Correlations between microsporogenesis and male cone development of Cunninghamia lanceolata

  Objective  This paper aims to explore the relationship between the meiosis process of Cunninghamia lanceolata microspore mother cell and the external morphological change of male cone, so as to provide references for further research on reproductive biology of C. lanceolata.

  Method  We selected the male cones of C. lanceolata as the material, and studied the process of meiosis of C. lanceolata microspore mother cell and development of male cones using the digital camera, stereoscope and the acetate magenta staining method.

  Result  The male cone of C. lanceolata was born on the top of new branch and was covered by bud scales. With the meiosis process of C. lanceolata microspore mother cells to carry out, the bud scales of male cone gradually open, the volume of the microsporophyll increased and gradually elongated beyond the bud scales eventually squeezing the bud scales of male cone to falling off. In addition, the color and size of the microsporophyll also varied markedly: the color changed from emerald green, yellow green, yellow brown, and finally to reddish brown; its length ranged from 3.278 to 5.229 mm, and diameter ranged from 2.626 to 3.868 mm. The observation of meiosis process of Chinese fir showed that the chromosome behavior of microspore mother cells was abnormal, such as the lagging chromosomes in the metaphase I of meiosis, the non-synchronous division of the late I and late II chromosomes, and the unequal division was observed in the tetrad stage, such as the diploid and the triad. The development of male cones in different positions was not synchronous; the meiosis process of different microspore leaves of the same male cone and the microspore mother cells of the same microspore leaf were also different, and the whole meiosis process lasted about 3 d.

  Conclusion  The meiosis process of C. lanceolata microspore mother cell is closely related to the change in external morphology and the microsporophyll color and size of male cone, and there are chromosomal abnormalities in its process of meiosis.