First report of Fusarium solani causing fruit rot of loquat (Eriobotrya japonica) in Pakistan

In Pakistan, loquat (Eriobotrya japonica) is a major fruit crop for local and export markets. In a 2014 survey, several fruit rots were observed in 34 loquat orchards located in Taxila, Wahcantt, Khanpur, Tret, Chatar, Muree, Kalar Kahar, and Choa Saidan Shah districts of Punjab Province; disease incidence ranged from 40 to 60%. Soft, dark brown to black lesions were observed on immature and mature fruit. A total of 89 symptomatic fruit were surface sterilized with 1% sodium hypochlorite for 2 min and rinsed three times with sterile distilled water. Excised segments (4 mm3) of sterilized tissue were transferred to potato dextrose agar (PDA) and incubated at 25 ± 2°C. After 1 week, white, fluffy, fast-growing colonies with septate and hyaline hyphae were observed; conidiophores were unbranched. A total of 71 isolates were used for morphological characterization. Microconidia were hyaline, ovoid, and 5.9 × 9.8 to 2.1 × 3.9 μm. Macroconidia were hyaline, curved and ranging from 19.8 × 29.9 to 3.9 × 5.8 μm. PCR was used to amplify the internal transcribed spacer (ITS) and translation elongation factor (EF) regions of isolates PAK51 and PAK52 with universal ITS1/4 and EF1/2 primers, respectively (Geiser et al. 2004; White et al. 1990). Sequence comparison of ITS (accession nos. KY000479 and KY000480) and EF (KY00081 and KY000482) revealed 99.0 to 99.5% homology with isolates of Fusarium solani (Mart.) Sacc. (teleomorph = Nectria hematococca (Berk. & Br.) available in GenBank and FUSARIUM-ID databases. To confirm pathogenicity, 10-μl aliquots of spore suspension (106 spores/ml) of the same two isolates were pipetted onto nonwounded and wounded asymptomatic healthy loquat fruits (three fruit per isolate) and sterile distilled water was used for a negative control. The pathogenicity tests were conducted twice and fruit were incubated at 25 ± 2°C in sterile glass chambers. Soft lesions consistent in appearance with the original symptoms were observed on inoculated loquat fruits, whereas no symptoms were recorded on the negative control fruit. The morphological characteristics of the fungus that was reisolated from each of the inoculated fruit was identical to that of the original cultures. Fusarium sp. has been reported to caused fruit rot of loquat in Okinawa Prefecture (Takushi and Kamekawa 2011) of Japan, but to our knowledge, this is the first report of F. solani causing fruit rot of loquat in Pakistan, where the disease poses a significant threat to sustainability of this major fruit crop.