文獻來源：HM Heidel-Fischer, D Freitak, N Janz, L Söderlind, H Vogel, S Nylin. 2009. Phylogenetic relatedness and host plant growth form influence gene expression of the polyphagous comma butterfly (Polygonia c-album). BMC Genomics 10:506. doi:10.1186/1471-2164-10-506關於限制植食性昆蟲食性範圍的機制目前尚未研究透徹，但是針對影響他們的機制與選汰力量之研究能使人們更了解較大尺度的生態交互作用。目前已知植物的化學防禦物質可影響植食性昆蟲的食性範圍，而植物的化學防禦物質則受植物親緣關係之影響、植物的生長形式亦會影響植物的防禦策略（首先是由Feeny, P.在1976年所提出的"plant apparency"假說）。在本研究中，作者希望藉由檢測取食三種不同寄主植物的幼蟲之基因表現，以分析出黃鉤蛺蝶(Polygonia c-album)能取食多樣化的植物之分子層次基礎，此三種植物為近緣關係(Urtica dioica and Ulmus glabra- 皆為蕁麻目)或有相同生長形式 (Salix caprea and Ulmus glabra -皆為樹木)。
作者在取食不同植物後的黃鉤蛺蝶身上總計找到120個具有差異表現的基因，其中55個位於中腸、65個位於幼蟲身體的其他部位。27個選取的測試基因中有14個 (10 in 中腸 and 4 in 身體其他部位)的表現樣式可以以獨立方法進行確認。對幼蟲中腸基因表現進行配對的相似性比較顯示，無論是在近緣的植物或具有相同生長形式的植物之間，均具有較高的相似性。相反地，幼蟲身體其他部位的基因與植物的類別間則無相對應的樣式。然而在取食不同寄主植物的幼蟲中腸中並未找到不同的解毒酵素以進行不同的調節。作者的研究資料顯示基因表現對取食不同寄主植物的反應是很複雜的，雖然每種植物需要幼蟲獨特的基因調節，但是寄主植物間親緣關係與寄主植物生長形式看來亦能影響廣食性的黃鉤蛺蝶之基因表現，此與蝶類寄主植物利用的親緣關係研究結果一致。
Background
The mechanisms that shape the host plant range of herbivorous insect are to date not well understood but knowledge of these mechanisms and the selective forces that influence them can expand our understanding of the larger ecological interaction. Nevertheless, it is well established that chemical defenses of plants influence the host range of herbivorous insects. While host plant chemistry is influenced by phylogeny, also the growth forms of plants appear to influence the plant defense strategies as first postulated by Feeny (the "plant apparency" hypothesis). In the present study we aim to investigate the molecular basis of the diverse host plant range of the comma butterfly (Polygonia c-album) by testing differential gene expression in the caterpillars on three host plants that are either closely related or share the same growth form.
Results
In total 120 genes were identified to be differentially expressed in P. c-album after feeding on different host plants, 55 of them in the midgut and 65 in the restbody of the caterpillars. Expression patterns could be confirmed with an independent method for 14 of 27 tested genes. Pairwise similarities in upregulation in the midgut of the caterpillars were higher between plants that shared either growth form or were phylogenetically related. No known detoxifying enzymes were found to be differently regulated in the midgut after feeding on different host plants.
Conclusion
Our data suggest a complex picture of gene expression in response to host plant feeding. While each plant requires a unique gene regulation in the caterpillar, both phylogenetic relatedness and host plant growth form appear to influence the expression profile of the polyphagous comma butterfly, in agreement with phylogenetic studies of host plant utilization in butterflies.
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