【摘要】 刚从小孢子囊中散发出的银杏GinkgobilobaL .成熟花粉为圆球形 ,具有巨大的单一萌发区。萌发区由两部分半圆形的、几近垂直的外壁围成。除萌发区外 ,花粉的外壁被有较致密的不规则的纹理和小刺。当花粉在空中或冷储条件下滞留一段时间后 ,即转变为两侧对称的船形 ,但在培养液中又很快转变为近圆球形。离体和活体实验都表明 ,银杏雄配子体萌发初期 ,管核都转过了一定的角度 ,并继而发生侧向萌发 ,但没有活性的花粉除变为圆球形外无其他变化。这些表明 ,花粉管的内部特征决定了银杏雄配子体侧向萌发的典型特征。这一稳定的生物学特性 ,加上银杏花粉的特殊形态特征 ,与苏铁属、松属等有明显的区别。这可能是银杏特殊系统位置的一个关键特征。更多还原

【Abstract】 WT5BZ]The four celled mature pollen of Ginkgo biloba L. just shed from the microsporangia, was round in shape and contained a very large germination area with monosulcate sulcus walled with two semicircular and nearly perpendicular parts of exine, and the pollen was coated with a compact irregular striations and spinules in parts other than the germination area. The pollen became boat shaped and was bilaterally symmetrical when it was in air or under cold storage, but rapidly rounded off in cultural solution. Studies on early morphogenesis of the male gametophyte in vitro and in vivo revealed that the tube nucleus turned a certain degree of angle, and was followed by lateral germination, while the non active pollen maintained its round shape. The results suggest that the internal feature of the pollen tube could be a determinant factor contributing to the expression of the characteristic events of lateral germination of the male gametophyte in G.biloba . Furthermore, this biologically consistent character, together with the characteristic pollen morphology, is quite different from those of other groups in gymnosperms such as Cycas and Pinus . This might be a critical character relevant to the systematic position of G.biloba . [WT5HZ]更多还原