Debellé F, Maillet F, Vasse J, Rosenberg C, de Billy F, Truchet G, Dénarié J, Ausubel F M
Department of Genetics, Harvard Medical School, Boston, Massachusetts 02114.
J Bacteriol. 1988 Dec;170(12):5718-27. doi: 10.1128/jb.170.12.5718-5727.1988.
Transfer of an IncP plasmid carrying the Rhizobium meliloti nodFE, nodG, and nodH genes to Rhizobium trifolii enabled R. trifolii to nodulate alfalfa (Medicago sativa), the normal host of R. meliloti. Using transposon Tn5-linked mutations and in vitro-constructed deletions of the R. meliloti nodFE, nodG, and nodH genes, we showed that R. meliloti nodH was required for R. trifolii to elicit both root hair curling and nodule initiation on alfalfa and that nodH, nodFE, and nodG were required for R. trifolii to elicit infection threads in alfalfa root hairs. Interestingly, the transfer of the R. meliloti nodFE, nodG, and nodH genes to R. trifolii prevented R. trifolii from infecting and nodulating its normal host, white clover (Trifolium repens). Experiments with the mutated R. meliloti nodH, nodF, nodE, and nodG genes demonstrated that nodH, nodF, nodE, and possibly nodG have an additive effect in blocking infection and nodulation of clover.
携带苜蓿根瘤菌（Rhizobium meliloti）nodFE、nodG和nodH基因的IncP质粒转移到三叶草根瘤菌（Rhizobium trifolii）后，使三叶草根瘤菌能够使苜蓿（Medicago sativa）结瘤，苜蓿是苜蓿根瘤菌的正常宿主。利用转座子Tn5连锁突变以及体外构建的苜蓿根瘤菌nodFE、nodG和nodH基因缺失，我们发现苜蓿根瘤菌nodH是三叶草根瘤菌在苜蓿上引发根毛卷曲和根瘤起始所必需的，并且nodH、nodFE和nodG是三叶草根瘤菌在苜蓿根毛中引发侵染线所必需的。有趣的是，苜蓿根瘤菌nodFE、nodG和nodH基因转移到三叶草根瘤菌后，阻止了三叶草根瘤菌感染其正常宿主白三叶（Trifolium repens）并使其结瘤。对突变的苜蓿根瘤菌nodH、nodF、nodE和nodG基因进行的实验表明，nodH、nodF、nodE以及可能的nodG在阻止三叶草感染和结瘤方面具有累加效应。
