title: Relative abundance of Delta(5)-sterols in plasma membrane lipids of root-tip cells correlates with aluminum tolerance of rice.
abstract: We investigated variations in aluminum (Al) tolerance among rice plants, using ancestor cultivars from the family line of the Al-tolerant and widely cultivated Japonica cultivar, Sasanishiki. The cultivar Rikuu-20 was Al sensitive, whereas a closely related cultivar that is a descendant of Rikuu-20, Rikuu-132, was Al tolerant. These two cultivars were compared to determine mechanisms underlying variations in Al tolerance. The sensitive cultivar Rikuu-20 showed increased permeability of the plasma membrane (PM) and greater Al uptake within 1 h of Al treatment. This could not be explained by organic acid release. Lipid composition of the PM differed between these cultivars, and may account for the difference in Al tolerance. The tolerant cultivar Rikuu-132 had a lower ratio of phospholipids to Delta(5)-sterols than the sensitive cultivar Rikuu-20, suggesting that the PM of Rikuu-132 is less negatively charged and less permeabilized than that of Rikuu-20. We used inhibitors of Delta(5)-sterol synthesis to alter the ratio of phospholipids to Delta(5)-sterols in both cultivars. These inhibitors reduced Al tolerance in Rikuu-132 and its Al-tolerant ancestor cultivars Kamenoo and Kyoku. In addition, Rikuu-132 showed a similar level of Al sensitivity when the ratio of phospholipids to Delta(5)-sterols was increased to match that of Rikuu-20 after treatment with uniconazole-P, an inhibitor of obtusifoliol-14alpha-demethylase. These results indicate that PM lipid composition is a factor underlying variations in Al tolerance among rice cultivars.
authors.affiliation: Faculty of Agriculture, Yamagata University, Tsuruoka, Japan.
authors.forename: M Shahadat Hossain
authors.initials: MS
authors.lastname: Khan
authors.forename: Keitarou
authors.initials: K
authors.lastname: Tawaraya
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Sekimoto
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Koyama
authors.forename: Yuriko
authors.initials: Y
authors.lastname: Kobayashi
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Murayama
authors.forename: Masaru
authors.initials: M
authors.lastname: Chuba
authors.forename: Mihoko
authors.initials: M
authors.lastname: Kambayashi
authors.forename: Yoshihito
authors.initials: Y
authors.lastname: Shiono
authors.forename: Matsuo
authors.initials: M
authors.lastname: Uemura
authors.forename: Satoru
authors.initials: S
authors.lastname: Ishikawa
authors.forename: Tadao
authors.initials: T
authors.lastname: Wagatsuma
mesh_terms: D000535:Aluminum / Q000494:pharmacology*; D002462:Cell Membrane / Q000187:drug effects; D019343:Citric Acid / Q000378:metabolism; D008293:Malates / Q000378:metabolism; D008563:Membrane Lipids / Q000378:metabolism*; D018519:Meristem / Q000187:drug effects*; D012275:Oryza / Q000187:drug effects* / Q000378:metabolism; D013261:Sterols / Q000037:antagonists & inhibitors / Q000378:metabolism*
chemical_list: D008293:Malates; D008563:Membrane Lipids; D013261:Sterols; D019343:Citric Acid; C030298:malic acid; D000535:Aluminum