以自然生长在盐碱地上的野大豆(Glycine soja)和不耐盐的栽培大豆(G. max)为材料，测定了它们在不同盐度条件下叶片、根部和种子的异黄酮含量，并测定了它们叶片的L_苯丙氨酸含量和苯丙氨酸裂解酶（PAL）活性，还测定了它们根部的结瘤量和固氮酶活性。通过两者比较，分析了它们的大豆异黄酮代谢和盐渍环境的关系。结果表明：盐渍处理不抑制盐生野大豆PAL酶的活性，其大豆异黄酮大量积累；相反，盐渍处理明显抑制栽培大豆PAL酶活性，其大豆异黄酮含量减少，而大豆异黄酮合成前体L_苯丙氨酸积累。 结果还显示：在盐渍条件下，盐生野大豆根部异黄酮积累的同时，其根瘤结瘤量较多，且固氮酶活性也较高；而栽培大豆随着其根部异黄酮的减少，其根瘤结瘤量大大减少，且固氮活性大大下降。野大豆和栽培大豆的这些差别说明：盐生野大豆积累大豆异黄酮有其生态学意义， 这很可能是野大豆通过异黄酮次生代谢途径适应盐渍环境的一种重要机制。
Aims Some species-specific secondary metabolites are key players in the interaction between plants and their environment. An ecotype of wild soybean (Glycine soja), naturally growing in saline soil of Yellow River delta in Shandong Province of China, shows substantial genetically determined salt-resistance, and its isoflavone content is higher than that in many cultivated soybeans. Our objective was to investigate the relationship between isoflavone and saline condition in Glycine sojathrough experimentation.
Methods The ecotype of wild soybean mentioned above and a variety (Huiming Soybean) of cultivated soybean (Glycine max) from same area were cultivated under saline condition. We determined the isoflavone contents in their leaves, roots and seeds, phenylalanine ammonialyase activities and phenylalanine contents in their leaves, the number of nodules and nitrogen-fixing enzyme activities in their roots.
Important findings Isoflavone anabolism in the wild soybean was promoted by salt while it was inhibited in the cultivated soybean. The higher isoflavones contents of the wild soybean were significantly associated with the higher activities and efficiency of nitrogen fixation in its roots. Results suggested that isoflavones, secondary metabolites of the wild soybean, played an important role in the wild soybean adapting to the saline environment. Underlying processes require further investigation.