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首页> 外文期刊>Journal of genetics >Meiotic behaviour in three interspecific three-way hybrids between Brachiaria ruziziensis and B. brizantha (Poaceae: Paniceae)
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Meiotic behaviour in three interspecific three-way hybrids between Brachiaria ruziziensis and B. brizantha (Poaceae: Paniceae)

机译：臂形臂孢菌和B. brizantha（禾本科：Paniceae）之间的三种种间三通杂种的减数分裂行为

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The meiotic behaviour of three three-way interspecific promising hybrids (H17, H27, and H34) was evaluated. These hybrids resulted from the crosses between B. ruziziensis ?— B. brizantha and crossed to another B. brizantha. Two half-sib hybrids (H27 and H34) presented an aneuploid chromosome number ($2n = 4x = 33$), whereas hybrid H17 was a tetraploid ($2n = 4x = 36$), as expected. Chromosome paired predominantly as multivalents suggesting that genetic recombination and introgression of specific target genes from B. brizantha into B. ruziziensis can be expected. Arrangement of parental genomes in distinct metaphase plates was observed in H27 and H34, which have different male genitors. Hybrids H17 and H34 have the same male genitor, but did not display this abnormality. In H17, abnormalities were more frequent from anaphase II, when many laggard chromosomes appeared, suggesting that each genome presented a different genetic control for meiotic phase timing. Despite the phylogenetic proximity among these two species, these three hybrids presented a high frequency of meiotic abnormalities, mainly those related to irregular chromosome segregation typical of polyploids, H34, 69.1%; H27, 56.1% and H17, 44.9%. From the accumulated results obtained through cytological studies in Brachiaria hybrids, it is evident that cytogenetical analysis is of prime importance in determining which genotypes can continue in the process of cultivar development and which can be successfully used in the breeding. Hybrids with high frequency of meiotic abnormalities can seriously compromise seed production, a key trait in assuring adoption of a new apomictic cultivar of Brachiaria for pasture formation.
机译：评价了三个三向种间有希望的杂种（H17，H27和H34）的减数分裂行为。这些杂种是由芸苔芽孢杆菌（B. ruziziensis）B-布里赞萨（B. brizantha）之间的杂交产生的，并与另一种枯萎芽孢杆菌（B. brizantha）杂交。正如预期的那样，两个半同胞杂种（H27和H34）表现出非整倍体染色体编号（$ 2n = 4x = 33 $），而杂种H17是四倍体（$ 2n = 4x = 36 $）。主要配对为多价体的染色体表明，可以预期特定目标基因的遗传重组和基因渗入，可以将其从B. brizantha引入B. ruziziensis。在H27和H34中观察到亲本基因组在不同的中期板中的排列，它们具有不同的雄性祖细胞。杂种H17和H34具有相同的雄性祖先，但没有表现出这种异常。在H17中，后期II出现了许多落后的染色体，异常现象更加频繁，这表明每个基因组对减数分裂相位的计时都表现出不同的遗传控制。尽管这两个物种在系统发育上接近，但这三个杂种表现出较高的减数分裂异常频率，主要与多倍体典型的不规则染色体分离有关，H34，占69.1％。 H27占56.1％，H17占44.9％。从通过臂虫杂种的细胞学研究获得的累积结果来看，很明显，细胞遗传学分析对于确定哪些基因型可以在品种开发过程中继续进行以及哪些可以成功用于育种至关重要。减数分裂异常频率高的杂种会严重损害种子产量，这是确保采用新的腕足无融合生殖栽培种来形成牧场的关键特征。

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