First report of Apium virus Y infecting <i>Scandia rosifolia</i>, an endangered New Zealand endemic

Unlike economically important crop species of Apiaceae such as carrot, celery, coriander and parsley, little attention has been given to the presence of viruses in native species in New Zealand (Guy et al., 2022). Scandia rosifolia (koheriki) is an endangered endemic species in the Apiaceae which grows in a few separate locations on the North Island and is being propagated for conservation in some botanic gardens. In March 2022, 47 of 53 plants in a large planting at the Dunedin Botanic Gardens were observed with mosaic and ringspot symptoms (Fig. 1). Transmission electron microscopy revealed the presence of flexuous virus particles (840-880 nm) in leaf dip preparations of diseased plants (Fig. 2). Leaf sap extracts from 12 diseased and two healthy plants were tested for 12 viruses using ELISA according to the manufacturers’ instructions (Table 1). A positive result was obtained from all diseased plants, but not the two healthy plants, with the general Potyvirus group ELISA tests. No plants tested positive with any other ELISA test. DSMZ (AS-0185) DSMZ (AS-0243) Agdia (SRA 15500) DSMZ (AS-0132) The putative potyvirus was not detected by ELISA in Chenopodium spp., Nicotiana spp., carrot, celery and coriander plants after mechanical inoculation using the sap of infected koheriki but was detected in symptomless parsley plants. The virus was not detected by ELISA in 96 seedlings grown from seed collected from diseased koheriki plants. Total RNA from two ELISA-positive and two negative koheriki samples was extracted and tested by RT-PCR with general potyvirus primers (Zheng et al., 2010) and primers specific to Apium virus Y (species Potyvirus apii, ApVY) (Tang et al., 2007) and celery mosaic virus (species Potyvirus apiumtessellati) (Karanfil et al., 2019). Only the ApVY primers produced an amplicon of the expected size (c. 425bp). The amplicons were purified and Sanger sequenced and the forward and reverse sequences were assembled and edited using the Geneious prime 23.0.1 program (Biomatters Ltd., New Zealand). A BLASTn search of GenBank indicated that the amplicon sequences shared 90.9-100% identity with ApVY isolates and had 100% nucleotide identity with the New Zealand isolate of ApVY from celery (GenBank Accession No. EU127499). The koheriki sequences were identical, therefore only one was lodged with GenBank (Accession No. PQ363005). This is the first report of ApVY infecting a New Zealand native species. Previously it was reported from celery and hemlock which may be acting as a reservoir for aphid transmission to koheriki and other native and cultivated species in New Zealand (Tang et al., 2007; Veerakone et al., 2015). Seed transmission in koheriki will be further investigated to see if seed collection is a viable way to establish virus-free seedlings for the propagation and dissemination of this endangered species. Thanks to the Dunedin Botanic gardens for access to their collection and to the Brenda Shore Trust for financial support.