• 作者： 江有龍
• 作者服務機構： 國立臺灣大學植物學系
• 中文摘要： 在美洲水蕨的多孢子培養中，我們發現影響性顯現的兩個作用不同的個體韋因子（荷爾蒙）
  。此二者都在發芽早和（或）生長快的具有缺刻分生組織原葉體meristic prothallium內產生
  ，卻不在發芽遲和（或）生長慢的不具分生組織的ameristic個體內產生。其一為藏精器的誘發
  因子antheridium-inducing factor，也就是促精素antheridiogen，它對發芽遲和（或）生長
  慢的不具分生組織的個體（由單一子葉裂片即第一裂片所組成）作用，使它產生藏精器後，成為
  雄性原葉體；另一為「維持雄性的因子」‘maleness-maintaining factor’，也就是??基－3－醋酸
  indole-3-acetic acid (IAA)（抗雄性原葉體兩性化因子），它因抑制雄性原葉體長出新的具有Ｖ
  字型缺刻分生組織的雌性延長部份female extension（第二和第三裂片所組成），而抑制其兩性
  化。這是和高等植物的頂芽優勢apical dominance類似的相關抑制現象，也就是具有分生組
  織原葉體內生之IAA對不具分生組織原葉體之優勢現象，可稱之為「分生優勢」‘meristic
  dominance’。至於對發芽早和（或）生長快的具分生組織的個體，此兩荷爾蒙都不發生作用。顯
  然的，生理活性不同的個體對這兩荷爾蒙的感受性susceptibility是「有區別的」‘differential’
  。因此，於移隔培養中，發芽早和（或）生長快的個體，它們雖能合成促精素和IAA，但本身
  並無感受性，故會長成雌性原葉體；而發芽遲和（或）生長慢的個體，雖對此二因子有感受性，
  但因其本身並不合成，亦無外加之荷爾蒙，故仍長成雌性原葉體。
  播孢密度大，且播距不定之萌芽孢子移隔前的多孢子培養中也有促精素之作用，因而促使個
  體於移隔後若干日內產生藏精器。如果移隔是從密度小（小於100孢子/2x2 cm2），且播距均一
  的100-孢子培養時，則殆無此種誘發現象。即使是多孢子培養，如果播孢密度小，則上述二個
  體?因子之作用，因達不到鄰近之個體，所以產生和移隔或單孢子培養同樣的結果。一般地說，
  密度越小，性比會越小，兩性化百分比會越大。此外，培育期延長也能減小性比，增大兩性化百
  分比。在密度為100孢子/1×1 cm2時，我們以100-孢子培養15天，能完全抑制兩性化的發生
  。若將此培養的培育期加倍（31天），就會發生兩性化；如果欲使31天之培養，保持零的兩性化t
• 英文摘要： In multispore cultures of Ceratopteris pte-ridoides, we have demonstrated two distinctpopulation factors or hormones which influencesexual development. Both are produced in theearly germinating and/or fast growing meristicprothallia, but not in late germinating and/orslow growing ameristic prothallia which lack anotch meristem. One is antheridium-inducingfactor or antheridiogen (a gibberellin) whichinduces late germinating and/or slow growingameristic prothallia (composed by a single co-tylendonary or first lobe) to form the antheridia.Another is the maleness-maintaining factor orindole-3-acetic acid (IAA) which inhibits thehermaph-roditization of ameristic male prothalliaby inhibiting the formation of female or meristicextensions with the V-shaped notch (composedof the second and third lobes). The latter refersto meristic prothallium or simply 'meristicdominance', an interprothallial correlative inhibi-tion, which is similar to apical dominance inhigher plants. To those early germinating and/orfast growing meristic prothallia, on the otherhand, these two hormones are ineffective. Thus,the prothallia with different physiologicalactivities (regarding time of germination andprothallial growth) appear to be differential intheir susceptibility to these two hormones.Therefore, in isolated cultures, early germinatingand/or fast growing prothallia become females,because they are insusceptible to antheridiogenand IAA they have produced. The late germina-ting and/or slow growing prothallia also becomefemales in isolation because they lack these twohormones although they are susceptible to them.The antheridiogen factor is evident even in theearly culture in which the spores are beginningto germinate. If the spores are isolated upongermination from a relatively dense culture inwhich 1 mg spores are randomly sown in 10 cmdish (about 100 spores/0.5 x 0.5 cm2) the anther-idiogen produced before isolation stimulates thegerminating spores to become males in severaldays after isolation. If, however, the isolationis carried out from a culture in which a limitednumber of spores (100) are sparsely and uniformlysown (100 spores/2×2 cm2), almost all germina-ting isolated spores become females. Even amultispore culture may produce a similar resultas an isolated culture if the spores are sown at5 mm or more intervals. In general, the moresparsely the spores are sown and/or the older theculture age is, the smaller the sex ratio, and thehigher the hermaphroditization percentage wemay get. We were able to maintain hermaph-roditization percentage as O (i. e. unisexual con-dition) in 100-spore, 15-day culture in whichthe sowing density was 100 spores/1 x 1 cm2.When the culture period is extended, the culturetends to produce bisexual prothallia. We have,however, been able to maintain sexual polarityup to the 31st day after sowing, by increasingthe sowing density from 100 spores/ 1 x 1 cm2 to100 spores/0.2 x 0.2 cm2. All hermaphrodites ob-tained within one month after sowing were pro-tandrous. Protogynous bisexual prothallia donot appear unless the culture period is longerthan one month. As 10 ppm gibberellic acid(GA3) has no influence on the prothallial popu-lation of this fern, it is considered that the an-theridiogen must be gibberellic acid or one ofits analogues and that it must be produced inrelatively large amounts. Since IAA in concen-trations of 10 ppm inhibited population growth,it is thought that endogenous IAA must beproduced in minute amounts. The prothalliacannot produce antheridia in the culture con-taining 10 ppm abscisic acid (ABA), because theantheridiogen is counteracted by ABA. 10 ppmABA also counteracts endogenous IAA and thusthe asexual spatulate prothallia form second andthird lobes to become females.
• 中文關鍵字： --
• 英文關鍵字： --