BREAD ABRDC: Genomic approaches to capture Novel Alleles in cultivated peanut to increase smallholder production.

University Of Georgia Research Foundation Inc, Athens GA

Investigators

Abstract

PI: Peggy Ozias-Akins (University of Georgia) CoPIs: Scott A. Jackson and Soraya Bertioli (University of Georgia), H. Thomas Stalker (North Carolina State University), and Daniel Fonceka (CIRAD and ISRA/CERAAS, Senegal) Cultivated peanut is an important food and oil crop in the U.S. and globally. Peanut is polyploid and originated relatively recently in evolutionary time from hybridization between two diploid species, followed by chromosome doubling. This domestication bottleneck limits variation among genes for resistance to most pests and diseases. Advances in breeding methods have resulted in the development of synthetic polyploids from the ancestral diploid species of peanut. Crossing and backcrossing synthetic polyploids with cultivated lines allows transfer of chromosomal segments carrying desirable traits to the cultivated genome. Given that the majority of peanuts are produced in developing countries and that potential for yield gains based on genetic improvement is large, the long-term impact on production of this nutritious crop will be substantial. Partnership with the Senegalese Institute for Agricultural Research will ensure that the outputs of this project reach smallholder farmers given their current inclusion in a network that is being used both for evaluation and pre-diffusion of the most promising germplasm. Well characterized germplasm also will be made available to breeding programs around the world. Cultivated peanut (Arachis hypogaea L.) is an important food and oil crop in the U.S. and internationally, particularly for small holder farmers. The allotetraploid cultivated species (2n = 4x = 40; AABB genomes) originated from two diploid species, A. duranensis (AA) and A. ipaensis (BB), has very low levels of DNA polymorphism, and only moderate levels of resistance to most pests and diseases. However, several diploid (2n = 2x = 20) Arachis species have extremely high levels of resistance or immunity to the most important diseases of peanut. Objectives of this project are to hybridize four A-genome disease-resistant species with two diploid B- and one K-genome species. The B- and K-genomes are recently described cytological variants of the B genome that likely have different recombination potentials with cultivated peanut. Synthetic tetraploids will be produced from twelve interspecific hybrid combinations and then hybridized with peanut cultivars so that selections can be made for early and late leaf spots, rust, other pathogen resistances, drought tolerance, and favorable pod and haulm traits. In addition, advanced generation interspecific hybrids from four AABB synthetics will be field tested in Africa for these same traits. Taking advantage of the expanding genomic resources for peanut, sequence-based genotyping will be conducted to survey allelic diversity between parental lines, to confirm the hybrid nature of crosses and backcrosses, to characterize introgressions during backcrossing, and to select for QTL conferring leaf spot and rust resistance and drought tolerance along with pod and haulm traits. It is expected that genotyping and phenotyping information generated will contribute to QTL and gene discovery bearing significance for peanut improvement in traits relevant to smallholder agriculture in Africa and other peanut growing regions of the world. These proposed activities will advance knowledge of peanut genetics, evolutionary relationships within the genus, genome structure and gene function enabling a more systematic approach for introgression of wild alleles into cultivated germplasm. Project activities will involve graduate and undergraduate students and provide an active learning environment with emphasis on modern plant breeding and genomics.