臺灣產玉葉金花屬植物之親緣關係與生殖生物學研究

Phylogenetic relationships and reproductive biology of Mussaenda species in Taiwan

鄭喬尹(Chiao-Yi Cheng)

指導教授 ： 胡哲明

國立臺灣大學/生命科學院/生態學與演化生物學研究所/碩士(2007年)

https://doi.org/10.6342/NTU.2007.03239

摘要

茜草科的玉葉金花屬植物，常利用膨大呈現鮮艷顏色的葉狀萼片來吸引授粉者。台灣產的玉葉金花植物，其葉狀萼片有時會有大小，以及顏色上的變異，因而在分類常造成困擾。台灣地區除了蘭嶼之外，在台灣植物志第二版中被認定的玉葉金花屬植物僅有毛玉葉金花 (Mussaenda pubescens W.T. Aiton) 一種；根據觀察發現，在台灣北部地區的玉葉金花植株，通常都缺乏吸引授粉者的膨大葉狀萼片構造或是僅有少數無法完整發育的葉狀萼片，但是仍然有果實的產生；而且其形態與Masamune (1939) 發表的台北玉葉金花 (M. taihokuensis Masam.) 的描述一致。從形態上的觀察，台灣北部與南部玉葉金花的花部構造有著明顯的差異，典型的北部短花冠類型植物之花冠顏色較為淺黃，而花冠筒的長度相較於南部長花冠類型短；兩個花冠類型的花萼與花萼筒長度比值都不及M. pubescens描述的標準。另外，我們將台灣北部與南部地區所採集到不同花冠長度的玉葉金花植株樣本，利用核內ITS序列與葉綠體內基因trnT至trnF間的序列，比對已發表的玉葉金花屬植物相關序列資料，發現到不論台灣北部短花冠型或是南部長花冠型的植株樣本，均與玉葉金花(M. parviflora Miq.) 以及四國玉葉金花 (M. shikokiana Makino) 較相近，而與已發表採自香港之M. pubescens序列不同。最後，我們針對長短花冠型的玉葉金花進行交叉授粉實驗，初步的結果發現兩個花冠型之間的交配無法產生果實，這個結果也顯示台灣南北不同花冠型的玉葉金花之間可能已存在初步的生殖隔離。綜合以上結果，台灣中南部常見具有膨大萼片的玉葉金花植株，應為玉葉金花 (M. parviflora)，而台灣北部地區缺乏膨大萼片的短花冠型植株應為種之階級，或可暫名為台北玉葉金花 (M. taihokuensis)。

關鍵字

玉葉金花 ； 台北玉葉金花 ； 生殖生物學

並列摘要

The enlarged and showy calyx lobes of the species of Mussaenda (Rubiaceae), have been known to attract pollinators. Variations on the size and color of Mussaenda species in Taiwan were observed, but the significance was unknown. In current taxonomic treatment by the second edition of the Flora of Taiwan, only one species was recognized in the island of Taiwan - Mussaenda pubescens Aiton. Based on the morphological observation, two forms of Mussaenda species can be found, one is mostly distributed on the northern part of Taiwan, another towards the southern part of Taiwan. The northern populations are congruent in the description of a previously recognized taxon, M. taihokuensis Masam., in having small calycophylls, and they show no sign of reproductive failures since they still set fruits in the field. Further examination shows that this northern form of Mussaenda has lighter petal color and shorter corolla tube than the southern form; and both northern and southern populations of Mussaenda have equal length of calyx teeth and calyx tube, which is incongruent with the description of M. pubescens.
Phylogenetic analyses were conducted based on nrITS and chloroplast trnT-F spacer and the results show that all sequenced individuals in Taiwan are grouped with M. parviflora Miq. and M. shikokiana Makino, and distinct from M. pubescens collected in Hong-Kong. Moreover, our data from crossed-pollination experiments for the northern and southern forms show that the crossed flowers cannot set fruits, indicating that these two forms have developed reproductive isolation even they can co-exist in the field. Based on all the results, the commonly seen Mussaenda species in middle and southern part of Taiwan should be named M. parviflora and the ones in northern part of Taiwan should be better named M. taihokuensis.

並列關鍵字

Mussaenda parviflora ； M. taihokuensis ； Reproductive biology

參考文獻

Li, H.L. (1963). Mussaenda Linnaeus. Woody Flora of Taiwan. New Land Press, Taipei, Taiwan. pp. 862-863.

Masamune, G. (1939). Miscellaneous notes on the flora of eastern asia X. Trans. Nat. Hist. Soc. Formosa 29, 179-180.

Alejandro, G.D., Razafimandimbison, S.G., and Liede-Schumann S. (2005). Polyphyly of Mussaenda inferred from ITS and trnT-F data and its implication for generic limits in Mussaendeae (Rubiaceae). American Journal of Botany 92, 544-557.

The Angiosperm Phylogeny Group (1998). An ordinal classification for the families of flowering plants. Annals of the Missouri Botanical Garden 85, 531–553

Barrett, S.C., Jesson, L.K., and Baker, A.M. (2000). The evolution and function of stylar polymorphisms in flowering plants. Annals of Botany 85, 253-265.