Epigenetic responses to Phytophthora citrophthora gummosis in citrus

Epigenetic Mechanisms Driving Adaptation in Tropical and Subtropical Plants: Insights and Future Directions

Epigenetic mechanisms, including DNA methylation, histone modifications, and Noncoding RNAs, play a critical role in enabling plants to adapt to environmental changes without altering their DNA sequence. These processes dynamically regulate gene expression in response to diverse stressors, making them essential for plant resilience under changing global conditions. This review synthesises research on tropical and subtropical plants-species naturally exposed to extreme temperatures, salinity, drought, and other stressors-while drawing parallels with similar mechanisms observed in arid and temperate ecosystems. By integrating molecular biology with plant ecology, this synthesis highlights how tropical plants provide valuable models for understanding resilience strategies applicable across broader plant taxa. This review underscores the potential of epigenetic mechanisms to inform conservation strategies and agricultural innovations aimed at bolstering plant resilience in the face of climate change.

Breeding Alnus species for resistance to Phytophthora disease in the Iberian Peninsula

Alders are widely distributed riparian trees in Europe, North Africa and Western Asia. Recently, a strong reduction of alder stands has been detected in Europe due to infection by Phytophthora species (Stramenopila kingdom). This infection causes a disease known as alder dieback, characterized by leaf yellowing, dieback of branches, increased fruit production, and bark necrosis in the collar and basal part of the stem. In the Iberian Peninsula, the drastic alder decline has been confirmed in the Spanish Ulla and Ebro basins, the Portuguese Mondego and Sado basins and the Northern and Western transboundary hydrographic basins of Miño and Sil, Limia, Douro and Tagus. The damaging effects of alder decline require management solutions that promote forest resilience while keeping genetic diversity. Breeding programs involve phenotypic selection of asymptomatic individuals in populations where severe damage is observed, confirmation of tree resistance via inoculation trials under controlled conditions, vegetative propagation of selected trees, further planting and assessment in areas with high disease pressure and different environmental conditions and conservation of germplasm of tolerant genotypes for reforestation. In this way, forest biotechnology provides essential tools for the conservation and sustainable management of forest genetic resources, including material characterization for tolerance, propagation for conservation purposes, and genetic resource traceability, as well as identification and characterization of Phytophthora species. The advancement of biotechnological techniques enables improved monitoring and management of natural resources by studying genetic variability and function through molecular biology methods. In addition, in vitro culture techniques make possible large-scale plant propagation and long-term conservation within breeding programs to preserve selected outstanding genotypes.

State of the Art of the Molecular Biology of the Interaction between Cocoa and Witches’ Broom Disease: A Systematic Review

Significant scientific advances to elucidate the Moniliophthora perniciosa pathosystem have been achieved in recent years, but the molecular biology of this pathogen-host interaction is still a field with many unanswered questions. In order to present insights at the molecular level, we present the first systematic review on the theme. All told, 1118 studies were extracted from public databases. Of these, 109 were eligible for the review, based on the inclusion and exclusion criteria. The results indicated that understanding the transition from the biotrophic-necrotrophic phase of the fungus is crucial for control of the disease. Proteins with strong biotechnological potential or that can be targets for pathosystem intervention were identified, but studies regarding possible applications are still limited. The studies identified revealed important genes in the M. perniciosa-host interaction and efficient molecular markers in the search for genetic variability and sources of resistance, with Theobroma cacao being the most common host. An arsenal of effectors already identified and not explored in the pathosystem were highlighted. This systematic review contributes to the understanding of the pathosystem at the molecular level, offering new insights and proposing different paths for the development of new strategies to control witches’ broom disease.

Drought tolerance memory transmission by citrus buds

Plants face recurrent drought events, and previous stresses can influence their responses to subsequent stress episodes. Studies on drought stress memory are recent in citriculture, although they show promise as a tool for crop improvement. Here, we investigated whether stress memory mechanisms can be detected in citrus plants grafted with buds from plants subjected to recurrent water deficit. Three rootstock varieties, namely 'Rangpur Santa Cruz' lime, 'Sunki Maravilha' mandarin and 'Sunki Tropical' mandarin, in combination with 'Valencia' orange, were either maintained under full irrigation or subjected to one, two, or three water deficit cycles. Buds from 'Valencia' orange were grafted onto 'Swingle' citrumelo rootstocks and were evaluated. This combination displayed improved physiological and biochemical performance under water limitation, especially 'Valencia' buds grafted onto 'Sunki Maravilha', with better photosynthetic performance under water deficit. These findings indicate that genotype-dependent epigenetic memory is a key factor in restoring citrus plants' capacity to rely on previous stress experiences to restore better photosynthetic and physiological responses when undergoing new water deficit events. Therefore, epigenetic marks can be stored and transmitted to new citrus plants and are a promising alternative to enable increased water deficit tolerance when plants are then challenged by drought-prone environments.

Plant Responses to Biotic Stress: Old Memories Matter

Plants are fascinating organisms present in most ecosystems and a model system for studying different facets of ecological interactions on Earth. In the environment, plants constantly encounter a multitude of abiotic and biotic stresses. The zero-avoidance phenomena make them more resilient to such environmental odds. Plants combat biotic stress or pathogenic ingression through a complex orchestration of intracellular signalling cascades. The plant-microbe interaction primarily relies on acquired immune response due to the absence of any specialised immunogenic cells for adaptive immune response. The generation of immune memory is mainly carried out by T cells as part of the humoral immune response in animals. Recently, prodigious advancements in our understanding of epigenetic regulations in plants invoke the "plant memory" theory afresh. Current innovations in cutting-edge genomic tools have revealed stress-associated genomic alterations and strengthened the idea of transgenerational memory in plants. In plants, stress signalling events are transferred as genomic imprints in successive generations, even without any stress. Such immunogenic priming of plants against biotic stresses is crucial for their eco-evolutionary success. However, there is limited literature capturing the current knowledge of the transgenerational memory of plants boosting biotic stress responses. In this context, the present review focuses on the general concept of memory in plants, recent advancements in this field and comprehensive implications in biotic stress tolerance with future perspectives.