Diversity and geographic distribution of fungal strains infecting field-grown common bean (Phaseolus vulgaris L.) in Tunisia

• Published in: European journal of plant pathology Vol. 153; no. 3; pp. 947 - 955
• Main Authors: Sendi, Yosra, Romdhane, Samir Ben, Mhamdi, Ridha, Mrabet, Moncef
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01.03.2019; Springer Nature B.V
• Subjects: Agriculture; Alternaria; Biomass; Biomedical and Life Sciences; Collection; Damping; Damping-off; Ecology; Fungal diseases; Fungi; Fusarium; Fusarium oxysporum; Geographical distribution; Interspecific; Life Sciences; Pathogenicity; Pathogens; Phaseolus vulgaris; Plant diseases; Plant Pathology; Plant Sciences; Reduction; Seedlings; Spacer region; Surveying; Tunisia; Fungi; Pathogenicity; Common bean; Internal transcribed spacer; Diversity
• DOI: 10.1007/s10658-018-01612-y
• ISSN: 0929-1873

A collection of 103 fungal strains was established from infected common bean plants ( Phaseolus vulgaris L.) field-grown in three geographic regions from Tunisia and known for their long history in bean culture; Boucharray, Chatt-Mariem, and Metline. The fungal strain collection was established from common bean root and aerial parts. The pathogenicity test carried out on germinated seedlings showed that among the fungal collection, 41% of fungal strains were assigned to be highly pathogenic. In fact, serious cases of seedling damping-off, as well as a significant reduction in root and shoot biomass in cv. Coco blanc were noticed (up to 90% biomass reduction) considering fungal strains from the three prospected localities. The identification of fungal isolates belonging to this high pathogenicity class, based on the internal transcribed spacer region (ITS), showed a wide generic and specific diversity among common bean pathogenic fungi in Tunisia. Fusarium spp. strains were dominant and represented 67% of the characterized fungal collection. Fungal genera including Alternaria (22%), Rhizoctonia (4%), Ascomycota (4%), Macrophomina (10%) and Phoma (4%) were also reported. The highest richness levels were found in the Chatt-Mariem and Boucharray regions, showing the highest generic and interspecific diversity. In this work, we revealed also a variability in the abundance and geographic distribution of fungal species between the three prospected regions. Fungal strains infecting common bean in Metline were represented exclusively by Fusarium oxysporum . However, the genus Fusarium represented about 66% of fungal strains recovered from Boucharray, and only 20% from Chatt-Mariem. The genus Alternaria represented 11% and 40% of total fungal isolates in Boucharray and Chatt-Mariem, respectively, and was isolated only from the foliar parts of diseased common bean plants. The present work represents an important database that should be considered for surveying common bean fungal diseases.