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    高温诱导银灰杨花粉败育的细胞学机理研究

    Cytological mechanism of pollen abortion induced by high temperature in Populus canescens

      摘要
    • 摘要:
        目的  研究高温处理对银灰杨小孢子发生的影响，揭示高温处理导致杨树花粉败育的细胞学机理，旨在完善高温处理诱导配子染色体加倍、选育林木三倍体的技术。
        方法  本研究以银灰杨为试验材料，利用38 ℃和41 ℃的高温，对不同减数分裂时期的银灰杨花粉母细胞进行3、6 h处理，研究处理温度、减数分裂时期以及持续处理时间对败育花粉比率的影响。在此基础上，通过比较未经高温处理和高温处理后银灰杨花粉母细胞减数分裂染色体行为、微管骨架动态变化以及减数后绒毡层细胞发育的差异，揭示高温处理诱导银灰杨花粉败育的细胞学机理。
        结果  （1）减数分裂时期、处理温度、持续处理时间以及减数分裂时期与处理温度、减数分裂时期与持续处理时间的交互作用均对败育花粉比率具有极显著的影响。41 ℃高温于中期Ⅰ持续处理3 h的败育花粉比率最高，为（25.11 ± 4.28）%。（2）与对照组相比，银灰杨雄花芽经高温处理后，花粉母细胞减数分裂微管骨架表现出不同程度的解聚，中期Ⅰ和中期Ⅱ的部分纺锤体微管缺失，致使后期Ⅰ和后期Ⅱ的同源染色体或姊妹染色单体分离异常，产生大量的落后染色体。这些落后染色体被遗弃在细胞质中，引起微核的产生，四分体时期形成多分体而导致花粉败育。（3）高温处理可导致银灰杨花药绒毡层退化延迟，但仍能正常开裂，释放出花粉粒，因此绒毡层延迟退化不是高温处理诱导银灰杨花粉败育的原因。
        结论  高温处理诱导银灰杨花粉母细胞中期Ⅰ和中期Ⅱ的部分纺锤体微管缺失，致使后期Ⅰ和后期Ⅱ产生大量的落后染色体，引起大量多分体的产生，是高温处理诱导银灰杨花粉败育的细胞学机理。

       

      Abstract:
        Objective  The effects of high temperature on microsporogenisis and cytological mechanism of pollen abortion induced by high temperature were conducted in P. canescens, aiming at improving the technology of forest triploid breeding though inducing gamete chromosme doubling by high temperature.
        Method  In this study, the effects of high temperature, meiotic stage and duration on percentage of aborted pollen were conducted after male flower buds being exposed to 38 ℃ for 3 or 6 h in P. canescens. Subsequently, the differences in chromosome behaviour, meiotic microtubule cytoskeleton and development of tapetum between untreated pollen mother cells (PMCs) and treated PMCs were studied to reveal the cytological mechanism of aborted pollen production induced by high temperature.
        Result  (1) Meiotic stages, temperature, duration, meiotic stage × temperature interactions and meiotic stage × duration interactions had significant effects on percentage of aborted pollen. The highest percentage of aborted pollen was (25.11 ± 4.28)% when PMCs were treated with 41 ℃ for 3 h at metaphase Ⅰ. (2) Compared with PMCs in the control group, meiotic microtubule cytoskeleton was depolymerized and some spindles were lost within the PMCs at metaphase Ⅰ and Ⅱ, leading to the abnormal chromosome segregation at anaphase Ⅰ and Ⅱ and forming a great number of lagging chromosomes. These lagging chromosomes were retained within cytoplasm, causing some micronuclei to form. Therefore, aborted pollen formed due to the formation of polyads at tetrad stage. (3) Although high temperature could also delay the degradation of the tapetum, the anthers normally dehisced and pollen grains were released. Thus, the delayed degradation of the tapetum was not responsible for the formation of aborted pollen.
        Conclusion  After male flower buds being treated by 38 ℃ for 3 or 6 h, some spindles are lost within the PMCs at metaphase Ⅰ and Ⅱ, leading to form a great number of lagging chromosomes and polyads, which is the cytological mechanism of aborted pollen formation induced by high temperature.

       

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