Decoding plant stress responses: molecular and physiological insights under combined stress

Plant diseases arise when four fundamental conditions occur simultaneously, described by the so-called “disease pyramid”: the presence of a pathogen, favorable climatic conditions, a susceptible host, and a sufficient period of time for these factors to interact and enable disease development. Climate change has significantly altered environmental conditions, one of the key elements of this pyramid, leading to effects such as rising temperatures and changes in precipitation patterns.

Fruit crops are directly affected by these environmental shifts and, at the same time, may experience stress caused by pathogens. To cope with these conditions, plants activate various defense mechanisms, including pathogen-associated molecular pattern-triggered immunity and effector-triggered immunity. These systems induce both local and systemic responses, helping to limit pathogen spread and colonization.

Stress conditions

In a collaborative study conducted between Chile, Argentina, and Italy, the response of two sweet cherry cultivars, “Santina” and “Bing,” was analyzed under stress conditions, with particular attention to the combination of biotic and abiotic factors. The objective was to identify differences in the physiological and molecular mechanisms that enable plants to adapt to unfavorable conditions, specifically infection by Pseudomonas syringae and water stress.

To assess plant health status, several parameters were measured, including water potentials, photosynthetic activity, and the production of compounds associated with stress responses. A key aspect of the study focused on the analysis of molecular mechanisms involved in stress responses. In particular, the expression of genes associated with defense systems was examined, including those responsible for antioxidant production and the regulation of cellular processes.

Cultivar differences

The activation of these mechanisms represents a fundamental strategy to limit damage and maintain internal balance within the plant. The results revealed significant differences between the two cultivars.

The cultivar Bing exhibited a particularly strong response, with the identification of 4,261 differentially expressed genes, showing a marked suppression of photosynthetic processes alongside the activation of defense- and hormone-related pathways. In contrast, the cultivar Santina displayed a more moderate response, with 674 differentially expressed genes, primarily associated with strengthening cellular structures and secondary metabolism.

Combined stress

Differences in sensitivity to abscisic acid between the two cultivars were linked to distinct regulation of specific transcription factors, despite similar hormone levels. Furthermore, both cultivars showed increased expression of the GIGANTEA gene, suggesting its central role as a regulatory hub coordinating circadian rhythm, stomatal function, and hormonal signaling interactions under combined stress conditions.

In conclusion, the study demonstrates that plant responses depend on a combination of genetic and environmental factors. The differences observed between cultivars highlight the crucial role of varietal selection in developing more resilient crops. Understanding the physiological and molecular mechanisms underlying stress tolerance can support the development of more sustainable agricultural strategies and help crops adapt to continuously changing environmental conditions.

Source: Carreras, C.; Zamorano, A.; Gamboa, C.; Villalobos-González, L.; Pimentel, P.; Pizarro, L.; Cui, W.; Pinto, M.; Rubilar-Hernández, C.; Llanes, A.; et al. Contrasting Response of Santina and Bing Sweet Cherry Cultivars Under Combined Biotic and Abiotic Stress. Plants 2026, 15, 450. https://doi.org/10.3390/plants15030450 

Image source: Stefano Lugli

Melissa Venturi
Ph.D. in Agricultural, Environmental, and Food Sciences and Technologies – Fruit Tree Physiology and Cultivation - Bologna, Italy

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