Théberge Marie-Claude, Prévost Danielle, Chalifour François-P
Département de phytologie, Faculté des sciences de l'agriculture et de l'alimentation, Université Laval, Québec (Québec), Canada G1K 7P4.
Centre de recherche et de développement sur les sols et les grandes cultures, Agriculture et Agroahmentaire Canada, 2560 boul. Hochelaga, Sainte-Foy, Québec, Canada G1V 2J3.
New Phytol. 1996 Dec;134(4):657-664. doi: 10.1111/j.1469-8137.1996.tb04931.x.
Fatty acid composition was determined in cells of strains CBhS and CBp7 of Rhizobium leguminosarum bv. viciae grown at four temperatures (10, 15, 22 and 30°C), and in bacteroids and nodules formed with faba bean (Vicia faba L.) grown at two day/night temperature regimes (22/15 and 15/10°C). Growth temperature markedly affected the fatty acid composition of free-living bacteria in both strains studied, and both showed similar variations at each temperature. The proportion of unsaturated fatty acids increased significantly with lowering of temperature. The major fatty acid found in bacteria and bacteroids was cis-vaccenic (C18: 1 ), which comprised up to c. 78 (bacteria) and 56% (bacteroids) of total fatty acids. The presence of polyunsaturated fatty acids (linoleic (C18: ) and linolenic (C18:3 ) acids) was noted only in bacteroids, indicating changes following the differentiation of bacteria into bacteroids in the nodules. The fatty acid composition of nodules was similar to that of bacteroids, although major differences were found in their proportions. The different day/night temperature regimes had contrasting effects in bacteroids and in nodules. In bacteroids of both strains, the proportions of stearic (C18:0) and linoleic (C18: ) acids decreased at the lower temperature regime. In nodules, the proportion of stearic (C18:0) acid decreased, while that of linolenic (C18:3 ) acid increased at the lower temperature regime. However, those of cis-vaccenic (C18:1 ), linoleic (C18: ) and palmitic (C16:0) acids increased or decreased depending on the rhizobial strain. The proportion of unsaturated fatty acids increased with the lowering of temperatures in bacteroids of both strains, and varied in whole nodules depending on the strain. Strain CBp7 showed a greater symbiotic efficiency (dry matter yield) than strain CBh5 under both temperature regimes, but no relationship was found with the proportion of unsaturated fatty acids of bacteria, bacteroids or nodules.
测定了在四种温度（10、15、22和30°C）下生长的豌豆根瘤菌蚕豆生物型菌株CBhS和CBp7细胞中的脂肪酸组成，以及在两种日/夜温度模式（22/15和15/10°C）下与蚕豆（Vicia faba L.）形成的类菌体和根瘤中的脂肪酸组成。生长温度显著影响了所研究的两种菌株中自由生活细菌的脂肪酸组成，并且在每个温度下两者都表现出相似的变化。不饱和脂肪酸的比例随着温度的降低而显著增加。在细菌和类菌体中发现的主要脂肪酸是顺式- vaccenic（C18:1），其分别占总脂肪酸的约78%（细菌）和56%（类菌体）。仅在类菌体中发现了多不饱和脂肪酸（亚油酸（C18:2）和亚麻酸（C18:3）），这表明细菌在根瘤中分化为类菌体后发生了变化。根瘤的脂肪酸组成与类菌体相似，尽管在它们的比例上发现了主要差异。不同的日/夜温度模式对类菌体和根瘤有相反的影响。在两种菌株的类菌体中，硬脂酸（C18:0）和亚油酸（C18:2）的比例在较低温度模式下降低。在根瘤中，硬脂酸（C18:0）的比例降低，而亚麻酸（C18:3）的比例在较低温度模式下增加。然而，顺式- vaccenic（C18:1）、亚油酸（C18:2）和棕榈酸（C16:0）的比例根据根瘤菌菌株而增加或减少。在两种菌株的类菌体中，不饱和脂肪酸的比例随着温度的降低而增加，并且在整个根瘤中根据菌株而变化。在两种温度模式下，菌株CBp7都显示出比菌株CBh5更高的共生效率（干物质产量），但未发现与细菌、类菌体或根瘤中不饱和脂肪酸的比例存在相关性。
