The type, functions, and mechanisms of biological nitrification inhibitors (BNIs) from rice were investigated using a combination of chemical and molecular techniques, bacterial bioassays, and soil microcosm experiments. We report the discovery of an effective nitrification inhibitor, syringic acid, in the root exudates of rice. Nitrification inhibition activity by syringic acid was verified in both weakly acidic and neutral pure cultures of Nitrosomonas europaea, and was superior to the widely used synthetic nitrification inhibitor, dicyandiamide (DCD). Moreover, syringic acid exhibited a dual inhibitory effect on ammonia monooxygenase (AMO), active in ammonium/ammonia oxidation, and on urease, active in urea hydrolysis. Nitrification inhibition by syringic acid was also demonstrated in a paddy soil system, and the abundance of ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) was significantly inhibited under all syringic acid treatments. A synergistic effect of syringic acid and another rice BNI, 1,9-decanediol, on nitrification was found in two pure Nitrosomonas cultures and a paddy soil. Together, our results enhance our understanding of BNI production by rice and enable the design of natural inhibitor formulations that regulate soil N transformation in a concerted manner.

结合化学和分子技术、细菌生物测定和土壤微观实验，研究了水稻中生物硝化抑制剂 (BNI) 的类型、功能和机制。我们报告在水稻的根系分泌物中发现了一种有效的硝化抑制剂丁香酸。丁香酸的硝化抑制活性在欧洲亚硝化单胞菌的弱酸性和中性纯培养物中得到验证，并且优于广泛使用的合成硝化抑制剂双氰胺 (DCD)。此外，丁香酸对氨单加氧酶（AMO）和尿素酶（在尿素水解中具有活性）和尿素酶具有双重抑制作用。丁香酸对硝化作用的抑制作用也在稻田土壤系统中得到证实，并且在所有丁香酸处理下，氨氧化细菌 (AOB) 和氨氧化古菌 (AOA) 的丰度都受到显着抑制。在两种纯亚硝化单胞菌中发现丁香酸和另一种水稻 BNI 1,9-癸二醇对硝化作用的协同作用文化和稻田。总之，我们的结果增强了我们对水稻生产 BNI 的理解，并能够设计出以协调方式调节土壤氮转化的天然抑制剂配方。