Abstract

Photodynamic treatment (PDT) is emerging as a promising and innovative technology for sustainable agriculture, particularly in the development of environmentally friendly alternatives to conventional chemical pesticides. The increasing demand for reduced agrochemical inputs and the mitigation of herbicide resistance in weeds have intensified interest in sustainable weed management strategies. PDT operates by activating a light-sensitive molecule, known as a photosensitizer (PS), using specific wavelengths of light or sunlight. Upon activation, the PS generates reactive oxygen species (ROS), including singlet oxygen and free radicals, which induce oxidative damage in nearby biological structures. This localized oxidative stress can selectively target specific cells, tissues, or organisms while minimizing broader environmental impact.
In the present study, the effects of PDT mediated by a tetrapyrrole-based photosensitizer were systematically investigated in two economically important cereal crops, wheat (Triticum aestivum) and barley (Hordeum vulgare) as well as in two widespread and problematic dicot weed species, black nightshade (Solanum nigrum) and chickweed (Stellaria media).
All plant species were cultivated under controlled in vitro conditions. Following exposure to the photosensitizer and a 16-hour photoperiod, both weed species exhibited pronounced sensitivity to PDT, characterized by systemic tissue damage, growth inhibition, and eventual plant death. In contrast, wheat and barley displayed only minor and highly localized effects, primarily restricted to the points of direct photosensitizer contact.
Differential plant responses were further characterized through comprehensive phenotypic, histochemical and biochemical analyses. Measurements of lipid peroxidation and antioxidant response assays indicated species specific defense capacities against ROS induced stress. Additionally, confocal microscopy demonstrated a faster and more extensive uptake of the photosensitizer in the roots of the dicot weeds chickweed and black nightshade, providing mechanistic insight into their heightened susceptibility.
Collectively, these results demonstrate that PDT represents a viable, selective, and sustainable approach for weed management with minimal adverse effects on economically important crop species, offering promising perspectives for the ongoing greenhouse and field trials, and eventually industrial-scale implementation.

Biography

Mohammad Muhie Ddine is a Ph.D. student at LABCiS collaborating with AgroDynaLux on photodynamic treatment (PDT) for agricultural applications. His research focuses on sustainable agriculture and weed science, where I develop and evaluate tetrapyrrole-based molecules as eco-friendly, cost-effective alternatives to conventional pesticides. He use photodynamic assays, crop models, biochemistry, molecular biology, and imaging techniques to study PDT plant interactions. Mohammad Muhie Ddine hold a Master’s degree in Applied Plant Biotechnology from the Lebanese University and a Master’s degree in Biosciences from École Normale Supérieure de Lyon (ENS de Lyon).

Abstract

The present study aims to unlock the cross-protection mechanism of the diazotrophic cyanobacterium Anabaena sp. PCC 7120. Heat pre-treatment elicited a beneficial response against subsequent cadmium stress as revealed by integrated morphological, physiological, biochemical, transcript, and proteomics analyses under four sets of experimental conditions: control (C), heat (HS), cadmium (Cd), and heat + cadmium (HS + Cd). Outcomes of the present study suggested a better survival strategy shown by Anabaena sp. PCC 7120 under HS + Cd compared to Cd. According to comparative proteomics, protochlorophyllide reductase, CO 2 hydration protein, and NAD(P)H quinone oxidoreductase work in concert to support the light and dark reactions of photosynthesis. Furthermore, in cross protection involvement of enzymes from pentose phosphate pathway and glycolysis for fulfilling cellular energy demand; antioxidants and antioxidant enzymes in scavenging ROS, cellular detoxification, and Cd che lation, chaperons and proteases in proper protein folding and synthesis; signaling and transporters to generate cross talk and Cd efflux were found. Increased accumulation of vegetative to heterocyst connection protein (FraH) in HS + Cd compared to Cd may be envisioned to manage better nitrogen fixation.

