A novel aphid resistance locus in cowpea identified by combining SSR and SNP markers

Abstract

The utility of combining simple sequence repeat (SSR) and single nucleotide polymorphism (SNP) marker genotyping was determined for genetically mapping a novel aphid (Aphis craccivora) resistance locus in cowpea breeding line SARC 1‐57‐2 and for introgressing the resistance into elite cultivars by marker‐assisted backcrossing (MABC). The locus was tagged with codominant SSR marker CP 171F/172R with a recombination fraction of 5.91% in an F2 population from ‘Apagbaala’ x SARC 1‐57‐2. A SNP‐genotyped biparental recombinant inbred line population was genotyped for CP 171F/172R, which was mapped to position 11.5 cM on linkage group (LG) 10 (physical position 30.514 Mb on chromosome Vu10). Using CP 171F/172R for foreground selection and a KASP‐SNP‐based marker panel for background selection in MABC, the resistance from SARC 1‐57‐2 was introduced into elite susceptible cultivar ‘Zaayura’. Five BC4F3 lines of improved ‘Zaayura’ that were isogenic except for the resistance locus region had phenotypes similar to SARC 1‐57‐2. This study identified a novel aphid resistance locus and demonstrated the effectiveness of integrating SSR and SNP markers for trait mapping and marker‐assisted breeding.

Determination of inheritance of aphid resistance in cowpea genotypes and identification of single sequence repeat markers linked to resistance genes

“…Huynh et al (2015), using SNP markers, discovered two QTLs involved in aphid resistance of IT97K556‐6: a major QTL, QAc‐vu7, and a minor QTL, QAc‐vu1.1. However, monogenic aphid resistance in cowpeas has also been reported (Kusi et al, 2018; Omoigui et al, 2017). Boukar et al (2018) reported that the single dominant gene conferring aphid resistance in cowpeas and incorporated in several improved breeding lines and varieties has become ineffective.…”

“…Markers linked to aphid resistance have also been reported in other studies. For instance, Kusi et al (2018) and Omoigui et al (2017) working with cowpeas found two markers (CP171/172 and KAD61) linked to genes involved in aphid resistance.…”

“…DNA extraction was conducted using FTA (Flanders Technology Associates) technology. FTA cards are media for storage and transport of DNA, wildly used for plant as well as animal DNA extraction (Kusi et al, 2018; Perozo et al, 2006; Stangegaard et al, 2011). To purify the DNA, a 1 cm 2 piece of the card containing macerated leaves was isolated using punch tool and placed in a tube (Eppendorf).…”

A Genome-Wide Scan Divulges Key Loci Involved in Resistance to Aphids (Aphis craccivora) in Cowpea (Vigna unguiculata)

“…The bulk of world cowpea production and consumption is in the savanna regions of West Africa [ 2 ], where Nigeria leads with an annual production of about 3.65 million metric tons [ 3 ]. Productivity of cowpea in this region and other parts of the world is hindered by numerous insect pests, cowpea aphids, A. craccivora Koch (Homoptera: Aphididae), being one of the most important pests, causing severe economic damage during the vegetative phase of the crop [ 4 , 5 , 6 , 7 ]. Like many sap-sucking insects, aphids cause damage in susceptible cowpea cultivars directly by altering plant metabolism and feeding on plant nutrients and indirectly by transmitting plant-pathogenic viruses, especially the aphid-borne cowpea mosaic viruses [ 6 , 8 ].…”

“…Consequently, there has been increased effort in the search for sources of resistance to cowpea aphids and better understanding of the nature and mechanism of resistance. Several sources of resistance to aphids have been identified in different breeding programs [ 5 , 13 , 14 , 15 , 16 ]. Aphid resistance is a priority trait in the cowpea breeding program of the International Institute of Tropical Agriculture (IITA).…”