title: Salinity induces membrane structure and lipid changes in maize mesophyll and bundle sheath chloroplasts.
abstract: The membranes of Zea mays (maize) mesophyll cell (MC) chloroplasts are more vulnerable to salinity stress than are those of bundle sheath cell (BSC) chloroplasts. To clarify the mechanism underlying this difference in salt sensitivity, we monitored changes in the glycerolipid and fatty acid compositions of both types of chloroplast upon exposure to salinity stress. The monogalactosyldiacylglycerol (MGDG) and digalactosyldiacylglycerol (DGDG) contents were higher in MC chloroplasts than in BSC chloroplasts, in both the presence and absence of salt treatment. Under salt conditions, the MGDG level in MC chloroplasts was significantly lower than under normal conditions, while it was unchanged in BSC chloroplasts. In both types of chloroplast, the contents of DGDG, phosphatidylglycerol and phosphatidylinositol remained at the same levels in control and salt-treated plants, whereas sulfoquinovosyldiacylglycerol and phosphatidylcholine were significantly lower and higher, respectively, upon salt treatment. In addition, the fatty acid composition and double bond index of individual lipid classes were changed by salt treatment in both BSC and MC chloroplasts, although these factors had no effect on glycerolipid content. These findings suggest that the difference in salt sensitivity of MC and BSC chloroplast membranes is related to differences in MGDG responses to salinity. Thus, we propose that the low MGDG content and the low sensitivity of MGDG to salinity in BSC chloroplasts render them more tolerant than MC chloroplasts to salinity stress.
authors.affiliation: Graduate School of Bioagricultural Sciences, Nagoya University, Chikusa, Nagoya, 464-8601, Japan.
authors.forename: Eiji
authors.initials: E
authors.lastname: Omoto
authors.affiliation: Graduate School of Bioagricultural Sciences, Nagoya University, Chikusa, Nagoya, 464-8601, Japan.
authors.forename: Yugo
authors.initials: Y
authors.lastname: Iwasaki
authors.affiliation: Graduate School of Bioagricultural Sciences, Nagoya University, Chikusa, Nagoya, 464-8601, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Miyake
authors.affiliation: Graduate School of Bioagricultural Sciences, Nagoya University, Chikusa, Nagoya, 464-8601, Japan.
authors.forename: Mitsutaka
authors.initials: M
authors.lastname: Taniguchi
mesh_terms: D002736:Chloroplasts / Q000187:drug effects / Q000648:ultrastructure; D038983:Galactolipids / Q000378:metabolism*; D006017:Glycolipids / Q000378:metabolism*; D050356:Lipid Metabolism / Q000187:drug effects*; D008566:Membranes / Q000187:drug effects / Q000648:ultrastructure; D058503:Mesophyll Cells / Q000187:drug effects / Q000648:ultrastructure; D054712:Salinity; D012965:Sodium Chloride / Q000494:pharmacology*; D013312:Stress, Physiological; D003313:Zea mays / Q000187:drug effects* / Q000378:metabolism / Q000648:ultrastructure
chemical_list: D038983:Galactolipids; D006017:Glycolipids; C007388:digalactosyldiacylglycerol; C013694:sulfoquinovosyl diglyceride; D012965:Sodium Chloride