Anthracnose is a disease caused by Colletotrichum spp., one of the world’s most damaging sweet and chili pepper pathogens, especially in tropical and subtropical regions. In the state of Rio de Janeiro, anthracnose is one of the main obstacles for pepper crops. However, to date no research has focused on the identification and characterization of the pathogen, which is fundamental to understand the scope of the disease in the state. Thus, the correct identification of the fungal species and pathogenicity studies can provide important support for disease management and control, apart from identifying possible resistance sources for exploitation in peppers breeding programs. In this study, 11 Colletotrichum isolates were collected from peppers with typical symptoms in the Rio de Janeiro state. These isolates were characterized based on morpho-cultural characteristics and sequencing data from five regions (ITS, ACT, CAL, β-TUB and GAPDH), and the genetic variability was estimated by AFLP markers. Simultaneously, microscopy images of the colonization by the fungal species on unripe Capsicum annuum fruits were taken. Pathogenicity was tested and resistance sources were sought by means of infection of ripe and unripe fruits of 50 Capsicum baccatum accessions. The resulting data showed that all isolates belong to Colletotrichum scovillei specie. About the pathogenicity of Capsicum baccatum, differentiated, stage-specific responses, with higher resistance of ripe fruits were recorded. In addition, four possible sources of Colletotrichum scovillei resistance were detected among the tested accessions. The combination of these data can contribute to future studies on the interaction of Colletotrichum scovillei-Capsicum spp., a research line that is still unexploited in the main areas of this anthracnose fungus.
The objective of this study was to characterize the Brazilian green Dwarf coconut (Cocos nucifera L.) by meiotic analysis and by conventional and differential karyotyping (CMA/DAPI and telomeric FISH). Sixteen pairs of bivalent were observed in the meiosis, indicating that the species is diploid and has 2n=2x=32 chromosomes. Some abnormalities were observed, such as asynchronous division and anaphase with converging fibers. The estimated recombination rate for this species was 17.04, equivalent to an average of 1.06 chiasmata per bivalent. The meiotic index was 79% and the pollen viability was 89.5%, both values considered satisfactory. The conventional karyotyping validated the observed number of chromosomes in the meiosis, i.e., 2n=32 chromosomes. The length of chromosomes ranged from 5.57 µm to 2.13 µm. The karyotype was considered asymmetric, with 11 metacentric and five submetacentric chromosomes pairs. The CMA/DAPI banding revealed terminal blocks in two chromosome pairs (one metacentric and one submetacentric), which was coincident with the nucleolus organizing region (NOR), and allowed the satellite characterization, which had 1.36 µm (chromosome 4) and 0.85 µm (chromosome 7). The telomeric FISH revealed signs only in the terminal region in all chromosomes, suggesting that this species has undergone no structural rearrangement of chromosomes during its evolution and that the telomeres of the coconut chromosomes are Arabidopsis type (TTTAGGG).
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