Plant Molecular Biology Laboratory, Department of Biology, McGill University, 1205 Docteur Penfield Avenue, Montreal, Quebec, Canada H3A 1B1.
EMBO J. 1984 Dec 1;3(12):2745-52. doi: 10.1002/j.1460-2075.1984.tb02205.x.
We have determined the structure of one of the leghemoglobin (Lb) genes of Phaseolus vulgaris (kidney bean) and deduced the chromosomal arrangement of leghemoglobin genes by genomic hybridizations with Lb and two other sequences, each specific to the 5' or 3' region of the soybean leghemoglobin loci. By comparing this organization with two other species of legumes, Glycine max (soybean) and G. soja (wild soybean), a phylogeny of leghemoglobin gene loci was traced. The intragenic structure of the kidney bean leghemoglobin gene shows the same intron/exon arrangement as that of soybean leghemoglobin genes and extensive sequence homologies in both coding as well as 5' and 3' non-coding regions. The presence in the kidney bean genome of four leghemoglobin genes suggests that tandem duplications of a single primordial plant globin gene had occurred to generate four leghemoglobin genes in an ;Lb-locus' before Glycine and Phaseolus species diverged. Chromosome duplication by tetraploidization in Glycine generated two loci containing four genes each. A large deletion in one of the two four-gene loci in soybean resulted in the generation of the Lbc(2) locus containing two leghemoglobin genes, one functional and another pseudo (LbPsi(2)). This pseudogene, unlike that present on the main locus, is represented by only two and a half exons and appears to be truncated. The two other truncated genes (LbT(1) and LbT(2)) were probably generated similarly in the genome of Glycine spp. following tetraploidization before the divergence of G. max and G. soja.
我们已经确定了菜豆（肾形豆）一种豆血红蛋白（Lb）基因的结构，并通过与 Lb 以及另外两个序列（每个序列都特异于大豆豆血红蛋白基因座的 5'或 3'区域）的基因组杂交，推导出了豆血红蛋白基因在染色体上的排列。通过将这种组织与另外两种豆科植物，大豆（Glycine max）和野生大豆（G. soja）进行比较，追踪了豆血红蛋白基因座的系统发生关系。菜豆豆血红蛋白基因的基因内结构与大豆豆血红蛋白基因具有相同的内含子/外显子排列，并且在编码区以及 5'和 3'非编码区都有广泛的序列同源性。在菜豆基因组中存在四个豆血红蛋白基因，这表明在 Glycine 和 Phaseolus 物种分化之前，单个原始植物珠蛋白基因的串联重复发生，从而在“Lb 基因座”中产生了四个豆血红蛋白基因。在大豆中，四倍体化导致两条染色体的重复，每条染色体含有四个基因。在大豆的两个四基因座之一中发生了一个大的缺失，导致了 Lbc(2)基因座的产生，该基因座含有两个豆血红蛋白基因，一个功能基因和另一个假基因（LbPsi(2)）。与主要基因座上的假基因不同，该假基因仅由两个半外显子组成，并且似乎是截断的。另外两个截断基因（LbT(1)和 LbT(2)）可能是在 Glycine spp.的基因组中在大豆的 Glycine max 和 G. soja 分化之前的四倍体化后类似地产生的。
