Article: First Report of Diaporthe foeniculina Causing Black Tip and Necrotic Spot on Hazelnut Kernel in Chile
Plant disease. 2020 Mar., v. 104, no. 3
2020
Abstract: Chile is the largest producer of European hazelnut (Corylus avellana L.) in the southern hemisphere. Currently, there are ∼22,000 ha established with a total yield per year reaching 19,000 metric tons. Fungi reduce the quality and condition of the ... ...
| Abstract | Chile is the largest producer of European hazelnut (Corylus avellana L.) in the southern hemisphere. Currently, there are ∼22,000 ha established with a total yield per year reaching 19,000 metric tons. Fungi reduce the quality and condition of the hazelnut kernel, in many cases exceeding the tolerance limits required by the Chilean hazelnut industry. During 2017, hazelnuts were collected from the Frutícola AgriChile reception center located in Cunco, Chile (39°00′45.0′′S, 72°19′16.0′′W). A total of 2,148 samples (120 hazelnuts per sample) of the cultivars Barcelona (n = 1,207) and Tonda di Giffoni (n = 941) from 265 orchards in five regions were cracked open and inspected for kernel defects in the laboratory. The incidence of black tips and necrotic spots on kernels was 5.37% for Barcelona and 8.68% for Tonda di Giffoni. Kernels with black tips and necrotic spots were disinfected with EtOH (70%) for 2 min, rinsed twice with sterile distilled water (SDW), and dried on sterile paper under laminar flow; they were then maintained in a humid chamber for 10 days. Kernel fragments with mycelia were transferred onto potato dextrose agar and incubated for 5 days at 25°C in the dark. Forty isolates displayed white, sparse aerial and slow-growth mycelia. Pycnidia formed 25 days later that were globose to subglobose, with an elongated and black neck. Alpha-conidia (8.2 ± 0.7 × 2.7 ± 0.3 μm, n = 50) were aseptate, hyaline, oval to fusoid, and biguttulate. Beta-conidia (27.1 ± 2.1 × 1.2 ± 0.2 μm, n = 50) were hyaline, aseptate, slightly curved, and more abundant that alpha-conidia. These morphological characteristics corresponded to Diaporthe spp. anamorphic state. DNA was extracted from three isolates (01PH18, 03PH18, and 04PH18) using the DNeasy Plant Mini Kit (Qiagen). The internal transcribed spacer region was amplified using ITS1/ITS4 primers (White et al. 1990), and the amplicon was partially sequenced and deposited in GenBank (accession nos. MK002742, MK002743, and MK002744). All isolates showed 100% identity with Diaporthe foeniculina (Sacc.) Udayanga & Castl. (Udayanga et al. 2014) (accession nos. LN651171 [Castanea sativa, Italy], KR909215 [Vitis vinifera, U.S.A.], and KU375676 [Citrus sinensis, Iran]). Pathogenicity was tested on hazelnut kernels of cultivar Tonda di Giffoni (n = 120) with three isolates of D. foeniculina. The samples were superficially disinfected with EtOH (70%) for 2 min, rinsed twice with SDW, dried, and maintained in plastic boxes. Two inoculation methods were used on the kernels with and without wounding with a sterile needle. The first method consisted of placing 10 μl of alpha- and beta-conidial suspension (107 cells/ml) on the kernel tip. Alternatively, 50 ml of mycelial suspension was sprayed on 120 kernels (∼40 μl/kernel) with a manual sprayer. The kernels were maintained for 30 days under greenhouse conditions (14 h/10 h dark/light, 20°C; 70% relative humidity) and exhibited the following symptoms: tip blackened and a few cases with shriveled, dark necrotic spots of variable size and shape; additionally, internal black discoloration was observed. Reisolation from lesion margins consistently recovered D. foeniculina, satisfying Koch’s postulates. Kernels with and without wounding inoculated with SDW showed no symptoms. D. eres was implicated as the dominant species associated with brown spot of hazelnuts in the Caucus region (Battilani et al. 2018). To our knowledge, this is the first report of D. foeniculina as a causal agent of black tip and necrotic spots on hazelnut kernel in Chile. |
|---|---|
| Keywords | anamorphs ; Corylus avellana ; cultivars ; culture media ; Diaporthe ; discoloration ; DNA ; DNA primers ; dominant species ; ethanol ; fungi ; greenhouse production ; hazelnuts ; industry ; inoculation methods ; internal transcribed spacers ; laminar flow ; mycelium ; orchards ; paper ; pathogenicity ; pycnidia ; relative humidity ; seeds ; sprayers ; Chile |
| Language | English |
| Dates of publication | 2020-03 |
| Publishing place | Plant Disease |
| Document type | Article |
| ZDB-ID | 754182-x |
| ISSN | 0191-2917 |
| ISSN | 0191-2917 |
| DOI | 10.1094/PDIS-06-19-1166-PDN |
| Database | NAL-Catalogue (AGRICOLA) |
More links
Kategorien
In stock of ZB MED Bonn / Germany
| Z 2043: Show issues |
Order via subito
This service is chargeable due to the Delivery terms set by subito. Orders including an article and supplementary material will be classified as separate orders. In these cases, fees will be demanded for each order.
Inter-library loan at ZB MED
Your chosen title can be delivered directly to ZB MED Cologne location if you are registered as a user at ZB MED Cologne.