title: Growth stimulation in inflorescences of an Arabidopsis tubulin mutant under microgravity conditions in space.
abstract: Cortical microtubules are involved in plant resistance to hypergravity, but their roles in resistance to 1 g gravity are still uncertain. To clarify this point, we cultivated an Arabidopsis α-tubulin 6 mutant (tua6) in the Cell Biology Experiment Facility on the Kibo Module of the International Space Station, and analyzed growth and cell wall mechanical properties of inflorescences. Growth of inflorescence stems was stimulated under microgravity conditions, as compared with ground and on-orbit 1 g conditions. The stems were 10-45% longer and their growth rate 15-55% higher under microgravity conditions than those under both 1 g conditions. The degree of growth stimulation tended to be higher in the tua6 mutant than the wild-type Columbia. Under microgravity conditions, the cell wall extensibility in elongating regions of inflorescences was significantly higher than the controls, suggesting that growth stimulation was caused by cell wall modifications. No clear differences were detected in any growth or cell wall property between ground and on-orbit 1 g controls. These results support the hypothesis that cortical microtubules generally play an important role in plant resistance to the gravitational force.
authors.affiliation: Department of Biology, Graduate School of Science, Osaka City University, Sumiyoshi-ku, Osaka, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Hoson
authors.forename: K
authors.initials: K
authors.lastname: Soga
authors.forename: K
authors.initials: K
authors.lastname: Wakabayashi
authors.forename: T
authors.initials: T
authors.lastname: Hashimoto
authors.forename: I
authors.initials: I
authors.lastname: Karahara
authors.forename: S
authors.initials: S
authors.lastname: Yano
authors.forename: F
authors.initials: F
authors.lastname: Tanigaki
authors.forename: T
authors.initials: T
authors.lastname: Shimazu
authors.forename: H
authors.initials: H
authors.lastname: Kasahara
authors.forename: D
authors.initials: D
authors.lastname: Masuda
authors.forename: S
authors.initials: S
authors.lastname: Kamisaka
mesh_terms: D017360:Arabidopsis / Q000166:cytology / Q000235:genetics / Q000254:growth & development*; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D001696:Biomechanical Phenomena; D002473:Cell Wall / Q000378:metabolism; D005118:Extraterrestrial Environment; D018506:Gene Expression Regulation, Plant; D018525:Germination; D056626:Inflorescence / Q000254:growth & development* / Q000378:metabolism; D009154:Mutation / Q000235:genetics*; D013997:Time Factors; D014404:Tubulin / Q000235:genetics* / Q000378:metabolism; D014893:Weightlessness
chemical_list: D029681:Arabidopsis Proteins; C000591004:Tua6 protein, Arabidopsis; D014404:Tubulin
keywords: Arabidopsis; gravity resistance; growth stimulation; microgravity; microtubules; space; tubulin mutant