芒屬 ( Miscanthus ) 為禾本科（Poaceae）黍亞科 ( Panicoideae ) 植物，主要分佈於東亞及東南亞。八丈芒 （Miscanthus sinensis var. condensatus）為中國芒（M. sinensis）之亞種，生長於台灣東部濱海沿岸地區，其棲地受海水以及降雨淋餘影響，具備高強度曝曬、日溫差大、高度鹽分等條件，因此大部份植物無法在此生長。根據這樣的特殊棲地環境，我推測八丈芒之所以能夠在如此惡劣條件下生長，必定具備多種非生物耐受性基因被天擇所偏好，在此本研究特別針對鹽分耐受度進行探討。
藉由與已完成全基因體定序的禾本科物種互相比較，包括高粱 （Sorghum bicolor） 、玉米 （Zea mays） 、小米 （Setaria italic） 、柳枝稷 （Panicum virgatum） 、水稻 （Oryza sativa） 、二穗短柄草 （Brachypodium distachyon），並進行演化以及天擇選汰的分析。本研究串連 3,515 條直系同源基因 （orthologous genes） 畫出物種樹，結果呈現八丈芒與高粱為最近緣種，並和玉米同屬於蜀黍族，小米和柳枝稷則屬於黍族並與蜀黍族為近緣，水稻和二穗短柄草則為外群。在 3,515 條直系同源基因中， 2,007 條基因的親緣樹與物種樹相符， 1,521 條基因發生過重組事件，2,094 條基因具有 GO （gene ontology）註解。
在這些基因中，我們鎖定 12 個與離子運輸相關的註解，包括 transport 、 transmembrane transport 、 ferrous iron transport 、 potassium ion transport / transmembrane transport 、 response to aluminum ion / metal ion 、 citrate transport 、 regulation of anion transport 、 anion / cation / metal ion transport ，其中 iron ion tranamembrane transport, potassium ion transport, response to metal ion, ferrous iron transport, response to aluminum ion 分類群的同源基因其受正向天擇偏好比率為 100 %，這些 GO term 功能都與離子的濃度有關，旨在調控生物膜內外的電位差平衡，這些 GO 的功能以及天擇基因的表現也顯現八丈芒在高鹽逆境下的天擇偏好。

In this study, I focused on the evolution of salt tolerance genes in Miscanthus sinensis var. condensatus via comparative genomics analyses on the NGS data. Miscanthus materials were collected from East Taiwan. Genomic DNA was sequenced with an Illumina Hiseq 2000 platform. Miscanthus genes were reference-assisted assembled with Ray and ABySS assembler based on Sorghum bicolor chromosome scale. Scaffolding was completed in two strategies via the blast results, with 26,075 and 24,073 scaffolds obtained respectively. Correspondingly, 12,756 and 18,656 proteins were respectively predicted by AUGUSTUS in a complete model. Among the 13,076 core orthologous genes that are shared with other 6 species (Sorghum bicolor, Zea mays, Setaria italic, Panicium virgatum, Oryza sativa, Brachypodium distachyon), I recognized 3,515 and 6,625 genes in Miscanthus, respectively, in the two assemblies. In the species trees reconstructed based on core orthologous genes, Miscanthus, Sorghum and maize were closely related, Setaria and Panicum formed a clade, and Oryza and Brachypodium were basal to the rest. And 1,521 core genes were detected with homolodous recombination. Interestingly, GO terms related to ion transport were 100 % of positively selection, such as iron ion transmembrane transport, potassium ion transport, response to metal ion, ferrous iron transport, response to aluminum ion, indicating adaptation of Miscanthus at extreme environments.

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