Marker-assisted backcrossing using microsatellites and validation of SCAR Phs marker for resistance to white mold in common bean

Flávia Fernandes Carneiro*¹ · João Bosco dos Santos¹ · Monik Evelin Leite¹ 

¹Departamento de Biologia, Universidade Federal de Lavras, Lavras, MG, Brazil

*Corresponding author: bioffc@yahoo.com.br

Financial support: Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES).

Keywords: backcross, genetic similarity, Phaseolus vulgaris, SCAR, Sclerotinia sclerotiorum, SSR assisted selection.

Molecular markers may accelerate selection through the identification of plants with higher proportion of recurrent parent genome, as well as identifying those plants bearing target alleles like quantitative traits loci (QTLs) for white mold resistance. The objectives of this work were: 1) to employ microsatellite markers (SSR) in order to accelerate the recovery of recurrent parent genome 2) to validate sequence characterized amplified region (SCAR) Phs associated with a QTL that confers resistance to white mold, as previously identified in bean populations. Lines G122 and M20 were crossed, which generated 267 F₁ plants from backcross (BC) BC₁ and 113 plants from backcross BC₂.SSR polymorphic markers were adopted. The relationship between BC plants and the recurrent parent was estimated based on the recurrent genome proportion (PR) in each BC plant, and the Sorensen-Dice genetic similarity (sg_ir). To determine how much the phenotypic variation is explained by SCAR Phs, 56 F_1:2BC₁ progenies were evaluated on the field following a random block design with two replications through the straw test method. SSR markers are efficient in identifying individuals with a greater proportion of the recurrent genome. SCAR Phs was not efficient for the indirect selection of common beans for white mold resistance.