Multi-omics analysis of Streptomyces djakartensis strain MEPS155 reveal a molecular response strategy combating Ceratocystis fimbriata causing sweet potato black rot.

To investigate the potential antifungal mechanisms of rhizosphere Actinobacteria against Ceratocystis fimbriata in sweet potato, a comprehensive approach combining biochemical analyses and multi-omics techniques was employed in this study. A total of 163 bacterial strains were isolated from the rhizosphere soil of sweet potato. Among them, strain MEPS155, identified as Streptomyces djakartensis, exhibited robust and consistent inhibition of C. fimbriata mycelial growth in in vitro dual culture assays, attributed to both cell-free supernatant and volatile organic compounds. Moreover, strain MEPS155 demonstrated diverse plant growth-promoting attributes, including the production of indole-3-acetic acid, 1-aminocyclopropane-1-carboxylate deaminase, phosphorus solubilization, nitrogen fixation, and enzymatic activities such as cellulase, chitinase, and protease. Notably, strain MEPS155 exhibited efficacy against various sweet potato pathogenic fungi. Following the inoculation of strain MEPS155, a significant reduction (P < 0.05) in malondialdehyde content was observed in sweet potato slices, indicating a potential protective effect. The whole genome of MEPS155 was characterized by a size of 8,030,375 bp, encompassing 7234 coding DNA sequences and 32 secondary metabolite biosynthetic gene clusters. Transcriptomic analysis revealed 1869 differentially expressed genes in the treated group that cultured with C. fimbriata, notably influencing pathways associated with porphyrin metabolism, fatty acid biosynthesis, and biosynthesis of type II polyketide products. These alterations in gene expression are hypothesized to be linked to the production of secondary metabolites contributing to the inhibition of C. fimbriata. Metabolomic analysis identified 1469 potential differently accumulated metabolites (PDAMs) when comparing MEPS155 and the control group. The up-regulated PDAMs were predominantly associated with the biosynthesis of various secondary metabolites, including vanillin, myristic acid, and protocatechuic acid, suggesting potential inhibitory effects on plant pathogenic fungi. Our study underscores the ability of strain S. djakartensis MEPS155 to inhibit C. fimbriata growth through the production of secretory enzymes or secondary metabolites. The findings contribute to a theoretical foundation for future investigations into the role of MEPS155 in postharvest black rot prevention in sweet potato.

Drosophila hydei as a Potential Vector of Ceratocystis fimbriata, the Causal Agent of Sweetpotato Black Rot, in Storage Facilities.

Ceratocystis fimbriata, the causal agent of sweetpotato black rot, is a pathogen capable of developing and spreading within postharvest settings. A survey of North Carolina sweetpotato storage facilities was conducted to determine the arthropods present and identify potential vectors of C. fimbriata. Sixteen taxonomic categories were recovered, and the genus Drosophila (Diptera: Drosophilidae) accounted for 79% of individuals sampled, with Drosophila hydei being the most abundant species. Behavioral assays were conducted to determine if D. hydei is attracted to C. fimbriata-inoculated roots and if the pathogen could be recovered from external or internal surfaces of the insect. Flies were released in insect-trapping pitchers containing either C. fimbriata-inoculated or noninoculated roots or Petri dishes. No significant differences in fly number were detected in sweetpotato-baited pitchers; however, significant differences were found in the pitcher baited with a mature C. fimbriata culture. Flies were subjected to washes to determine if viable C. fimbriata was present (internally or externally); washes were plated onto carrot agar plates and observed for the presence of C. fimbriata colonies. Both external and internal washes had viable C. fimbriata inocula with no significant differences, and inoculated sweetpotatoes had a significantly higher number of flies carrying C. fimbriata. This study suggests that D. hydei can carry C. fimbriata from infected sweetpotatoes and move viable C. fimbriata inocula both externally and internally, making this the first report of any Drosophila sp. serving as a potential vector for the Ceratocystis genus.

Novel Multiresistant Osmotin-like Protein from Sweetpotato as a Promising Biofungicide to Control Ceratocystis fimbriata by Destroying Spores through Accumulation of Reactive Oxygen Species.

