Molecular Evaluation of Interspecific Hybrids between Acer albopurpurascens and A. buergerianum var. formosanum

域外保育是復育瀕危物種時經常使用的策略，植物園通常扮演了植物保育的重要功能。未經深思熟慮下進行的植物移植與種原保存，可能會導致種間雜交或是遺傳滲入問題出現，這種因人工移植造成的自然雜交現象現今發生在台北植物園的樟葉槭及台灣三角楓二近緣物種間，此二原生特有種在野外分布無重疊，在植物園種植後取得之第一子代的表型及基因型呈現中間型現象，皆證實二特有種間產生雜交現象。本研究藉由母系遺傳的葉綠體DNA作為分子標幟，我們確認了台灣三角楓為花粉的接受者（母本），樟葉槭則在雜交過程中扮演花粉提供者的角色（父本）。藉由ITS序列的分析得知F1雜交子代除與親本共享部分祖先型的遺傳變異外，尚有許多基因型與親本在遺傳組成上有些微的不同，而擁有更高的遺傳變異度，此現象符合雜交後所致之「稀有對偶基因現象」。根據基因型的對照、最少重組事件的估計及概率比值檢測的結果證明雜交子代的遺傳變異多來自重組的發生，因此稀有對偶基因現象的發生可能與基因重組有關。本研究以分子評估的方式確認植物園內種間自然雜交的發生，並建議進行域外保育時須著重空間隔離的效應。

關鍵字

槭樹；域外保育；雜交；稀有對偶基因現象；基因重組

並列摘要

Ex situ conservation is a common strategy for the restoration of endangered species. Botanical gardens play an important role in the restoration of plants; however, hybridization could happen if transplantation is not considered carefully. Two naturally allopatric taxa Acer albopurpurascens and A. buergerianum var. formosanum, grown in the Taipei Botanical Garden, hybridized spontaneously. Hybridization was shown by the presence of intermediate phenotypes and genetic data. To confirm the direction of pollen flow, indirect evidence of maternally inherited chloroplast DNA indicated that A. buergerianum var. formosanum was the pollen receiver. The hybrids shared parts of ancestral genetic variations with their parents. Furthermore, several novel haplotypes that were slightly different from their parents were cloned, which revealed higher genetic diversity of the hybrid population than the parental populations. Such a phenomenon is called the rare allele phenomenon. In comparison with haplotypes of parents and hybrids, and according to the estimation of minimum recombination events and the likelihood ratio tests, the genetic variations were brought about by recombination events, such that the rare allele phenomenon might be related to the recombination. The hybridization that occurred in the botanical garden underscores the importance of spatial isolation when carrying out ex situ plantations.

並列關鍵字

Acer ； Ex situ conservation ； Hybridization ； Rare allele phenomenon ； Recombination

國際替代計量

Molecular Evaluation of Interspecific Hybrids between Acer albopurpurascens and A. buergerianum var. formosanum

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