Genomic characteristics that make plants good candidates for domestication
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 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. during centuries of culture. Researchers drew on vast amounts of corn and soybean genome data and compared particular sections of the genomes of wild and domestic 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 of a dataset of wild and domesticated soybeans.
"We cut the genomes into specific sections and compared them," said Jianming Yu, professor of agronomy and Pioneer Distinguished Chair in Corn Selection. "This is a new angle that few people have examined about the evolution and domestication of the genome, we have been looking for" macro changes "or major genome-wide patterns - and we have found them."
Human culture has created a bottleneck in the genetic material associated with corn and soybeans, Yu said. As people selected for particular traits they found desirable in their crops, they limited the genetic variation available in the genome of the plant. However, the 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 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 DNA molecule . Methylation can change the activity of a DNA segment without changing its sequence.
The study examined the occurrence of mutations in the genomes of domesticated crops and their progenitor species.
"We now believe that good candidates for domestication, such as corn and soybeans, are likely to occupy an intermediate position in their willingness to mutate," said Xianran Li, associate professor of agronomy and co-author. corresponding of the study.
"If there is no mutation, then everything stays the same and we have no evolution," said Yu. "But too many mutations can annihilate a species."
The results of the study revealed 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.
The research was funded by the National Science Foundation, the Raymond F. Baker Plant Breeding Center at Iowa State University, and the ISU Plant Sciences Institute.