Osmotin-like proteins (OLPs) play an important role in host-plant defense. In this study, a novel multiresistant OLP (IbOLP1) was screened from sweetpotato (Ipomoea batatas) with a molecular weight of 26.3 kDa. The expression level of IbOLP1 was significantly higher in resistant cultivars than susceptible ones after inoculation with Ceratocystis fimbriata, which causes black rot disease in sweetpotato. The expression of IbOLP1 in Pichia pastoris led to the lysis of yeast cells themselves. The recombinant IbOLP1 displayed antifungal, antibacterial, and antinematode activity and stability. IbOLP1 could restrain the mycelial growth and lyse spores of C. fimbriata, distinctly reducing the incidence of black rot in sweetpotato. The IbOLP1 can trigger the apoptosis of black rot spores by elevating the intracellular levels of reactive oxygen species. Collectively, these findings suggest that IbOLP1 can be used to develop natural antimicrobial resources instead of chemical agents and generate new, disease-resistant germplasm.

Long-Read Sequencing Genome Assembly of Ceratocystis fimbriata Enables Development of Molecular Diagnostics for Sweetpotato Black Rot.

Ceratocystis fimbriata is a destructive fungal pathogen of sweetpotato (Ipomoea batatas) that leads to losses at all stages of sweetpotato production. Accurate detection of C. fimbriata would allow for more efficient deployment of management tactics in sweetpotato production. To develop a diagnostic assay, a hybrid genome assembly of C. fimbriata isolate AS236 was generated. The resulting 31.7-MB assembly was near-chromosome level, with 18 contigs, 6,481 predicted genes, and a BUSCO completion score of 98.4% when compared with the fungus-specific lineage database. Additional Illumina DNA reads from C. manginecans, C. platani, and a second C. fimbriata isolate (C1421) were then mapped to the assembled genome using BOWTIE2 and counted using HTSeq, which identified 148 genes present only within C. fimbriata as molecular diagnostic candidates; 6 single-copy and 35 highly multi-copy (>40 BLAST hits), as determined through a self-BLAST-P alignment. Primers for PCR were designed in the 200-bp flanking region of the first exon for each candidate, and the candidates were validated against a diverse DNA panel containing Ceratocystis species, sweetpotato pathogens, and plants. After validation, two diagnostic candidates amplified only C. fimbriata DNA and were considered to be highly specific to the species. These genetic markers will serve as valuable diagnostic tools with multiple applications including the detection of C. fimbriata in seed, soil, and wash water in sweetpotato production.

Evaluación de la dinámica del crecimiento in vitro en callos de Ipomoea batatas / Evaluation of the dynamics of the growth in vitro callus of Ipomoea batatas

El cultivo del boniato presenta una gran importancia, ya que se puede emplear en la alimentación humana y animal, así como en la industria; el mismo produce raíces reservantes de gran valor calórico y nutritivo con alto contenido de carbohidratos. Entre las raíces y tubérculos cultivados es el segundo en importancia y representa más del 80% de la producción mundial. El empleo de las técnicas in vitro constituye una poderosa herramienta en la explotación comercial, propiciando el empleo de la micropropagación en diferentes especies. Para desarrollar el presente trabajo se recolectaron raíces tuberosas pertenecientes al clon Inivit B 93-1. Se procedió a la formación de callos potencialmente embriogénicos, para lo cual se emplearon explantes de limbos foliares, desinfectados con hipoclorito de sodio (1%) y sembrados en el medio de cultivo propuesto por Murashige y Skoog (1962), vitaminas MS (10,0 ml/l-1), mioinositol (100 mg/l-1), sacarosa (3%), gelrite (0,2%), 2,4-D (0,25-2,5 mg/l-1) y 6-BAP (0,25-1,0 mg/l-1), el pH fue ajustado a 5,8 ± 0,01 mantenidos en la oscuridad durante treinta días, lográndose los mejores resultados con el uso del 2,4-D (0,50 mg/l-1) y 6-BAP (0,25 mg/l-1), y en los mismos se evaluó la dinámica del crecimiento y se lograron los mejores resultados entre los 28 y 32 días después de la siembra, para lo cual los resultados obtenidos servirán de base a otros estudios y permitirán evaluar, controlar y desarrollar estrategias para la conservación y el uso de los recursos naturales, dando cumplimiento al objetivo referente a estudiar la dinámica del crecimiento en la formación de callos potencialmente embriogénicos en el cultivo del boniato.

