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Broad-sense heritability and genetic gain for powdery mildew resistance in multiple pseudo-F2 populations of flowering dogwoods (Cornus florida L.)

Parikh, Lipi, Mmbaga, M.T., Kodati, S., Blair, M., Hui, D., Meru, G.
Scientia horticulturae 2016 v.213 pp. 216-221
Cornus florida, Erysiphe pulchra, crossing, cultivars, fungicides, gene flow, genes, genetic improvement, genetic resistance, genotype, greenhouse production, heritability, inheritance (genetics), parents, planting, powdery mildew, progeny
Powdery mildew caused by Erysiphe pulchra is one of the most destructive diseases of flowering dogwoods (Cornus florida L.). Control of powdery mildew relies heavily on chemical fungicides. Developing genetic resistance and planting powdery mildew resistant cultivars is a desirable long term control strategy for the disease. Information on inheritance characteristics associated with powdery mildew resistance in C. florida is needed to facilitate development of breeding strategies for a new generation of powdery mildew resistant cultivars. The objectives of this study were to determine broad-sense heritability, genetic gain and minimum number of effective genes associated with resistance to powdery mildew in C. florida. Progeny segregating for powdery mildew resistance were developed through controlled crosses between susceptible cultivar [Cherokee Princess (CP)], resistant selection (R14) and moderately resistant cultivars [MI9 and Cherokee Brave (CB)]. The parents and progeny were evaluated for resistance/susceptibility to powdery mildew under greenhouse conditions and estimates for broad-sense heritability, genetic gain and minimum number of effective genes was determined. Broad-sense heritability ranged from 60% to 88% while corresponding narrow-sense heritability ranged from 53% to 86.6%. The highest predicted genetic gain for powdery mildew resistance was obtained in the R14x CP (78%) and CB x MI9 (61%) crosses while the lowest genetic gain was observed in the CP x MI9 (34%) and MI9x CB (36%) crosses. These results indicate that CB x MI9 and R14x CP crosses are best parental lines for developing resistance to powdery mildew among the genotypes tested. Use of these parental lines and understanding the gene flow of resistance to powdery mildew in dogwoods will help researchers to develop a targeted breeding approach in generating new generation of resistant cultivars.