The genus Passiflora, comprising more than 520 recognized species, its a taxonomic group of substantial ethnobotanical, horticultural, medicinal, and economic importance (Moraes et al., 2020; Ożarowski and Karpiński, 2021). Its cultivation is predominantly concentrated in tropical and subtropical regions, with Brazil, Colombia, Peru, and Ecuador standing out as the main producers in South America (Fischer et al., 2021). Notably, Colombia is acknowledged as one of the principal centers of genetic diversity, as its heterogeneous agroecological conditions provide optimal environments for the cultivation and diversification of multiple species (Martínez et al., 2020).

In Colombia, the commercial cultivation of passionflowers encompasses taxa of significant agronomic, nutritional, and economic importance, including yellow passion fruit (Passiflora edulis f. flavicarpa Degener, locally known as maracuyá), purple passion fruit (P. edulis f. edulis Sims, gulupa), sweet granadilla (P. ligularis Juss., granadilla), banana passion fruit (P. tripartita var. mollissima [Kunth], curuba), and stone granadilla (P. maliformis L., cholupa) (Fischer et al., 2021). As of 2024, passion fruit cultivation in Colombia covered approximately 32,430 hectares across 28 departments, yielding an estimated production of 449,775 tons (Ministerio de Agricultura y Desarrollo Rural (MADR), 2025).

Passiflora maliformis is also a species of considerable agronomic interest. Based on morphological and genetic analyses, it is classified within the supersection Stipulata, section Granadillastrum, and series Tiliifolia (Yockteng and Nadot, 2004; Ramaiya et al., 2014). Native to the tropical regions of the Americas, this vigorous vine produces large, pendulous hermaphroditic flowers, which display high self-incompatibility (~95%), and fruits that mature within 50–60 days (Molano-Avellaneda et al., 2020). Its phytochemical profile, characterized by a high content of total phenols and strong antioxidant activity, confers extracts with antioxidant, cytotoxic, and antimicrobial properties (Sabogal-Palma et al., 2016).

Another Passiflora species of major agronomic importance in Colombia is purple passion fruit (P. edulis f. edulis), currently ranked as the third most exported fruit. Its profitability and strong demand in European and Canadian markets have driven a steady expansion of its cultivation (López Plazas, 2020). This product is consumed fresh or incorporated into various culinary preparations due to its characteristic aroma and flavor. Its fruits are rich in carbohydrates, essential minerals (Fe, Cu, P, K, Mg), vitamins (riboflavin, niacin, vitamin C), and bioactive compounds with recognized nutraceutical and industrial applications (Fonseca et al., 2022; Pereira et al., 2023). Altogether, these characteristics consolidate purple passion fruit as a strategic crop for Colombia’s agricultural sector and a benchmark for the development of other Passiflora species.

Despite their growing socioeconomic relevance, cultivated passionflower species are severely affected by soilborne pathogens, notably Fusarium oxysporum and F. solani, which cause vascular wilt and stem rot (Fischer and Rezende, 2008; Kiptui et al., 2020; Mukoye et al., 2022; Bernal-Moreno and Rodríguez, 2023; Wang et al., 2023). Under severe infections, these diseases may result in total crop losses (100%) (Torres et al., 1999; Salazar-Gonzalez et al., 2022). Given their persistence in soil and aggressive colonization strategy, these pathogens represent major constraints for purple passion fruit cultivation worldwide, raising significant concerns due to their economic impact (Fischer and Rezende, 2008; Yadeta and Thomma, 2013; Aiello et al., 2021; Kashyap et al., 2021; Gonçalves Barros Silva, 2023).

The infection cycle of Fusarium spp. comprises root adhesion, cell wall degradation through enzymatic activity, and xylem colonization by microconidia. These events trigger systemic dissemination that culminates in vascular blockage, physiological water stress, and host death (Ekwomadu and Mwanza, 2023). Fusarium wilt and stem rot progress acropetally and manifest through early chlorosis, wilting desiccation of aerial tissues, defoliation, vascular discoloration, and plant death (Ortiz et al., 2014). Stem rot is further characterized by necrosis at the root collar and development of perithecia, although its diagnosis is often complicated by overlapping symptoms with Fusarium wilt (Agrios, 2005; Ploetz, 2005).

Managing vascular wilt pathogens is particularly challenging due to their long persistence in soil and their capacity to infect plants at any developmental stage. Conventional control methods, including chemical, physical, and cultural practices, are often ineffective and economically unsustainable (Aiello et al., 2021; Bahadur, 2022; Ekwomadu and Mwanza, 2023). Consequently, increasing emphasis has been placed on genetic strategies such as breeding and grafting with resistant genotypes, which provide sustainable alternatives for the management of Fusarium infections (Panth et al., 2020; Carvalho et al., 2021). Grafting, in particular, has been extensively applied in agriculture to enhance crop tolerance to both biotic and abiotic stresses (Hurtado-Salazar et al., 2021; Williams et al., 2021).

