Key Laboratory of the MOE for Plant Developmental Biology, College of Life Sciences, Wuhan University, Wuhan, China Engineering Research Center of Wetland Agriculture in the Middle Reaches of the Yangtze River, Ministry of Education, College of Agriculture, Yangtze University, Jingzhou, Hubei, China Hubei Academy of Agricultural Sciences, Wuhan, China.
Plant Biol (Stuttg). 2012 Sep;14(5):734-44. doi: 10.1111/j.1438-8677.2011.00553.x. Epub 2012 Feb 6.
Allopolyploidisation is a prominent evolutionary force that involves two major events: interspecific hybridisation and genome doubling. Both events have important functional consequences in shaping the genomic architecture of the neo-allopolyploids. The respective effects of hybridisation and genome doubling upon genomic and transcriptomic changes in Brassica allopolyploids are unresolved. In this study, amplified fragment length polymorphism (AFLP), methylation-sensitive amplification polymorphism (MSAP) and cDNA-AFLP approaches were used to track genetic, epigenetic and transcriptional changes in both allohexaploid Brassica (ArArBcBcCcCc genome) and triploid hybrids (ArBcCc genome). Results from these groups were compared with each other and also to their parents Brassica carinata (BBCC genome) and Brassica rapa (AA genome). Rapid and dramatic genetic, DNA methylation and gene expression changes were detected in the triploid hybrids. During the shift from triploidy to allohexaploidy, some of the hybridisation-induced alterations underwent reversion. Additionally, novel genetic, epigenetic and transcriptional alterations were also detected. The proportions of A-genome-specific DNA methylation and gene expression alterations were significantly greater than those of BC-genome-specific alterations in the triploid hybrids. However, the two parental genomes were equally affected during the ploidy shift. Hemi-CCG methylation changes induced by hybridisation were recovered after genome doubling. Full-CG methylation changes were a more general process initiated in the hybrid and continued after genome doubling. These results indicate that genome doubling could ameliorate genomic and transcriptomic alterations induced by hybridisation and instigate additional alterations in trigenomic Brassica allohexaploids. Moreover, genome doubling also modified hybridisation-induced progenitor genome-biased alterations and epigenetic alteration characteristics.
异源多倍化是一种重要的进化力量，涉及两个主要事件：种间杂交和基因组加倍。这两个事件在塑造新异源多倍体的基因组结构方面具有重要的功能后果。杂种化和基因组加倍对芸薹属异源多倍体的基因组和转录组变化的各自影响尚未解决。在这项研究中，扩增片段长度多态性（AFLP）、甲基化敏感扩增多态性（MSAP）和 cDNA-AFLP 方法被用于跟踪异源六倍体芸薹属（ArArBcBcCcCc 基因组）和三倍体杂种（ArBcCc 基因组）的遗传、表观遗传和转录变化。这些组的结果相互比较，并与它们的亲本芸薹属甘蓝（BBCC 基因组）和芸薹属白菜（AA 基因组）进行比较。在三倍体杂种中检测到快速而剧烈的遗传、DNA 甲基化和基因表达变化。在从三倍体向异源六倍体转变的过程中，一些杂种诱导的改变发生了逆转。此外，还检测到新的遗传、表观遗传和转录改变。三倍体杂种中 A 基因组特异性 DNA 甲基化和基因表达改变的比例明显大于 BC 基因组特异性改变的比例。然而，在倍性转变过程中，两个亲本基因组受到的影响是相同的。杂种化诱导的半 CCG 甲基化变化在基因组加倍后得到恢复。全 CG 甲基化变化是一个更普遍的过程，在杂种中启动，并在基因组加倍后继续进行。这些结果表明，基因组加倍可以改善杂交诱导的基因组和转录组改变，并在三基因组芸薹属异源六倍体中引发额外的改变。此外，基因组加倍还改变了杂种化诱导的亲本组偏向改变和表观遗传改变特征。
