Fungal Communities Within Pitaya Fruit Peel Shift During Ripening and Early Canker Onset

Area of Science:

• Plant Pathology
• Microbial Ecology
• Tropical Fruit Production

Background:

• Canker disease causes significant yield losses in pitaya (dragon fruit).
• The interplay between fruit ripening and fungal community dynamics in pitaya peels is not well understood.
• Previous research often focuses on single pathogens, neglecting community-level interactions.

Purpose of the Study:

• To investigate fungal community diversity, assembly, co-occurrence networks, and functional guilds in healthy and canker-diseased pitaya fruit peels.
• To determine the influence of fruit maturity (immature vs. mature) and disease status on these fungal communities.
• To elucidate the ecological processes shaping fungal communities during pitaya fruit development and pathogenesis.

Main Methods:

• ITS1 amplicon sequencing was used to analyze fungal communities in pitaya fruit peels.
• Fungal diversity, community structure, and assembly mechanisms (stochastic vs. deterministic) were assessed.
• Co-occurrence network analysis was employed to visualize interactions within fungal communities.
• Functional guilds (pathotrophs, saprotrophs, symbiotrophs) were characterized.

Main Results:

• Fruit maturity had a stronger impact on fungal community structure than disease status, with ripening decreasing diversity and increasing dominance.
• Immature diseased peels showed a shift from stochastic to deterministic assembly, while mature diseased peels maintained stochastic processes.
• Healthy mature peels had complex, cooperative fungal networks, whereas healthy immature peels had fragmented networks; disease disrupted these networks.
• Diseased fruits showed an increased abundance of pathotrophs and saprotrophs, indicating a shift towards pathogenicity and decomposition.

Conclusions:

• Pitaya canker is an ecological process involving community-wide fungal restructuring, not just a single pathogen.
• Fruit ripening influences fungal community assembly and network complexity, affecting disease resistance.
• Preserving stochastic assembly and cooperative fungal networks is crucial for enhancing pitaya's resistance to canker disease.
• Findings support stage-specific, microbiome-targeted disease management strategies for tropical fruits.