title: A suite of Lotus japonicus starch mutants reveals both conserved and novel features of starch metabolism.
abstract: The metabolism of starch is of central importance for many aspects of plant growth and development. Information on leaf starch metabolism other than in Arabidopsis (Arabidopsis thaliana) is scarce. Furthermore, its importance in several agronomically important traits exemplified by legumes remains to be investigated. To address this issue, we have provided detailed information on the genes involved in starch metabolism in Lotus japonicus and have characterized a comprehensive collection of forward and TILLING (for Targeting Induced Local Lesions IN Genomes) reverse genetics mutants affecting five enzymes of starch synthesis and two enzymes of starch degradation. The mutants provide new insights into the structure-function relationships of ADP-glucose pyrophosphorylase and glucan, water dikinase1 in particular. Analyses of the mutant phenotypes indicate that the pathways of leaf starch metabolism in L. japonicus and Arabidopsis are largely conserved. However, the importance of these pathways for plant growth and development differs substantially between the two species. Whereas essentially starchless Arabidopsis plants lacking plastidial phosphoglucomutase grow slowly relative to wild-type plants, the equivalent mutant of L. japonicus grows normally even in a 12-h photoperiod. In contrast, the loss of GLUCAN, WATER DIKINASE1, required for starch degradation, has a far greater effect on plant growth and fertility in L. japonicus than in Arabidopsis. Moreover, we have also identified several mutants likely to be affected in new components or regulators of the pathways of starch metabolism. This suite of mutants provides a substantial new resource for further investigations of the partitioning of carbon and its importance for symbiotic nitrogen fixation, legume seed development, and perenniality and vegetative regrowth.
authors.affiliation: Metabolic Biology, John Innes Centre, Colney, Norwich, United Kingdom.
authors.forename: Cécile
authors.initials: C
authors.lastname: Vriet
authors.forename: Tracey
authors.initials: T
authors.lastname: Welham
authors.forename: Andreas
authors.initials: A
authors.lastname: Brachmann
authors.forename: Marilyn
authors.initials: M
authors.lastname: Pike
authors.forename: Jodie
authors.initials: J
authors.lastname: Pike
authors.forename: Jillian
authors.initials: J
authors.lastname: Perry
authors.forename: Martin
authors.initials: M
authors.lastname: Parniske
authors.forename: Shusei
authors.initials: S
authors.lastname: Sato
authors.forename: Satoshi
authors.initials: S
authors.lastname: Tabata
authors.forename: Alison M
authors.initials: AM
authors.lastname: Smith
authors.forename: Trevor L
authors.initials: TL
authors.lastname: Wang
mesh_terms: D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics; D002874:Chromosome Mapping; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D051599:Glucose-1-Phosphate Adenylyltransferase / Q000235:genetics / Q000378:metabolism*; D000070116:Lotus / Q000201:enzymology / Q000235:genetics*; D008969:Molecular Sequence Data; D009154:Mutation; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D017422:Sequence Analysis, DNA; D013213:Starch / Q000378:metabolism*; D013329:Structure-Activity Relationship
chemical_list: D010940:Plant Proteins; D013213:Starch; D051599:Glucose-1-Phosphate Adenylyltransferase