Searching for mechanisms behind meiotic abnormalities in Crotalaria spectabilis Roth

ABSTRACT The identification of epigenetic marks associated with problems in the meiotic process can enlighten the mechanisms underlying the irregularities and the impacts in the genetic constitution of gametes. Therefore, this study aimed to verify the relationship between the pattern of phosphorylation in serine 10 of histone H3 (H3S10ph), a (peri) centromeric epigenetic mark, with meiotic abnormalities in a wild population of Crotalaria spectabilis Roth. The main abnormalities observed were transfer of genetic material through cytoplasmatic connections, DNA elimination and abnormal spindle array. Different forms of elimination (chromatin fragmentation, ring formation, lagging chromosomes and micronuclei) were observed from the early phases until tetrad formation. The eliminated chromatin was either positive or negative for the immunosignal of H3S10ph, so it may be occurring elimination of acentric fragments, as well as of chromosomes with active or inactive centromeres. Therefore, dysfunctional centromere is not the only candidate cause for elimination. The transfer of genetic material and the abnormal spindle arrays are evidence that this population can produce aneuploid gametes and 2n pollen grains.

摘要 鉴定与减数分裂过程异常相关的表观遗传标记，可为阐明此类异常的潜在分子机制及其对配子遗传组成的影响提供理论依据。为此，本研究旨在验证组蛋白H3丝氨酸10磷酸化（H3S10ph）——一种（近）着丝粒表观遗传标记——的分布模式与美丽猪屎豆（Crotalaria spectabilis Roth）野生种群的减数分裂异常之间的关联。本次观测到的主要减数分裂异常包括通过细胞质连接进行的遗传物质转移、染色质消除以及纺锤体阵列异常。从减数分裂早期直至四分体形成阶段，均观察到多种形式的染色质消除现象，涵盖染色质片段化、环结构形成、滞后染色体及微核形成。被消除的染色质对H3S10ph的免疫信号呈阳性或阴性，提示该消除过程可能同时涉及无着丝粒片段的清除，以及着丝粒活化或失活的染色体的清除。由此可见，功能异常的着丝粒并非导致染色质消除的唯一潜在诱因。遗传物质转移与纺锤体阵列异常均表明，该野生种群可产生非整倍体配子与二倍体花粉粒。