Autogamy of an endangered species: Loropetalum subcordatum (Hamamelidaceae)
Autogamy of an endangered species: Loropetalum subcordatum (Hamamelidaceae)
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DOI：
10.3724/sp.j.1002.2008.08029
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发表时间：
2008-09-01
影响因子：
3.7
通讯作者：
Zhang, Dian-Xiang
中科院分区：
文献类型：
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作者：
Gu, Lei;Zhang, Dian-Xiang
对亚心形金龟子的生殖生物学进行了研究。对其花物候、花粉组织化学、花粉-胚珠比(P/O)、花粉生活力和访花情况进行了调查和测定。通过辅助授粉试验，对亚心莲的繁育体系进行了研究。用扫描电子显微镜(SEM)和荧光显微镜(FM)观察花粉萌发和花粉管生长情况。结果表明：(1)亚心莲的开花期为9月至次年2月，9~10月为盛花期，单花寿命为4~6d。(2)亚心形花药为雌雄同株，花药展开后12~24 h在自体柱头上可见花粉粒。(3)花粉活力(四甲基偶氮唑蓝试验)保持约26h，无淀粉，P/O为8420+/-720.86(n=10)，未观察到分泌蜜液。(4)蓟马(Thrips sp.)是唯一观察到的访花植物，但很少在花序间移动，因此在授粉中起到的作用有限。(5)套袋(5.30±1.83%)和人工辅助异花授粉(6.67±1.91%)与开放花(4.79±1.45%)的座果率差异不显著。(6)扫描电子显微镜和FM观察表明，花粉在自花柱头上萌发，花粉管以自花柱形式生长。结果表明，亚心形花序为兼性自交，无无融合生殖。异交和雌雄同体的可能性可能表明该物种最初是一个异交者。9-10月授粉的花朵通常在来年夏季开始胚珠生长，并在次年10月(下一个开花高峰期之后)结实，表明胚胎发育迟缓。文中还讨论了金缕梅科植物的自交性可能是由苍蝇授粉形成的。
The reproductive biology of Loropetalum subcordatum was studied. The floral phenology, pollen histochemistry, pollen-ovule ratio (P/O), pollen viability and floral visitors were investigated and determined. Assisted pollination experiments were carried out to examine the breeding system of L. subcordatum. Scanning electron microscopy (SEM) and fluorescence microscopy (FM) were employed to check the pollen germination and the growth of pollen tubes. Results were obtained as follows: (1) The flowering period of L. subcordatum was from September to the next February with a peak at September-October; the longevity of a single flower was 4-6 days. (2) L. subcordatum was protogynous, and pollen grains could be found on self-stigmata when the anthers opened 12-24 h after petals unrolling. (3)The pollen viability (MTT test) maintained for ca. 26 hours; the pollen was starchless; the P/O was 8420 +/- 720.86 (n=10); no nectar secretion was observed. (4) Thrips (Thrips sp.) were the only floral visitors observed but which seldom moved among inflorescences, thus played limited role in pollination. (5) Fruit sets of untreated bagged (5.30 +/- 1.83%) and hand assisted cross pollinated flowers (6.67 +/- 1.91%) were not significantly different from that of open flowers (4.79 +/- 1.45%). (6) SEM and FM observations proved that pollen germinated on self-stigmata and pollen tubes growed in self-styles. The results indicated that L. subcordatum was facultatively autogamous and without apomixes. The possibility of outcrossing and the protogyny might indicate that the species was originally a crosser. Flowers pollinated in September-October usually start ovule growth in next summer, and set mature fruits in next October (after the next flowering peak), suggesting the occurrence of retard embryo development. The possibility that autogamy in Hamamelidaceae could have been developed from fly pollination was also discussed.