橡胶树双受精作用的研究

Double Fertilization of Hevea brasiliensis

采用石蜡切片、苏木精和孚尔根等杂色法，对橡胶树的双受精过程作了详细的观察。结果表明：（1）授粉后0．5－1h花粉粒开始在柱子头上萌发。随后花粉管沿着花柱的引导组织往下生长．12h后经珠心喙进入胚囊，释放内含物。（2）卵细胞受精过程为：授粉后13－13．5h，精子贴附在卵细胞的质膜上．随后进入卵核．染色质散开和出现雄性核仁。20h后两性核仁融合，形成合一个核仁的受精卵。橡胶树的受精作用属有丝分裂前型。（3）极核受精过程与卵细胞受精类似，但完成较快，授粉后18h便完成受精。极核受精是3个核的融合过程，由于各核结合的先后差异．有3种不同的类型：①两极核先融合成含一个核仁的次生核，然后次生核与精核融合。②两极核先融合，但两者的核仁未融合，因此形成一个含二核仁的次生核。这样的次生核，当与精核的校质融合并出现雄性核仁后．次生核的两个核仁才融合成一个次生核仁。然后才和雄性核仁融合。③上极核先与精核融合．然后才和下极核融合。这3种受精类型．其所形成的初生胚乳核，均含一个核仁。

The process of Heven double fertilization was observed via paraffin sections staining with haematoxylin and feulgen reaction, and the results are as follows: An half to one hour after pollination, the pollen grains germinated and then the pollen tubes grew down the transmitting tissues in the style. After 12 hours, the pollen tubes ran through the nucellar beak to the embryo sac and released the contents with two sperms. Egg cell fertilization. The sperms were attached to the egg cell plasma membrane after l3h to l3. 5h of pollination, and then entered into the egg nucleus. The sperm chr0matin showed disper- sion and the male nucleolus appeared. The male and female nucleoli were combined and fused to form a single nucleolus, and the egg cell came to be fertilized after 20 hours. The fertilization 0fHe vea is of premit0sis type. The P0lar nucleus fertilization is similar to the egg cell fertilizati0n, but it pr0ceeds quickly and is finished in 18 hours after Poll ination. Because the Polar nucleus fertilization is a kind of three - nucleus fusion, and the joining sequence of each nucleus is different, resulting in three types of polar nucleus fertilization: (1 ) (P + P) + S - a type. The two polar nuclel fuse thoroughly to forrn a completely fused secondary nucleus Which contains one nucleolus, and then the sec0ndary nucleus fuses with thesperm; (2) (P + P) + S - b type. The two polar nuclei are fused without immediate combination of two nucleoli to form an incompletely fused secondary nucleus which contains two nucle01i. The two nucleoli do not join each other to form one secondary nucleolus untill the sperm nucleus enters into the sec0rdary nucleus to form a male nueleolus. The secondary nucleolus, when formed, fuses with the male nucleolus; (3) (P + S) + P type. The upper polar nucleus fuses with the sperm nucleus and then with an- other polar nucleus (the lower one). For all the three types of the polar nucleus fertilization, the resultant primary end0sperm nucleus contains only one nucleolus.