【摘要】：膜蕨科植物是薄囊蕨類中種類最多的科,主要分布在潮濕的熱帶地區(qū),擁有陸生、附生、半附生和攀生等多種生態(tài)型。為進(jìn)一步了解膜蕨科植物輻射式物種分化的分子適應(yīng)機(jī)制,該研究在時(shí)間框架下采用位點(diǎn)模型對(duì)膜蕨科植物rbc L基因的進(jìn)化式樣進(jìn)行分析。結(jié)果表明:共鑒定出6個(gè)氨基酸正選擇位點(diǎn)(125I、227L、231A、258F、304S和351L),其中位點(diǎn)304S位于環(huán)六上,對(duì)維持Rubisco功能有重要作用。此外,還計(jì)算了Rubisco大亞基內(nèi)部氨基酸位點(diǎn)之間的共進(jìn)化關(guān)系,共檢測(cè)出39組(35個(gè)氨基酸)共進(jìn)化位點(diǎn),其中位點(diǎn)在α螺旋上的占46%,在β折疊上的占14%。膜蕨科植物rbc L基因這種復(fù)雜的進(jìn)化式樣可能與其起源較早有關(guān)。鑒于此,基于UCLD分子鐘模型對(duì)膜蕨科植物的分化時(shí)間進(jìn)行了估計(jì),結(jié)果顯示膜蕨科植物首次發(fā)生分歧的時(shí)間在三疊紀(jì)早期,瓶蕨屬和膜蕨屬的分歧時(shí)間分別發(fā)生在侏羅紀(jì)早期和白堊紀(jì)晚期,并且得出陸生生態(tài)型是其它生態(tài)型進(jìn)化的基礎(chǔ),推測(cè)最近幾次最熱事件可能對(duì)物種分化的形成產(chǎn)生一定的作用。該研究結(jié)果對(duì)認(rèn)識(shí)膜蕨科植物如何應(yīng)對(duì)被子植物興起所導(dǎo)致的陸地生態(tài)系統(tǒng)改變具重要意義。
[Abstract]:Pteridaceae is the family of the most species of ferns, mainly distributed in humid tropical areas, with terrestrial, epiphytic, semi-epiphytic and climbing ecotypes. In order to further understand the molecular adaptation mechanism of radiative species differentiation in the family Pteridaceae, the evolutionary pattern of rbc L gene was analyzed by locus model under the time frame. The results showed that six positive amino acid selection sites (125Ion 227L, 231A, 258FN 304S and 351L) were identified, among them, 304S was located on ring VI, which played an important role in maintaining the function of Rubisco. In addition, the coevolutionary relationships among amino acid sites in the large subunit of Rubisco were calculated and 39 groups (35 amino acids) were detected, of which 46 were located in 偽 helix and 14 in 尾 folding. The complex evolutionary pattern of rbc L gene may be related to its early origin. Based on the UCLD molecular clock model, the differentiation time of Pteridaceae was estimated. The results showed that the first time of divergence occurred in the early Triassic. The diverging time of Dryopteris and Dryopteris occurred in the early Jurassic and late Cretaceous respectively, and the terrestrial ecotype was the basis of the evolution of other ecotypes. It is speculated that the most recent heat events may play a role in the formation of species differentiation. The results of this study are important for understanding how to deal with the terrestrial ecosystem changes caused by the rise of angiosperms.
【作者單位】： 黔南民族師范學(xué)院生物科學(xué)與農(nóng)學(xué)院;
【基金】：貴州省科學(xué)技術(shù)基金(黔科合J字[2015]2137號(hào)) 貴州省自然科學(xué)基金重點(diǎn)項(xiàng)目(黔教合KY字[2015]380號(hào))~~
【分類號(hào)】：Q943.2

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