Germplasm Pools for Quinoa Improvement

Quinoa (Chenopodium quinoa, 2n = 4x = 36, AABB subgenomes) is a highly nutritious crop with the potential to diversify global diets and alleviate malnutrition. It is also adaptable for production in soils increasingly affected by salinization and water scarcity. Quinoa was domesticated and artificially selected as a crop within the Andes Mountains, the geographically isolated Mediterranean climate zone of coastal Chile, and along the northwestern fringe of the Argentine dry Pampas. In addition, there is now abundant information regarding the wild species that were its immediate ancestors and which should be viewed as its secondary and tertiary breeding gene pools. These same ancestors contributed to independent domestications of the other forms of “quinoa” in ancient Mesoamerica and eastern North America from a common AABB ancestor-species, C. berlandieri, known commonly as pitseed goosefoot (PG). This review explores the biogeography of the diploid and polyploid relatives of the AABB allotetraploid goosefoot complex (ATGC). The seven or more ecotypes of PG, including the South American taxon C. hircinum, or avian goosefoot (AG), contain broad genetic variability, and some can be used directly as crossing partners in making quinoa breeding populations. Of the extant diploid relatives, C. subglabrum (SMG) is most closely related to the original maternal subgenome A of PG, while C. suecicum (SWG) or C. ficifolium (FG) are most closely related to paternal subgenome B. These and the other AA and BB diploids are valuable model organisms for locating and modifying genes of interest and their expression, the ultimate goals being to increase quinoa’s yield potential, improve its nutritional attributes, explore value-adding industrial uses, and enhance quinoa’s already formidable mechanisms to resist environmental stresses. This review is an update on the current state of quinoa breeding, with an emphasis on the value of wild genetic resources for quinoa improvement. It provides a comprehensive review of the scientific literature for scientists interested in adding quinoa to their breeding program.