First Report of Fusarium Root Rot of Castor Caused by Fusarium solani Species Complex in Zhanjiang, China

HomePlant DiseaseVol. 103, No. 9First Report of Fusarium Root Rot of Castor Caused by Fusarium solani Species Complex in Zhanjiang, China PreviousNext DISEASE NOTES OPENOpen Access licenseFirst Report of Fusarium Root Rot of Castor Caused by Fusarium solani Species Complex in Zhanjiang, ChinaY. H. Zhou, Y. L. Liu, X. G. Yin, J. N. Lu, and J. R. TangY. H. ZhouGuangdong Ocean University, Zhanjiang, China 524088, Y. L. Liu†Corresponding author: Y. L. Liu; E-mail Address: mushwoman@126.comhttp://orcid.org/0000-0002-4145-9278Guangdong Ocean University, Zhanjiang, China 524088, X. G. YinGuangdong Ocean University, Zhanjiang, China 524088, J. N. LuGuangdong Ocean University, Zhanjiang, China 524088, and J. R. TangGuangdong Ocean University, Zhanjiang, China 524088AffiliationsAuthors and Affiliations Y. H. Zhou Y. L. Liu † X. G. Yin J. N. Lu J. R. Tang Guangdong Ocean University, Zhanjiang, China 524088 Published Online:23 Jul 2019https://doi.org/10.1094/PDIS-01-19-0125-PDNAboutSectionsSupplemental ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmailWechat Castor (Ricinus communis L.) is an important oil crop (Liu et al. 2016). Fusarium root rot of castor has been observed in Zhanjiang (21.17°N, 110.18°E), China, since 2016. In this reported outbreak, about 1,800 plants in a field (0.66 ha) were affected, and the disease incidence reached 26.2%. Early symptoms comprised the wilt of lower leaves and the darkening of vascular tissue of roots, which turned brown. Progressively, the whole plant wilted, the roots rotted, and the plant ultimately died. Five diseased plants were collected from the field. The roots of the symptomatic plants were surface disinfested before isolation. Potato dextrose agar (PDA) medium was used to isolate the pathogen. Successively, pure cultures were obtained by transferring hyphal tips to new PDA plates. Eighteen isolates were obtained from 25 pieces of roots. Two single-spore isolates (RFR1-4 and RFS2-1) were obtained from the hyphal-tip isolates, with each isolate being identical based on preliminary molecular analyses of their DNA sequences of ITS by BLASTn in the NCBI GenBank database. Therefore, the representative isolate RFR1-4 with typical morphology and molecular characteristics was selected for further study. Isolate RFR1-4 was grown on PDA and formed colonies of approximately 4.2 cm (diameter) in 5 days at 25 ± 1°C. Colonies exhibited entire margins, and the color varied from white to cream. Macroconidia were falciform, hyaline, three to four septate, with a characteristic foot-shaped basal cell and blunt apical cell, 37.2 to 45.5 µm (average 41.20 µm) × 4.7 to 6.4 µm (average 5.25 µm) (n = 40). Microconidia were hyaline, one to two cells, oval or reniform,12.2 to 22 0.4 µm (average 17.43 µm) × 4.5 to 6.7 µm (average 5.10 µm) (n = 40). Chlamydospores were spherical, single or in chains, 10.7 to 12.6 µm (average 11.14 µm) × 7.4 to 8.9 µm (average 8.35 µm) (n = 10). Morphological characteristics of isolate RFR1-4 were consistent with the description provided for Fusarium solani sensu lato (Nelson et al. 1983). Three regions of the internal transcribed spacer (ITS), translation elongation factor (EF1-α), and β-tubulin genes were amplified and sequenced with the primer pairs ITS1/ITS4, EF-1α-F/EF-1α-R (O'Donnell 2000), and Beta-F/Beta-R (O'Donnell and Cigelnik 1997). Analysis of the ITS (accession no. KY432816), EF1-α (KY432817), and β-tubulin (KY432818) sequences revealed a 100% identity with one isolate of the F. solani species complex (FSSC) (CBS 475.67; MLST type: 3+4-ccc; FD_01363) by