Swanson-Wagner Ruth A, DeCook Rhonda, Jia Yi, Bancroft Tim, Ji Tieming, Zhao Xuefeng, Nettleton Dan, Schnable Patrick S
Iowa State University, Ames, IA 50011, USA.
Science. 2009 Nov 20;326(5956):1118-20. doi: 10.1126/science.1178294.
Heterosis refers to the superior performance of hybrid progeny relative to their inbred parents, but the mechanisms responsible are unknown. Hybrids between the maize inbred lines B73 and Mo17 exhibit heterosis regardless of cross direction. These reciprocal hybrids differ from each other phenotypically, and 30 to 50% of their genes are differentially expressed. We identified approximately 4000 expression quantitative trait loci (eQTL) that allowed us to identify markers linked to variation in expression. We found that over three-quarters of these eQTL act in trans (78%) and that 86% of these differentially regulate transcript accumulation in a manner consistent with gene expression in the hybrid being regulated exclusively by the paternally transmitted allele. This result suggests that widespread imprinting contributes to the regulation of gene expression in maize hybrids.
杂种优势是指杂交后代相对于其自交亲本的优良表现，但其背后的机制尚不清楚。玉米自交系B73和Mo17之间的杂交种无论杂交方向如何都表现出杂种优势。这些正反交杂种在表型上彼此不同，并且它们30%至50%的基因存在差异表达。我们鉴定出了大约4000个表达数量性状基因座（eQTL），这些基因座使我们能够识别与表达变异相关的标记。我们发现，这些eQTL中有超过四分之三以反式作用（78%），并且其中86%以与杂交种中基因表达仅由父本传递的等位基因调控相一致的方式差异调节转录本积累。这一结果表明广泛的印记作用有助于调控玉米杂交种中的基因表达。
