Department of Agronomy, Kansas State University, 66506, Manhattan, KS, USA.
Theor Appl Genet. 1988 Aug;76(2):277-84. doi: 10.1007/BF00257856.
The genomic relationship between cultivated sorghum [Sorghum bicolar (L.) Moench, race bicolor, De Wet, 2n=20] and Johnsongrass [S. halepense (L.) Pers., 2n=40] has been a subject of extensive studies. Nevertheless, there is no general consensus concerning the ploidy level and the number of genomes present in the two species. This research tested the validity of four major genomic models that have been proposed previously for the two species by studying chromosome behaviors in the parental species, 30-chromosome hybrids [sorghum, (2n=20) x Johnsongrass, (2n=40)], 40-chromosome hybrids [sorghum, (2n=40) x Johnsongrass, (2n=40)] and 60-chromosome amphiploids. Chromosome pairings of amphiploids are reported for the first time. Chromosomes of cultivated sorghums paired exclusively as 10 bivalents, whereas Johnsongrass had a maximum configuration of 5 ring quadrivalents with occasional hexavalents and octovalents. In contrast, 40-chromosome cultivated sorghum had up to 9 ring quadrivalents and 1 hexavalent. Pairing in the 30-chromosome hybrids showed a maximum of 10 trivalents, and that in the 40-chromosome hybrids exhibited 8 quadrivalents, 5 of which were rings, together with a few hexavalents. Amphiploid plants showed up to 3 ring hexavalents, 1 chain hexavalent and a chain of 12 chromosomes. The data suggest that cultivated sorghum is a tetraploid species with the genomic formula AAB1B1, and Johnsongrass is a segmental auto-allo-octoploid, AAAA B1B1B2B2. The model is further substantiated by chromosome pairing in amphiploid plants whose proposed genomic formula is AAAAAA B1B1B1B1 B2B2.
栽培高粱[Sorghum bicolar（L.）Moench，race bicolor，De Wet，2n=20]和约翰逊草[S. halepense（L.）Pers.，2n=40]之间的基因组关系一直是广泛研究的课题。然而，关于这两个物种的倍性水平和基因组数量，尚无普遍共识。本研究通过研究亲本物种[20 染色体高粱（2n=20）x 40 染色体约翰逊草（2n=40）]、30 染色体杂种[20 染色体高粱（2n=20）x 40 染色体约翰逊草（2n=40）]、40 染色体杂种[40 染色体高粱（2n=40）x 40 染色体约翰逊草（2n=40）]和 60 染色体双二倍体中染色体行为，检验了先前提出的用于这两个物种的四个主要基因组模型的有效性。首次报道了双二倍体的染色体配对。栽培高粱的染色体仅作为 10 对二价体配对，而约翰逊草的最大构型为 5 个环状四价体，偶尔出现六价体和八价体。相比之下，40 染色体栽培高粱的最高可达 9 个环状四价体和 1 个六价体。30 染色体杂种的配对显示最大为 10 个三价体，而 40 染色体杂种的配对显示 8 个四价体，其中 5 个是环，还有一些六价体。双二倍体植物显示最多 3 个环状六价体、1 个链状六价体和 12 条染色体的链。数据表明，栽培高粱是一个四倍体物种，基因组公式为 AAB1B1，约翰逊草是一个节段性自交八倍体，AAAAA B1B1B2B2。该模型进一步通过双二倍体的染色体配对得到证实，其提出的基因组公式为 AAAAAA B1B1B1B1 B2B2。
