玉帘离体萌发花粉管中生殖细胞核的有丝分裂和无丝分裂

MITOSIS AND AMITOSIS OF GENERATIVE CELL NUCLEI IN ARTIFICIALLY GERMINATED POLLEN TUBES IN ZEPHYRANTHES CAN DIDA (LINDL.) HERB

应用 DAPI—DNA 荧光显微术观察了玉帘【Zephyranthes candida(Lindl.)Herb.】人工萌发花粉管中生殖细胞核有丝分裂前后营养核的形态变化及其与前者的空间联系,着重研究了低温预处理诱导生殖细胞核无丝分裂和异常有丝分裂的现象。正常条件下,生殖细胞和营养核贴合后开始进行有丝分裂,这期间营养核弥散、延伸。精子形成后,营养核逐渐恢复原来状态。花粉经低温预处理后萌发的花粉管中,部分生殖细胞核进行无丝分裂,此时观察不到前述营养核的形态变化及其与生殖细胞的贴合。形成的精细胞核也可进一步发生无丝分裂以及形成微核的现象。低温预处理亦诱导了部分生殖细胞核进行异常有丝分裂。

This paper deals with the comportment of the vegetative nucleus and its spatial association, with the generatrve cell and sperm cells in the artificially germinated pollen tubes of Zephyran- thes candida (Lindl.) Herb. before and after generative cell mitosis with the use of DNA-speci- fic fluochrome 4',6-diamidino-2-phenylindole (DAPI). The induction of auaitosis and abnormal mitosis of generative cell nuclei by cold-pretreatment of the pollen prior to germination was stu- died in particular. In normal case, the generative cell, after appressing to the vegetative nucleus for certain time, underwent mitosis to form two sperms, while the vegetative nucleus became markedly elongated,, diffused, and exhibited blurring of its fluorescence. After division, a pair of sperms remained shortly in close connexion with the vegetative nucleus. Then the vegetative nu- cleus returned to its original state. In the pollen tubes germinated from cold-pretreated pollen, amitosis of some generative cell nuclei were frequently observed. Amitosis took place via either equal or unequal division with a mode of constriction. During amitosis, the dynamic change of vegetative nucleus and its intimate association with generative cell afore described did not occur. Sperm nuclei produced from amitosis could further undergo amitisis resulting in micronuclei. Factors affecting the amitosic rate of generative cells, such as pollen developmental stage, tem- perature and duration of cold-pretreatmen^+, were studied. Besides amitosis, cold-pretreatment also induced some abnormal mitotic behavior leading to the formation of micronuclei. Based on our observations and previously reported facts in other plant materials, i^+ is inferred that the ve- getative nucleus plays an important role in normal mitosis of generative cell and development of sperms.