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Molecular genetic diversity in segregates of Vitis: implications for the breeding of grapevine aiming at resistance to Pratylenchus brachyurus

dos Santos, Paulo Ricardo, Viana, Alexandre Pio, Santos, Eileen Azevedo, de Barros Walter, Fernando Henrique, Riaz, Summaira, Walker, Andrew Michael
Euphytica 2019 v.215 no.4 pp. 78
DNA, Pratylenchus brachyurus, Vitis vinifera, agronomic traits, breeding programs, cetyltrimethylammonium bromide, cultivars, genetic distance, genetic markers, genetic similarity, genetic variation, heterozygosity, hybrids, interspecific hybridization, new variety, parents, pest resistance, vegetative propagation
This study presents a grapevine breeding project that examines technologies for the development of new cultivars with a view to combining nematode resistance with desirable agronomic traits. The objectives of this study were to undertake a genetic-molecular characterization of a segregating population with resistance to the nematode P. brachyurus, resulting from hybridizations between different selections of Vitis, and to indicate superior segregants for future crosses. Seventy-four interspecific hybrids, seven parents, and variety Niagra were used. The genomic DNA of each individual was extracted by the CTAB method, and 10 microsatellite markers were employed. The number of fragments per primer ranged from 2 to 4. Mean observed heterozygosity (0.52) was higher than expected heterozygosity (0.42), and the fixation index averaged − 0.230. These values indicate broad genetic variability and are within the expected limits for grapevine, considering that the best performances are obtained with heterozygous individuals maintained through vegetative propagation. The genetic distance calculated by the weighted index and represented by dendrogram based UPGMA method resulted in the formation of five groups. Groups IV and V stood out with the highest number of individuals. Group IV had approximately 6% of its individuals with greater genetic similarity to the parents of V. vinifera origin. The largest group (Group V) had approximately 82% of its individuals with greater similarity to the parents of V. vinifera origin. Interspecific hybrids resistant to P. brachyurus and genetically closer to one of the parents of Vitis vinifera origin will be selected for future crosses, enabling the continuity of the grapevine breeding program.