Split-root study of autoregulation of nodulation in the model legume Lotus japonicus

We used a split-root system to determine the timing for induction of the autoregulation of nodulation (AUT) in Lotus japonicus (Regel) Larsen after inoculation with Mesorhizobium loti. The signal took at least five days for full induction of AUT and inhibition of infection thread formation. Strain ML 108 ( able to nodulate but unable to fix nitrogen) induced full AUT, but ML 101 (unable to nodulate or to fix nitrogen) did not induce autoregulation. These results indicate that Nod factor-producing strains induce AUT, but that the nitrogen fixed by rhizobia and supplied to the plant as ammonia does not elicit the AUT in L. japonicus.

我们利用分根系统来确定日本百脉根（Lotus japonicus (Regel) Larsen）在接种中慢生根瘤菌（Mesorhizobium loti）后结瘤自动调控（AUT）的诱导时间。该信号至少需要五天才能完全诱导AUT并抑制侵染线的形成。ML 108菌株（能够结瘤但不能固氮）能完全诱导AUT，而ML 101菌株（不能结瘤也不能固氮）则不能诱导自动调控。这些结果表明，产生结瘤因子的菌株可诱导AUT，但根瘤菌固定并以氨的形式供给植物的氮不会在日本百脉根中引发AUT。