Abstract
Biocontrol offers a promising alternative to synthetic fungicides for the control of a variety of pre- and post-harvest diseases of crops. Black rot, which is caused by the pathogenic fungus Ceratocytis fimbriata, is the most destructive post-harvest disease of sweet potato, but little is currently known about potential biocontrol agents for this fungus. Here, we isolated several microorganisms from the tuberous roots and shoots of field-grown sweet potato plants, and analyzed their ribosomal RNA gene sequences. The microorganisms belonging to the genus Pantoea made up a major portion of the microbes residing within the sweet potato plants, and fluorescence microscopy showed these microbes colonized the intercellular spaces of the vascular tissue in the sweet potato stems. Four P. dispersa strains strongly inhibited C. fimbriata mycelium growth and spore germination, and altered the morphology of the fungal hyphae. The detection of dead C. fimbriata cells using Evans blue staining suggested that these P. dispersa strains have fungicidal rather than fungistatic activity. Furthermore, P. dispersa strains significantly inhibited C. fimbriata growth on the leaves and tuberous roots of a susceptible sweet potato cultivar (“Yulmi”). These findings suggest that P. dispersa strains could inhibit black rot in sweet potato plants, highlighting their potential as biocontrol agents.
Highlights
Biocontrol offers a promising alternative to synthetic fungicides for the control of a variety of preand post-harvest diseases of crops
The isolates were identified as bacteria belonging to 15 genera: Arthrobacter, Bacillus, Bacterium, Burkholderia, Cupriavidus, Enterobacter, Leclercia, Lysinibacillus, Microbacteriaceae, Microbacterium, Pantoea, Pseudomonas, Psychrobacillus, Serratia, and Streptomyces; fungi belong to 17 genera: Aspergillus, Cladosporium, Cryptococcus, Fusarium, Gongronella, Mortierella, Mucor, Neurospora, Papiliotrema, Penicillium, Phoma, Rhizomucor, Rhodosporidium, Rhodotorula, Sakaguchia, Torula, and Mucor
The phylogenetic tree based on the 16S rRNA, gyrB and rpoB gene which generated from NJ, ML and ME algorithm showed that all species of the genus Pantoeas divided into multiple clades, while Pantoea isolates in this study fell into two clades, P. dispersa, and P. ananatis (Fig. 1; Supplementary Figs S1 and S2)
Summary
Biocontrol offers a promising alternative to synthetic fungicides for the control of a variety of preand post-harvest diseases of crops. Black rot, which is caused by the pathogenic fungus Ceratocytis fimbriata, is the most destructive post-harvest disease of sweet potato, but little is currently known about potential biocontrol agents for this fungus. P. dispersa strains significantly inhibited C. fimbriata growth on the leaves and tuberous roots of a susceptible sweet potato cultivar (“Yulmi”) These findings suggest that P. dispersa strains could inhibit black rot in sweet potato plants, highlighting their potential as biocontrol agents. Black rot, which is caused by Ceratocystis fimbriata, is one of the most devastating, causing serious economic and resource losses worldwide[24,25,26] These pathogenic fungi are carried in the tuberous roots and cause disease in the progeny, www.nature.com/scientificreports and cannot currently be controlled by fungicides or other chemicals. While the endophyte P. agglomerans has been isolated from the stem of sweet potato[34], it remains unknown whether bacteria in this genus can counteract the growth of sweet potato fungal pathogens
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