Passion fruit, a tropical crop of growing economic importance, suffers devastating yield losses when unexpected cold snaps hit. Now, researchers have uncovered the molecular strategies that allow some varieties to withstand low temperatures while others wither. By integrating transcriptomic and metabolomic analyses of cold-tolerant and cold-sensitive cultivars, the team identified three key metabolic pathways—sphingolipid, phenylpropanoid, and terpene metabolism—that are dramatically reprogrammed under cold stress. The findings reveal that cold tolerance in passion fruit does not rely on the well-known ICE-CBF-COR pathway found in Arabidopsis and other plants, but instead employs a distinct set of protective mechanisms.
Low-temperature stress is a growing threat to global agriculture, and tropical crops like passion fruit are especially vulnerable. Originating in warm climates, passion fruit lacks innate freezing tolerance—damage can begin below 8°C, and temperatures near 0°C are often lethal. Even in traditional growing regions, sporadic cold events can slash production. While the molecular basis of cold acclimation is well characterized in model plants like Arabidopsis thaliana, centered on the conserved ICE-CBF-COR transcription regulatory module, these pathways appear poorly developed in tropical species. Previous studies in passion fruit have been largely phenomenological, documenting physiological markers without uncovering causal mechanisms. Given these challenges, a systems-level understanding of the regulatory and metabolic networks that confer cold adaptation in passion fruit is urgently needed.
A research team from Guangxi University and the State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, in collaboration with the Guangxi Academy of Agricultural Sciences, published (DOI: 10.1093/hr/uhag164) their findings in Horticulture Research in 2026. The open-access study, licensed under Creative Commons Attribution 4.0, provides the first comprehensive multi-omics dissection of cold tolerance mechanisms in this high-value horticultural crop.
The team compared two cold-tolerant varieties (H1 and G15) with two cold-sensitive ones (QM9 and TN1) across stem, leaf, pericarp, and pulp tissues. Using liquid chromatography-mass spectrometry (LC-MS), gas chromatography-mass spectrometry (GC-MS), and RNA sequencing (RNA-Seq), they identified 1,236 metabolites and thousands of differentially expressed genes. Surprisingly, the canonical ICE-CBF-COR cold-signaling pathway showed no significant differential expression in tolerant varieties—suggesting passion fruit evolved alternative cold-defense strategies. Instead, three pathways emerged as central: sphingolipid metabolism, where genes like PesSPT and PesKDSR drive accumulation of sphinganine to stabilize cell membranes; phenylpropanoid metabolism, producing chlorogenic acid via PesHCT; and flavonoid biosynthesis, generating rutin through PesFG2. Exogenous application of sphinganine, chlorogenic acid, rutin, and three terpenoids significantly boosted cold tolerance in sensitive cultivars. Conversely, virus-induced gene silencing (VIGS) of core biosynthetic genes compromised cold resistance, leading to increased oxidative damage and severe wilting. Overexpression of these genes in cold-sensitive plants reversed the effect, confirming their protective roles. The study also revealed that the protective effects of chlorogenic acid and rutin were not simply due to reactive oxygen species (ROS) scavenging, suggesting alternative mechanisms such as osmotic adjustment or metabolic feedback regulation are at play.
"We were quite surprised to find that the classical ICE-CBF-COR pathway—the gold-standard cold response in model plants—barely registers in passion fruit," the authors said. "Instead, cold-tolerant varieties rely on a sophisticated metabolic rewiring across sphingolipid, phenylpropanoid and terpene networks. These pathways don't just passively respond to cold—they actively build a protective shield, from stabilizing membranes to deploying antioxidant metabolites. What excites us most is that we've moved beyond correlation to causation: we can now spray these compounds onto sensitive plants and watch them survive the cold."
The findings open multiple avenues for improving cold tolerance in passion fruit and other tropical crops. Exogenous spraying of key metabolites—sphinganine, chlorogenic acid, rutin, or specific terpenoids—offers a practical, immediate strategy for protecting crops when cold snaps are forecast. For long-term solutions, the identified genes (PesSPT, PesKDSR, PesHCT, PesFG2) provide precise targets for molecular breeding or genetic engineering. The study also challenges the assumption that cold tolerance mechanisms are universally conserved across plant species, urging researchers to look beyond model-organism paradigms when studying tropical crops. As climate variability intensifies, these insights could help secure sustainable cultivation of passion fruit and guide similar efforts in other cold-sensitive, high-value horticultural species.
