title: Diversity and evolutionary history of lettuce necrotic yellows virus in Australia and New Zealand.
abstract: Lettuce necrotic yellows virus (LNYV) is the type member of the genus Cytorhabdovirus, family Rhabdoviridae, and causes a severe disease of lettuce (Lactuca sativa L.). This virus has been described as endemic to Australia and New Zealand, with sporadic reports of a similar virus in Europe. Genetic variability studies of plant-infecting rhabdoviruses are scarce. We have extended a previous study on the variability of the LNYV nucleocapsid gene, comparing sequences from isolates sampled from both Australia and New Zealand, as well as analysing symptom expression on Nicotiana glutinosa. Phylogenetic and BEAST analyses confirm separation of LNYV isolates into two subgroups (I and II) and suggest that subgroup I is slightly older than subgroup II. No correlation was observed between isolate subgroup and disease symptoms on N. glutinosa. The origin of LNYV remains unclear; LNYV may have moved between native and weed hosts within Australia or New Zealand before infecting lettuce or may have appeared as a result of at least two incursions, with the first coinciding with the beginning of European agriculture in the region. The apparent extinction of subgroup I in Australia may have been due to less-efficient dispersal than that which has occurred for subgroup II - possibly a consequence of suboptimal interactions with plant and/or insect hosts. Introduction of subgroup II to New Zealand appears to be more recent. More-detailed epidemiological studies using molecular tools are needed to fully understand how LNYV interacts with its hosts and to determine where the virus originated.
authors.affiliation: Institute of Applied Ecology, School of Applied Sciences, Auckland University of Technology, Private Bag 92006, Auckland, 1142, New Zealand. colleen.higgins@aut.ac.nz.|AUT Roche Diagnostics Laboratory, Auckland University of Technology, Private Bag 92006, Auckland, 1142, New Zealand. colleen.higgins@aut.ac.nz.
authors.forename: Colleen M
authors.initials: CM
authors.lastname: Higgins
authors.affiliation: Institute of Applied Ecology, School of Applied Sciences, Auckland University of Technology, Private Bag 92006, Auckland, 1142, New Zealand.
authors.forename: Wee-Leong
authors.initials: WL
authors.lastname: Chang
authors.affiliation: Plant Health and Environment Laboratory, Ministry for Primary Industries, P.O. Box 2095, Auckland, 1140, New Zealand.
authors.forename: Subuhi
authors.initials: S
authors.lastname: Khan
authors.affiliation: Plant Health and Environment Laboratory, Ministry for Primary Industries, P.O. Box 2095, Auckland, 1140, New Zealand.
authors.forename: Joe
authors.initials: J
authors.lastname: Tang
authors.affiliation: Plant Health and Environment Laboratory, Ministry for Primary Industries, P.O. Box 2095, Auckland, 1140, New Zealand.
authors.forename: Carol
authors.initials: C
authors.lastname: Elliott
authors.affiliation: Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, St Lucia, QLD, 4072, Australia.
authors.forename: Ralf G
authors.initials: RG
authors.lastname: Dietzgen
mesh_terms: D001315:Australia / Q000453:epidemiology; D016000:Cluster Analysis; D019143:Evolution, Molecular; D014644:Genetic Variation; D018545:Lactuca / Q000821:virology*; D017720:Molecular Epidemiology; D008969:Molecular Sequence Data; D009520:New Zealand / Q000453:epidemiology; D019251:Nucleocapsid / Q000235:genetics; D010802:Phylogeny; D010935:Plant Diseases / Q000821:virology*; D012367:RNA, Viral / Q000235:genetics; D012209:Rhabdoviridae / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification; D017422:Sequence Analysis, DNA; D017385:Sequence Homology
chemical_list: D012367:RNA, Viral