Dual Threats of Imperiled Native Agroecosystems and Climate Change to World Food Security: Genomic Perspectives

All of our crop plants originated in the Vavilovian centers of plant genetic diversity. Following domestication, crop plants went through a period of reduced diversity caused by a domestication bottleneck. The cultivation of crop plants in native habitats where crop plants and their wild relatives grew in close contact created native agroecosystems, which facilitated frequent genetic exchange between crop plants and their wild ancestors, thereby enriching the crop gene pool. These native agroecosystems even produced new crop plants, such as bread wheat. Humans traveled with their crop plants spanning the globe, and the enriched crop gene pools were adapted to diverse habitats, creating landraces that nourished preindustrial agriculture and human civilizations. Genomic research has shown that many of the genes that were exploited in the Green Revolution evolved recently by the active evolutionary processes made possible by functioning native agroecosystems and the selection pressure imposed by various abiotic and biotic stresses. With the dawn of the scientific method of breeding, the genetic diversity in the landraces of crop plants and wild relatives was exploited to develop highly productive crop cultivars. Population pressure, habitat destruction, and the spread of modern industrialization are destroying the very native agroecosystems that are our lifeline. We need functioning native agroecosystems as well as springs of new genetic diversity in response to changing climate. Although the genetic diversity conserved in crop genebanks is, and will be, useful in the long run, they may not contain the new genes that we may need as an insurance policy against the vagaries of drastic climate change. A plan of action is suggested for the conservation of native agroecosystems.