Understanding Grass Domestication through Maize Mutants

• Published in: Trends in genetics Vol. 35; no. 2; pp. 118 - 128
• Main Authors: Dong, Zhaobin, Alexander, Martin, Chuck, George
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.02.2019
• Subjects: Branch; Domestication; Gene Expression Regulation, Plant; Genome, Plant - genetics; Humans; maize; meristem; Mutation - genetics; Phenotype; Plant Proteins - genetics; Poaceae - genetics; Poaceae - growth & development; Selection, Genetic; spikelet; transcription factor; Zea mays - genetics; Zea mays - growth & development; transcription factor; meristem; spikelet; maize; Branch; domestication
• ISSN: 0168-9525
• DOI: 10.1016/j.tig.2018.10.007

As an economically important model crop plant, rich in genetic resources, maize has been useful for uncovering the genetic pathways responsible for domestication and plant improvement. However, several of the pathways that have been shown by recent studies to be important for domestication and/or yield in other grasses function differently in maize. In several cases, this unexpectedly wide functional divergence between genes from closely related grasses appears to be due to alternative modes of regulation rather than to simple differences in protein function. This indicates that domestication genes need to be understood within the architecture of the whole genome and the species-specific processes that they influence before they can serve as the foundation to improve plants. A key domestication gene, tb1, encodes a transcription factor that targets other domestication genes, thus placing it at the top of a domestication hierarchy. Despite having divergent functions in different grasses, domestication genes can still improve yield traits depending on where they are expressed. Dominant domestication phenotypes can result from alternative modes of gene regulation due to transposon insertion or a lack of miRNA-mediated repression. Mutations in developmental genes that normally result in sterility may improve yield when weak alleles are used in diploid crop plants. Alternatively, in polyploid crop plants, the presence of extra gene copies may partially compensate for strong loss-of-function alleles to achieve similar positive effects on yield.