Evaluation of the resistance of some sunflower genotypes to natural infection of downy mildew and rust
2017
Cucereavîi, A. (AMG-Agroselect Comerţ, Chisinau (Republic of Moldova)
In field experiments conducted in 2013-2014 sunflower breeding material (maternal and paternal lines of different origin) and hybrids from the collection of the company “AMG-Agroselect Comert” (Republic of Moldova) were evaluated for their resistance to natural infection by downy mildew (Plasmopara halstedii) and rust (Puccinia helianthi). During the experiments the number of attacked plants and the percentage of attack per plant were recorded as well as disease frequency and intensity and the degree of disease attack were calculated. The data of the field observations were correlated with the results of the molecular studies on the presence or ab-sence of downy mildew and rust resistance genes (Pl6, Pl5/8and R1), which were performed previously. Thus, the genotypes which contain Pl6, Pl5/8 genes were not infected at all or exhibited an insignificant level of infection by Plasmopara halstedii (maximum 2.4%). The infection by Puccinia helianthi was detected in all maternal lines with cytoplasmic male sterility which lack rust resistance gene (R1). The degree of attack ranged from 0.1 to 93.5%. The paternal lines and the hybrids that possess R1gene were not attacked by the pathogen. The established cor-relations denote the effectiveness of molecular screening in rapid and accurate evaluation of the material used in plant breeding and of the obtained hybrids. The native MS-2570C line (adapted to the pedoclimate and cultivation conditions specific to the region and characterized by a low degree of attack or the complete lack thereof) is of a particular interest to plant breeding programs as a source of downy mildew and rust resistance.
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