First report of Colletotrichum gloeosporioides causing anthracnose on loquat in Pakistan

F. Naz, M. F. Abbas, C. A. Rauf, A. Tariq, A. Mumtaz, G. Irshad, F. A. Shaheen, I. Hassan

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19 Citations (Scopus)

Abstract

Anthracnose is a destructive postharvest (Palou et al. 2016) and foliar disease of loquat (Eriobotria japonica). Anthracnose was observed in loquat orchards of Taxila (33°44′13″N. 72°47′57″E) and Wah Cantt (33°46′17″N, 72°45′3″E) areas of Pakistan during April 2013 to July 2015. Leaf symptoms initiated as small circular necrotic spots that enlarged into reddish brown, round to irregular necrotic brown areas visible on adaxial and abaxial surfaces. Fruit exhibited dark brown sunken lesions, which later turned into black, hard, and shriveled mummies. Anthracnose affected 39 and 23% of the plants in Taxila and Wah Cantt, respectively. Leaf (120) and fruit (80) samples were collected from 10 loquat orchards. Small pieces (5 to 10 mm2) were cut from the margins of lesions on fruits and leaves, surface disinfested with 1% sodium hypochlorite for 2 min, washed three times in sterilized distilled water, dried, and placed aseptically on Czapek Dox agar (CDA) plates (Thom and Raper 1945), followed by incubation at 25°C for 4 to 5 days. White cottony mycelia with a concentric zone of shiny orange conidial masses were consistently observed on CDA after 4 days. Conidia were hyaline, cylindrical with rounded ends, and aseptate, measuring 12.7 to 18.8 × 3.3 to 6.7 µm (mean 15.5 × 4.8 μm, n = 50 conidia). Appressoria were light brown, ovate to obovate, and 6 to 10 × 4.5 to 7.5 µm (mean 8.6 × 5.8 μm). All these characteristics matched with those described for Colletotrichum gloeosporioides (Sawant et al. 2012). For verification of pathogen identity, DNA of two representative isolates (TAX-1 and WAH-1) was extracted and three loci including the internal transcribed spacer (ITS) region, actin (ACT), and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) were amplified using primers ITS1/ITS4, ACT512F/ACT783R, and GDF/GDR, respectively (Weir et al. 2012). The purified PCR products were sequenced by Macrogen Inc., Korea. GenBank accession numbers for isolate TAX-1 (KR075160, KX185669, KX378683) and WAH-1 (KR075159, KX216403, KX379458) were assigned for ITS, ACT, and GAPDH, respectively. BLAST analyses showed 98 to 100% identity with C. gloeosporioides accessions HQ874906, KF712382, and HQ022565 for ITS, ACT, and GAPDH, respectively. In order to determine the pathogenicity of the isolates, conidial suspensions (1.5 × 105 conidia/ml) were prepared for each of 35 isolates, which were sprayed until run-off on three detached healthy, unwounded leaves and fruit for each isolate. Three control leaves and fruit were inoculated with sterile distilled water and placed at 25 ± 2°C. The symptoms on all inoculated leaves initiated as pinpoint, round, reddish brown, circular necrotic spots after 3 days that later coalesced into irregular spots. On fruit, dark brown necrotic sunken lesions developed after 4 days, which later covered the whole fruit. Symptoms were similar to those observed in the orchards, and control leaves and fruit remained symptomless. This is the first report of C. gloeosporioides infecting loquat in Pakistan. Further studies are needed to ascertain the best control measures for the management of the disease in commercial orchards.

Original languageEnglish
Pages (from-to)1550
Number of pages1
JournalPlant Disease
Volume101
Issue number8
DOIs
Publication statusPublished - Aug 2017
Externally publishedYes

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