Development and applications of KASP markers distinguishing A- and B/K-genomes of Arachis

Authors: LEVINSON, C M - University Of Georgia; BERTIOLI, D J - University Of Georgia; CHU, Y - University Of Georgia; HOPKINS, M - University Of Georgia; LEAL-BERTIOLI, S.C.M. - University Of Georgia; Gao, Dongying; STALKER, H T - North Carolina State University; OZIAS-AKINS - University Of Georgia

Submitted to: Euphytica
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/10/2021
Publication Date: 9/30/2021
Citation: Levinson, C., Bertioli, D., Chu, Y., Hopkins, M., Leal-Bertioli, S., Gao, D., Stalker, H., Ozias-Akins 2021. Development and applications of KASP markers distinguishing A- and B/K-genomes of Arachis. Euphytica. 217:196. https://doi.org/10.1007/s10681-021-02923-8.
DOI: https://doi.org/10.1007/s10681-021-02923-8

Interpretive Summary: Like many other important crops, the cultivated peanut materials show low genetic diversity that makes peanut vulnerable to diseases and pests. Introgression of resistance genes from wild species into cultivated peanut is an important way for expanding peanut genetic base and for enhancing its resistance to biotic and abiotic stresses. However, the majority of wild peanut species are diploids and can not be directed used to make crosses with the tetraploid cultivated peanut as their hybrids will be sterile, thus development of allotetraploid wild peanuts with interspecific hybridizations between different wild species is a practical strategy to overcome the ploidy barrier. The conventional method for identifying interspecific wild hybrids is to use the phenotypic traits such as flower colors and pollen viability. However, this protocol is time-consuming and inefficient in some cases as only a very limited phenotypic traits can be used for confirming real wild hybrids. Our studies developed 105 kompetitive allele specific PCR (KASP) markers that can be used to distinguish the wild species with A- and B/K-genomes. These markers provide a fast method for identifying true hybrids between the wild species with different genome types. The markers also can be used to track the introgression of unique traits from wild peanut species.

Technical Abstract: Peanut is an important global food crop with a narrow genetic base due to its domestication bottleneck and the ploidy barrier between it and almost all of its wild diploid relatives. Increasingly, peanut breeders have been introgressing beneficial alleles from its diploid relatives into the cultigen to improve agronomic traits along with its pathogen and pest resistances. To overcome the ploidy barrier, the process of introgression can be initiated by making hybrids between A- and B/K-genome Arachis diploid species and then doubling their chromosomes to induce tetraploidy. These allotetraploids are generally cross-compatible with peanut. Previously, true allotetraploids were distinguished from selfed progeny by infertile pollen grain counts; however, markers that can distinguish allele dosage between A- and B/K-genomes allow allotetraploids to be confirmed before flowering or even planting and can be more reliable than infertile pollen grain counts. These markers also can be used to confirm and track the inheritance of previously discovered homoeologous recombination events, which commonly occur in synthetic allotetraploid-derived materials. In this study, 105 KASP markers distinguishing A- and B/K-genomes were designed to span the entire peanut genome. These markers can be used as a time and cost-efficient alternative to using the Axiom_Arachis SNP arrays where high-resolution is not required.