摘要:
Psathyrostachys huashanica is an endemic species in China and possesses multi-resistance to biotic and abiotic stresses.In order to develop Ns genome-specific molecular markers of P.huashanica,random amplified polymorphic DNA (RAPD) analysis was performed on genome DNA of P.huashanica and wheat (Triticum aestivum) using 204 arbitrary primers.Primer OP-D15 and OP-F19 could specifically amplify fragments in P.huashanica,but not in China Spring (CS).The two Ns genome-specific sequences,named with Psh-D15 and Psh-F19,were isolated and characterized.Psh-D15 was 1 106 bp containing one copy of CAAAA motif,one pair of direct repeat as well as one pair of invert repeat.Psh-F19 was 1 344 bp long and two copies of CAAAA motif,direct repeats as well as invert repeats were also present in this sequence.The results of BLAST analysis indicated that Psh-D15 had 66% sequence identity to a long terminal repeat (LTR) Gypsy retrotransposon which was part of sequence of T.aestivum (AM932686.1),and Psh-F 19 shared 78% homology with LTR Copia retrotransposon which was part of sequence of T.aestivum (HG670306.1).Thus,it could be inferred that both Psh-D15 and Psh-F19 were novel Ns genome-specific repeated sequences of P.huashanica belonging to Gypsy-like and Copia-like retrotransposons,respectively.Based on the sequence information,two pairs of sequence characterized amplified region (SCAR) primers were designed from the low-homologous regions of Psh-D15 and Psh-F19,respectively,and they were designated as Psh-D15 F/R and Psh-F19 F/R.These two pairs of SCAR primers could successfully amplify target bands 270 and 558 bp,respectively,only in P.huashanica,but not in the other genetic stocks,such as Aegilops,Dasypyrum,Leymus、Elytrigia,Agropyron,Hordeum,Secale,Triticum urartu,Triticum durum and T.aestivum.This result indicated that the two novel SCAR markers could reliably and easily distinguish the chromatin of P.huashanica,thus,they could be used as Ns genome-specific markers for monitoring genetic materials of P.huashanica,and designated as Psh-D15270 and Psh-F19558.The development of species-specific markers,Psh-D15270 and Psh-F19558,provides a new tool for characterizing wheat-P.huashanica alien genetic stocks.%华山新麦草(Psathyrostachys huashanica)是我国特有的物种,表现出多种抗病以及抗逆性状.为建立华山新麦草Ns基因组特异的分子标记,本研究利用204余条随机引物对华山新麦草、普通小麦的基因组DNA进行随机扩增多态性DNA (random amplified polymorphic DNA,RAPD)标记分析,其中随机引物OP-D15和OP-F19能在华山新麦草的基因组DNA中稳定扩增出特异的DNA片段,长度分别为1 106和1 344 bp,分别命名为Psh-D15和Psh-F 19.经序列比对分析发现,Psh-D15和Psh-F19分别属于Gypsy类型和Copia类型的反转录转座子序列.随后根据其与小麦中同源序列的比对结果,在二者低同源区设计了两对特定序列扩增(sequence characterized amplified regions,SCAR)引物Psh-D 15 F/R和Psh-F 19 F/R,并利用其同时对华山新麦草、山羊草属(Aegilops)、簇毛麦属(Dasypyrum)、赖草属(Leymus)、偃麦草属(Elytrigia)、冰草属(Agropyron)、大麦属(Hordeum)、黑麦(Secale)、乌拉尔图小麦(Triticum urartu),硬粒小麦(Triticum durum),以及普通小麦(Triticum aestivum)的基因组DNA进行PCR扩增,以检验其有效性和特异性.结果表明,两对引物均只在华山新麦草的基因组DNA中扩增出了目标条带,表明这两个SCAR标记是华山新麦草的Ns基因组所特有的,分别命名为Psh-D15270和Psh-F19558.新的Ns基因组特异SCAR标记Psh-D15270和Psh-F1 9.8的开发为小麦-华山新麦草杂种材料的分子鉴定提供了新的有力工具.