First report of Cotton bunchy top virus‐1 in okra in Iraq

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Okra (Abelmoschus esculentus), also known as lady's fingers, is one of the main vegetable crops in Iraq, being cultivated widely with two crops per season (Al-Kanani et al., 2019). In September 2023, okra plants showing extensive leaf yellowing (Fig. 1), and light green, short petioles and internodes were observed in okra fields in Baghdad Province, Iraq, with a disease incidence of 20–30%. Forty diseased leaf samples were sampled from 20 fields selected from different locations in the province. Fifteen diseased leaf samples were selected randomly and bulked together before screening for virus infection using an Illumina HiSeq (San Diego, USA). Geneious Prime® 2024.0.4 (Biomatters; Auckland, New Zealand) with default parameters was used for bioinformatic data analysis. A total of 35,855,946 paired-end reads were obtained. The reads which were unmapped to the complete genome sequence of A. esculentus were de novo assembled using the Velvet assembler (v. 1.2.10) (Lahuf, 2021). BLASTn analysis revealed >83% pairwise nucleotide identity and coverage of 97% with the whole genome of Cotton bunchy top virus-1 (CBTV-1) isolate 3092-1 (GenBank Accession No. MT966040.1). The average sequencing depth of the genome sequence of CBTV-1 obtained was ×10. The genome sequence of CBTV-1 isolate Iraq-1 was deposited in GenBank (PP680224.1). A specific RT-PCR primer set, CBTV-5F / CBTV-5R (Ellis et al., 2013), was used successfully to detect CBTV-1 in 18 out of the 25 remaining leaf samples previously collected, and a further 33 out of 50 diseased leaf samples collected from the same okra fields. CBTV-1 causes a severe disease of cotton (Gossypium hirsutum) in Australia as well as infecting other plant hosts including Cicer arietinum, Euphorbia hirta, Gossypium sturtianum and Malva parviflora (Sharman et al., 2022). To our knowledge, this is the first report of CBTV-1 in Iraq. Subsequent investigations are necessary to verify the incidence of CBTV-1 in other Iraqi plant hosts, mainly cotton (G. hirsutum), and to identify the interaction with potential insect vectors in Iraq. This knowledge would be vital in the selection of practical management approaches. The authors would like to express their gratitude to the Plant Protection Department, Agriculture College, University of Kerbala, and the Iraqi Ministry of Higher Education and Scientific Research for their support.

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