Publicação
Chestnut rots: disease incidence and molecular identification of causal agents
| Resumo: | Chestnut fruits are popular fruits commercialized as fresh or processed ready to be used as products. Because of its high moisture and suitable nutrient content, the chestnut kernel has the potential to support the growth of a wide spectrum of spoilage fungi. The major postharvest problems associated with stored chestnut fruits are rots, which result in major losses in fruit quality. Although the empirical knowledge determines a high level of rot in Portuguese chestnuts, there are no scientific studies on the incidence and severity of the problem, and the causal agents have never been identified. This knowledge is of the utmost importance and urgency for industry and retailers to correctly address the issue, in an effort to reduce yield loss due to rot. The aims of this work were: i) to determine the incidence, abundance and diversity of rots in three chestnut varieties of Trás-os-Montes – Judia, Longal and Martaínha – at different postharvest stages of storage and processing, and ii) to identify the main potential agents of rots. For this purpose chestnuts were internally and externally inspected for presence of damages, infestation and infection. Samples from variety Martaínha were identified as the most resistant to fungal growth, while samples from variety Longal were less resistant to fungal growth and infestation. A high diversity of species has been molecularly identified by sequencing the ITS region: 37 different species belonging to 16 genera. The dominant fungal species found with high frequency were Mucor racemosus f. sphaerosporus (24.2% of frequency), Penicillium brevicompactum (16.7%) and Penicillium thomii (causal agents of green rot; 13.9%), Ciboria batschiana (the causal agent of black rot; 10.6%) and Botrytis cinerea (the causal agent of grey rot10.6%). Gnomoniopsis smithogilvyi, the causal agent of brown rot, was also identified with a frequency of 6.4%. The results show that the causal agents of various chestnut rots already identified in other countries are also present in Portuguese nuts. Studies must follow with the aim of developing control measures against the identified rot-causing fungi. |
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| Autores principais: | Driss, Jihen Oueslati |
| Assunto: | Black rot Brown rot Storage fungi Gnomoniopsis smithogilvyi Ciboria batschiana Penicillium sp. |
| Ano: | 2019 |
| País: | Portugal |
| Tipo de documento: | dissertação de mestrado |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Instituto Politécnico de Bragança |
| Idioma: | inglês |
| Origem: | Biblioteca Digital do IPB |
| Resumo: | Chestnut fruits are popular fruits commercialized as fresh or processed ready to be used as products. Because of its high moisture and suitable nutrient content, the chestnut kernel has the potential to support the growth of a wide spectrum of spoilage fungi. The major postharvest problems associated with stored chestnut fruits are rots, which result in major losses in fruit quality. Although the empirical knowledge determines a high level of rot in Portuguese chestnuts, there are no scientific studies on the incidence and severity of the problem, and the causal agents have never been identified. This knowledge is of the utmost importance and urgency for industry and retailers to correctly address the issue, in an effort to reduce yield loss due to rot. The aims of this work were: i) to determine the incidence, abundance and diversity of rots in three chestnut varieties of Trás-os-Montes – Judia, Longal and Martaínha – at different postharvest stages of storage and processing, and ii) to identify the main potential agents of rots. For this purpose chestnuts were internally and externally inspected for presence of damages, infestation and infection. Samples from variety Martaínha were identified as the most resistant to fungal growth, while samples from variety Longal were less resistant to fungal growth and infestation. A high diversity of species has been molecularly identified by sequencing the ITS region: 37 different species belonging to 16 genera. The dominant fungal species found with high frequency were Mucor racemosus f. sphaerosporus (24.2% of frequency), Penicillium brevicompactum (16.7%) and Penicillium thomii (causal agents of green rot; 13.9%), Ciboria batschiana (the causal agent of black rot; 10.6%) and Botrytis cinerea (the causal agent of grey rot10.6%). Gnomoniopsis smithogilvyi, the causal agent of brown rot, was also identified with a frequency of 6.4%. The results show that the causal agents of various chestnut rots already identified in other countries are also present in Portuguese nuts. Studies must follow with the aim of developing control measures against the identified rot-causing fungi. |
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