From within the genetic diversity of wild teosinte – the evolutionary ancestor of modern maize –valuable traits lay hidden. In searching the ancestral genome, researchers report the discovery of UPA2 , a rare allele long-lost to the selective pressures of domestication in modern maize, which can be used to directly increase the crop yields of densely planted maize by altering the angle of the plants leaves. “The work suggests that re-domesticating crops may identify other useful traits hidden in our crop’s ancestors,” writes Sarah Hake in a related Perspective. The ability to grow ever-increasing amounts of food to meet global demand relies on our ability to reap more from limited agricultural land. Increasing the density of planted crops can improve yields; however, for many crops, maize included, crowded plantings impose competition between plants for water, sunlight and soil nutrients. By adapting new varieties of maize with more upright leaves, the planting density of maize has been drastically increased. However, human selection comes at the cost of genetic diversity, which can limit the adaptive potential and genetic health of future generations. Recognizing the breadth of genetic variation within wild teosinte, Jinge Tian and colleagues created recombinant inbred lines between modern maize and teosinte and revealed a molecular regulatory network controlling the UPA2 allele. According to the results, UPA2 confers upright and narrow plant growth in teosinte, but the gene is absent in maize. Introgression of the lost allele into modern maize resulted in hybrids with significantly increased yield under high-density planting, the authors say. Tian et al. suggest the advantage of these traits have only recently become relevant and could explain why the gene was not conserved over domestication.
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Science