Evaluating cacao pod resistance to black pod disease caused by three Phytophthora species
- 1Department of Plant Pathology and Emerging Pathogens Institute, University of Florida, Gainesville, FL 32611, U.S.A.
Abstract
Black pod disease is a major threat to global cacao (Theobroma cacao L.) production. It is caused by multiple Phytophthora species with geographic ranges from regionally restricted to pantropical, and developing resistant cultivars requires screening against the diversity of these pathogens. This study evaluated the response of 25 cacao clones to 13 isolates of P. palmivora (eight), P. megakarya (two), and P. theobromicola (three) by nonwounding inoculation of detached pods. Lesion size and lesion expansion status were evaluated 4 days after inoculation. The linear mixed model included 178 combinations among 17 clones and 12 isolates, each represented by at least two biological replicate pods. Lesion size differed among clones (F(16, 449.2) = 25.16) and among isolates (F(11, 416.0) = 32.90), and the clone by isolate interaction was significant (F(150, 465.4) = 1.72; all P < 0.001). PENTAGONA-17 had the smallest estimated marginal lesion size (9.3 mm) and fitted values of 3.8 to 16.9 mm across 11 isolates representing all three species. ARF-31, ICS-47, POUND-7, and PMCT-73 had the next four smallest estimates, whereas NA-246 had the largest (36.7 mm). Isolate estimates varied more than fourfold, from 9.6 to 42.0 mm. Despite a marginal estimate of 12.9 mm, POUND-7 had a fitted estimate of 49.2 mm with P. megakarya GH34. The probability of lesion expansion also differed among clones and isolates (both P < 0.001). Together, these findings identify candidates for further resistance evaluation and show that multi-isolate screening provides a stronger basis for selecting materials for black pod resistance breeding.
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BibTeX
@misc{herreracorzo2026evaluating,
title = {{Evaluating cacao pod resistance to black pod disease caused by three Phytophthora species}},
author = {M. Herrera-Corzo and I. Schlathoelter and A. Arciniegas-Leal and B. A. Bailey and A. S. Puig and Y. Y. Jaimes Suarez and S. Sundram and T. T. N. Nguyen and D. Santos Britto and D. C. Rodezno and D. R. Drost and J.-P. Marelli and J. T. Brawner and E. M. Goss},
howpublished = {bioRxiv},
year = {2026},
month = sep,
doi = {10.64898/2026.09.17.752234},
url = {https://www.biorxiv.org/content/10.64898/2026.09.17.752234v1},
note = {CC BY-NC-ND},
}
RIS
TY - UNPB
TI - Evaluating cacao pod resistance to black pod disease caused by three Phytophthora species
AU - M. Herrera-Corzo
AU - I. Schlathoelter
AU - A. Arciniegas-Leal
AU - B. A. Bailey
AU - A. S. Puig
AU - Y. Y. Jaimes Suarez
AU - S. Sundram
AU - T. T. N. Nguyen
AU - D. Santos Britto
AU - D. C. Rodezno
AU - D. R. Drost
AU - J.-P. Marelli
AU - J. T. Brawner
AU - E. M. Goss
PY - 2026
DA - 2026/09/17
PB - bioRxiv
DO - 10.64898/2026.09.17.752234
UR - https://www.biorxiv.org/content/10.64898/2026.09.17.752234v1
AB - Black pod disease is a major threat to global cacao (Theobroma cacao L.) production. It is caused by multiple Phytophthora species with geographic ranges from regionally restricted to pantropical, and developing resistant cultivars requires screening against the diversity of these pathogens. This study evaluated the response of 25 cacao clones to 13 isolates of P. palmivora (eight), P. megakarya (two), and P. theobromicola (three) by nonwounding inoculation of detached pods. Lesion size and lesion expansion status were evaluated 4 days after inoculation. The linear mixed model included 178 combinations among 17 clones and 12 isolates, each represented by at least two biological replicate pods. Lesion size differed among clones (F(16, 449.2) = 25.16) and among isolates (F(11, 416.0) = 32.90), and the clone by isolate interaction was significant (F(150, 465.4) = 1.72; all P < 0.001). PENTAGONA-17 had the smallest estimated marginal lesion size (9.3 mm) and fitted values of 3.8 to 16.9 mm across 11 isolates representing all three species. ARF-31, ICS-47, POUND-7, and PMCT-73 had the next four smallest estimates, whereas NA-246 had the largest (36.7 mm). Isolate estimates varied more than fourfold, from 9.6 to 42.0 mm. Despite a marginal estimate of 12.9 mm, POUND-7 had a fitted estimate of 49.2 mm with P. megakarya GH34. The probability of lesion expansion also differed among clones and isolates (both P < 0.001). Together, these findings identify candidates for further resistance evaluation and show that multi-isolate screening provides a stronger basis for selecting materials for black pod resistance breeding.
ER -