Cérémonie H, Cournoyer B, Maillet F, Normand P, Fernandez M P
Laboratoire d'Ecologie Microbienne du Sol, UMR-CNRS 5557, Université Claude Bernard Lyon 1, Villeurbanne, France.
Mol Gen Genet. 1998 Oct;260(1):115-9. doi: 10.1007/s004380050877.
Two divergent reports have been published on the genetic complementation of rhizobial nod mutants using Frankia DNA. In 1991 putative Frankia cosmid library clones were reported to restore normal nodulation properties to Rhizobium leguminosarum biovar viciae nodD::Tn5, but no supporting sequence data were published. In 1992 a second group reported a failure to find any evidence of functional complementation of various rhizobial nod mutants by Frankia DNA (nodA, nodB and nodC). Complementation tests of nine NodR. leguminosarum bv. viciae or Sinorhizobium meliloti Tn5 mutants (nodA-, nodB-, nodC-, nodD-, nodF-, nodL-, nodH-) were thus performed using a Frankia gene library in pLAFR3 to clarify this situation. Rhizobial transconjugants obtained by tri-parental matings were screened for restoration of the nodulation phenotype on their host plants, Vicia sativa subsp. nigra or Medicago sativa. Nodulation was observed on plants inoculated with transconjugants of the R. leguminosarum bv. viciae nodC::Tn5 mutant. The Nod+ rhizobial transconjugants were isolated and analysed. The Nod+ phenotype of these transconjugants was found to be due to Tn5 excision/transposition. No functional complementation was found with any of the mutants used, suggesting that rhizobial complementation of nod mutants with Frankia DNA is unlikely to occur.
关于使用弗兰克氏菌DNA对根瘤菌结瘤突变体进行基因互补，已发表了两篇不同的报告。1991年，有报道称推测的弗兰克氏菌黏粒文库克隆可恢复豌豆根瘤菌生物变种蚕豆nodD::Tn5的正常结瘤特性，但未发表支持性序列数据。1992年，另一组报告称未找到任何证据表明弗兰克氏菌DNA（nodA、nodB和nodC）对各种根瘤菌结瘤突变体有功能互补作用。因此，使用pLAFR3中的弗兰克氏菌基因文库对9个豌豆根瘤菌蚕豆生物变种或苜蓿中华根瘤菌Tn5突变体（nodA-、nodB-、nodC-、nodD-、nodF-、nodL-、nodH-）进行互补试验，以澄清这种情况。通过三亲本杂交获得的根瘤菌转接合子在其寄主植物黑籽野豌豆或紫花苜蓿上筛选结瘤表型的恢复情况。在用豌豆根瘤菌蚕豆生物变种nodC::Tn5突变体的转接合子接种的植物上观察到了结瘤现象。分离并分析了结瘤阳性的根瘤菌转接合子。发现这些转接合子的结瘤阳性表型是由于Tn5切除/转座。在所使用的任何突变体中均未发现功能互补，这表明用弗兰克氏菌DNA对结瘤突变体进行根瘤菌互补不太可能发生。
