Occurrence of Pineapple Heart Rot caused by Phytophthora nicotianae Breda de Haan. on MD2 pineapple (Ananas comosus) in Colombia

Pineapple heart rot disease (PHRD) has been reported as one of the most important diseases affecting commercial pineapple (⁸). Plant material with PHRD symptoms was collected from June to October 2019 in Valle del Cauca, Colombia, under a collecting permit by the Colombian National Authority for Environmental Permits, Resolution No.1466-Dec 3, 2014 (⁷). A total of 95 oomycete isolates were obtained and morphologically characterized. They presented growth rate (Tc) average of 8.12 mm/day and predominant rosette colony pattern (64%). Under the microscope, isolates showed branched sporangiophores in compound sympodium, intercalary and terminal chlamydospores, and coralloid hyphae with swellings. Identification was conducted based on a representative subsample of 22 isolates distinguished by non-deciduous sporangia, mostly ovoid, globose and limoniform, with prominent papillae and an average size of 35.16 µm x 26.68 µm. Chlamydospores were spherical with an average diameter of 25.24 µm (Figure 1). The morphological characteristics coincided with those reported for Phytophthora nicotianae by Abad et al. (¹), Ocwa et al. (⁶), Das et al. (⁴), and Tao et al. (¹⁰). DNA from the 22 isolates was extracted (¹¹), and PCR amplification of the ITS region was conducted using the primer pair ITS4 and ITS6 (³). Expected bands of approximately 900 bp were visualized, and amplified products were sequenced (³). Sequences were edited and aligned using the software GENEIOUS Prime 2022.2.1. Nucleotide identity was determined based on BLASTn (NCBI). Results showed that the isolates shared a 100% sequence identity with the reported isolates of Phytophthora nicotianae. The nine consensus sequences of 858 bp obtained in the present study were deposited in GenBank under the accession numbers between OQ076297 and OQ076305. The maximum likelihood method was used to build a phylogenetic tree with the nine accessions, P. nicotianae ex-type strain MG865550, 11 reference sequences of other species belonging to clade 1 reported by Abad et al. (¹), six P. nicotianae sequences from pineapple fields worldwide deposited in GenBank (², ⁵, ⁹) and the outgroup sequence of Phytopythium vexans. An alignment of 830 positions was obtained with ClustalW algorithm; the best-fitting substitution model was HKY+G and the tree was built based on 1000 bootstraps using MEGA 11 software. The reference accessions were distributed among the four reported subclades (1a, 1b, 1c and 1d), and the accessions generated in the present study clustered within subclade 1d reported for P. nicotianae (¹) (Figure 2). In addition, the pathogenicity of the nine isolates was confirmed through inoculation into healthy MD2 pineapple plants under screenhouse conditions. The plants were inoculated at the heart base (10⁵ zoospores/mL) (²) and, four days post-inoculation (4 d.p.i), typical PHRD symptoms were observed in all evaluated plants, except controls (Figure 3). Phytophthora nicotianae was consistently re-isolated from symptomatic inoculated plants, fulfilling Koch’s postulates. In summary, we confirm Phytophthora nicotianae as the etiological agent associated with pineapple heart rot affecting MD2 pineapple in Valle del Cauca, Colombia, providing a baseline for improved diagnosis and disease management.

Figure 1
Phytophthora nicotianae characteristic structures: (a) limoniform Sporangia (size of 38.1 µm x 25.61 µm) (40X). (b) Terminal chlamydospore (24.69 µm diameter) (40X). (c) Branched sporangiophores in compound sympodium (10X). Photos by C.L. Puentes-Díaz.

Figure 2
A maximum likelihood phylogenetic tree constructed based on the ITS region of Phytophthora species found in the present study and retrieved from GenBank. The subclade 1d clustered by P. nicotianae accessions is highlighted in red.

Figure 3
Pathogenicity test of Phytophthora nicotianae isolates causing PHRD under screenhouse conditions. (a and b) PHRD initial level; (c and d) PHRD intermediate level; (e and f) PHRD advanced level and (g and h) Control plants. Photos by C.L. Puentes-Díaz.

ACKNOWLEDGMENTS

The Ministry of Agriculture and Rural Development of Colombia funded the first phase of this research work. The second phase was funded by The Ministry of Science, Technology and Innovation of Colombia (FONDO NACIONAL DE FINANCIAMENTO PARA LA CIENCIA, LA TECNOLOGÍA Y LA INNOVACIÓN “FRANCISCO JOSÉ DE CALDAS” Projeto 452-2021). The authors are grateful to Natalia Martínez and Yaneth Ladino for their assistance in the sporangia production and zoospore release protocols. The authors have no competing interests to declare relevant to this article’s content.

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Edited by

• EDITOR CIENTÍFICO:
  Edson Luiz Furtado https://orcid.org/0000-0002-6924-835X

• EDITOR ASSOCIADO:
  José Otávio Machado Menten https://orcid.org/0000-0002-9644-5770

Publication Dates

• Publication in this collection
  15 May 2026
• Date of issue
  2026

History

• Received
  27 Mar 2023
• Accepted
  12 Feb 2026