Allelic Variation of Gene Expression in Maize Hybrids[W]

Abstract

Allelic expression variation of nonimprinted autosomal genes has recently been uncovered in mouse hybrids and humans. The allelic expression variation is attributed to differences in noncoding DNA sequences and does not involve epigenetic regulation or gene imprinting. This expression variation is suggested to play important roles in determining phenotypic diversity. Virtually nothing is known about such allele-specific expression variation in a hybrid plant where two alleles are compared in the same genetic context. We examined parental transcript accumulation in maize (Zea mays) hybrids using allele-specific RT-PCR analysis. Among 15 genes analyzed, 11 showed differences at the RNA level, ranging from unequal expression of the two alleles (biallelic) to expression of a single allele (monoallelic). Maternal or paternal transmission had little effect on the allele-specific transcript ratio of nearly all genes analyzed, suggesting that parent-of-origin effect was minimal. We analyzed the allelic difference in genetically contrasting hybrids and hybrids under high planting density and drought stress. Whereas a genetically improved modern hybrid expressed both alleles, a less improved old hybrid frequently showed mono-allelic expression. Furthermore, the two alleles in the hybrid responded differentially to abiotic stresses. The results of allele-specific regulation in different tissues in responding to environment and stress suggest an unequivalent function of the parental alleles in the hybrid, which may have an impact on heterosis.

Isolation and characterization of CCoAOMT in interspecific hybrid of Acacia auriculiformis x Acacia mangium - a key gene in lignin biosynthesis

“…In addition, polymorphism in the noncoding DNA sequences (regulatory domains and intron regions) can affect the level of gene expression or RNA stability, and result in quantitative variants. Both types of genetic variation may produce functional changes and affect phenotypes of an organism (Guo et al, 2004). The frequency and nature of SNPs in forest trees have received considerable attention in recent years (Zhang and Zhang, 2005).…”

A transcriptomic analysis of superhybrid rice LYP9 and its parents

“…In maize, both allelic diversity and expression variation were found between inbred parents and their hybrid (4). In maize hybrids, not only the allelic variation in gene expression but also different responses to extrinsic stimuli supported the presence of allelic expression variation in the same genetic context (5). Large-scale transcriptome profiling has been used for heterosis studies in maize (6), Arabidopsis (7), and wheat (8).…”

Species Occurrence, Hybridization and Speciation in Postglacial East and South Asia

“…One of the most famous of Pteris is the P. quadriaurita complex. Species complex may involve multiple mechanisms, including hybridization, polyploidy, morphological plasticity, gene expression, geographical divergence, and reproductive traits (Rosenthal et al, 2002;Guo et al, 2004;Lai et al, 2005;Zhuang & Adams, 2007;Guggisberg et al, 2009). As all of these are closely associated with speciation, species complex could be considered a group of taxa undergoing speciation.…”