Peanut Has Little Genetic Variety. Researchers Mapped What There Is and Bred From It.

Researchers have built a combined genetic map of cultivated peanut and used it to read the DNA of 2,320 accessions, meaning distinct samples held in a seed bank. The work was published on September 15 in Nature Genetics.

Cultivated peanut carries little genetic variation, and the paper says that has hampered breeding progress and yield improvement. The authors describe what they assembled as genomic resources meant to speed up gene discovery and peanut breeding.

The map is a graph pan-genome: rather than one plant's genome serving as the single reference, it holds the DNA of many plants at once. Yiyang Liu, Shubo Wan and colleagues at the Shandong Academy of Agricultural Sciences in Jinan, China, built it from 14 genomes covering all six varieties of the cultivated crop. Co-authors came from ICRISAT, an international crop research institute in India, and from Murdoch University in Australia.

Those samples cover 88.03% of ICRISAT's core peanut collection and 59.21% of the U.S. Department of Agriculture's, the authors report.

Peanut is a hybrid of two wild species, so it carries two near-identical sets of chromosomes, and stretches of DNA swap between them. That swapping confuses the usual ways of reading peanut DNA, and the graph map worked around it. Working from the map, the team cataloged large structural differences in the crop's DNA and examined how the swapping shaped the split between peanut populations. It also identified genes behind flowering and dwarf growth. They then bred short-stemmed peanut lines that the paper calls high-yielding.