While both grafting and breeding provide valuable opportunities for disease management, their application has not been fully extended to all commercial crops, partly due to genetic variability in the response of passion fruit species to pathogens such as Fusarium (Ferreira et al., 2023). In this context, studies conducted in producing countries such as Brazil and Colombia, have evaluated the resistance to F. oxysporum and F. solani of some passion fruit species grown in greenhouses or nurseries (Londoño, 2012; Silva Flores et al., 2012; Ortiz et al., 2014; Forero et al., 2015; Papadaki et al., 2017; Rios Ribeiro et al., 2018; Patiño Pacheco, 2020; Miguel-Wruck et al., 2021).

On the other hand, although P. maliformis has been proven to exhibit high compatibility and potential as a rootstock for purple passion fruit (P. edulis f. edulis), systematic evaluations of its resistance to Fusarium spp., particularly under controlled conditions, remain scarce (Betancourt and Muñóz, 2012; Miguel-Wruck et al., 2021; Roncatto et al., 2021). Therefore, the present study aimed to elucidate the resistance mechanisms of Passiflora maliformis var. pubescens against F. oxysporum (Fusarium wilt) and F. solani (stem rot), with emphasis on histopathological traits. The results provide a foundation for enhancing disease resistance and productivity in passionflower crops, supporting the validation of this wild genotype as a resistant rootstock and a valuable candidate for breeding programs.

This study was carried out at the BIOPLASMA-UPTC Plant Tissue Culture Laboratory in four main phases: (I) ex vitro and in vitro propagation of Passiflora maliformis var. pubescens seedlings, (II) obtaining pathogenic isolates of F. oxysporum and F. solani complexes, (III) inoculation of plant material and response evaluation, and (IV) histological analysis.

Research related to diseases affecting crops is essential to guide comprehensive prevention, management and control strategies (Rahut et al., 2022; Zhang et al., 2023). Also, being relevant for the production of safe and healthy food, it can contribute to food security (Li et al., 2023). In the Passiflora production sector, it is a priority to have cultivars that are resistant to Fusarium wilt and meet nutritional, productive and industrial demands (Amorim-Pereira et al., 2019). However, our current knowledge of the relationship between F. oxysporum and F. solani and wild genotypes of Passiflora is still incomplete. This study contributes to filling that gap, through the evaluation of the response of a wild genotype to the action of Fusarium wilt and stem rot causal agents (Mukoye et al., 2022; Nassimbwa et al., 2022). This analysis included aspects frequently reported to determine the response of Passiflora species/accessions to the action of Fusarium spp., in addition to a histopathological description.

F. oxysporum affected less than 17% of the seedlings, with a low symptomatic progression, a severity index of up to 0.5, and an average AUDPC of 6.25. Although inoculation with F. solani led to an incidence ≤50%, symptomatology was mild, the severity index was less than 1.75 and disease progress (AUDPC) had a mean value of 21.5. In addition, mortality after 27 dpi in inoculated plants was less than 7%, with similar records for F. oxysporum and F. solani. These results contrast with those reported for species susceptible to Fusarium wilt and stem rot such as Passiflora edulis f. flavicarpa Degener, P. edulis f. edulis Sims and P. ligularis Juss, where incidence generally ranges between 40-100% (Forero et al., 2015; Melo et al., 2020; Rocha et al., 2021) with medium-high affectation (Ortiz and Hoyos-Carvajal, 2016) and a severity index ranging from 5-7.5 (on a scale of 1-10) (Lima et al., 2019). Likewise, mortality of up to 70% and survival of less than 30% have been reported (Pires et al., 2022).

On the other hand, in the case of resistant accessions, previous studies have reported incidences between 0 and 50% (Londoño, 2012; Patiño-Pacheco and Pérez-Cardona, 2021), mortality rates below 50% (Amorim-Pereira et al., 2019; Melo et al., 2020) survival rates of 67-100% (Carvalho et al., 2021; Oliveira et al., 2022), and progression of severity (AUDPC) close or equal to zero (Pérez and Forbes, 2008); which would indicate a low level of infection in the genotype evaluated in this study.

