Response of olive tree (Olea europaea L.cv. Chemlali) to infection with soilborne fungi

In the last years, the spread of wilt and dieback diseases in olive trees (Olea europaea), caused by the soilborne pathogens, has often been related to intensive modern farming of highly productive cultivars, planted at high densities, usually in an irrigated system. Plants have developed different strategies to trigger defense signaling to defend themselves and to maintain surveillance against pathogens. However, the response of olive tree to pathogen infections is not well studied yet. The present work is aimed at studying the response of olive tree to soilborne fungi isolated from different affected areas in Tunisia, such as Fusarium spp. Verticillium dahliae, Cylindrocarpon sp. and Rhizoctonia solani. Artificial inoculation on young olive trees cv. ‘Chemlali’ confirmed the pathogenicity of all these pathogens by reproducing typical symptoms of root rot with varied degrees. Biochemical analysis realized after 21 days of inoculation has shown that chlorophyll pigments, solubles sugar, total polyphenols and proline contents were highly detected in plants infected by V. dahliae and F. solani. The expression of four genes Olest 06, Olest 47, Olest 73 and Olest 30 involved in the signaling biotic and abiotic stress and transcriptional activation of pathogenesis-related proteins was analyzed by reverse transcription-PCR after 21 days of inoculation. The transcript level of Olest 73 was relatively constant in all tested fungi. The expression of gene Olest 47 was observed in the leaves of olive in vitro plants infected by V. dahliae and Fusarium spp. and the gene expression of Olest 30 was detected only in plants infected by V. dahliae. No PCR product was detected for Olest 06 in all inoculated olive trees. In conclusion, according to results obtained by biochemical and molecular analysis, the olive trees develop variable responses to pathogenic soil fungi attack.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Analysis of the Cultivable Endophytic Bacterial Diversity in the Date Palm (Phoenix dactylifera L.) and Evaluation of Its Antagonistic Potential against Pathogenic Fusarium Species that Cause Date Palm Bayound DiseaseAnalysis of the Cultivable Endophytic

Abstract Biological control still remains an unexploited issue in southern countries such as Tunisia. Thus, the present study focused on the diversity of cultivable endophytic bacteria in the internal tissues (roots and leaves) of Tunisian date palm trees (Phoenix dactylifera L.). In order to assess their antagonistic potential towards date palm pathogens, particularly Fusarium. Indeed, the Genus Fusarium includes the causative agent of the Bayound disease, Fusarium oxysporum, a major treat for date production North Africa. Twenty two bacterial isolates presenting distinct colony morphology on TSA media were selected. The latter were characterized using Gram staining, biochemical tests, and molecular identification techniques based on 16S rRNA gene sequencing. Cultivable endophytic isolates were assigned into seven distinct groups. The species Arthrobacter agilis and Bacillus subtilis exhibited lasting antagonistic properties against a range of Fusarium species including the causing agent of the Bayoud disease, thus demonstrating their strong potential for future applications in the inoculation of date palm trees for biocontrol purposes. The isolates showed extracellular enzymatic activity including cellulase (76, 92%), protease (69, 23%) and amylase (38, 46%). This study thus demonstrates for the first time that the diversity of endophytic bacteria is abundant in date palm trees (Phoenix dactylifera L.) and could present varying biotechnological applications and particularly disease control

Analysis of the Cultivable Endophytic Bacterial Diversity in the Date Palm (Phoenix dactylifera L.) and Evaluation of Its Antagonistic Potential against Pathogenic Fusarium Species that Cause Date Palm Bayound Disease

International audienceBiological control still remains an unexploited issue in southern countries such as Tunisia. Thus, the present study focused on the diversity of cultivable endophytic bacteria in the internal tissues (roots and leaves) of Tunisian date palm trees (Phoenix dactylifera L.). In order to assess their antagonistic potential towards date palm pathogens, particularly Fusarium. Indeed, the Genus Fusarium includes the causative agent of the Bayound disease, Fusarium oxysporum, a major treat for date production North Africa. Twenty two bacterial isolates presenting distinct colony morphology on TSA media were selected. The latter were characterized using Gram staining, biochemical tests, and molecular identification techniques based on 16S rRNA gene sequencing. Cultivable endophytic isolates were assigned into seven distinct groups. The species Arthrobacter agilis and Bacillus subtilis exhibited lasting antagonistic properties against a range of Fusarium species including the causing agent of the Bayoud disease, thus demonstrating their strong potential for future applications in the inoculation of date palm trees for biocontrol purposes. The isolates showed extracellular enzymatic activity including cellulase (76, 92%), protease (69, 23%) and amylase (38, 46%). This study thus demonstrates for the first time that the diversity of endophytic bacteria is abundant in date palm trees (Phoenix dactylifera L.) and could present varying biotechnological applications and particularly disease control