Different Reaction of Citrus Genotypes To Citrus Yellow Vein Clearing Virus

Background and aim: citrus yellow vein clearing virus (cyvcv), belongs to the genus mandarivirus, family alphaflexiviridae, order tymovirales and realm riboviria has been reported in recent years from iran and a number of asian countries. it is considered as a new threat for citriculture of the world, due to its rapid spread and severe damage. yield losses of the chinese lemon orchards affected by cyvcv are estimated 50-70%. vein clearing and water-soaking of the lateral veins of the new leaves are symptoms of the virus in well-known host, lemon (citrus limon). after reporting the virus in 2017, in addition to lemon cultivars, sour orange (c. aurantium), persian lime (c. latifolia), clementine (c. clementina) and satsuma (c. unshiu) were found as natural hosts in iran. to find tolerant genetic resources, reaction of several genotypes to cyvcv was investigated in greenhouse condition.methods: the budwoods of eureka lemon, persian lime, clementine, satsuma, moro blood orange (c. sinensis), etrog citron (c. medica), flame grapefruit (c. paradisi), mineola tangelo (c. paradisi x c. reticulate), and siavaraz local orange (citrus sp.) were propagated on sour orange rootstocks. these plants were inoculated with a characterized field isolate of cyvcv (genbank accession number: kx902488) and maintained in a greenhouse with optimum temperature for viral activity (23±3). after six months, the presence of the virus in the experimental varieties and genotypes was confirmed by rt-pcr using specific primers of the coat protein gene of cyvcv. non-inoculated plants were considered as negative controls.results: an expected product of about 600 bp was obtained after rt-pcr analysis of the infected plants, six months after inoculation. based on symptoatology, different reactions were observed in the infected varieties and genotypes. eureka lemon and persian lime were classified as very susceptible hosts according to severity and time of symptom appearance. clementine, satsuma, moro blood orange, mineola tangelo and siavaraz local orange were less susceptible based on their mild reactions. up to now no symptoms were seen in etrog citron and flame grapefruit.conclusion: our results indicated that unsusceptible hosts such as etrog citron and flame grapefruit can be used as genetic resources for improving new tolerant cultivars to cyvcv.