Citrus trees are natural hosts to several viroid species, all of which are capable of inducing severe yield losses and, consequently, significant economic damage in commercial orchards. The spread of these pathogens is facilitated by the use of infected propagation material in rootstock/scion combinations that are tolerant to viroid infection and do not show any symptoms. Additionally, dissemination between different production areas is expedited by a lack of robust phytosanitary monitoring. Among the known citrus-infecting viroids, Citrus dwarfing viroid (CDVd), belonging to the species Apscaviroid nanocitri is an emerging and widely distributed pathogen that has been found in citrus-growing areas in several countries worldwide. In addition to exhibiting considerable genetic variability, CDVd has been associated with stunting and growth reduction in susceptible hosts (Dang et al. , 2021). Citrus cultivation in Bosnia and Herzegovina is restricted to the southern, marginal growing zone adjacent to the Adriatic Sea and it is characterized predominantly by scattered trees in household gardens rather than by organized commercial orchards. The total area of cultivated citrus is estimated to encompass approximately 6 hectares (Delić et al. 2013). In this context, and with the aim of assessing the phytosanitary status of citrus cultivations in Bosnia and Herzegovina, a total of 34 samples of mandarin (Citrus reticulata) were collected in early 2025. Samples were collected from individual trees located across eight sites within the Herzegovina-Neretva Canton of the Federation of Bosnia and Herzegovina (Polog, Mostar, Krućevići, Žitomislići, Jasenica, Buna, Rodoč, Stolac). Among the sampled trees, several exhibited dwarfing and viroid-like symptomatology, including leaf chlorosis and reduced vigor and yield. Total RNA was extracted from petiole tissue and analyzed by RT-PCR, as described by Bernad and Duran-Vila (2006), using the primer pair CVd-III-F1 (5′-GGCAGCTAAGTTGGTGACGC-3′) and CVd-III-R1 (5′-TTCGTCGACGACGACAGGTA-3′). The expected amplicons were obtained from 10 samples collected in Polog and Rodoč. Two PCR products were selected, purified and sequenced (Macrogen Europe, The Netherlands). The resulting 202-nt-long sequences were deposited in GenBank as isolate M1. DvHz (Accession No. PX935918) and isolate M26. DvHz (PX935917). BLASTn analysis revealed that both isolates shared 99. 40% nucleotide identity with CDVd isolate PTZ 57R/T (KY654681) and 98. 81% with CDVd isolate GB4 (EU934019) (Figure 1). These reference isolates originated from sweet orange in Iran and Oman, respectively. To our knowledge, this study represents the first report of CDVd in Bosnia and Herzegovina. Further research will be required to determine its distribution and incidence in the country.
Agrò et al. (Thu,) studied this question.