The evolution of leaf scald (Xylella fastidiosa) resistance was evaluated in individuals of seven plum segregating populations, consisted of seedling progenies originating from crosses involving nine plum cultivars, with varied levels of resistance. Plants were submitted to artificial inoculation in 2001 and evaluated annually from 2002 to 2007 for the evolution of leaf scald symptoms. All populations showed an evolution of symptom severity during the evaluated period. The population Amarelinha x Carazinho was the most resistant while populations Chatard x Santa Rosa and Chatard x Simka were the most susceptible ones. The populations Chatard x Harry Pickstone and Chatard x Angeleno exhibited an intermediate behavior. The analysis of genetic segregation of microsatellite markers and disease resistance curves in different populations indicated that inheritance to leaf scald resistance is polygenic and predominantly recessive, with an eventual presence of major QTLs in susceptible parents.
Prunus salicina; late symptoms; inheritance of resistance
