Quantitative Trait loci (QTL) Identification for Resistance to Mal de Rio Cuarto Virus (MRCV) in Maize Based on Segregate Population

Abstract

Mal de Río Cuarto virus (MRCV) is one of the most devastating pathogens in maize (Zea mays L.) causing serious yield loss in susceptible cultivars in Argentina. An effective solution to control the virus is to use resistant genes to improve the behavior of susceptible genotypes. The goals of this work are to identify simple sequence repeats (SSR) linked to quantitative trait loci (QTL), for resistance to MRCV, and to validate QTL found in previous research with different genetic backgrounds. Two hundred and eight F_2:3 families derived from a cross between a susceptible inbred line, B73, and a resistant inbred line, LP116, were evaluated across three environments in the disease-endemic region. Disease incidence (INC), disease severity (SEV) and disease severity index (DSI) were employed to evaluate F_2:3 families. Based on this segregant population, ninety-eight simple sequence repeat (SSR) markers selected from 173 markers were used. The means of all measured traits followed near-normal distribution; therefore these traits may be considered as quantitatively inherited characters. For INC, SEV and DSI all estimates showed a moderate heritability ranging from 0,33 to 0,72. Some quantitative trait loci (QTL), each explaining around 10% of phenotypic variance were found on chromosome 1, 6, 8 and 10. The identification of QTL conferring resistance to MRCV may contribute to breeding programs seeking to protect the crop through improved genetic resistance.