The search for new sources of resistance against Fusarium wilt and stem rot requires efficient detection methods that provide information on physical and chemical response mechanisms (Sampaio et al., 2020). Upon an attack of pathogenic microorganisms plants activate complex immune networks to prevent or minimize colonization of their internal structures and deprivation of nutrients (Margaritopoulou et al., 2020; Duarte-Alvarado et al., 2021). In vascular wilt, the formation of structural barriers in and around the vascular bundles is one of the most important components of defense against the disease according to Kashyap et al. (2021).

Internal anatomical analysis revealed intercellular and intracellular secretion of dense substances, as well as possible lignification of cell walls and tyloses formation, as potential response mechanisms of P. maliformis var. pubescens to infection by isolates of the F. oxysporum and F. solani complexes. These reactions play a crucial role in limiting the spread of the pathogen, since physical structures neutralize or reduce further spread and chemicals can lead to the death or inhibition of pathogen growth (De Micco et al., 2016; Chakraborty et al., 2022).

In the initial steps of the response to Fusarium wilt, gels are formed within the xylem that are mainly composed of polysaccharides and phenolic compounds exuded from the parenchymal cells adjacent to the infection point. Once these compounds are fused to the cell wall, oxidation and polymerization reactions occur to form a durable barrier at the interface of the infected and healthy tissues (Ardila et al., 2014). Gels and dense substances fix conidia on vascular elements and localize the pathogen when F. oxysporum infection occurs (Muche and Yemata, 2022).

Other common barrier mechanisms against the disease are cell wall strengthening due to lignin deposition and the synthesis and accumulation of callose and phenolic compounds in inter- or intracellular spaces that block Fusarium progression in the host (Sampaio et al., 2020). Phenols have antifungal capacity by affecting the cell permeability of microorganisms, causing structural and functional changes in enzymes and membrane proteins, leading to alterations in the pH gradient and in the ATP production and conservation system (Carmona et al., 2020).

The results of this study suggested a high response capacity of the genotype since the defense mechanisms limited the pathogenic action of Fusarium spp. and low internal and external tissue damage was observed. Overall, both inoculated and non-inoculated SE and SI seedlings exhibited comparable shoot and root growth and development, which may indicate that the defense mechanisms of the genotype were effective in maintaining normal physiological performance. In this sense, the use of in vitro culture allowed the rapid and large-scale production of plant material, while providing a platform to evaluate resistance traits under controlled conditions. This dual functionality reinforces its potential application in breeding programs and integrated disease management strategies (Bernal- Moreno et al., 2018; Bernal-Moreno and Rodríguez, 2023). Therefore, these results are especially relevant, as this wild genotype and its genetic background may serve as a strategic resource to address key biotechnological and agronomic challenges currently faced by promising Passiflora species.

Given the severe limitations caused by Fusarium wilt and stem rot in passion fruits agricultural systems, management of these diseases often relies on synthetic fungicides (Liu et al., 2025). Such as benzimidazoles (e.g., carbendazim), triazoles (e.g., tebuconazole) and strobilurins (e.g., azoxystrobin), which alter fungal membrane integrity or interfere with mitochondrial respiration. However, their continued use has raised increasing concerns about high economic costs, limited systemic mobility, persistence in the environment, risks to human health, and the emergence of resistant pathogen populations (Mikaberidze et al., 2014).

Ecological alternatives for the biorational control of F. oxysporum and F. solani include fungal and bacterial antagonists such as Trichoderma harzianum, T. asperellum, T. virens, Bacillus subtilis, B. amyloliquefaciens, Pseudomonas fluorescens, P. putida, and P. protegens. These microorganisms have demonstrated inhibition rates of up to 94% in vitro and, in some cases, in the field, through mechanisms that include mycoparasitism, the production of hydrolytic enzymes (e.g., chitinase and β-1,3-glucanase), the emission of volatile organic compounds, and the induction of systemic resistance in host plants (Verma et al., 2007; Ongena and Jacques, 2008; Ben Khedher et al., 2015; Mehmood et al., 2023; Yao et al., 2023). However, the effectiveness of these strategies in the field remains variable, largely influenced by factors such as interactions with native soil microbiota, climate variability, and the limited persistence of inoculants in the rhizosphere (Awu et al., 2023; Wang et al., 2024).

In this context, the use of resistant rootstocks emerges as a complementary and sustainable solution. Resistant genotypes do not require repeated applications, do not generate toxic residues, and are less susceptible to environmental fluctuations (Ayala-Doñas et al., 2020; Suansia and Chandra Samal, 2021). Therefore, the identification of Passiflora rootstocks resistant to Fusarium wilt and stem rot represents a significant contribution to Colombia, one of the world’s leading producers and exporters. This strategy offers a low environmental impact alternative that can improve the productivity of commercial species, reduce the incidence and severity of Fusarium-related diseases, and promote adaptability in various growing conditions.