First Report of Celery mosaic virus Infecting Celery (Apium graveolens) in Indonesia Laporan Pertama Celery mosaic virus yang Menginfeksi Seledri ( Apium graveolens ) di Indonesia

Celery mosaic virus (CeMV), member of genus Potyvirus , is reported for the first time in Indonesia, from celery plants ( Apium graveolens ) in a vegetable field at Berastagi, North Sumatera Province. The plants possessed mosaic and vein clearing symptoms on the leaves as typical of CeMV infection. Virus incidence was confirmed by RT-PCR using degenerate potyvirus primer which amplified partial coat protein and 3'-UTR of the viral genome. Phylogenetic tree analysis placed Indonesian CeMV isolates in one separated clade within CeMV group and shared 96.5%–96.7% nucleotide identity with exemplar isolate of CeMV.

Although it has a worldwide distribution, CeMV is not considered as serious problem in Indonesia.The infection of CeMV was firstly reported in California (US) from celery in early 1922 (Poole 1922).Current geographic distribution of CeMV expands to Europe, Australasia, South America, and Asia (Bos et al. 1989;Fernández et al. 2007;Fox et al. 2022;Iwaki and Komuro 1970;Karanfil et al. 2019).
In 2023, a field survey was conducted in a vegetable growing field at Berastagi, North Sumatera Province.The vegetables were planted in inter-cropping system, consisted of chili pepper (Capsicum annuum), cauliflower (Brassica oleracea var.botrytis), and celery (Figure 1).Mosaic and vein clearing symptoms were found on the celery leaves, suggestive of a viral infection (Figure 2).To support this hypothesis, the leaf samples were collected from three different symptomatic celery plants for further detection through RT-PCR (reverse transcription polymerase chain reaction).
Total nucleic acid extraction was carried out using GeneJet RNA Purification kit following manufacturer's protocol (Thermo Fisher Scientific, Memphis, USA).Amplification was done using degenerate potyvirus primer, U341 (5'-CCG GAA TTC ATG RTI TGG TGY ATI GAI AAY GG-3') and Poty-1 (5'-GGA TCC CGG GTT TTT TTT TTT TTT TTT V-3') (Gibbs and MacKenzie 1997;Langeveld et al. 1991) which amplify partial coat protein and 3-'UTR with expected size of 600-800 bp.One-step RT-PCR conditions were conducted as follows: cDNA synthesis at 45 °C for 1 h and one cycle of initial denaturation at 94 °C for 1 min, 35 cycles of denaturation at 94 °C for 10 sec, annealing at 50 °C for 10 sec, extension at 72 °C for 1 min and then followed by one cycle of final extension at 72 °C for 10 mins.Amplicons were then electrophoresed on a 1% agarose gel containing 1% FluoroVue TM nucleic acid gel stain (SMOBIO Technology Inc., Hsinchu City, Taiwan).Positive amplicons then were sent to 1 st BASE Malaysia for Sanger sequencing.
Each sequence (forward and reverse) was trimmed and assembled to create a contig sequence.Each contig sequence then was checked in BLASTN program to search the highest sequence matches in the NCBI nucleotide database.Selected sequences and samples then were aligned using ClustalW in Geneious software (Biomatters Ltd., New Zealand).Sequence identity matrix was calculated and visualized using SDTv1.3software (Muhire et al. 2014).Phylogenetic tree was inferred using Maximum-Likelihood method based on Tamura-Nei model with 1000 replicates in MEGA 11 software (Tamura et al. 2021).

2022).
Maximum-Likelihood phylogenetic tree analysis placed three Indonesian CeMV isolates in one separated sub-clade within CeMV group (Figure 5).Two closely related potyvirus species to CeMV, Carrot virus Y (CarVY) and Apium virus Y (ApVY) were employed as outgroups to confirm the identification of Indonesian CeMV isolates.The data indicates that Indonesian CeMV isolates have variations and place in different group from previously known CeMV isolates in GenBank.Further identity analysis of CeMV strain for Indonesian viral isolates is needed as virus strains may determine the severity of the disease (Koike et al. 2008).To date, there have been only 18 CeMV isolates that lodged in GenBank.There was no available sequence from Asian isolates even though the incidence of CeMV infecting carrot has been recorded in Japan by Iwaki and Komuro (1970).The sequences information from this study might gave an insight of the possibility of CeMV variants which present in Asia.
To our knowledge, this is the first report of CeMV infecting celery in Indonesia.Further biological study and disease monitoring for the possibility of CeMV and another closely related potyvirus infection on carrot and other celeriac in the field should be considered as they commonly present in mix infection.

ACKNOWLEDGEMENT
We thank to Prof Sri Hendrastuti Hidayat (IPB University) and A/Prof John Thomas (The University of Queensland) for their generous guidance during the field survey.

Figure 1
Figure 1 Inter-cropping planting system in a vegetable field in Berastagi, North Sumatera.The celery plants are shown in white arrows.

Figure 2 Figure 3
Figure 2 Celery leaf showing vein clearing and mosaic symptoms (left and right with yellow arrow) and asymptomatic leaf (right with white arrow).

Figure 4
Figure 4 Pairwise identity matrix of Celery mosaic virus (CeMV) inferred using SDT matrix in 'two-color' mode.Indonesian CeMV isolates are indicated by red letter.The percentage of pairwise identity is visualized by the color-coded boxes.