First Report of Fusarium Wilt Caused by Fusarium oxysporum on Strawberry in Bangladesh

Document Type

Article

Publication Date

2018

College/Unit

Davis College of Agriculture, Natural Resources and Design

Department/Program/Center

Agricultural & Extension Education

Abstract

Strawberry (Fragaria × ananassa) is a newly introduced small fruit crop in Bangladesh, which has gained considerable interest from both growers and consumers. Increasing incidence of wilt and crown rot diseases is a challenge for strawberry growers. In March 2016, wilted foliage and dead strawberry plants of cv. Strawberry Festival were found in a strawberry nursery in Rajshahi district of Bangladesh affecting 10% of the plants. Symptoms included wilting of foliage, drying and withering of older leaves, stunted growth, and reduced fruit production, leading to eventual plant collapse. A lengthwise cut through the crown of diseased plants showed distinct brown to reddish discoloration similar to that described by Koike et al. (2009). The crowns were surface sterilized in 2% NaOCl for 1 min followed by 70% ethanol for 5 min. Small pieces (2 × 2 mm) of the internal discolored tissue were placed on half-strength potato dextrose agar (PDA) medium and incubated for 7 days at 25°C. Single-spore isolates (BRSP-02 and BRSP-12) were obtained and plated to PDA, cornmeal agar, and V8 juice agar. Isolates had a growth rate 0.8 cm/day on PDA medium and produced sporodochia with septate macroconidia. Colonies also produced single-celled microconidia from unbranched, short, monophialidic conidiophores on PDA consistent with Fusarium oxysporum (Nelson et al. 1983). The internal transcribed spacer (ITS1, 5.8S rRNA, and ITS2), actin (ACT), and translation elongation factor 1-alpha (EF-1α) of the isolates were amplified using primers ITS-1/ITS-4, ACT-512F/ACT-783R, and EF1-728F/EF1-986R, respectively (Carbone and Khon 1999; White et al. 1990). ITS sequences of the isolates BRSP-02 and BRSP-12 (GenBank accession nos. LC383470 and LC383471, respectively) showed 99% similarity with the sequence from F. oxysporum strain SHBV2 (KY090783). Sequence identity for EF-1α (GenBank accession nos. LC383472 and LC383473, respectively) was 98 to 99% with the sequence from F. oxysporum isolate BRIP59170 (KX434915). The ACT sequences (GenBank accession nos. LC383784 and LC383785, respectively) showed 97 to 98% similarity with the sequence from F. oxysporum isolate C-11 (KY798318). Based on the aligned sequences of ITS and EF-1α, molecular phylogenetic analysis by the maximum likelihood method and maximum parsimony method, the isolates (BRSP-02 and BRSP-12) were named as F. oxysporum. The isolates are archived in the Department of Biotechnology at Bangabandhu Sheikh Mujibur Rahman Agricultural University in Bangladesh on dried filter paper at 4°C and are available on request. To confirm the pathogenicity of the fungus, five 3-month-old tissue-cultured ‘Strawberry Festival’ plants were inoculated by dipping the roots into either 400 ml of conidial suspension (with 5 × 106 conidia/ml) of the isolate BRSP-12 or into sterile distilled water (control) for 15 min. The inoculated plants were transplanted into plastic pots with artificial peat-based soil mix and maintained in the greenhouse with a high daytime temperature of 25°C and low nighttime temperature of 20°C. After 3 weeks, all plants inoculated with isolate BRSP-12 were stunted and developed wilt symptoms similar to those observed in the field, whereas the control plants remained healthy. Plants were then dug out, and crowns were cut longitudinally to check for internal discoloration. Light orange discoloration of crown tissues was observed in inoculated plants, but all the control plants remained symptomless. The fungus was successfully reisolated on half-strength PDA medium from 100% of crowns and had morphology as characterized before, fulfilling Koch’s postulates. To the best of our knowledge, this is the first report of Fusarium wilt of strawberry in Bangladesh. This disease has been reported from a number of other countries including Argentina, Australia, China, South Korea, Spain, the United States, and Japan (Koike et al. 2009; Williamson et al. 2012).

Source Citation

Surovy, M. Z., Kabir, M. K., Gupta, D. R., Hassan, O., Mahmud, N. U., Sabir, A. A., Rahman, M. M., Chang, T., Panaccione, D. G., & Islam, M. T. (2019). First Report of Fusarium Wilt Caused by Fusarium oxysporum on Strawberry in Bangladesh. Plant Disease, 103(2), 367. https://doi.org/10.1094/pdis-07-18-1121-pdn

Comments

This research was partially funded by the World Bank through HEQEP CPSF # 2071 to M. T. Islam of Department of Biotechnology of BSMRAU, and by the USDA Foreign Agricultural Service program contract Agr SR-CR-13–002. We also highly acknowledge the Fulbright Foundation of the U.S. State Department for The James William Fulbright Visiting Scholar Fellowship to M. T. Islam.

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