HomePlant DiseaseVol. 100, No. 9Aspergillus niger Causes Fruit Rot of Lemon and Grapefruit in Pakistan PreviousNext DISEASE NOTES OPENOpen Access licenseAspergillus niger Causes Fruit Rot of Lemon and Grapefruit in PakistanF. Liaquat, S. Arif, M. Ashraf, H. J. Chaudhary, M. F. H. Munis, and A. B. U. FarooqF. LiaquatSearch for more papers by this author, S. ArifSearch for more papers by this author, M. AshrafSearch for more papers by this author, H. J. ChaudharySearch for more papers by this author, M. F. H. MunisSearch for more papers by this author, and A. B. U. FarooqSearch for more papers by this authorAffiliationsAuthors and Affiliations F. Liaquat S. Arif M. Ashraf H. J. Chaudhary M. F. H. Munis , Department of Plant Sciences, Quaid-i-Azam University, Islamabad, Pakistan A. B. U. Farooq , Department of Environmental Sciences, COMSATS Institute of Information Technology, Vehari, Pakistan. Published Online:6 Jul 2016https://doi.org/10.1094/PDIS-02-16-0199-PDNAboutSectionsSupplemental ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmailWechat During a survey from December to February 2014, lemons (Citrus × limon) and grapefruit (Citrus × paradisi) exhibiting dark brown wrinkled lesions were collected from citrus production operations in Islamabad Capital Territory (33°44′50″ N, 73°08′20″ E) and adjacent areas including Rawalpindi, Taxila, and Wah districts, Pakistan. The highest disease severity was observed in operations in Islamabad (36.6% of 30 randomly selected lemon trees and 42.8% of 21 randomly selected grapefruit trees), followed by Rawalpindi (23% of 26 randomly selected lemon trees and 33.3% of 18 randomly selected grapefruit trees), Taxila (23% of 30 randomly selected lemon trees and 26.6% of 15 randomly selected grapefruit trees), and Wah District (20% of 25 randomly selected lemon trees and 31.2% of 16 randomly selected grapefruit trees). Lesions began as small (<1.0 cm diam.) dark brown spots, which enlarged to encompass a large portion of the epidermis, became wrinkled, and led to premature fruit drop. Over time, the lesions developed short dark brown conidiophores sporulating with dark conidia. Five to 10 diseased lemon fruits and four to six diseased grapefruits were collected from three operations from each location. Sporulating sections of lesions were removed and single-spore isolations were made on Sabouraud dextrose agar (SDA) medium. The single spore isolates developed into a compact white or yellow basal mycelium covered with a dense layer of conidiophores covered with dark brown to black spores. The vesicles of the conidiophores were large (up to 3 mm × 15 to 20 µm in diameter) and globose. The conidiophores were smooth-walled, hyaline, and became melanized toward the vesicle. These characteristics of the fungus were similar to those described for Aspergillus niger (de Hoog et al. 2000). For molecular characterization, genomic DNA was extracted from a single pure colony of fungus and the ITS region of rDNA was amplified and sequenced as described by O’Donnell and Cigelnik (1997) and White et al. (1990). Sequence analysis indicated 100% similarity with A. niger strain A7 (GenBank accession KR708636.1). A pathogenicity test was performed by removing spores from isolated colonies and inoculating wounded fruit with a spore suspension at a concentration of 105 conidia/ml. A total of nine lemons (cultivar Desi Lemon) and 10 grapefruit (cultivar Shamber) were inoculated with the spore suspension. At the same time, six fruit of the same cultivars were wound inoculation with sterilized water to serve as a control. All inoculated and control fruits were covered with sterilized muslin cloth to avoid contamination from outside sources. After 7 days, dark brown rot lesions consistently developed on fruit inoculated with the spore suspensions, and identical putative A. niger colonies were consistently reisolated from these fruit. Control fruit developed no symptoms. To our knowledge, this is the first report of A. niger causing fruit rot of lemon and grapefruit in Pakistan. Rapid identification of this emerging pathosystem would help with sustainability of the citrus industry in Pakistan.