拟斯卑尔脱山羊草的FISH核型分析

Karyotypic Analysis of Aegilops speltoides Revealed by FISH

【目的】建立拟斯卑尔脱山羊草的FISH核型,分析明确不同来源拟斯卑尔脱山羊草的FISH核型特点,比较不同拟斯卑尔脱山羊草及其与普通小麦的FISH核型差异。【方法】以荧光标记的寡核苷酸Oligo-pTa535和Oligo-pSc119.2为探针,利用荧光原位杂交(fluorescence in situ hybridization,FISH)技术分析pTa535和pSc119.2在不同拟斯卑尔脱山羊草、四倍体小麦和普通小麦染色体上的杂交信号分布特点;以禾本科植物着丝粒专化寡核苷酸Oligo-CCS1为探针,明确拟斯卑尔脱山羊草的着丝粒位置,测量拟斯卑尔脱山羊草染色体相关参数;通过FISH核型比较明确不同拟斯卑尔脱山羊草及其与小麦核型的多态性差异。【结果】Oligo-pTa535主要分布在小麦的D和A组染色体上,在小麦的B组染色体上仅有零星分布,在5份拟斯卑尔脱山羊草的染色体中未显示Oligo-pTa535杂交信号。Oligo-pSc119.2杂交信号主要分布在小麦的B组染色体上,在小麦的A、D组染色体中分布较少,但在5份拟斯卑尔脱山羊草染色体上均有广泛分布。根据Oligo-pTa535和Oligo-pSc119.2杂交信号在小麦染色体上的分布特点,可以将小麦的不同染色体相互区分开来。Oligo-pSc119.2杂交信号在不同倍性、不同品种的小麦B组染色体上的分布特点基本相似,而不同来源拟斯卑尔脱山羊草的Oligo-pSc119.2的FISH核型差异较大,甚至在同一细胞内的2条同源染色体上Oligo-pSc119.2杂交信号的分布也具有明显差异。不同来源的拟斯卑尔脱山羊草与小麦B染色体组的FISH核型存在明显差异。PI542238的7对染色体均为中间着丝粒染色体,核型公式为2n=14=14m。其余4份拟斯卑尔脱山羊草的4S染色体均为近中着丝粒染色体,其余染色体均为中间着丝粒染色体,核型公式皆为2n=14=12m+2sm。【结论】拟斯卑尔脱山羊草染色体上含有丰富的与pSc119.2高度同源的重复序列,不含有与pTa535高度同源的重复序列。不同来源的拟斯卑尔脱山羊草之间以及同一来源的拟斯卑尔脱山羊草的个体间甚至同一个体内的同源染色体间在pSc119.2的分布上均具有遗传多样性。以Oligo-pSc119.2为探针建立的拟斯卑尔脱山羊草染色体FISH核型与小麦B组染色体的核型具有显著差异。利用荧光标记的Oligo-pTa535和Oligo-pSc119.2为探针进行FISH分析,可以准确区分拟斯卑尔脱山羊草的不同染色体,并能将拟斯卑尔脱山羊草与小麦的染色体区分开来。

[Objective] The objective of this study is to reveal the karyotypic polymorphism ofAegilops speltoides （Aegilops short for Ae. hereafter） and the karyotypic difference between common wheat and Ae. speltoides via the establishment of FISH karyotype of Ae. speltoides. [Method] Multicolor fluorescence in situ hybridization （mc-FISH） was employed to detect the distribution of Oligo-pScll9.2 and Oligo-pTa535 in chromosomes ofAe. speltoides; centromere-specific oligonucleotide CCS1 was used to identify the location of centromeres on chromosomes; FISH karyotype comparison was conducted to show the karyotypic differences between Ae. speltoides and wheat. [Result] In wheat, oligo-pTa535 signals were observed mainly on chromosomes in A and D genomes, and only very sporadic signals were found in B genome. However, oligo-pTa535 signals were absent in Ae. speltoides of five accessions. Oligo-pScll9.2, compared to a little distribution in A and D genomes, shined plentiful fluorescence in the whole genome B in wheat, and especially in S genomes in Ae. speltoides of five accessions used in this study. Different pairs of chromosomes in wheat could be distinguished from each other according to the distribution of Oligo-pScll9.2 and Oligo-pTa535 on chromosomes of wheat. FISH patterns produced by Oligo-pScll9.2 in wheat showed similarity among wheat materials whether of different ploidy or of different varieties of same ploidy, and that in Ae. speltoides varied depending on accessions. Even homologous chromosomes in one cell in Ae. speltoides exhibited differences in FISH pattern. Oligo-pScll9.2 FISH patterns of five accessions each showed obvious differences from that of B genomes in wheat. Four of five Ae. speltoides accessions possess six pairs of metacentric chromosomes except for homologous pairs 4S of submetacentric chromosomes, which were involved in the karyotype formula 2n = 14 = 12m ＋ 2sm, and the rest one, PI542238, however, houses seven pairs of metacentric chromosomes which resulted in the karyotype formula 2n = 14 = 14m. [ Conclusion] Chromosomes ofAe. speltoides house rich repetitive DNA sequences highly homologous to pSc119.2 and lack that highly homologous to pTa53. The distribution ofpSc119.2 on chromosomes ofAe. speltoides showed differences between accessions, between plants of one accession and even between homologous chromosomes in one plant. FISH patterns produced by Oligo-pScll9.2 on Ae. speltoides chromosomes exhibited significant difference from that on chromosomes orb genomes in wheat. FISH analysis, using Oligo-pScll9.2 and Oligo-pTa535 as probes, not only could differentiate the chromosomes in wheat from that in Ae. speltoides, but also could dishtinguish the chromosomes from each other whether in wheat or in Ae. speltoides.