title: Significance of structural variation in thylakoid membranes in maintaining functional photosystems during reproductive growth.
abstract: Structural variation in the stroma-grana (SG) arrangement of the thylakoid membranes, such as changes in the thickness of the grana stacks and in the ratio between grana and inter-grana thylakoid, is often observed. Broadly, such alterations are considered acclimation to changes in growth and the environment. However, the relation of thylakoid morphology to plant growth and photosynthesis remains obscure. Here, we report changes in the thylakoid during leaf development under a fixed light condition. Histological studies on the chloroplasts of fresh green Arabidopsis leaves have shown that characteristically shaped thylakoid membranes lacking the inter-grana region, referred to hereafter as isolated-grana (IG), occurred adjacent to highly ordered, large grana layers. This morphology was restored to conventional SG thylakoid membranes with the removal of bolting stems from reproductive plants. Statistical analysis showed a negative correlation between the incidences of IG-type chloroplasts in mesophyll cells and the rates of leaf growth. Fluorescence parameters calculated from pulse-amplitude modulated fluorometry measurements and CO2assimilation data showed that the IG thylakoids had a photosynthetic ability that was equivalent to that of the SG thylakoids under moderate light. However, clear differences were observed in the chlorophyll a/b ratio. The IG thylakoids were apparently an acclimated phenotype to the internal condition of source leaves. The idea is supported by the fact that the life span of the IG thylakoids increased significantly in the later developing leaves. In conclusion, the heterogeneous state of thylakoid membranes is likely important in maintaining photosynthesis during the reproductive phase of growth.
authors.affiliation: Research Center for Advanced Plant Factory (SU-PLAF), Faculty of Textile Science and Technology, Shinshu University, Nagano, 386-8567, Japan.
authors.forename: Hatsumi
authors.initials: H
authors.lastname: Nozue
authors.affiliation: Department of Applied Biology, Faculty of Textile Science and Technology, Shinshu University, Nagano, 386-8567, Japan.
authors.forename: Kaori
authors.initials: K
authors.lastname: Oono
authors.affiliation: Faculty of Agriculture, Shizuoka University, Shizuoka, 422-8529, Japan.
authors.forename: Yoshinobu
authors.initials: Y
authors.lastname: Ichikawa
authors.affiliation: Department of Applied Biology, Faculty of Textile Science and Technology, Shinshu University, Nagano, 386-8567, Japan.
authors.forename: Shun
authors.initials: S
authors.lastname: Tanimura
authors.affiliation: Research Center for Advanced Plant Factory (SU-PLAF), Faculty of Textile Science and Technology, Shinshu University, Nagano, 386-8567, Japan.
authors.forename: Kana
authors.initials: K
authors.lastname: Shirai
authors.affiliation: Faculty of Education and Integrated Arts and Sciences, Waseda University, Tokyo, 162-8480, Japan.
authors.forename: Kintake
authors.initials: K
authors.lastname: Sonoike
authors.affiliation: Research Center for Advanced Plant Factory (SU-PLAF), Faculty of Textile Science and Technology, Shinshu University, Nagano, 386-8567, Japan.|Department of Applied Biology, Faculty of Textile Science and Technology, Shinshu University, Nagano, 386-8567, Japan.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Nozue
authors.affiliation: Department of Applied Biology, Faculty of Textile Science and Technology, Shinshu University, Nagano, 386-8567, Japan.
authors.forename: Nobuaki
authors.initials: N
authors.lastname: Hayashida
mesh_terms: D010788:Photosynthesis / Q000502:physiology*; D018515:Plant Leaves / Q000378:metabolism; D012098:Reproduction / Q000502:physiology*; D020524:Thylakoids / Q000378:metabolism*