A next generation of studies: Heterosis and inbreeding depression
نویسندگان
چکیده
Heterosis or hybrid vigor is a phenomenon in which the F1 progeny is superior in characteristics than its inbred parents. Inbreeding depression refers to the reduced vigor in the offspring from matings involving related parents. The world’s most important grain crop, Zea mays exhibits significant heterosis and inbreeding depression, and despite billions of dollars of sales and investments in hybrid maize, the underlying molecular and genetic mechanisms responsible for inbreeding depression and heterosis still remain unknown. We used next generation sequencing technologies and a sample of the most elite publicly available germplasm to explore the role of gene expression in hybrids vs. inbreds. A comparison of transcript counts from inbred parents and their hybrids revealed additive gene action to be the most prevalent among differentially expressed genes. Gene expression that deviated from additivity showed high parent dominance, suggesting that the alleles from the high parent affected the expression in the hybrid more than the alleles from the low parent. Most differentially expressed genes were inconsistent among families, however at a higher level of organization these sets of genes belonged to the same metabolic pathways and were up-regulated in different parents and hybrids, indicating that organisms often utilize compensatory/complementary genetic networks to perform the same task. Allele-specific expression analysis for all inbred-hybrid combinations showed that a majority of alleles that were preferentially expressed in the hybrids also were expressed differentially between its inbred parents. Cis-trans statistical tests revealed that although most alleles exhibit conserved expression, cis-regulation was found to affect alleles more than trans-regulation. Cis regulation was found to be strongly correlated with additive gene action identified from the
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