The evolution of fertilization modes independent of the micropyle in Fagales and `pseudoporogamy'
The evolution of fertilization modes independent of the micropyle in Fagales and `pseudoporogamy'
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DOI：
10.1007/s00606-006-0409-x
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发表时间：
2006-05
影响因子：
1.9
通讯作者：
A. Sogo;H. Tobe
中科院分区：
文献类型：
--
作者：
A. Sogo;H. Tobe
与大多数被子植物显示孔花受精相反，已知几个壳斗科如桦木科和木麻黄科显示合点受精，其中受精是由花粉管穿过合点而不是珠孔来实现的。我们对杨梅（杨梅科，壳斗目）雌蕊中花粉管生长的发育研究进一步表明，花粉管在珠孔由珠被形成之前就到达了珠心。由于受精胚珠的出现就像是花粉管穿过珠孔进行受精，我们提出了一个新的术语“假受精”。通过绘制依赖或独立于珠孔的不同受精方式在壳斗目系统发育树上的分布图，发现受精方式从孔配到合点配，再从合点配到假孔配。本文还讨论了壳斗目受精方式独立于珠孔演化的可能原因。
In contrast to a majority of angiosperms showing porogamous fertilization, several fagalean families such as Betulaceae and Casuarinaceae are known to show chalazogamy, where fertilization is effected by a pollen tube passing through the chalaza instead of the micropyle. Our developmental study of pollen-tube growth in pistils ofMyrica rubra(Myricaceae, Fagales) further shows that pollen tubes reached the nucellus before the micropyle is formed by the integument. Since fertilized ovules appeared as if the pollen tube had passed through the micropyle for fertilization, we propose the new term `pseudoporogamy' to this mode. By mapping diverse modes of fertilization, dependent or independent of the micropyle, onto a phylogenetic tree of Fagales, it appears that fertilization mode evolved from porogamy to chalazogamy and then further from chalazogamy to pseudoporogamy. Possible reasons for the evolution of fertilization modes independent of the micropyle in Fagales are discussed.