polyphasic identification of the FUSARIUM-ID database. Also, a phylogenetic tree was built using the EF-1 genetic region to compare RFR1-4 with species in the FSSC. Pathogenicity tests were conducted in vivo, in a greenhouse with a relative humidity of 80%, at temperatures ranging from 24 to 30°C. Twenty healthy seedlings grew in 10 pots, respectively. They were inoculated with 100 ml of spore suspension (105 spores/ml), which was poured over the roots of castor seedlings (three true leaves). Another 20 healthy seedlings were used as controls treated with sterile water. The assay was repeated three times. The first symptoms were observed after 1 month, and the disease incidence came to 100% 2 months later, whereas the controls remained asymptomatic. The pathogen reisolated from the diseased tissues was identical to the inoculated isolates by morphology and ITS analysis. It has been reported that F. oxysporum f. sp. ricini caused castor Fusarium wilt (Desai et al. 2003). In this study, morphological and molecular analyses showed that the pathogenic isolate (RFR1-4) was identified as a member of the FSSC, and it was the causal agent of the disease. So, this study is the first report that a member of the FSSC caused Fusarium root rot of castor in China. This study will also provide critical information on the causal agent for growers to implement disease management strategies and future research.The author(s) declare no conflict of interest.References:Desai, A. G., et al. 2003. J. Mycol. Plant Pathol. 33:37. Google ScholarLiu, S., et al. 2016. Ind. Crops Prod. 89:103. https://doi.org/10.1016/j.indcrop.2016.04.063 Crossref, ISI, Google ScholarNelson, P. E., et al. 1983. Fusarium Species: An Illustrated Manual for Identification. Pennsylvania State University Press, University Park, PA. Google ScholarO'Donnell, K. 2000. Mycologia 92:919. https://doi.org/10.2307/3761588 Crossref, ISI, Google ScholarO'Donnell K., and Cigelnik E. 1997. Mol. Phylogenet. Evol. 7:103. Google ScholarThe author(s) declare no conflict of interest.Funding: This research was supported by National Natural Science Foundation of China (31271759) and Science and Technology Project of Guangdong Province (2014A020208119).DetailsFiguresLiterature CitedRelated Vol. 103, No. 9 September 2019SubscribeISSN:0191-2917e-ISSN:1943-7692 DownloadCaptionLeaf spot caused by Allophoma tropica on lettuce (Gullino et al.). Photo credit: M. L. Gullino. Red grapevine leaves showing symptoms of 'Candidatus Phytoplasma solani' (Jamshidi et al.). Photo credit: G. Romanazzi. Metrics Article History Issue Date: 30 Aug 2019Published: 23 Jul 2019First Look: 12 Apr 2019Accepted: 8 Apr 2019 Page: 2470 Information© 2019 The American Phytopathological SocietyFundingNational Natural Science Foundation of ChinaGrant/Award Number: 31271759Science and Technology Project of Guangdong ProvinceGrant/Award Number: 2014A020208119KeywordsRicinus communisFusarium solaniroot rotThe author(s) declare no conflict of interest.Cited byCsMYB60 Confers Enhanced Resistance to Fusarium solani by Increasing Proanthocyanidin Biosynthesis in CucumberJialin Li, Qianqian Luan, Jing Han, Chunhua Chen, and Zhonghai Ren28 February 2022 | Phytopathology®, Vol. 112, No. 3Biotic Stresses in Castor Plant19 March 2022Molecular identification and pathogenicity of Fusarium and Alternaria species associated with root rot disease of wolfberry in Gansu and Ningxia provinces, China4 October 2020 | Plant Pathology, Vol. 70, No. 2First Report of Fusarium solani Causing Root Rot on Peucedanum praeruptorum (Qian Hu) in Anhui Province, ChinaJi Ma, Xiong Xiao, Xingyu Wang, and Min Guo6 December 2019 | Plant Disease, Vol. 104, No. 2