First Report of Tobacco ringspot virus infecting apple plants in South Tyrol

Erstnachweis von Tobacco ringspot virus am Apfel in Südtirol
Prima segnalazione del Tobacco ringspot virus in piante di melo in Alto Adige
Andreas Gallmetzer1, Christian Springeth1, Yazmid Reyes Dominguez1
1 Laimburg Research Centre, 39040 Auer/Ora, BZ, Italy
Cite article as
Gallmetzer Andreas, Springeth Christian, Reyes Dominguez Yazmid et.al. (2024). First Report of Tobacco ringspot virus infecting apple plants in Northern Italy. Laimburg Journal 06/2024.004
DOI: 10.23796/LJ/2024.004
Corresponding Author
Yazmid Reyes Dominguez
Laimburg Research Centre, Laimburg 6 – Pfatten/Vadena, 39040 Auer/Ora, BZ, Italy
yazmid.reyes-dominguez@laimburg.it
+390471969587
Keywords
nepovirus, apple viruses

A Malus domestica (Borkh.) plant conserved in the nuclear stock of mother plants at the Laimburg Research Centre (Autonomous Province of South Tyrol, Northern Italy) was tested positive to Tobacco ringspot virus (TRSV) in May 2023 during a routine phytosanitary inspection for the presence of quarantine viruses. TRSV quarantine status in the EPPO region (European and Mediterranean Plant Protection Organization, an international organization responsible for cooperation and harmonization in plant protection within the European and Mediterranean region, which currently has 52 member countries) is A2, meaning that the virus is locally present.

Following importation of the scion from North America in November 2021 and prior to grafting onto woody Malus domestica M9 rootstocks, the material was tested negative for the apple latent viruses Apple stem grooving virus (ASGV), Apple stem pitting virus (ASPV) and Apple chlorotic leaf spot virus (ACLSV), for the viroids Apple scar skin viroid (ASSVd) and Apple dimple fruit viroid (ADFVd) as well as for the nepoviruses Cherry rasp leaf virus (CRLV), Tomato ring spot virus (ToRSV) and TRSV. TRSV has its origin in central and eastern North America and in other parts of the world the presence of the virus is probably associated with material exported from North America [1].
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  • [1] European and Mediterranean Plant Protection Organization (ed.) (2022). EPPO Datasheet. Tobacco ringspot virus. Retrieved June 6, 2023, from https://pra.eppo.int/organism/TRSV00.
As required by the regulation on protective measures against plant pests, the grafted mother plant was kept in the post-entry quarantine facility until May 2023 [2]. The plant was asymptomatic throughout the entire period.
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  • [2] European Parliament, Council of the European Union (eds.) (2016). Regulation (EU) 2016/2031 of the European Parliament of the Council of 26 October 2016 on protective measures against pests of plants, amending Regulations (EU) 228/2013, (EU) 652/2014 and (EU) 1143/2014 of the European Parliament and of the Council and repealing Council Directives 69/464/EEC, 74/647/EEC, 93/85/EEC, 98/57/EC, 2000/29/EC, 2006/91/EC and 2007/33/EC. OJ L 317, 23.11.2016, pp. 4-104. Retrieved June 6, 2023, from https://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX:32016R2031&from=RO.
Total RNA was isolated from the leaves of the plant in question using the RNeasy Plant Mini Kit (Qiagen, Hilden, Germany). Virus detection was performed by a two-step RT-PCR and the obtained PCR fragments were analysed by sequencing the amplicons with TRSVf2/TRSVr2 primers [3]. A BLAST (http://blast. ncbi.nlm.nih.gov/Blast.cgi) analysis was performed on the sequences and revealed 97.91% identity (E value of 9e-86) with the TRSV isolate Budblight (accession number MT210151). These results confirmed the presence of a TRSV infection in the asymptomatic Malus domestica plant.
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  • [3] Martin R.R., Pinkerton J.N., Kraus J. (2009). The use of collagenase to improve the detection of plant viruses in vector nematodes by RT-PCR. Journal of virological methods 155 (1), 91-95, DOI: 10.1016/j.jviromet.2008.10.002.
Due to the wide host range of TRSV and its broad transmission profile via nematodes, thrips, seeds, sap inoculation and grafting, it represents a major risk for many agricultural crops [4]. TRSV has a wide host range and has been reported in more than 100 different herbaceous and woody plant species. The cultures that are mainly affected by infection with TRSV are Vaccinium corymbosum, Vitis vinifera and Glycine max and to a lesser extent Nicotiana tabacum and many plants of the Cucurbitaceae family [5]. The symptoms on the infected plants are very different depending on the infected species, for example TRSV can cause stem dieback and stunting in Vaccinium corymbosum, in tobacco causes ring and line patterns on the foliage and stunting, in cherry, the leaves show irregular chlorotic blotching over the whole leaf blade and the leaf margins are deformed and lobed [1].
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  • [4] Tolin S.A. (2008). Tobacco Viruses. In: Mahy B.W.J. (ed.). Encyclopedia of Virology. Elsevier, Amsterdam, Niederlande, here pp. 60-67.
  • [5] Hill J.H., Whitham S.A. (2014). Control of virus diseases in soybeans. In: Loebenstein G., Katis N. (eds). Control of Plant Virus Diseases. Seed-Propagated Crops. (Advances in Virus Research ; 90). Elsevier, Amsterdam, Niederlande, here pp. 355-390, DOI: 10.1016/B978-0-12-801246-8.00007-X
  • [1] European and Mediterranean Plant Protection Organization (ed.) (2022). EPPO Datasheet. Tobacco ringspot virus. Retrieved June 6, 2023, from https://pra.eppo.int/organism/TRSV00.
One of the most efficient ways of spreading TRSV over longer distances is the movement of infected vegetatively propagated plants, grafts and seeds. Infected grafted plants can establish new infections when introduced to soils where the vector is present. In areas such as the EPPO region where vector transmission has so far not been known to occur, establishment of TRSV can easily be prevented by removal and destruction of infected plants [1].
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  • [1] European and Mediterranean Plant Protection Organization (ed.) (2022). EPPO Datasheet. Tobacco ringspot virus. Retrieved June 6, 2023, from https://pra.eppo.int/organism/TRSV00.
The fact that many infected hosts remain symptomless means that there is a considerable risk of spreading the virus. Hence, it is of critical importance to carry out all the necessary phytosanitary controls and to establish virus-free nuclear stocks from which plants or grafts can be propagated and subsequently distributed through a certification scheme [6].
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  • [6] European and Mediterranean Plant Protection Organization (ed.) (2008). PM 4/8 Pathogen-tested material of grapevine varieties and rootstocks. (Schemes for the production of healthy plants for planting). Retrieved June 08, 2023, from https://gd.eppo.int/download/standard/87/pm4-008-2-en.pdf.

