Chromosomal behaviour during megasporogenesis and microsporogenesis has been studied in ornamental Delphinium ajacis L. Meiosis in female sex cell initiates later than male. The floral buds which carry egg mother cell (EMC) at diplotene stage has pollen mother cells (PMCs) at tetrad stage of meiosis suggesting protandry. Although the 16 chromosomes formed regular eight bivalents in both the sex cells, they differed in overall chiasma frequency which was 32.95% higher in EMCs and found to be 18.52 ± 2.12 per cell. In PMCs, the average chiasma frequency recorded was 13.93 ± 1.40 per cell. Interestingly, this variation in chiasma frequency was largely confined to the two large bivalents which shared 42.61% chiasma per EMC. The use of Q–Q plot, Box plot and Whisker plot showed departure in the chiasma frequency distributions in EMCs and PMCs from the normal distribution pattern. The difference in chiasma frequency in the two sex cells was significant at all levels as indicated by the low P values of 3.094 × 10−11 obtained from nonparametric test, i.e. Wilcoxon rank-sum test. It is suggested that the two different mechanisms of recombination are operational in the two sex cells, and the sex differences of chiasma frequency could have arisen due to differential epigenetic modifications of the chromatin which pattern the double-strand breaks, and the position and frequency of crossing over visible as chiasmata.

中文翻译：

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雄性和雌性减数分裂在交叉形成中表现出差异模式：以观赏植物 Delphinium ajacis L 为例。

已在观赏翠雀 (Delphinium ajacis L) 中研究了大孢子发生和小孢子发生过程中的染色体行为。雌性性细胞的减数分裂比雄性晚。在双线期携带卵母细胞 (EMC) 的花芽在减数分裂的四分体期具有花粉母细胞 (PMC)，表明前行。尽管这 16 条染色体在两个性细胞中形成了规则的 8 个二价体，但它们的整体交叉频率不同，在 EMC 中高 32.95%，发现每个细胞为 18.52 ± 2.12。在 PMC 中，记录的平均交叉频率为每个细胞 13.93 ± 1.40。有趣的是，这种交叉频率的变化主要限于两个大的二价化合物，每个 EMC 具有 42.61% 的交叉。使用Q-Q图，箱线图和胡须图显示 EMC 和 PMC 中的交叉频率分布偏离正态分布模式。从非参数检验（即 Wilcoxon 秩和检验）获得的 3.094 × 10-11 的低 P 值表明，两种性别细胞中交叉频率的差异在所有水平上均显着。这表明两种不同的重组机制在两个性细胞中起作用，交叉频率的性别差异可能是由于染色质的差异表观遗传修饰导致双链断裂，以及交叉频率的位置和频率。交叉可见为交叉。094 × 10−11 从非参数检验获得，即 Wilcoxon 秩和检验。这表明两种不同的重组机制在两个性细胞中起作用，交叉频率的性别差异可能是由于染色质的差异表观遗传修饰导致双链断裂，以及交叉频率的位置和频率。交叉可见为交叉。094 × 10−11 从非参数检验获得，即 Wilcoxon 秩和检验。这表明两种不同的重组机制在两个性细胞中起作用，交叉频率的性别差异可能是由于染色质的差异表观遗传修饰导致双链断裂，以及交叉频率的位置和频率。交叉可见为交叉。