Estimation of narrow sense heritability of powdery mildew resistance in pseudo F2 (F1) population of flowering dogwoods (cornus Florida L)

Powdery mildew disease caused by Erysiphe (sect. Microsphaera ) pulchra a (Cook & Peck, Braun & Takamatsu) is a devastating disease in flowering dogwoods ( Cornus Florida ) throughout southeastern USA where flowering dogwood is widely grown. Host resistance is the most sustainable and economical way for controlling this disease, but resistance breeding has been slow and genetic information on powdery mildew resistance is unavailable. In this study, pseudo F 2 populations derived from crosses between selected resistant (R) and susceptible (S) plants (RxR, RxS and SxR), were evaluated for disease severity at two locations in three years, McMinnville in 2005 and 2012, and McMinnville and Nashville, TN, in 2013. Disease reaction in progeny from reciprocal crosses was similar indicating that there was no cytoplasmic inheritance of resistance genes. Disease severity of progenies showed continuous distributions, suggesting that powdery mildew resistance is inherited quantitatively. High narrow sense heritability (0.74 in 2005, 0.84 in 2012 and 0.90 in 2013) and broad sense heritability (0.9) in parental clones were observed. This information will be useful in breeding programs for dogwood improvement.