ABSTRACT
The filamentous Ascomycota Colletotrichum gloeosporioides sensu lato is a fungus that has been reported worldwide as a causal agent of anthracnose disease in avocado and other crops. In Mexico, this species affects fruits from an early stage of development in the orchard until the post-harvest stage. Although fungicides are continuously applied to control Colletotrichum species, pericarp cankers and soft rot mesocarp in fruits are still frequently observed. Considering the lack of a precise description of the causative agent, the aim of the current study was to determine the pathogens involved in this symptomatology. Twenty-four isolates were consistently obtained from the pericarp of avocado fruits cv. “Hass” collected in the central avocado-producing area of Mexico. Morphological features such as colony growth, conidia size, and mycelial appressorium were assessed. Bayesian multilocus phylogenetic analyses were performed using amplified sequences of the internal transcribed spacer region of the nuclear ribosomal DNA; actin, chitin synthase, glyceraldehyde-3-phosphate dehydrogenase partial genes; and APn2-Mat1-2 intergenic spacer and mating type Mat1-2 partial gene from the nine selected isolates. In addition, fruits were inoculated with a conidial suspension and reproducible symptoms confirmed the presence of Colletotrichum fructicola in this area. This pathogenic species can now be added to those previously reported in the country, such as C. acutatum, C. boninense, C. godetiae, C. gloeosporioides, and C. karstii. Disease management programs to reduce the incidence of anthracnose should include C. fructicola to determine its response to fungicides that are routinely applied, considering that the appearance of new species is affecting the commercial quality of the fruits and shifting the original population structure.
Subject(s)
Actins , Ascomycota , Chitin Synthase , Colletotrichum , Disease Management , DNA, Ribosomal , Fruit , Fungi , Incidence , Mexico , Oxidoreductases , Persea , Spores, FungalABSTRACT
Pepper anthracnose caused by Colletotrichum species is one of the most important limiting factors for pepper production in Korea, its management being strongly dependent on chemicals. The aim of this work was to evaluate the possibilities of using silver nanoparticles instead of commercial fungicides. In this study, we evaluated the effect of silver nanoparticles against pepper anthracnose under different culture conditions. Silver nanoparticles (WA-PR-WB13R) were applied at various concentrations to determine antifungal activities in vitro and in the field. The application of 100 ppm concentration of silver nanoparticles produced maximum inhibition of the growth of fungal hyphae as well as conidial germination in comparison to the control in vitro. In field trials, the inhibition of fungi was significantly high when silver nanoparticles were applied before disease outbreak on the plants. Scanning electron microscopy results indicated that the silver nanoparticles caused a detrimental effect on mycelial growth of Colletotrichum species.
Subject(s)
Colletotrichum , Disease Outbreaks , Fungi , Germination , Hyphae , Korea , Microscopy, Electron, Scanning , Nanoparticles , SilverABSTRACT
Sweet persimmons have been increasingly cultivated in the southern part of Korea. However, anthracnose disease caused by Colletotrichum species is one of the major hindrances in cultivation and productions. In this study, we used polymerase chain reaction(PCR) to detect Colletotrichum species with the AFLP(amplified fragment length polymorphism) method. In AFLP, we used E3(5'-GACTGCGTACCAATTCTA-3') and M1(5'-GATGAGTCCTGAGTAACAG-3') primer combination and, as a result, 262 bp segment was observed in Colletotrichum species only. Specific PCR primers were designed from the sequence data and used to detect the presence of the fungus in genomic DNA isolated from symptomless sweet persimmon plants. Based on sequence data for specific segments, Co.B1(5'-GAGAGAGTAGAATTGCGCTG-3') and Co.B2(5'-CTACCATTCTTCTA GGTGGG-3') were designed to detect Colletotrichum species. The 220 bp segment was observed in Colletotrichum species only, but not in other fungal and bacterial isolates.