Meiotic behavior was analyzed in 6 progenies from 3 artificially induced tetraploid (2n = 4x = 36) sexual genotypes (C31, C41, and C48) of the normally apomicticBrachiaria brizantha (Hochst. ex A. Rich.) Stapf., syn.Urochloa brizantha (Hochst. ex A. Rich.) R. Webster. These are key plants to allow intraspecific hybridization of this important forage species, widely used for pastures in the tropics. The percentage of abnormal cells among the plants ranged from 39.8% to 63.2%. In the single plant derived from C48, only the common meiotic abnormalities typical of polyploids were observed, while in plants derived from C31 and C41, a distinct behavior was found. In the majority of cells of those plants, the chromosomes remained scattered in the cytoplasm in the first division, without forming a metaphase plate. This abnormality blocked chromosome movements at anaphase I. Several micronuclei of various sizes were formed and, after the occurrence of an irregular first cytokinesis, the meiocytes progressed normally to the second division, generating polyads with unbalanced microspores. Pollen viability was not correlated with meiotic abnormalities. The importance of these findings to theBrachiaria breeding program is discussed. The sexual progeny of C48 seems most suitable as female parents to be used in intra-and interspecific hybridization.

中文翻译：

---

秋水仙碱诱导的 Brachiaria brizantha（禾本科）四倍体基因型的异常减数分裂：其对育种的影响。

分析了来自 3 个人工诱导的四倍体 (2n = 4x = 36) 有性基因型（C31、C41 和 C48）的正常无融合生殖 Brachiaria brizantha（Hochst. ex A. Rich.）Stapf. 的6 个后代的减数分裂行为。紫菖蒲（Hochst。前 A. Rich。）R. 韦伯斯特。这些是允许这种广泛用于热带牧场的重要草料物种进行种内杂交的关键植物。植物中异常细胞的百分比在39.8%到63.2%之间。在源自 C48 的单一植物中，仅观察到多倍体典型的常见减数分裂异常，而在源自 C31 和 C41 的植物中，发现了不同的行为。在这些植物的大多数细胞中，染色体在第一次分裂时仍然分散在细胞质中，没有形成中期板。这种异常阻止了后期 I 的染色体运动。形成了几个不同大小的微核，在发生不规则的第一次胞质分裂后，性母细胞正常进行第二次分裂，产生具有不平衡小孢子的多聚体。花粉活力与减数分裂异常无关。这些发现对研究的重要性讨论了臂形虫育种计划。C48 的有性后代似乎最适合作为用于种内和种间杂交的母本。