Gravitropism in leaves of Arabidopsis thaliana (L.) Heynh.
In higher plants, stems and roots show negative and positive gravitropism, respectively. However, current knowledge on the graviresponse of leaves is lacking. In this study, we analyzed the positioning and movement of rosette leaves of Arabidopsis thaliana under light and dark conditions. We found that the radial positioning of rosette leaves was not affected by the direction of gravity under continuous white light. In contrast, when plants were shifted to darkness, the leaves moved upwards, suggesting negative gravitropism. Analysis of the phosphoglucomutase and shoot gravitropism 2-1 mutants revealed that the sedimenting amyloplasts in the leaf petiole are important for gravity perception, as is the case in stems and roots. In addition, our detailed physiological analyses revealed a unique feature of leaf movement after the shift to darkness, i.e. movement could be divided into negative gravitropism and nastic movement. The orientation of rosette leaves is ascribed to a combination of these movements.
Mano
Eriko
E
Department of Biosystems Science, School of Advanced Sciences, The Graduate University for Advanced Studies, Shonan Village, Hayama, Kanagawa, 204-0193 Japan.
Horiguchi
Gorou
G
Tsukaya
Hirokazu
H
D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000502:physiology; D003624:Darkness; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D018522:Gravitropism / Q000502:physiology*; D018466:Gravity Sensing / Q000502:physiology; D008027:Light; D009154:Mutation; D010733:Phosphoglucomutase / Q000235:genetics / Q000502:physiology; D010740:Phospholipases / Q000235:genetics / Q000502:physiology; D018515:Plant Leaves / Q000502:physiology*; D018520:Plant Shoots / Q000502:physiology; D013997:Time Factors
D029681:Arabidopsis Proteins; D010740:Phospholipases; C455511:SGR2 phospholipase, Arabidopsis; D010733:Phosphoglucomutase