Sogo Akiko, Jaffré Tanguy, Tobe Hiroshi
Department of Botany, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan.
J Plant Res. 2004 Jun;117(3):249-51. doi: 10.1007/s10265-004-0148-4. Epub 2004 Mar 20.
A unique mode of fertilization called "chalazogamy", whereby the pollen tube passes through the chalaza instead of the micropyle, is known in several species of derived genera in Casuarinaceae. In this paper we report the occurrence of chalazogamy in Gymnostoma ( G. poissonianum), the most primitive genus in the family. We also show that the pollen tube grows discontinuously from the stigma to ovules in about 3 months. At the time of pollination, the ovules have not yet formed in the ovary, and require a long time to develop. The pollen tube(s) lie in a zigzag line and are branched in the upper region of the style, and their growth is arrested there until the ovary develops further. Studies of the relevant literature further revealed discontinuous pollen-tube growth in relation to a prolonged period between pollination and fertilization, as well as chalazogamy, in Betulaceae, Juglandaceae and/or Fagaceae that are closely related to Casuarinaceae. This feature may have derived early in the evolution of Fagales.
一种名为“合点受精”的独特受精方式，即花粉管穿过合点而非珠孔，在木麻黄科几个衍生属的物种中存在。在本文中，我们报道了该科最原始的属——裸孔木属（泊氏裸孔木）中合点受精的发生情况。我们还表明，花粉管从柱头到胚珠的生长过程断断续续，大约需要3个月。在授粉时，胚珠尚未在子房内形成，需要很长时间来发育。花粉管呈之字形排列，并在花柱上部区域分支，其生长在那里停滞，直到子房进一步发育。对相关文献的研究进一步揭示，在与木麻黄科密切相关的桦木科、胡桃科和/或壳斗科中，花粉管生长不连续与授粉和受精之间的较长时间间隔以及合点受精有关。这一特征可能在壳斗目的进化早期就已出现。
