二重雌雄异型异熟物种色木槭3种表型花的细胞形态学研究

doi:10.3724/SP.J.1003.2011.07035

摘要/Abstract

摘要：

二重雌雄异型异熟, 即雌雄功能按雄-雌-雄顺序分别表达, 是有花植物中较为少见的异熟机制。槭属(Acer)大部分物种具有二重雌雄异型异熟的开花物候, 且第一期雄花与第二期在形态上差别较大。为深入探讨花发育模式对花形态和开花物候的影响, 本文应用石蜡切片技术和光镜技术, 对色木槭(Acer mono)各个发育时期的3种类型花(雄花I, II和雌花)的形态学和细胞学进行观察比较。结果发现: 色木槭一期雄花(雄I)在大孢子四分体退化形成功能性大孢子时期, 子房萎缩并迅速退化消失; 而二期雄花(雄II)在此时期胚珠和子房表现为逐渐退化败育, 但成熟子房内仅剩蘑菇云状的败育胚珠, 形态上可见子房和二分裂柱头; 雌花由于绒毡层延缓解体, 并缺少与花药开裂有关的唇细胞, 导致成熟花药无法开裂散粉, 发生了结构性的雄性不育。结果表明, 色木槭的3种类型的花均起源于两性花, 在花发育过程中通过成熟花药的不开裂和子房胚珠的败育分别产生功能性雌花或雄花, 而雄I和雄II在形态上的差异, 是由子房是否迅速退化造成的。

关键词: Acer mono, 二重雌雄异型异熟, 功能性雌花或雄花, 细胞形态学

Abstract

Duodichogamy, where individual plants produce two batches of male flowers that are temporally separated by a batch of female flowers, is the rarest temporal sexual system in flowering plants. Duodichogamy is present in some species of Acer, whose flowers of the first (male I) and second male phases (male II) differ morphologically. To explore the influence of floral development on flower morphology and phenology, we used paraffin methods and light microscopy to compare morphological and cytological differences among male (I and II) and female flowers at different developmental stages. Our main results were as follows: the ovary of male I degenerated and disappeared quickly upon megaspore tetrad degeneration, and developed into macrosporocytes; while the ovary of male II degenerated gradually during this period and only traces of residual ovule remained in the fully-developed ovary; the failure of anthers of female flowers to dehisce might be caused by retardant degeneration of tapetum tissue and loss of lip cells, i.e. formation sterility. In conclusion, both pistil and stamen primordial could be found in male (I and II) and female flower buds at early phases of sex differentiation, but selective abortion occurred in later developmental phases.

Key words: Acer mono, duodichogamy, functional male and female flowers, morphology, cytology

张灵芝, 商辉, 罗毅波, 程鑫, 白伟宁 (2011) 二重雌雄异型异熟物种色木槭3种表型花的细胞形态学研究. 生物多样性, 19, 551-557. DOI: 10.3724/SP.J.1003.2011.07035.

Lingzhi Zhang, Hui Shang, Yibo Luo, Xin Cheng, Weining Bai (2011) Morphology and cytology of three flower phenotypes in a duodichogamous tree species, Acer mono. Biodiversity Science, 19, 551-557. DOI: 10.3724/SP.J.1003.2011.07035.

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链接本文: https://www.biodiversity-science.net/CN/10.3724/SP.J.1003.2011.07035

https://www.biodiversity-science.net/CN/Y2011/V19/I5/551

图/表 3

图1 色木槭盛花期的雄花和雌花。(A)雄I, 示8枚雄蕊; (B) 雄II, 示小柱头和子房; (C)雌花, 示不开裂的花药和发育完整的雌蕊。St: 雄蕊; Pi: 雌蕊。

Fig. 1 Male and female flowers of Acer monoat anthesis. (A) Male I flower, showing eight stamens; (B) Male II, showing small ovary and style; (C) Female flower, showing no-dehiscent stamens and normal pistil. St, Stamen; Pi, Pistil.

