Gautam Mayank, Dang Yanwei, Ge Xianhong, Shao Yujiao, Li Zaiyun
National Key Laboratory of Crop Genetic Improvement, National Center of Oil Crop Improvement (Wuhan), College of Plant Science and Technology, Huazhong Agricultural University Wuhan, China.
College of Chemistry and Life Science, Hubei University of Education Wuhan, China.
Front Plant Sci. 2016 Apr 12;7:438. doi: 10.3389/fpls.2016.00438. eCollection 2016.
Allopolyploidization with the merger of the genomes from different species has been shown to be associated with genetic and epigenetic changes. But the maintenance of such alterations related to one parental species after the genome is extracted from the allopolyploid remains to be detected. In this study, the genome of Brassica napus L. (2n = 38, genomes AACC) was extracted from its intergeneric allohexaploid (2n = 62, genomes AACCOO) with another crucifer Orychophragmus violaceus (2n = 24, genome OO), by backcrossing and development of alien addition lines. B. napus-type plants identified in the self-pollinated progenies of nine monosomic additions were analyzed by the methods of amplified fragment length polymorphism, sequence-specific amplified polymorphism, and methylation-sensitive amplified polymorphism. They showed modifications to certain extents in genomic components (loss and gain of DNA segments and transposons, introgression of alien DNA segments) and DNA methylation, compared with B. napus donor. The significant differences in the changes between the B. napus types extracted from these additions likely resulted from the different effects of individual alien chromosomes. Particularly, the additions which harbored the O. violaceus chromosome carrying dominant rRNA genes over those of B. napus tended to result in the development of plants which showed fewer changes, suggesting a role of the expression levels of alien rRNA genes in genomic stability. These results provided new cues for the genetic alterations in one parental genome that are maintained even after the genome becomes independent.
不同物种基因组的合并所导致的异源多倍体化已被证明与遗传和表观遗传变化有关。但是，从异源多倍体中提取基因组后，与一个亲本物种相关的此类变化的维持情况仍有待检测。在本研究中，通过回交和异源附加系的培育，从甘蓝型油菜（2n = 38，基因组AACC）与另一种十字花科植物诸葛菜（2n = 24，基因组OO）的属间异源六倍体（2n = 62，基因组AACCOO）中提取了甘蓝型油菜的基因组。对在9个单体附加系的自交后代中鉴定出的甘蓝型油菜类型植株，采用扩增片段长度多态性、序列特异性扩增多态性和甲基化敏感扩增多态性方法进行分析。与甘蓝型油菜供体相比，它们在基因组组成（DNA片段和转座子的丢失和获得、外源DNA片段的渗入）和DNA甲基化方面表现出一定程度的修饰。从这些附加系中提取的甘蓝型油菜类型之间变化的显著差异可能是由于单个外源染色体的不同作用。特别是，那些含有携带比甘蓝型油菜显性rRNA基因的诸葛菜染色体的附加系，往往导致变化较少的植株发育，这表明外源rRNA基因的表达水平在基因组稳定性中起作用。这些结果为即使在基因组独立后仍能维持的一个亲本基因组中的遗传改变提供了新线索。
