Berkeleyomyces basicola causing root rot on carrots (Daucus carota) in the state of Bahia, Brazil

The carrot (Daucus carota L., Apiaceae) is very important worldwide. In Brazil, this vegetable is cultivated on a large scale in the southeast, northeast and southern regions. Considering Bahia State, the most important producing municipalities at present are Lapão, Irecê and João Dourado. Among postharvest diseases affecting carrots, black rot can cause significant losses.

In a commercial establishment in the municipality of Ilhéus, Bahia State, ‘Brasília’ carrot roots were found showing typical symptoms of black rot (Figure 1). The symptomatic material was taken to the Laboratory of Plant Pathology and Nematology of “Universidade Estadual de Santa Cruz (UESC)”. A fungus was isolated in Potato-Dextrose-Agar medium (PDA) in 9cm-diameter Petri dishes from fragments removed from the lesions, previously disinfested in 2% sodium hypochlorite for 30 seconds and rinsed in sterile distilled water. Following incubation at 25 ±1 ^oC for 72 hours, the initial mycelium was transferred to new Petri dishes with PDA to obtain the pure culture. To verify the pathogenicity of the isolate, 50 µL of a suspension of 2.5 × 10⁶ phialoconidia / mL were inoculated into previously disinfested healthy carrot roots injured with a sterilized needle (five replicates). Sterile water was utilized as control. The inoculated roots were incubated in a humid chamber at 25 ±1 ^oC and four days after inoculation typical necrotic lesions were observed. Abundant reproductive structures of the fungus were observed under a light microscope (Figure 2): conidiophores 18–66 × 3–4 µm, multicellular, dark brown, thick wall, 10–15 × 7–10 µm; phialides 57.5–212.5 × 5–7.5 µm at the base and 2.5–5 µm at apex; phialoconidia 10–18 × 4 µm, unicellular, cylindrical, hyaline. Based on such characteristics, Berkeleyomyces basicola (Berk. & Broome) W.J. Nel, Z.W. de Beer, T.A. Duong & M.J. Wingf. (synonyms: Thielaviopsis basicola [Berk. & Broome] Ferraris; Chalara elegans Nag Raj & W.B. Kendr.) was confirmed as the causal agent of the disease. Blades with reproductive structures and herborized fragments of infected roots were deposited in Tropical Fungarium (TFB 792), at UESC.

Figure 1
Natural infection of carrot roots by Berkeleyomyces basicola.

Figure 2
Asexual structures of Berkeleyomyces basicola. A – artroconidia (chlamydospores); B – terminal phialide (arrow). C – unicellular cylindric phialoconidia. D – globose to pyriform aleuroconidia (Arrow).

To our knowledge, this is the first report of B. basicola on D. carota in the state of Bahia. In Brazil, the fungus was previously reported in post-harvest carrots in Rio de Janeiro as Ceratocystis fimbriata Ellis & Halst. (¹), Rio Grande do Sul as C. elegans (²), and Federal District (³) and Maranhão (⁴) as T. basicola.

REFERENCES

• ¹
  Carvalho, A.O.; Carmo, M.G.F. Podridão pós-colheita de cenoura causada por Ceratocystis fimbriata Fitopatologia Brasileira, Brasília, v.28, n.1, p.108, 2003.
• ²
  Dalbosco, M.; El Tassa, S.O.M.; Duarte, V. Ocorrência de Podridão Negra, causada por Chalara elegans, em raízes de cenoura no Rio Grande do Sul. Fitopatologia Brasileira, Porto Alegre, v.29, n.3, p.336, 2004.
• ³
  Inácio, C.A.; Lemes, G.P.; Café-Filho, A.C.; Lopes, C.A. First report of Thielaviopsis basicola causing black rot on carrot in Central Brazil. In: 45º Congresso Brasileiro de Fitopatologia, Tropical Plant Pathology, Brasília, v. 37, Resumo 752, Suplemento, 1 CD-ROM, 2012.
• ⁴
  Silva, G.S.; Costa, D.L.M.M. Ocorrência da podridão negra da cenoura no Estado do Maranhão. Summa Phytopathologica, Botucatu, v.39, n.4, p.294, 2013.

ERRATA

• Na página 129, em um dos autores do artigo, onde se lia:
  “Elisabeth Amélia Alves Duarte”
  Leia-se:
  “Elizabeth Amélia Alves Duarte”
  Revista Summa Phytopathologica, v. 47, n. 3, 10.1590/0100-5405/214388a, 2021.

Publication Dates

• Publication in this collection
  09 Aug 2021
• Date of issue
  Apr-Jun 2021

History

• Received
  01 Oct 2018
• Accepted
  26 Mar 2021