Options
Morphological, molecular and pathogenetic characterization of Lasiodiplodia laeliocattleyae associated with dieback and pod rot on cacao in Ecuador
Journal
Physiological and Molecular Plant Pathology
ISSN
0885-5765
Date Issued
2025-03-01
Author(s)
Hayron Fabricio Canchignia Martinez
Angel Virgilio Cedeño-Moreira
Felipe R. Garcés Fiallos
Abstract
Cacao (Theobroma cacao L.) is a crop that holds significant economic and social importance in Ecuador. Cocoa clones such as CCN-51, known for their resistance to diseases and high yield, have been widely established in the country. However, in January 2021, several CCN-51 plants showed dieback and fruit rot. Thus, this study focused on morphologically, molecularly, and pathogenically identifying the causal agent of these symptoms in cacao. Two fungal isolates (LT1A and LT2A) were obtained from symptomatic CCN-51 cacao pods.
Both strains were characterized through morphological analysis (assimilative and asexual reproductive structures), molecular identification (using ITS, EF1α, and BTU markers), and pathogenicity testing (inoculation of seedlings and pods).
The average temperature for optimal growth and pycnidia production for both strains was 28 °C. The mean size of conidia was 25.2 x 13.7 μm. Molecular analysis identified the isolates as Lasiodiplodia laeliocattleyae. Pathogenicity tests confirmed that L. laeliocattleyae causes dieback in seedlings and pod rot on cacao. In seedlings and pods, the incidence of disease was 100 %, with the strain LT2A having a higher severity in pods (353.85 ± 35.15 mm) compared to LT1A (135.15 ± 61.09 mm) at 7 days after inoculation (Student T-test, P ≤ 0.05). To our knowledge, this is the first report of L. laeliocattleyae causing dieback in seedlings and pod rot on cocoa worldwide. These findings provide crucial information on the Lasiodiplodia-cacao pathosystem and highlight the need for further research on control measures to mitigate the spread and impact of L. laeliocattleyae in Ecuador.
Both strains were characterized through morphological analysis (assimilative and asexual reproductive structures), molecular identification (using ITS, EF1α, and BTU markers), and pathogenicity testing (inoculation of seedlings and pods).
The average temperature for optimal growth and pycnidia production for both strains was 28 °C. The mean size of conidia was 25.2 x 13.7 μm. Molecular analysis identified the isolates as Lasiodiplodia laeliocattleyae. Pathogenicity tests confirmed that L. laeliocattleyae causes dieback in seedlings and pod rot on cacao. In seedlings and pods, the incidence of disease was 100 %, with the strain LT2A having a higher severity in pods (353.85 ± 35.15 mm) compared to LT1A (135.15 ± 61.09 mm) at 7 days after inoculation (Student T-test, P ≤ 0.05). To our knowledge, this is the first report of L. laeliocattleyae causing dieback in seedlings and pod rot on cocoa worldwide. These findings provide crucial information on the Lasiodiplodia-cacao pathosystem and highlight the need for further research on control measures to mitigate the spread and impact of L. laeliocattleyae in Ecuador.