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杉木[(Cunninghamia lanceolata (Lamb.) Hook)]是我国特有的用材林树种,是南方各省区最重要的乡土造林树种之一,我国人民使用杉木的历史逾8 000年[1]。因此,对杉木进行持续、多目标的遗传改良,对于提高杉木遗传增益,培育多用途杉木品种具有重要意义。
杉木种子园是生产杉木良种的主要单元,也是进行杉木育种的重要载体,开展种子园人工控制授粉和遗传评价,建立世代清晰的高世代种子园和高改良轮次种子园是有效利用杉木遗传增益并保持种子园较高遗传基础的途径,为了充分发挥种子园的效能,育种工作者对杉木生殖发育、花粉散布规律进行了研究,对杉木大小孢子发育进程有较为完整的了解。而杉木在长期的进化过程中,为适用各地的气候,导致不同种源之间物候期的特征差异较大[2],四川是杉木分布的西部核心分布区,与东部和中部分区的杉木在物候上存在差异,而四川杉木减数分裂时期,小孢子叶球与小孢子发育的行为特征未见报道,杉木雄球花采集过早,小孢子尚处于发育阶段,干燥过程中容易失活死亡,采完了,则花粉开始散落,收集效果不佳。
以四川杉木种子园为研究对象,对同一小孢子叶球、同一小孢子叶上花粉的发育成熟状态进行了研究,并比较了不同基因型杉木花粉散布时期,以期为杉木杂交授粉中的花粉精准采收奠定基础。
Development Characteristics of Chinese Fir Microspores and its Application in Cross Breeding
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摘要: 以四川杉木种子园母株为试验材料,观察春季雄球花和小孢子叶球外部形态发育与小孢子发育的对应关系,结果表明,同一个小孢子叶球上的小孢子叶发育基本同步;小孢子叶的颜色和长度与小孢子发育极其相关,小孢子叶球整体呈青色、长5 mm时,其内部小孢子基本处于四分体时期;当小孢子叶之间的鳞片失水变黄、小孢子囊壁变为淡黄色时,其内部小孢子基本处于单核靠边期,采集小孢子叶球为此状态的雄球花,在干燥温室中放置12~24 h后,能收获大量成熟的、活力旺盛的花粉。Abstract: Using the mother plant of Sichuan Cunninghamia lanceolata seed orchard as the test material, the corresponding relationship between the external morphological development of spring male cones, microstrobilus and the development of microspores were observed. The results showed that the development of microsporophyll on the same microstrobilus was basically synchronized. The color and length of microsporophyll were closely related to the development of microspores. When the whole microstrobilus was blue and up to 5 mm long, the internal microspores were basically in the tetrad stage. When the scales among the microsporophylls lost water and turned yellow and the wall of the microsporangia turned light yellow, the internal microspores were basically at the stage of mononuclear. After collecting the male cones with the microstrobiluses in this state and placing them in a dry greenhouse for 12—24 hours, a large number of mature and vigorous pollen could be harvested.
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图 1 杉木小孢子发育进程(A,D:体式显微镜拍摄;B,C,E:醋酸洋红染色;F:花粉粒明场)
A:四分体时期小孢子叶球形态;B:四分体时期;C:单核中间期;D:单核中间期小孢子叶球形态;E:单核靠边期,左侧花粉可见中央大液泡;标尺=40 μm。
Fig. 1 Development process of Chinese fir microspores (A, D: Stereomicroscope; B, C, E: Acetate magenta staining; F: Bright field of pollen grains).
A: Morphology of microstrobilus at the tetrad stage; B: Tetrad stage; C: Mononuclear intermediate stage; D: Morphology of microstrobilus in the mononuclear intermediate stage; E: Mononuclear at the side stage, left pollen has large vacuoles; F: Mature pollen. Ruler=40 μm.
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