高山植物扁蕾的延迟自交机制

doi:10.17521/cjpe.2007.0014

摘要/Abstract

摘要：

扁蕾(Gentianopsis barbata)具有鲜艳的花和显著的腺体,并且花开放的前5 d柱头和花药始终处于不同的位置(雌雄异位),这些花综合征表明该植物应为异花传粉。为检验这一假设,我们对青藏高原植物扁蕾的海北站种群进行了3年的传粉生物学研究实验。与花综合征所表明的繁育系统相反,两年的野外观察发现昆虫的访花频率十分低,不去雄并隔离昆虫处理也能产生大量种子,说明这一种群的繁殖主要是依赖于自花传粉。尽管利用种子结实评价的柱头可授性从花开放4 d后开始下降,但随着花的发育进程,雄蕊的伸长能使得花药与柱头完全接触。实验也证明,柱头可授性和花粉活力都超过5 d,说明花药和柱头的接触能够发生自花授粉。扁蕾的这种自花传粉机制应属于典型的延迟自交类型。自花授粉发生在单花花期快要结束前,自交之前仍然保持异交传粉机制,这种延迟自交避免了自交与异交竞争造成的花粉或者种子折损,并为扁蕾在青藏高原极端环境下由于访花昆虫缺乏造成的异交失败提供了繁殖保障。

关键词: 雌雄异位, 延迟自交, 繁殖保障, 扁蕾, 青藏高原

Abstract:

Aims Gentianopsis barbata displays showy flowers and conspicuous nectaries and has stigma and anthers at different positions (herkogamy) until the fifth day after flower opening. All of these floral syndromes were assumed to favor outcrossing.

Methods We studied pollination biology of this species at Haibei Station on the Qinghai-Tibetan Plateau for three years to test this assumption.

Important findings Contrary to expectation, reproduction in the studied population was mainly through self-pollination. Pollinator visitation was rare, and bagged flowers with anthers set abundant seeds. Both stigma receptivity and pollen viability extended beyond five days. Although stigma receptivity based on seed number decreased after the fourth flowering day, contact of anthers and stigma during floral development resulted in delayed selfing in this species. This delayed selfing retained the floral syndromes and mechanisms for outcrossing, avoided competition between selfing and outcrossing and insured reproduction of G. barbata despite lack of pollinators in arid habitats of the Qinghai-Tibetan Plateau.

Key words: herkogamy, delayed selfing, reproductive assurance, Gentianopsis barbata, Qinghai-Tibetan Plateau

段元文, 何亚平, 张挺锋, 刘建全. 高山植物扁蕾的延迟自交机制. 植物生态学报, 2007, 31(1): 110-117. DOI: 10.17521/cjpe.2007.0014

DUAN Yuan-Wen, HE Ya-Ping, ZHANG Ting-Feng, LIU Jian-Quan. DELAYED SELFING IN AN ALPINE SPECIES GENTIANOPSIS BARBATA. Chinese Journal of Plant Ecology, 2007, 31(1): 110-117. DOI: 10.17521/cjpe.2007.0014

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链接本文: https://www.plant-ecology.com/CN/10.17521/cjpe.2007.0014

https://www.plant-ecology.com/CN/Y2007/V31/I1/110

图/表 7

表1 2002年扁蕾的花综合特征

Table 1 Floral syndrome of Gentianopsis barbata in 2002

	平均值 Mean	标准误 SE	范围 Range	样本量 Sample size
萼片 Sepal (mm)	23.5	0.6	20.1~33.5	25
花冠筒 Corolla tube (mm)	33.6^a	0.5	28.5~38.9	25
花冠檐直径 Diameter of corolla brim (mm)	25.3	0.7	19.8~32.3	25
花冠口径Diameter of corolla mouth (mm)	3.0	0.1	2.5~3.5	25
花粉、胚珠比例 Pollen/ovule ratio	40.9	5.4	10.8~100.2	20

图1 A. 花蕾期柱头张开但花药未散粉 B. 花开放,花药正在散粉,但位于柱头下部 C. 花开放后第五天,花药正在散粉,并与柱头接触 D. 花冠闭合后花药散粉结束,位于柱头上部

Fig.1 A. The stigma was bifurcate but anthers did not shed pollen and were situated below stigma in bud stage B. Anthers were shedding pollen but situated below stigma when a flower just opened C. Anthers were shedding pollen and touched stigma on the fifth day after opening D. Anthers terminated shedding pollen and were situated above stigma when corolla brims closed

表2 2003年扁蕾花持续期

Table 2 Floral duration of Gentianopsis barbata in 2003

	平均值 Mean	标准误 SE	范围 Range
散粉持续期 Duration of pollen shedding	4.7^a	0.1	4.3~5.4
花持续期 Duration of flower opening	4.7^a	0.1	4.3~5.4

图2 花开放后柱头与花药间的距离变化

Fig.2 Change of distance from stigma and anthers after flower opening

表3 扁蕾不同处理的成熟种子数目

Table 3 No. of mature seeds/fruits from different treatment of Gentianopsis barbata

	2002	2003
	成熟种子数(平均值±标准误) No. of mature seeds/fruits (Mean±SE)	成熟种子数(平均值±标准误) No. of mature seeds/fruits (Mean±SE)
对照 Control	754.2±36.1^a	797.0±31.2^a
不去雄隔离昆虫 Isolation without emasculation	857.8±37.4^a	650.6±26.7^b
去雄不隔离昆虫 Emasculation without isolation	53.1±16.3^b	84.0±20.2^c
去雄隔离昆虫 Isolation after emasculation	30.0±8.6^b	36.4±11.6^c

图3 花开放后不同时间授粉的成熟种子数图中有不同字母的值表示在0.01水平有显著差异

Fig.3 No. of mature seeds/fruits pollinated after flower opening Values with different letters indicated the difference are significant at the 0.01 level

图4 花开放后不同时间花粉萌发率图中有不同字母的值表示在0.01水平有显著差异

Fig.4 Pollen germination rate after flower opening Values with different letters indicated the difference are significant at the 0.01 level

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