Molecular and biological characterization of two potyviruses infecting lettuce in southeastern France

Abstract

Several potyviruses affect lettuce (Lactuca sativa) and chicory (Cichorium spp.) crops worldwide and are important constraints for production because of the direct losses that they induce and/or because of their seed transmission. Here, the molecular and biological properties are described of two potyviruses that were recently isolated from lettuce plants showing mosaic or strong necrotic symptoms in an experimental field in southeastern France. The first potyvirus belongs to the species Endive necrotic mosaic virus and is present in a large number of wild plant species, especially Tragopogon pratensis. It is unable to infect lettuce cultivars with a resistance to Turnip mosaic virus that is present in many European cultivars and probably conferred by the Tu gene. The second potyvirus belongs to the tentative species lettuce Italian necrotic virus and was not observed in wild plants. It infected all tested lettuce cultivars. Wild accessions of Lactuca serriola, Lactuca saligna, Lactuca virosa and Lactuca perennis were identified as resistant to one or the other potyvirus and could be used for resistance breeding in lettuce. No resistance against these two potyviruses was observed in the tested Cichorium endivia cultivars. In contrast, all tested Cichorium intybus cultivars or accessions were resistant.

Growth stage‐dependent resistance to the potyviruses lettuce Italian necrotic virus and Lettuce mosaic virus displayed by Lactuca sativa introgression lines carrying the Mo3 locus from L. virosa

“…The origins of the French isolate LINV‐Fr and of isolates LMV‐9 and LMV‐13 are described in Desbiez et al . () and Dinant & Lot (), respectively. LMV‐9 overcomes the mo1 1 resistance allele, whereas LMV‐13 overcomes both mo1 1 and mo1 2 resistance alleles.…”

“…Lettuce ( Lactuca sativa , family Asteraceae) crops are affected by several potyviruses (genus Potyvirus ; family Potyviridae ), including Lettuce mosaic virus (LMV), Turnip mosaic virus (TuMV), Bidens mottle virus (BiMoV), Endive necrotic mosaic virus (ENMV) and lettuce Italian necrotic virus (LINV) (Christie et al ., ; Zink et al ., ; Zitter & Guzman, ; Provvidenti & Hampton, ; Blancard et al ., ; Ciuffo et al ., ; Desbiez et al ., ). LINV was recently described in lettuce crops in Italy and southeast France and induces severe necrosis and plant wilting, leaf distortion and/or vein clearing.…”

“…Its natural host range seems to be limited to L. sativa cultivars. However, experimental inoculations showed that it can infect plants of other species in the family Asteraceae ( Calendula spp., Cichorium spp., Helianthus annuus , Tragopogon pratensis and Zinnia elegans ) and Nicotiana benthamiana (Desbiez et al ., ). Transmission by Myzus persicae (Homoptera: Aphididae) was demonstrated experimentally (Ciuffo et al ., ; Desbiez et al ., ).…”

“…LINV is phylogenetically related to LMV in the genus Potyvirus . No source of resistance to LINV was found in L. sativa accessions carrying known potyvirus resistance genes such as the mo1 1 or mo1 2 alleles conferring LMV resistance, or the Tu gene conferring TuMV resistance (Desbiez et al ., ). However, a few accessions of the wild species L. virosa and L. perennis were found to be resistant to a French isolate of LINV (LINV‐Fr).…”

“…However, a few accessions of the wild species L. virosa and L. perennis were found to be resistant to a French isolate of LINV (LINV‐Fr). The L. virosa accession PIVT1398 appears particularly interesting because it has a broad resistance spectrum including to LMV and ENMV‐Fr isolates (Desbiez et al ., ) and because of the possibility of obtaining fertile intercrosses between L. virosa and L. sativa (Maisonneuve et al ., ). The LMV resistance of PIVT1398 was shown to be conferred by the single gene Mo3 in F 1 , F 2 and F 3 progenies derived from crosses with the LMV‐susceptible accession L. virosa PIVT280 (Maisonneuve et al ., ).…”