, Volume 27, Issue 2, pp 162-176
Date: 11 Nov 2008

Genome-wide Comparisons of Gene Expression for Yield Heterosis in Maize

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Abstract

Although heterosis is widely used in conventional plant breeding, its genetic mechanism has not been well understood at the molecular level. In this study, we identified a highly heterotic hybrid (C8605-2 × W1445) and a low heterotic hybrid (C8605-2 × W245) for yield performance in maize from 33 hybrids obtained from an incomplete diallel mating scheme. Using high-density maize oligomicroarrays, we analyzed and compared gene expression profiles of the highly heterotic hybrid, its parent lines, and the low heterotic hybrid. A total of 2,366 differentially expressed genes were identified in C8605-2 × W1445 and its two parents. These genes exhibited heterogeneous expression patterns in the hybrid relative to its parents, and covering additivity, high-parent dominance, low-parent dominance, overdominance, underdominance, and partial-dominance. The functions of several genes fell in diverse biological processes, including metabolism, signal transduction, transport, biological regulation, and development, among others. Notably, among those highly upregulated genes in the hybrid, there were genes known to play vital roles in stress tolerance and yield enhancement and groups of transcriptional factors that might contribute to overall enhanced quality of the hybrid. Further comparisons between high- and the low-heterotic hybrids also revealed a subset of differentially expressed genes. Together, this genome-wide comparison among maize lines exhibiting varying degrees of heterosis, during the early developmental phase of immature ears, will provide valuable information for further studies on linkage between specific gene expression and phenotype of heterosis.

This work was supported by Key Project of Chinese National Programs for Fundamental Research and Development (2007CB109003).