In early August 2023, a disease outbreak on hot banana peppers (Capsicum annuum cv. Golden Dagger) was reported in Cattaraugus County, New York (NY). Disease incidence was at least 60%. Affected developing and mature fruit had at least one tan, soft, sunken lesion with salmon-colored spore masses surrounded by brown, necrotic margins. Microscopic observation of the lesions identified acervuli and setae typical of Colletotrichum spp. Isolations were made from these lesions by spreading conidia from the acervuli on 2% water agar (WA) + 0.02% (w/v) ampicillin. Colonies were hyphal tipped and transferred onto clarified V8 juice agar (CV8) and incubated at 20°C. The isolation frequency was 100% and a total of six isolates were obtained: Coll23Pep001, Coll23Pep003, Coll23Pep005, Coll23Pep007, Coll23Pep008, and Coll23Pep010. After 10 days, colonies were subcultured to potato dextrose agar (PDA) and CV8. On PDA, colonies appeared off-white to dark gray with sparse aerial mycelia. On CV8, the colony was pale gray with acervuli and orange-colored spore masses in the center. Conidia were hyaline, smooth and fusiform to round, and tapered at both ends. Mean conidial dimensions (n = 20) were 20.2 (13.75 to 25) µm long × 4.7 (3 to 6.25) µm wide. To confirm the identity of the isolates, DNA was extracted, and PCR performed to amplify the internal transcriber spacer (ITS) region (primers ITS1/ITS4; White et al. 1990), and actin (ACT) (primers ACT-512F/ACT-783R; Carbone and Kohn 1999) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) genes (primers GDF1/GDR1; Guerber et al. 2003). Pairwise alignment of the sequences showed all isolates had 100% similarity to C. scovillei ex. holotype CBS 126529 (Damm et al. 2012). Sequences from all isolates were deposited in GenBank with accessions PP556967 to PP556972 (ITS), PP565766 to PP565771 (ACT), and PP565772 to PP565777 (GAPDH). For pathogenicity testing, all isolates were grown on CV8 at 20°C in the dark for 10 days. Conidia were harvested by flooding the plates of each isolate with sterile distilled water and filtering the suspension through a double layer of cheesecloth. The concentration of the conidial suspension was adjusted to 5 × 105 spores per ml. Pathogenicity of the six isolates was tested on banana pepper fruit by using a sterile toothpick to pierce the skin at the two opposite ends. A droplet (10 µl) of the conidial suspension was placed on each wound. The same number of fruit were inoculated without wounding, and non-inoculated control fruit received a droplet of sterile distilled water (either wounded or unwounded). The experiment was repeated twice. All fruit were placed in a humid box at room temperature for 7 days. All wounded and inoculated fruit developed sunken lesions filled with salmon-colored conidial masses. Disease did not occur on the unwounded, inoculated fruit nor the non-inoculated controls. C. scovillei was recovered from all inoculated fruit by reisolating onto CV8 media and isolates had similar morphology and conidial dimensions to the original isolates. To the best of our knowledge, this is the first report of C. scovillei causing anthracnose on pepper in NY. C. scovillei has been reported in South Carolina (Toporek and Keinath 2021), Brazil (Caires et al. 2014), eastern Asia (de Silva et al. 2019), and Kosovo (Xhemali et al. 2023). The pathogen is particularly aggressive on pepper and poses substantial threats to pepper production around the world.
Nondestructive plant phenotyping forms a key technique for unraveling molecular processes underlying plant development and response to the environment. While the emergence of high-throughput phenotyping facilities can further our understanding of plant development and stress responses, their high costs greatly hinder scientific progress. To democratize high-throughput plant phenotyping, we developed sets of low-cost image- and weight-based devices to monitor plant shoot growth and evapotranspiration. We paired these devices to a suite of computational pipelines for integrated and straightforward data analysis. The developed tools were validated for their suitability for large genetic screens by evaluating a cowpea (Vigna unguiculata) diversity panel for responses to drought stress. The observed natural variation was used as an input for a genome-wide association study, from which we identified nine genetic loci that might contribute to cowpea drought resilience during early vegetative development. The homologs of the candidate genes were identified in Arabidopsis (Arabidopsis thaliana) and subsequently evaluated for their involvement in drought stress by using available T-DNA insertion mutant lines. These results demonstrate the varied applicability of this low-cost phenotyping system. In the future, we foresee these setups facilitating the identification of genetic components of growth, plant architecture, and stress tolerance across a wide variety of plant species.