图2 色木槭雄蕊发育过程。(A)花发育早期, 雄花(I和II)及雌花均处于两性阶段; (B)小孢子四分体形成, 呈四面体状; (C)小孢子从四分体里释放出来; (D)大液泡出现将小孢子核推向细胞边缘, 即为单核靠边期小孢子; (E)、(F)、(I)三图依次为雄I和II的二核花粉形成、成熟和开裂过程; (G)、(H)分别为雌花F的二核花粉形成及成熟过程; (J)、(K)为色木槭的成熟花粉粒扫描电镜观察, (J)为雄I和II, (K)为雌花。Lc: 唇细胞; Ta: 绒毡层; An: 花药; Ov: 子房; Fl: 纤维层; Mmc: 小孢子母细胞; Ms: 小孢子; Gc: 生殖细胞; Vc: 营养细胞。标尺: A = 50 µm, B到K = 20 µm。

Fig. 2 The process of stamen development in Acer mono. (A) The early development of flowers, both male (I and II) and female flowers are in the bisexual stage; (B) The tetrahedral tetrads are formed; (C) The microspores are released from the tetrad; (D) Formation of a large vacuole pushes the single nucleus towards the wall; (E), (F) and (I) are showing the process of formation, maturation and dehiscence of two-celled pollens in male I and II, respectively; (G) and (H) are the formation and maturation of two-celled pollens in female flowers, respectively; (J) and (K) are showing SEM micrographs for mature pollen grains in A.mono, and (J) for male I and II, (K) for female flowers, respectively. Lc, Lip cell; Ta, Tapetum; An, Anther; Ov, Ovary; Fl, Fibrous layer; Mmc, Microspore mother cell; Ms, microspore; Gc, Generative cell; Vc, Vegetative cell. Scale bars = 50 µm for A, 20 µm for B to K.

图3 色木槭雌蕊发育过程。(A)子房和胚珠的纵切面, 雄花也处于两性期; (B)胚珠原基分化形成双珠被, 并产生大孢子母细胞; (C)大孢子母细胞减数分裂形成线性排列的大孢子四分体; (D)到(G)雄花I和II的雌蕊败育过程: (D)胚珠边界细胞界限开始模糊; (E)整个胚珠细胞界限模糊不清; (F)蘑菇云状的败育胚珠; (G)败育的胚珠及退化萎缩的子房; (H)到(N)雌花的完整雌蕊发育过程: (H)合点端功能大孢子生成, 即单核胚囊, 其余3个大孢子退化; (I)二核胚囊; (J)到(K)为四核胚囊; (L)到(N)为成熟八核胚囊。Mmc: 大孢子母细胞; Mt: 大孢子四分体; Fm: 功能性大孢子; Ec: 卵细胞; Sy: 助细胞; Pn: 中央极核; Art: 反足细胞。标尺: A, F, G = 20 µm; B to E = 10 µm; H to N = 10 µm。

Fig. 3 The process of pistil development in Acer mono. (A) Longitudinal section of ovary and ovule, showing the bisexual stage of male flowers; (B) Both integuments arise from the ovule primordium, and the megaspore mother cell is formed; (C) Linear megaspore tetrad is formed as result of meiosis of the megaspore mother cell; (D) to (G) The process of pistil abortion in male I and II; (D)The marginal cells of ovule are obscure; (E) The whole ovule cells become unclear; (F) The mushroom cloud abortive ovule; (G) The depauperate ovary with the wholly abortive ovule; (H) to (N) The process of perfect pistil development in female flowers: (H) Chalazal megaspore is functional, while the other three megaspores have degenerated; (I) Two-nucleate embryo sac; (J) to (K) Fournucleate embryo sac; (L) to (N) 8-nucleate embryo. Mmc, Megaspore mother cell; Mt, Megaspore tetrad; Fm, Functional megaspore; Ec, Egg cell; Art, Antipodal cell; Pn, Polar nucleus; Sy, Synergid. Scale bars = 20 µm for A, F,G; 10 µm for B to E, and H to N.

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