Department of Genetics, Biological Research Center, Hungarian Academy of Sciences, P.O. Box 521, H-6701, Szeged, Hungary.
Plant Mol Biol. 1987 Jan;8(1):61-75. doi: 10.1007/BF00016435.
The internal structural portion of genes nodC and nodD (representatives of the two transcription units coding for common nodulation functions) and of hsnB and hsnD (genes from the two transcription units determining host-specificity of nodulation) have been cloned from Rhizobium meliloti into M13 vectors and used as probes against genomic DNAs from different Rhizobium strains and species. nodC and nodD were found in all species with one exception, indicating that they are common and widely spread genes, though the nodD gene hybridized only very weakly with slow-growing rhizobia. Interestingly, reiteration of nodD sequences was observed in almost all fast-growing strains (with the exception of R. leguminosarum). hsnB and, more so, hsnD are present only in a few species tested, supporting their specific involvement in R. meliloti-Medicago sativa symbiosis. In several cases the hybridizing bands from total Rhizobium DNA were compared to those found in recombinant plasmids carrying functional nodulation regions, and these analyses supported the notion that the bands indicate the presence of functional genes.
基因 nodC 和 nodD（代表编码共同结瘤功能的两个转录单元的代表）以及 hsnB 和 hsnD（决定结瘤宿主特异性的两个转录单元的基因）的内部结构部分已从根瘤菌 meliloti 中克隆到 M13 载体中，并用作针对来自不同根瘤菌菌株和种的基因组 DNA 的探针。nodC 和 nodD 存在于除一个例外的所有物种中，表明它们是常见且广泛分布的基因，尽管 nodD 基因与生长缓慢的根瘤菌杂交仅非常弱。有趣的是，在几乎所有快速生长的菌株中都观察到 nodD 序列的重复（除了 R. leguminosarum）。hsnB，更确切地说，hsnD 仅存在于测试的少数几种物种中，支持它们在 R. meliloti-Medicago sativa 共生中的特异性参与。在某些情况下，将总根瘤菌 DNA 中的杂交带与携带功能性结瘤区的重组质粒中发现的杂交带进行比较，这些分析支持了这样的观点，即这些带表明存在功能性基因。
