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Abstract
About 49 million tons of peanut (Arachis hypogaea L.) are produced globally each year; however, pathogen and insect pests plague global production. Average peanut yields in developing countries are only a fraction of the average yield achieved in the United States primarily because of pathogen and insect pressures. High yields in the United States reflect accessibility to effective chemicals for pathogen control, yet these chemicals are costly to apply. Genetically improved cultivars with stronger, more durable resistance are needed to feed the world’s growing population in a sustainable manner. Yet, the narrow genetic base of cultivated peanut limits crop improvement.
There are more than 80 wild Arachis species with a wide range of genetic and phenotypic diversity, including strong, diverse resistances, that can be deployed for peanut cultivar improvement. The most efficient way to introgress genetic variability from wild Arachis species into cultivated peanut is to produce allotetraploid interspecific hybrids that are cross-compatible to peanut. To enable effective utilization of allotetraploids, morphological, reproductive, and pathogen and insect resistance characterization of novel allotetraploids and allotetraploid-derived breeding materials was performed. In this study, allotetraploids were found to generally have greater production of flowers during the growing season, larger flowers, larger and hairier leaves, taller main stems, longer primary laterals, longer internodes, lower percentage of reproductive nodes, heavier plant body masses, and smaller seeds and pods than cultivated peanut. This diversity will likely need to be selected against while desirable traits such as pathogen and insect resistance are maintained. In addition, the weak peg strength of wild Arachis species was thought to be potentially detrimental to yield; however, peg strength comparable to that of peanut breeding lines was recovered in F1 hybrids. Therefore, weak peg strength is a minor concern to plant breeders when using these materials. Resistance to fall armyworm and rust were identified in allotetraploids, and five, novel putative QTL for tomato spotted wilt orthotospovirus resistance were discovered that can be utilized for marker-assisted selection once validated. This work will contribute to producing high-yielding, resistant cultivars that will protect peanut production in the United States and promote global food security.
There are more than 80 wild Arachis species with a wide range of genetic and phenotypic diversity, including strong, diverse resistances, that can be deployed for peanut cultivar improvement. The most efficient way to introgress genetic variability from wild Arachis species into cultivated peanut is to produce allotetraploid interspecific hybrids that are cross-compatible to peanut. To enable effective utilization of allotetraploids, morphological, reproductive, and pathogen and insect resistance characterization of novel allotetraploids and allotetraploid-derived breeding materials was performed. In this study, allotetraploids were found to generally have greater production of flowers during the growing season, larger flowers, larger and hairier leaves, taller main stems, longer primary laterals, longer internodes, lower percentage of reproductive nodes, heavier plant body masses, and smaller seeds and pods than cultivated peanut. This diversity will likely need to be selected against while desirable traits such as pathogen and insect resistance are maintained. In addition, the weak peg strength of wild Arachis species was thought to be potentially detrimental to yield; however, peg strength comparable to that of peanut breeding lines was recovered in F1 hybrids. Therefore, weak peg strength is a minor concern to plant breeders when using these materials. Resistance to fall armyworm and rust were identified in allotetraploids, and five, novel putative QTL for tomato spotted wilt orthotospovirus resistance were discovered that can be utilized for marker-assisted selection once validated. This work will contribute to producing high-yielding, resistant cultivars that will protect peanut production in the United States and promote global food security.