Biography

Dr. Antra Chatterjee has pursued her PhD from Banaras Hindu University and is currently working as assistant professor in Department of Botany, University of Allahabad. She has won several national and international fellowships. She has visited Spain with prestigious European Molecular Biology Organization fellowship to learn protein crystallography. She has qualified DST- Women Scientist -C fellowship and gained training in Intellectual Property Rights from IIT Kharagpur. She has worked as IP analyst in service providing industry. She has won several prizes in poster and oral presentations in national and international seminars. She has gained research experience from Institute of Environmental Studies and Wetland Management, and Indian institute of Vegetable Research. She is a life member of Indian Science Congress, Indian Society of Vegetable Science, Organization for Women in Science for the Developing World (International society), The Biotech Research Society, and The Association of Microbiologists of India. She has bagged several research and review articles in reputed peer reviewed journals, chapters and book of international publication houses. She has teaching experience in degree college and Universities. In extracurricular activities she is NCC and Yoga diploma certificate holder and won prizes in classical dance, sports, etc.

Abstract

Saltmarshes are critical ecosystems that play key roles in biodiversity conservation and carbon sequestration, providing multiple ecological and economic values essential for sustainable development. Yet, saltmarshes are threatened by human activities and sea-level rise (SLR). Long-term restoration and management strategies are necessary but often hindered by an insufficient understanding of the past, present, and future processes that influence tidal wetland functionality and change. Since understanding vegetation distribution in relation to elevation and tidal hydroperiod generally forms the basis of tidal wetland restoration strategies, this research investigated the relationships between micro-topography, tidal hydroperiod, and the distribution of saltmarshes, mangroves, and unvegetated flats in a tropical estuary situated within a Great Barrier Reef Catchment in North Queensland, Australia. We used a combination of high-resolution unattended-aerial-vehicle (UAV)- derived digital elevation model (DEM) and land cover coupled with 2D hydrodynamic modelling to investigate these aspects. We found overlapping distribution across elevation, highlighting that zonation was more complex than strict zonation patterns generally recognised in restoration and legislation. In addition, although each type of tidal wetland cover had distinct mean hydroperiods, and elevation and hydroperiods were strongly correlated, elevation explained only 15% of the variability in tidal wetland cover distribution. This finding implies that additional factors likely play a role in shaping tidal wetland cover zonation patterns in tropical tidal wetlands. These results hold significance as they underscore the need to exercise caution when applying oversimplistic explanations for the causality of tidal wetlands. The suitability of applying simplistic rules in management and restoration is likely to be context-dependent, as demonstrated in our study site. Contextual variabiltiy in environmental and biological factors may lead to different distribution patterns of tidal wetland components, and hence varying restoration and management success. This research also explored the potential effects of sea-level rise (SLR) on the tidal hydroperiods and connectivity of the study site. Our results showed that the inundation experienced by each tidal wetland cover may increase importantly if vegetation does not keep up with SLR. This underlines the importance of acquiring detailed spatio-temporally resolved data to enable the development of robust long-term and adaptive saltmarsh management strategies. This research highlights the uncertainties and complexities in understanding the processes influencing tropical tidal wetland functionality. Recognising these complexities is paramount for effectively managing and restoring tidal wetland ecosystems and, hence, maintaining their critical ecological and economic values.

Biography

I am a PhD candidate at James Cook University, Australia, and I have recently submitted my PhD on the eco-hydrological aspects of saltmarshes connectivity in tropical seascapes under the supervision of Assoc. Prof Nathan Waltham, Dr Jack Koci, and Dist. Prof Marcus Sheaves. Before doing a PhD, I completed my Bachelor of Marine Biology at James Cook University and in Hawaii at the University of Hilo. I then conducted my honours at James Cook University on the ecological connectivity of dry tropical freshwater streams under the supervision of Assoc. Prof Nathan Waltham and Dist. Prof Marcus Sheaves. During my studies, I have volunteered in Asia and Oceania while giving guest lectures and tutoring Bachelor and Master students. I am also supervising masters and honours theses. Overall, I have broad interests in tidal and freshwater aquatic ecosystem functioning, ecology and hydrology, as well as terrestrial and coastal ecosystem management, conservation, and restoration. I believe that multi-disciplinary collaboration and establishing strong links with communities and stakeholders are critical for successful long-term ecosystem management and restoration.