*; D007887:Fabaceae / Q000201:enzymology / Q000235:genetics / Q000254:growth & development; D000070116:Lotus / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development*; D008954:Models, Biological; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D053204:Root Nodules, Plant / Q000201:enzymology / Q000235:genetics / Q000254:growth & development; D043324:beta-Fructofuranosidase / Q000235:genetics / Q000378:metabolism*
chemical_list: D010940:Plant Proteins; D020033:Protein Isoforms; D043324:beta-Fructofuranosidase