Yokoyama T, Kobayashi N, Kouchi H, Minamisawa K, Kaku H, Tsuchiya K
National Institute of Agrobiological Resources, Kannondai 2-1-2, Tsukuba, Ibaraki, 305-8602, Japan.
Plant J. 2000 Apr;22(1):71-8. doi: 10.1046/j.1365-313x.2000.00713.x.
Lipochito-oligosaccharides (Nod factors) produced by Rhizobium or Bradyrhizobium are the key signal molecules for eliciting nodulation in their corresponding host legumes. To elucidate the signal transduction events mediated by Nod factors, we investigated the effects of Nod factors on the cytosolic [Ca2+] of protoplasts prepared from roots and suspension-cultured cells of soybean (Glycine max and G. soja) using a fluorescent Ca2+ indicator, Fura-PE3. NodBj-V (C18:1, MeFuc), which is a major component of Nod factors produced by Bradyrhizobium japonicum, induces transient elevation of cytosolic [Ca2+] in the cells of soybean within a few minutes. This effect is specific to soybean cells and was not observed in the tobacco BY-2 cells. Furthermore, NodBj-V without MeFuc did not induce any cytosolic [Ca2+] elevation in soybean cells. Exclusion of Ca2+ from the medium, as well as pre-treatment of the cells with an external Ca2+ chelator or with a plasma membrane voltage-dependent Ca2+ channel inhibitor, suppressed the Nod factor-dependent cytosolic [Ca2+] elevation. These results indicate that transient Ca2+ influx from extracellular fluid is one of the earliest responses of soybean cells to NodBj-V (C18:1, MeFuc) in a host-specific manner.
由根瘤菌或慢生根瘤菌产生的脂壳寡糖（结瘤因子）是在其相应宿主豆科植物中引发结瘤的关键信号分子。为了阐明由结瘤因子介导的信号转导事件，我们使用荧光钙指示剂Fura-PE3，研究了结瘤因子对从大豆（Glycine max和G. soja）根和悬浮培养细胞制备的原生质体胞质[Ca2+]的影响。日本慢生根瘤菌产生的结瘤因子的主要成分NodBj-V（C18:1，MeFuc）在几分钟内可诱导大豆细胞胞质[Ca2+]瞬时升高。这种效应是大豆细胞特有的，在烟草BY-2细胞中未观察到。此外，不含MeFuc的NodBj-V不会诱导大豆细胞胞质[Ca2+]升高。从培养基中去除Ca2+，以及用细胞外Ca2+螯合剂或质膜电压依赖性Ca2+通道抑制剂对细胞进行预处理，均抑制了结瘤因子依赖性胞质[Ca2+]升高。这些结果表明，细胞外液中Ca2+的瞬时内流是以宿主特异性方式对大豆细胞对NodBj-V（C18:1，MeFuc）的最早反应之一。
