牛耳朵传粉生物学研究(英文)

Pollination biology of Primulina eburnea

关键词:  报春苣苔属, 传粉, 繁育系统, 喀斯特地貌, 广域分布

Key words:  Primula Hance, pollination, breeding systems, karst landform, eurychoric distribution

摘要:

苦苣苔科(Gesneriaceae)报春苣苔属(Primulina Hance)是一个近年来备受关注的类群,其纷繁复杂的物种多样性和属下种间的特有分布引起了分类学家和植物学研究者的极大兴趣。该属除了极少数的物种如牛耳朵[(Primulina eburnea(Hance)Y. Z. Wang)]以外,绝大部分的物种为狭域分布或地方特有种,其分布范围很窄。为了揭示牛耳朵的传粉生物学和繁育系统对其生殖过程和拓殖能力的影响机制,作者系统地研究了牛耳朵的开花物候、花粉与柱头活性、访花昆虫的种类和访花行为、花粉胚珠比、OCI指数和套袋实验结实率,探究其传粉等生殖过程对牛耳朵的广布是否有正面影响。结果表明:牛耳朵的自然花期是3—5月,全花期约45 d,其中盛花期约20 d,单花期6～8 d; 开花后1～2 d花粉活力最强,开花前柱头没有可授性; 花粉胚珠比为537; 杂交指数为5; 去雌套袋、去雄套袋均无法结实,说明本种不存在无融合生殖; 与自然授粉相比,自花授粉结实率略低,异花授粉结实率略高,说明自交亲和; 牛耳朵的主要传粉者是花条蜂(Anthophora florea)和熊蜂(Bombus sp.)。花蜜产量较高、花粉量较大、花粉活力较强等特点,有利于牛耳朵完成传粉和结实的整个繁殖过程。因此,这一结果显然有利于牛耳朵的拓殖进而广布在我国华南至西南地区的喀斯特地区。

Abstract:

Primula Hance(Gesneriaceae)is a group that has attracted much attention in recent years. Its intricate species diversity and its endemic distribution among species have aroused great interest among taxonomists and botany researchers. Except for a few species, like Primulina eburnea (Hance)Y. Z. Wang, most species have a very narrow distribution range, which belong to narrow distribution species or endemic species. In order to reveal the effects of the pollination biology and breeding system of P. eburnea on its reproductive process and colonization ability, we systematically studied the flowering phenology, the pollen and stigma viability, the species and visiting behavior of flower visiting insects, the pollen ovule ratio, the OCI index and the seed setting rate of manipulated pollination of P. eburnea. Besides, we explored whether its reproductive processes such as pollination had a positive effect on the spread of P. eburnea. The results showed that the natural flowering stage of P. eburnea was from March to May, and the entire flowering stage was about 45 d. Its full flowering stage was about 20 d, and the single flower flowering stage was 6-8 d. Pollens had the strongest viability 1-2 d after flowering, stigma did not have receptivity before flowering. The pollen ovule ratio was 537, and the hybridization index was 5. Bagged and emasculation could not bear fruit, indicating that this species did not have apomixis. Compared with natural pollination, the seed setting rate of hand self-pollination was slightly lower, and the seed setting rate of hand xenogamy was slightly higher, indicating self-compatibility. The main pollinators of P. eburnea were Anthophora florea and Bombus sp. Therefore, higher nectar volume, larger pollen amount and stronger pollen viability of P. eburnea were obviously beneficial for it to complete the entire process of pollination and reproduction. This result was obviously conducive to the colonization of P. eburnea and then widely spread in the karst areas of South China to Southwest China.