He Ping, Friebe Bernd R, Gill Bikram S, Zhou Jian-Min
Department of Plant Pathology, Kansas State University, Manhattan, KS 66506, USA.
Plant Mol Biol. 2003 May;52(2):401-14. doi: 10.1023/a:1023965400532.
Hexaploid wheat (Triticum aestivum) contains triplicated genomes derived from three distinct species. To better understand how different genomes are coordinated in the same nucleus of the hexaploid wheat, we globally compared gene expression of a synthetic hexaploid wheat with its diploid (Aegilops tauschii) and tetraploid (T. turgidum) parents by cDNA-AFLP display. The results suggested that the expression of a significant fraction of genes was altered in the synthetic hexaploid; most appeared to be diminished and some were activated. We characterized nine cDNA clones in details. Cytogenetic as well as genomic sequence analyses indicated that the gene silencing was not due to chromosome/DNA loss but was caused by gene regulation. Northern and RT-PCR divided these genes into three groups: (I) four genes were down-regulated nonspecifically, likely involving both parental orthologues; (II) four genes were down-regulated in an orthologue-dependent manner; (III) one gene was activated specifically in the synthetic hexaploid wheat. These genes were often altered non-randomly in different synthetic hexaploids as well as natural hexaploid wheat, suggesting that many of the gene expression changes were intrinsically associated with polyploidy.
六倍体小麦（普通小麦）包含源自三个不同物种的三组重复基因组。为了更好地理解不同基因组在六倍体小麦的同一个细胞核中是如何协调的，我们通过cDNA-AFLP展示技术，对一个人工合成六倍体小麦与其二倍体亲本（节节麦）和四倍体亲本（硬粒小麦）的基因表达进行了全面比较。结果表明，人工合成六倍体中相当一部分基因的表达发生了改变；大多数基因的表达似乎减弱了，还有一些被激活了。我们详细鉴定了9个cDNA克隆。细胞遗传学和基因组序列分析表明，基因沉默不是由于染色体/DNA丢失，而是由基因调控引起的。Northern杂交和RT-PCR将这些基因分为三组：（I）四个基因非特异性下调，可能涉及双亲的直系同源基因；（II）四个基因以直系同源基因依赖的方式下调；（III）一个基因在人工合成六倍体小麦中特异性激活。这些基因在不同的人工合成六倍体以及天然六倍体小麦中常常非随机地发生改变，这表明许多基因表达变化与多倍体本质上相关。
