Duzan Haifa M, Mabood Fazli, Souleimanov Alfred, Smith Donald L
Department of Plant Science, McGill University, Macdonald Campus, Ste. Anne de Bellevue, Que., Canada.
J Plant Physiol. 2006 Jan;163(1):107-11. doi: 10.1016/j.jplph.2005.04.029. Epub 2005 Aug 1.
Nod factors (Lipo-chitooligosaccharides, or LCOs) act as bacteria-to-plant signal molecules that modulate early events of the Bradyrhizobium-soybean symbiosis. It is known that low root zone temperature inhibits the early stages of this symbiosis; however, the effect of low soil temperature on bacteria-to-plant signaling is largely uninvestigated. We evaluated the effect of low growth temperatures on the production kinetics of Nod factor (LCO) by B. japonicum. Two strains of B. japonicum, 532C and USDA110, were tested for ability to synthesize Nod Bj-V (C(18:1), MeFuc) at three growth temperatures (15, 17 and 28 degrees C). The greatest amounts of the major Nod factor, Nod Bj-V (C(18:1), MeFuc), were produced at 28 degrees C for both strains. At 17 and 15 degrees C, the Nod factor production efficiency, per cell, of B. japonicum 532C and USDA110 was markedly decreased with the lowest Nod factor concentration per cell occurring at 15 degrees C. Strain 532C was more efficient at Nod factor production per cell than strain USDA 110 at all growth temperatures. The biological activity of the extracted Nod factor was unaffected by culture temperature. This study constitutes the first demonstration of reduced Nod factor production efficiency (per cell production) under reduced temperatures, suggesting another way that lower temperatures inhibit establishment of the soybean N(2) fixing symbiosis.
结瘤因子（脂壳寡糖，或LCOs）作为细菌与植物之间的信号分子，调节慢生根瘤菌与大豆共生的早期事件。已知根区低温会抑制这种共生的早期阶段；然而，土壤低温对细菌与植物信号传导的影响在很大程度上尚未得到研究。我们评估了低生长温度对日本慢生根瘤菌产生结瘤因子（LCO）动力学的影响。测试了两株日本慢生根瘤菌532C和USDA110在三种生长温度（15、17和28摄氏度）下合成Nod Bj-V（C(18:1)，MeFuc）的能力。两种菌株在28摄氏度时产生的主要结瘤因子Nod Bj-V（C(18:1)，MeFuc）量最大。在17和15摄氏度时，日本慢生根瘤菌532C和USDA110每细胞的结瘤因子产生效率显著降低，每细胞的结瘤因子浓度在15摄氏度时最低。在所有生长温度下，532C菌株每细胞产生结瘤因子的效率都比USDA 110菌株更高。提取的结瘤因子的生物活性不受培养温度的影响。这项研究首次证明了在低温下结瘤因子产生效率（每细胞产量）降低，这表明低温抑制大豆固氮共生体建立的另一种方式。
