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Plant Diversity ›› 2015, Vol. 37 ›› Issue (06): 793-800.DOI: 10.7677/ynzwyj201515070

• 研究论文 • 上一篇    下一篇

红豆蔻专性异交主导下的主动自交机制

 崔煜文1、2, 李庆军1   

  1. 1 中国科学院西双版纳热带植物园,云南 勐腊666303; 2 中国科学院大学,北京100049
  • 收稿日期:2015-04-23 出版日期:2015-11-25 发布日期:2015-08-04

Autonomous Selfpollination under Dominant Flexistylous Outcorssing Mechanism in Alpinia galanga (Zingiberaceae)

 CUI  Yu-Wen-1、2, LI  Qing-Jun-1   

  1. 1 Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla, Yunnan 666303, China;
    2 University of Chinese Academy of Sciences, Beijing 100049, China
  • Received:2015-04-23 Online:2015-11-25 Published:2015-08-04

摘要:

主动自交一直以来都被认为是植物在面对极端环境,例如传粉者稀缺的情况下所采取的繁殖保障机制,它不利的一面主要表现为近交衰退和花粉或胚珠贴现。在姜科植物部分属,如山姜属和豆蔻属当中,存在着一种被称作花柱卷曲(flexistyly)的特殊机制。过去的研究认为这种机制的意义在于避免自交和性别干扰,但是根据我们的野外观察,如果下垂型花朵的花粉在其花柱开始向下弯曲时仍然留在花药之上,柱头就很有可能接触到花粉从而完成主动自交。为此我们探索了红豆蔻 (Alpinia galanga) 的繁殖系统,研究结果表明:(1) 红豆蔻自交亲和,并存在一定的近交衰退;(2) 上举型为异交,较之下垂型投入了更多的资源;(3) 上举型的花粉胚珠比显著低于下垂型,由于红豆蔻的胚珠数是固定的六枚,故两种表型花粉胚珠比的差异反映了其花粉数目的差异。这可能与上举型仅仅为下垂型提供花粉,而下垂型除为上举型提供花粉外,还需要有足够的花粉以备自交所需。因此,红豆蔻当中存在主动自交机制,并且其花柱卷曲机制在避免不必要的自交和性别干扰的同时,也为作为繁殖保障所必需的延迟主动自交创造了有利条件。同时通过控制主动自交发生的时间达到避免三种功能之间的相互冲突。这种只在姜科植物当中存在的特殊机制充分展示了其进化过程中对不利环境的适应。

关键词: 红豆蔻, 主动自交, 繁殖保障, 花柱卷曲, 适应性

Abstract:

Autonomous selfpollination is considered to be a reproductive assurance mechanism for plants when facing extreme environments that scarce in pollinators, and it also has disadvantages like inbreeding depression and pollen/ovule discounting. In several genera of Zingiberaceae like Alpinia and Amomum, a specialized mechanism named flexistyly exists, precedent studies consider its significance as preventing unnecessary selfpollination and sexual interference. However according to our field observation, if pollen grains on cataflexistylous (CATA) flowers remain on the anther when the style curves downwardly, potential exists that the stigma contacts the pollen, thus autonomous selfpollination occurs. Here, we studied the breeding system of Alpinia galanga, the results show that (1) Alpinia galanga is selfcompatible in which inbreeding depression occurs to some degree; (2) The anaflexistylous (ANA) morph of Alpinia galanga allocates more resource into outcrossing than the CATA morph; (3) The P/O ratio of the ANA morph is significantly lower than that of the CATA morph, as Alpinia galanga has constant six ovules in each ovary, the significant difference in P/O value reflects the contrast in pollen production. This phenomenon may be interpreted as the ANA morph provides pollen exclusively for the CATA morph. But the CATA morph, despite delivers pollen to the ANA morph, also need its own pollen for potential autonomous selfpollination. In summary, autonomous selfpollination exists in Alpinia galanga, and while flexistyly functions to avoid unnecessary selfpollination and sexual interference, it also provides advantages for delayed autonomous selfpollination as a necessary reproductive assurance and preventing conflict among these three major features by controlling the time of autonomous selfpollination. This peculiar mechanism in Alpinia galanga thoroughly demonstrates its adaptation to unfavorable surrounding during the evolutionary process.

Key words:  Alpinia galanga, Autonomous self-pollination, Reproductive assurance, Flexistyly, Adaptive significance

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