Research highlights genomic features that make plants good candidates for domestication

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New research released this week identifies genomic features that may have made domestication possible for corn and soybeans, two of the world's most critically cultured crops.

The research, published Thursday in the peer-reviewed academic journal Genome biology, has implications for how scientists understand domestication, or the process by which humans have been able to select plants for desirable traits in centuries of culture. The researchers drew on vast amounts of genome data for corn and soybean and compared particular sections of wild-type genomes and national varieties, noting where the genomes diverged most clearly.

Researchers at Iowa State University worked with scientists from the University of Georgia, Cornell University, and the University of Minnesota. Researchers studied more than 100 accessions from comparisons between maize and teosinte, its progenitor species. They also examined 302 entries from a wild and domestic soybean dataset.

"We cut the genomes into specific sections and compared them," said Jianming Yu, professor of agronomy and Pioneer Chair Distinguished on Corn Selection. "This is a new angle that few people have examined regarding the evolution and domestication of the genome." We looked for "macro-changes" or major genome-scale patterns – and we found them. "

Human culture has created a bottleneck in the genetic material associated with corn and soy, Yu said. As people selected for particular traits they found desirable in their crops, they limited genetic variation available in the genome of the plant. However, researchers found several areas in the genomes of the species involved in the study where the genomic divergence seemed to be concentrated.

"These patterns of genome-wide base changes provide insight into how domestication affects species genetics," said Jinyu Wang, the journal's first author and graduate student in agronomy.

Variation of nucleotide bases between wild and domesticated species appeared more pronounced in nongenic parts of genomes, or in parts of genomes that do not encode proteins. The study also revealed greater variation in the pericentromeric regions, or in areas near the centromere of chromosomes, and in areas of high methylation, or in areas in which methyl groups are added to a molecule of higher molecular weight. # 39; DNA. Methylation can change the activity of a segment of DNA without changing its sequence.

The study examined the appearance of mutations in the genomes of domesticated crops and their progenitor species.

"We now think that it is likely that good candidates for domestication, such as corn and soy, occupy an intermediate position in their willingness to mutate," said Xianran Li, associate agronomy professor and author co-correspondent of the study.

"If there is no mutation, then everything stays the same and we have no evolution," Yu said. "But too many mutations can wipe out a species. "

The results of the study have highlighted important links between the sun's UV radiation and the evolution of the genome. UV rays are a natural mutagen, and they leave a special imprint when they occur, Yu said. The study's authors found many more footprints in modern corn and soybeans than their wild relatives.

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