As demonstrated in this work, one of the main aims of our laboratory is to safeguard South Tyrolean agriculture through the early diagnosis of phytopathogens not only in fruit, but in every culture that is relevant to the region.

References

  • [1] European and Mediterranean Plant Protection Organization (ed.) (2022). EPPO Datasheet. Tobacco ringspot virus. Retrieved June 6, 2023, from https://pra.eppo.int/organism/TRSV00.
  • [2] European Parliament, Council of the European Union (eds.) (2016). Regulation (EU) 2016/2031 of the European Parliament of the Council of 26 October 2016 on protective measures against pests of plants, amending Regulations (EU) 228/2013, (EU) 652/2014 and (EU) 1143/2014 of the European Parliament and of the Council and repealing Council Directives 69/464/EEC, 74/647/EEC, 93/85/EEC, 98/57/EC, 2000/29/EC, 2006/91/EC and 2007/33/EC. OJ L 317, 23.11.2016, pp. 4-104. Retrieved June 6, 2023, from https://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX:32016R2031&from=RO.
  • [3] Martin R.R., Pinkerton J.N., Kraus J. (2009). The use of collagenase to improve the detection of plant viruses in vector nematodes by RT-PCR. Journal of virological methods 155 (1), 91-95, DOI: 10.1016/j.jviromet.2008.10.002.
  • [4] Tolin S.A. (2008). Tobacco Viruses. In: Mahy B.W.J. (ed.). Encyclopedia of Virology. Elsevier, Amsterdam, Niederlande, here pp. 60-67.
  • [5] Hill J.H., Whitham S.A. (2014). Control of virus diseases in soybeans. In: Loebenstein G., Katis N. (eds). Control of Plant Virus Diseases. Seed-Propagated Crops. (Advances in Virus Research ; 90). Elsevier, Amsterdam, Niederlande, here pp. 355-390, DOI: 10.1016/B978-0-12-801246-8.00007-X
  • [6] European and Mediterranean Plant Protection Organization (ed.) (2008). PM 4/8 Pathogen-tested material of grapevine varieties and rootstocks. (Schemes for the production of healthy plants for planting). Retrieved June 08, 2023, from https://gd.eppo.int/download/standard/87/pm4-008-2-en.pdf.