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目前石蒜基因组的进化机制尚不清楚,而反转录转座子是植物基因组进化的主要来源。本研究以二倍体(2n=2x=22)和三倍体(2n=3x=33)石蒜(Lycoris radiata)为实验材料,利用Ty1-copia类反转录转座子反转录酶基因(reverse transcriptase,RT)序列的简并引物克隆RT片段,并对其进行相关分析。其中,从二倍体和三倍体石蒜中分别获得了16条(2RA1~2RA16,Gen Bank登录号:KP275626~KP275641)和17条(3RA1~3RA17,Gen Bank登录号:KP275642~KP275658)RT序列。这些序列长度范围为248~266 bp,二倍体石蒜核苷酸序列相似性为49.05%~87.83%,三倍体石蒜为40.75%~89.73%;二倍体石蒜氨基酸序列相似性为18.60%~91.95%,三倍体石蒜为18.07%~88.51%。从这两种石蒜中获得的RT序列均具有多态性和高度异质性,且三倍体石蒜序列差异较二倍体大。33条氨基酸序列构建的N.J.系统进化树,表明二倍体和三倍体石蒜反转录转座子之间不仅发生了横向传递,而且发生了纵向传递,证明石蒜RT序列的分类情况与倍性没有直接相关性。和其他植物的系统进化分析表明石蒜RT序列与草本植物亲缘关系较近,与藻类植物团藻(Volvox carteri)、苔藓植物曲尾藓(Dicranum scoparium)、蕨类植物桂香蕨(Osmunda cinnamomea)和蔺木贼(Equisetum scirpoides);单子叶植物玉米(Zea mays)、小麦(Triticum aestivum)、荸荠(Eleocharis quinqueflora)、铁皮石斛(Dendrobium officinale);双子叶植物拟南芥(Arabidopsis thaliana)、番茄(Lycopersicon esculentum)、杨树(Populus ciliate)、欧洲云杉(Picea abies)、水葡萄(Beta procumbens)、大豆(Glycine max)同源性较高,且来自于二倍体石蒜的2RA16是石蒜Ty1-copia反转录转座子序列中最古老的一条。此外,研究表明二倍体石蒜很可能是石蒜复合体中的原始类群,三倍体石蒜为同源三倍体。研究结果对石蒜种内进化以及三倍体石蒜的起源有了更深入的了解,为进一步揭示石蒜核型进化机制提供科学依据,同时也为石蒜属的多倍体育种提供了理论基础。
At present, the evolutionary mechanism of Lycoris herma genome is not clear, and retrotransposons are the main source of plant genome evolution. In this study, we use the diploid (2n = 2x = 22) and triploid (2n = 3x = 33) Lycoris radiata as the experimental material, using the Ty1-copia retrotransposon reverse transcriptase gene (RT) sequence of degenerate primers cloned RT fragment, and its correlation analysis. Among them, 16 (2RA1 ~ 2RA16, GenBank accession numbers: KP275626 ~ KP275641) and 17 (3RA1 ~ 3RA17, GenBank accession numbers: KP275642 ~ KP275658) were obtained from diploid and triploid Lycoris sequence. The length of these sequences ranged from 248 to 266 bp, the similarity of diploid Lycoris radiata sequences was 49.05% -87.83%, and that of triploid Lycoris radiatum was 40.75% -89.73%. The amino acid sequence similarity of diploid Lycoris radiata was 18.60% ~ 91.95%, tripterygium was 18.07% ~ 88.51%. The RT sequences obtained from these two kinds of Lycoris radiata were polymorphic and highly heterogeneous, and triploid Lycoris radiate sequences were more different than diploid. 33 amino acid sequence constructed NJ phylogenetic tree, indicating that diploid and triploid Lycoris retrotransposons not only occurred between the lateral transmission, and the vertical transmission occurred to prove that the Lycoris radiatc RT sequence classification and Ploidy is not directly related. Phylogenetic analysis of Lycoris radiata and other plants showed that Lycoris radiatus RT sequences are more closely related to herbaceous plants than those of Volvox carteri, Dicranum scoparium, Osmunda cinnamomea and Equisetum scirpoides; Zea mays, Triticum aestivum, Eleocharis quinqueflora, Dendrobium officinale; dicot Arabidopsis thaliana, Lycopersicon esculentum, Populus ciliate, Picea abies, Beta procumbens and Glycine max, and 2RA16 derived from diploid Lycoris radiata was Lycium Ty1 -copia The oldest of the transposon sequences. In addition, studies have shown that diploid Lycoris probably the original group in the Lycoris complex, triploid Lycoris triad triploid. The results of the study on the evolution of Lycoris species and the origin of triploid Lycium have a more in-depth understanding, in order to further reveal the evolutionary mechanism of Lycoris nucleus to provide a scientific basis, but also for Lycoris species polyploid breeding provide a theory basis.