Etiology of quick decline disease of citrus on Bakraee (Citrus sp.) rootstock in southern Kerman

The emerged citrus quick decline disease has destroyed many of citrus plants grafted onto Bakraee rootstock in southern Kerman during recent years. Disease symptoms are included leaf wilting, root rot, and quick decline. In this project, the etiology of quick decline disease was studied. Symptomatic and asymptomatic plants were tested for the presence of plant pathogenic prokaryotes using PCR with universal and specific primers, and Miseq Illumina method. Furthermore, ELISA, RT-PCR, inoculation on index plants, and dsRNA extraction were used for detection of viruses and viroids in symptomatic and asymptomatic plants. The correlation between the presence of Tylenchulus semipenetrans, Phytophthora nicotiana, and quick decline disease was investigated by isolation and quantification of pathogens from root and rhizosphere of asymptomatic and infected plants. Overall, results indicated the association of Candidatus Liberibacter asiaticus with citrus (on Bakraee rootstock) quick decline disease in southern Kerman. In addition, drought and heat stresses and co-infection of the diseased plants by Ca. Phytoplasma aurantifolia, Phytophthora nicotiana, and Tylenchulus semipenetrans lead to severe symptoms of the disease and accelerated the decline of the infected plants.