Inheritance pattern of fire blight resistance in pear

Abstract

Fire blight caused by Erwinia amylovora is a serious disease that directly affects pear agriculture and production around the world. The most effective way to struggle with disease is develop new varieties and rootstocks. In this study, for a better understanding of the genetic base of fire blight such as heritability of disease resistance, breeding values of parents and maternal effect were investigated on F1 hybrid pear population. According to results, disease resistance shows polygenic inheritance and multiple factors were effective in heredity. Resistance to disease is transmitted to next generations by both parents. However, the influence of the female parent on inheritance is much greater than pollinator. ‘Magness’ and ‘Mustafa Bey’ varieties were found more effective for the transmission of disease resistance as female parents to next progenies. Similar results were obtained from ‘Kiefer’ and ‘Limon’ as pollinator. In addition to the importance of the parents exclusively in disease resistance, gene interactions between the parents also had a significant effect on this matter. Heritability of fire blight that was calculated from the non-additive genes was 23%, likewise 32% was calculated from additive genes. Broad-sense heritability of fire blight, representing the sum of this two situations was 55%. Maternal gene effects were greater than the pollinator and maternal effect had a 7% effect on the disease resistance, indicating that the cytoplasmic gene effects had important roles in the resistance. Obtained results will form basis for the development of new varieties that become resistant to fire blight by hybridization.