Springer Nathan M, Stupar Robert M
Department of Plant Biology, Microbial and Plant Genomics Institute, University of Minesota, St. Paul, Minnesota 55108, USA.
Plant Cell. 2007 Aug;19(8):2391-402. doi: 10.1105/tpc.107.052258. Epub 2007 Aug 10.
We employed allele-specific expression (ASE) analyses to document biased allelic expression in maize (Zea mays). A set of 316 quantitative ASE assays were used to profile the relative allelic expression in seedling tissue derived from five maize hybrids. The different hybrids included in this study exhibit a range of heterosis levels; however, we did not observe differences in the frequencies of allelic bias. Allelic biases in gene expression were consistently observed for approximately 50% of the genes assayed in hybrid seedlings. The relative proportion of genes that exhibit cis- or trans-acting regulatory variation was very similar among the different genotypes. The cis-acting regulatory variation was more prevalent and resulted in greater expression differences than trans-acting regulatory variation for these genes. The ASE assays were further used to compare the relative expression of the B73 and Mo17 alleles in three tissue types (seedling, immature ear, and embryo) derived from reciprocal hybrids. These comparisons provided evidence for tissue-specific cis-acting variation and for a slight maternal expression bias in approximately 20% of genes in embryo tissue. Collectively, these data provide evidence for prevalent cis-acting regulatory variation that contributes to biased allelic expression between genotypes and between tissues.
我们采用等位基因特异性表达（ASE）分析来记录玉米（Zea mays）中的等位基因表达偏差。一组316个定量ASE检测用于分析来自五个玉米杂交种的幼苗组织中的相对等位基因表达。本研究中纳入的不同杂交种表现出不同程度的杂种优势；然而，我们并未观察到等位基因偏差频率的差异。在杂交幼苗中检测的约50%的基因中持续观察到基因表达的等位基因偏差。在不同基因型中，表现出顺式或反式作用调控变异的基因的相对比例非常相似。对于这些基因，顺式作用调控变异更为普遍，并且导致的表达差异比反式作用调控变异更大。ASE检测还用于比较来自正反交杂种的三种组织类型（幼苗、未成熟穗和胚）中B73和Mo17等位基因的相对表达。这些比较为组织特异性顺式作用变异以及胚组织中约20%的基因存在轻微的母本表达偏差提供了证据。总体而言，这些数据为普遍存在的顺式作用调控变异提供了证据，这种变异导致了基因型之间和组织之间的等位基因表达偏差。
