东乡野生稻与栽培稻正反交种间杂种F_1的雄配子发生与发育

Cytological Studies of Male Gametogenesis and Development in the Reciprocal Interspecific Hybrid F_1 of Dongxiang Wild Rice (Oryza rufipogon) and Oryza sativa

该文以东乡野生稻与栽培稻(美国光壳稻P1003)的正反交种间杂种F1(正交为光壳稻P1003×东乡野生稻;反交为东乡野生稻×光壳稻P1003)为试材,研究其各个减数分裂时期的染色体行为特征、染色体交换重组及雄配子发育特点。结果表明:正反交杂种F1花粉母细胞细胞核减数分裂的同步性较高,细胞质为连续型胞质分裂类型。在细胞核分裂的过程中,核仁在前期I到中期I逐渐消失。染色体在前期I到中期I逐渐收缩,变得更加清晰可见。在终变期和中期I,90.54%以上的花粉母细胞能形成12个二价体(含少数棒状二价体和8字型二价体),部分花粉母细胞(正交9.46%,反交7.65%)出现少量的单价体、三价体和四价体。后期I观察到1.27%–1.35%的花粉母细胞含有1至数条落后染色体。最终有92.6%–94.8%的小孢子能发育成形态正常、染色能力强的成熟花粉粒。另外,在正交杂种F1的粗线期中存在2个核仁,而反交杂种F1及其双亲的粗线期只有1个核仁。这些研究结果可为作物品种改良、种质资源创新以及种间亲缘关系研究提供细胞学证据。

The reciprocal interspecific hybrid F1 from Oryza sativa L.（smooth indica rice P1003 of USA） crossed with Dongxiang wild rice（Oryza rufipogon Griff.） was used to investigate the meiosis behavior,chromosome recombination,and characteristics of male gametophytes.The pollen mother cells（PMCs） of the reciprocal interspecific hybrid F1 showed successive cytokinesis and a relatively higher synchronization in nuclear division.The nucleolus disappeared gradually from prophase I to metaphase I.With condensation of chromatins,chromosomes became more identifiable from pro-phase I to metaphase I.At diakinesis and metaphase I,90.5% of PMCs could form 12 bivalent chromosome configura-tions,including a few bar-bivalents and ＂8＂-shaped bivalents.Low frequency univalents,trivalents and tetravalents were observed in other PMCs（9.46% PMCs in the original cross;7.65% PMCs in the reciprocal cross）.At anaphase I,one or more lagging chromosomes were observed in 1.27%–1.35% of PMCs.Finally,92.6%–94.8% of microspores could de-velop into normal and stainable pollen grains.In addition,2 nucleoli were observed in P1003 × Dongxiang wild rice at prophase I.However,Dongxiang wild rice × P1003 and their parents had only one nucleolus.These results provide cy-tological evidence for crop enhancement and phylogenic relationships of rice.