title: Changes in chloroplast lipid contents and chloroplast ultrastructure in Sulla carnosa and Sulla coronaria leaves under salt stress.
abstract: The possible involvement of chloroplast lipids in the mechanisms of NaCl tolerance was studied in leaves of two varieties of Fabaceae: Sulla carnosa and Sulla coronaria, which were subjected to 200mM NaCl over 20days. Changes in membrane lipid peroxidation, chloroplast lipids content, fatty acids (FA) composition and the ultrastructure of chloroplasts under salt stress were investigated. Chloroplast lipids were separated and quantified by high performance liquid chromatography coupled to evaporative light scattering detection (HPLC/ELSD). The results showed that salinity induced a significant decrease in digalactosyldiacylglycerol (DGDG), phosphatidylglycerol (PG) and sulfoquinovosylglycerol (SQDG) content in both S. carnosa and S. coronaria leaves, whereas monogalactosyldiacylglycerol (MGDG) content did not change significantly in S. carnosa leaves. The MGDG/DGDG ratio remained stable in S. coronaria leaves but increased in those of S. carnosa. In addition, the unsaturated-to-saturated fatty acids ratio (UFAs:SFAs) did not change under salt stress in S. coronaria leaves, while it decreased significantly in S. carnosa leaves. Moreover, salinity did not induce significant changes in MGDG and DGDG unsaturation level in S. carnosa leaves, in contrast to S. coronaria, in which salinity seems to enhance the unsaturation level in MGDG, DGDG and PG. Furthermore, the level of membrane lipid peroxidation, as expressed by malondialdehyde (MDA) levels, increased at 200mM in S. carnosa leaves, while it did not change significantly in those of S. coronaria. With respect to the ultrastructure of chloroplasts at 200mM NaCl, investigated by transmission electron microscopy (TEM), salt-stress caused the swelling of thylakoids in S. carnosa mesophyll. These ultrastructural changes were observed especially in the spongy tissue in S. coronaria. Taken together, these findings suggest that the stability of MGDG/DGDG ratio, the unchanged unsaturation level, and increasing unsaturation level in MGDG, DGDG and PG may be effective to some degree in suppressing the ultrastructural damage caused by salinity effects and may contribute to protect the chloroplast membrane integrity against salt stress.
authors.affiliation: Laboratory of Extremophile Plants, Center of Biotechnology of Borj-Cedria (LEP-CBBC), P.O. Box 901, 2050 Hammam-Lif, Tunisia. Electronic address: bjaouifatma@gmail.com.
authors.forename: Fatma
authors.initials: F
authors.lastname: Bejaoui
authors.affiliation: Instituto de la Grasa (CSIC), Edificio 46, Campus Universitario Pablo de Olavide, Carretera de Utrera, Km. 1, 41013 Sevilla, Spain.
authors.forename: Joaquín J
authors.initials: JJ
authors.lastname: Salas
authors.affiliation: laboratory of legumes, Center of Biotechnology of Borj-Cedria (CBBC), P.O. Box 901, 2050 Hammam-Lif, Tunisia.
authors.forename: Issam
authors.initials: I
authors.lastname: Nouairi
authors.affiliation: Laboratory of Extremophile Plants, Center of Biotechnology of Borj-Cedria (LEP-CBBC), P.O. Box 901, 2050 Hammam-Lif, Tunisia.
authors.forename: Abderrazak
authors.initials: A
authors.lastname: Smaoui
authors.affiliation: Laboratory of Extremophile Plants, Center of Biotechnology of Borj-Cedria (LEP-CBBC), P.O. Box 901, 2050 Hammam-Lif, Tunisia.
authors.forename: Chedly
authors.initials: C
authors.lastname: Abdelly
authors.affiliation: Instituto de la Grasa (CSIC), Edificio 46, Campus Universitario Pablo de Olavide, Carretera de Utrera, Km. 1, 41013 Sevilla, Spain.
authors.forename: Enrique
authors.initials: E
authors.lastname: Martínez-Force
authors.affiliation: Laboratory of olive biotechnology, Center of Biotechnology of Borj-Cedria (CBBC), P.O. Box 901, 2050 Hammam-Lif, Tunisia.
authors.forename: Nabil Ben
authors.initials: NB
authors.lastname: Youssef
mesh_terms: D002736:Chloroplasts / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure*; D007887:Fabaceae / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D005227:Fatty Acids / Q000378:metabolism; D038983:Galactolipids / Q000378:metabolism; D006017:Glycolipids / Q000378:metabolism; D015227:Lipid Peroxidation / Q000187:drug effects; D008055:Lipids / Q000737:chemistry*; D008315:Malondialdehyde / Q000378:metabolism; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D012965:Sodium Chloride / Q000494:pharmacology*; D013312:Stress, Physiological / Q000187:drug effects*
chemical_list: D005227:Fatty Acids; D038983:Galactolipids; D006017:Glycolipids; D008055:Lipids; C007388:digalactosyldiacylglycerol; C009909:monogalactosyldiacylglycerol; D012965:Sodium Chloride; D008315:Malondialdehyde
keywords: Chloroplast lipids; Fatty acids; Lipid peroxidation; Sulla carnosa; Sulla coronaria; Ultrastructure