She Chao-Wen, Wei Lin, Jiang Xiang-Hui
Key Laboratory of Research and Utilization of Ethnomedicinal Plant Resources of Hunan Province, Huaihua University, Huaihua, Hunan, 418008, China.
Key Laboratory of Xiangxi Medicinal Plant and Ethnobotany of Hunan Higher Education, Huaihua University, Huaihua, Hunan, 418008, China.
Comp Cytogenet. 2017 Sep 12;11(4):579-600. doi: 10.3897/CompCytogen.v11i4.13604. eCollection 2017.
The two cultivated (Adanson, 1763) species, (N. J. von Jacquin, 1788) A. P. de Candolle, 1825 and (Linnaeus, 1753) A. P. de Candolle, 1825 are closely related based on morphological and molecular phylogenetic data. However, the similarities and differences in genome organization between them have not been evaluated at molecular cytogenetic level. Here, detailed karyotypes of both species were constructed using combined PI and DAPI (CPD) staining, rDNA-FISH and self-genomic hybridization (sGISH). For further comparison, comparative genomic hybridization (cGISH) and sequence analysis of 5S rDNA were applied. Their chromosomes were accurately identified by sGISH and rDNA-FISH signals. Both species had the karyotype formula 2n = 22 = 18m + 4m-SAT, but the karyotype of was shorter and more asymmetric than that of . They displayed similar CPD bands at all 45S rDNA sites and centromeres. had ten centromeric 5S rDNA loci and two SC (secondary constriction)-associated 45S rDNA loci. had nine centromeric and one interstitial 5S loci, two SC-associated and one proximal 45S loci. Their sGISH signal patterns displayed both basic similarities and distinct differences. Reciprocal cGISH generated prominent signals in all pericentromeric regions and 45S sites. There was lower level of sequence identity of the non-transcribed spacer between their 5S rDNA repeats. These data confirmed the evolutionary closeness between and and demonstrated obvious differentiation between their genomes, and supported the opinion that is more advanced in evolution than .
基于形态学和分子系统发育数据，两种栽培种（Adanson，1763年）、（N. J. von Jacquin，1788年）A. P. de Candolle，1825年和（Linnaeus，1753年）A. P. de Candolle，1825年关系密切。然而，它们之间基因组组织的异同尚未在分子细胞遗传学水平上进行评估。在此，使用碘化丙啶（PI）和4',6-二脒基-2-苯基吲哚（DAPI）联合染色（CPD）、核糖体DNA荧光原位杂交（rDNA-FISH）和自身基因组杂交（sGISH）构建了这两个物种的详细核型。为了进一步比较，应用了比较基因组杂交（cGISH）和5S核糖体DNA的序列分析。通过sGISH和rDNA-FISH信号准确识别了它们的染色体。两个物种的核型公式均为2n = 22 = 18m + 4m-SAT，但的核型比的更短且更不对称。它们在所有45S核糖体DNA位点和着丝粒处显示出相似的CPD带。有10个着丝粒5S核糖体DNA位点和2个与次缢痕（SC）相关的45S核糖体DNA位点。有9个着丝粒和1个居间5S位点、2个与SC相关的和1个近端45S位点。它们的sGISH信号模式既有基本相似性也有明显差异。相互cGISH在所有着丝粒周围区域和45S位点产生显著信号。它们5S核糖体DNA重复序列之间的非转录间隔区的序列同一性水平较低。这些数据证实了和之间的进化亲缘关系，并表明它们的基因组之间存在明显分化，支持了在进化上比更高级的观点。
