Cosio E G, Weissenböck G, McClure J W
Department of Botany, Miami University, Oxford, Ohio 45056.
Plant Physiol. 1985 May;78(1):14-9. doi: 10.1104/pp.78.1.14.
Mature soybean (Glycine max L. cv Harosoy 63) leaves normally contain kaempferol-3-glycosides but they accumulate no other flavonoids. Whole leaves sprayed with the diphenyl ether herbicide Acifluorfen and maintained in the light developed small necrotic lesions and accumulated isoflavone aglycones, isoflavone glucosides, and pterocarpans. Isoflavonoid accumulation was preceded by induced activity for chalcone synthase (CHS) and by increased activity for phenylalanine ammonia-lyase (PAL) and UDP-glucose:isoflavone 7-O-glucosyl transferase (IGT). PAL and CHS activity was highest between 24 and 30 hours after treatment, isoflavone aglycones and pterocarpans at 48 hours, IGT at 72 hours, and isoflavone glucosides at 96 hours.Mesophyll cells isolated from control leaves contained no activity for PAL, CHS, or IGT and no flavonoids of any class. Cells isolated from treated leaves at the stage of maximal enzyme activity or isoflavonoid content contained PAL (12% of the whole leaf activity), CHS (24%), IGT (20%), and 25% of the whole leaf isoflavone glucosides, but only traces, presumably as contaminants, of the other flavonoids. We suggest that the isoflavone glucosides were synthesized and accumulated in intact mesophyll cells as soluble detoxification products, while the isoflavone aglycones and pterocarpans accumulated in the epidermis or extracellularly within the mesophyll. To our knowledge this is the first report of tissue-specific induction of isoflavonoid glucosides and key enzymes of their biosynthesis in any plant.
成熟大豆（Glycine max L. cv Harosoy 63）叶片通常含有山奈酚 - 3 - 糖苷，但不积累其他黄酮类化合物。用二苯醚除草剂三氟羧草醚喷洒全叶并置于光照下，会形成小的坏死斑，并积累异黄酮苷元、异黄酮糖苷和紫檀烷。异黄酮积累之前，查尔酮合酶（CHS）活性被诱导，苯丙氨酸解氨酶（PAL）和UDP - 葡萄糖：异黄酮7 - O - 葡萄糖基转移酶（IGT）活性增加。处理后24至30小时PAL和CHS活性最高，48小时异黄酮苷元和紫檀烷积累，72小时IGT活性最高，96小时异黄酮糖苷积累。从对照叶片分离的叶肉细胞中，PAL、CHS或IGT均无活性，也不含任何类别的黄酮类化合物。在酶活性或异黄酮含量最高阶段从处理叶片分离的细胞含有PAL（全叶活性的12%）、CHS（24%）、IGT（20%）以及全叶异黄酮糖苷的25%，但其他黄酮类化合物仅含痕量，可能是污染物。我们认为异黄酮糖苷作为可溶性解毒产物在完整的叶肉细胞中合成并积累，而异黄酮苷元和紫檀烷则在表皮或叶肉细胞外积累。据我们所知，这是在任何植物中首次报道组织特异性诱导异黄酮糖苷及其生物合成关键酶。