The cultivation of the sweet potato presents a great importance, since you can use in the human feeding, animal as well as in the industry, the same one produces roots reservantes of great caloric and nutritious value with high content of carbohydrates. Between the roots and cultivated tubers it is the second in importance and it represents more than 80% of the world production. The employment of the techniques in vitro constitutes a powerful tool in the commercial, propitiated exploitation the employment of the micropropagación in different species. It is for it that you/they were gathered to develop the present work tuberous roots of the clon INIVIT B 93-1. Was realized the formation of callus with embryogenic structures, explantes of leaves were used, disinfected with hipoclorito of sodium (1%) and inoculated in the tissue culture medium proposed by Murashige and Skoog (1962), vitamins MS (10.0 ml/l-1), myoinositol (100 mg/l-1), sucrose (3%), gelryte (0.2%), 2,4-D (0.25-2.5 mg/l-1) and 6-BAP (0.25-1.0 mg/l-1), the pH was adjusted 5.8 ± 0.01 maintained in the darkness during thirty days, being achieved the best results with the use of the 2,4-D (0.50 mg/l-1) and 6-BAP (0,25 mg/l-1) and was evaluated the grow dynamic and obtained the better resulted between 28 and 32 days after culture, for that which the obtained results will serve from base to other studies and they will allow to evaluate, to control and to develop strategies for the conservation and use of the natural resources, giving execution to the objective with respect to studying the dynamics of the growth potentially in the formation of tripes embriogénicos in the cultivation of the sweet potato.

Evaluación de métodos para la conservación de hongos fitopatógenos del ñame (Dioscorea sp) / Evaluating methods for preserving yam (Dioscorea sp) phytopathogenic fungii

Un elemento esencial en la investigación con microorganismos fitopatógenos es su conservación y uso seguro.Desde este punto de vista, en este estudio se evaluaron métodos de conservación de hongos que atacanel ñame, empleando como factores de respuesta el potencial de viabilidad, y la estabilidad y presencia o ausenciade cambios en las características macro y microscópicas. Como resultado del trabajo se proponen los métodos más adecuados para los géneros Colletotrichum y Fusarium, hongos causantes de las mayores pérdidasen las plantaciones de ñame en la Costa Caribe colombiana. Las cepas utilizadas en este estudio provienen de las colecciones de la Universidad de Sucre, del Instituto de Biotecnología de la Universidad Nacional de Colombia (IBUN) y de una donación de la doctora Lucía Afanador de la Universidad Nacional, Sede Medellín.Estas fueron sometidas a diferentes métodos de conservación, entre ellos criopreservación, liofilizacióny cultivo periódico con y sin aceite mineral. Los resultados obtenidos permitieron elegir la criopreservacióncomo el método más eficiente para la conservación de la colección, y el cultivo periódico con aceite mineralcomo método alternativo y complementario. Estos minimizan el riesgo de pérdida del material biológico y brindan condiciones de manejo que conservan las características biológicas bajo estudio desde campos comola microbiología, la bioquímica y la biología molecular, entre otros.

An essential element in phytopathogenic microorganism research is their preservation and safe use. The purposeof this study was to evaluate methods for preserving fungi producing diseases in yam, using potential viability, stability and the presence or absence of macro- and microscopic characteristic changes as response factors. More suitable methods for Colletotrichum and Fusarium genera were proposed as a result of the work; these are fungi causing the greatest losses in yam plantations on the Colombian Caribbean Coast. The strains used in this study came from collections kept at the University of Sucre and the Universidad Nacional de Colombia’s Institute of Biotechnology (IBUN) in Bogota and a donation from Dr Lucia Afanador from the Universidad Nacional in Medellín. These strains were subjected to different preservation methods, including cryopreservation, lyophilisation and periodic culture with and without mineral oil. The results led to choosing cryopreservation as the most efficient method for preserving the collection and the periodic culture withmineral oil as an alternative and complementary method. These minimised the risk of biological material loss and provided handling conditions conserving the biological characteristics of the fungi being studied from the fields of microbiology, biochemistry and molecular biology.