Leaf Senescence in Arabidopsis thaliana and Brassica napus: From Molecular Regulation to Nutrient Remobilization Processes

Leaf senescence is the final stage of leaf development and guarantees successful survival of a plant and its progeny. It follows a coordinated, genetically encoded program, which involves the differential expression of thousands of genes as basis of an ordered execution of events. The aim of senescence is the degradation of macromolecules so that released nutrients can be reallocated to storage organs or developing parts of the plant. Transcription factors (TFs) are generally accepted as crucial elements in senescence regulation and coordination. Ethylene response factors (ERFs) as well as WKRY TFs are superfamilies of TFs that are overrepresented in the senescence transcriptome. Furthermore, the role of hydrogen peroxide (H2O2) as signaling molecule in senescence has often been demonstrated and it induces the expression of many senescence associated genes (SAGs), amongst them WKRY53, which is a central player in senescence regulation. We identified a small sub-network between WRKY18, WRKY25 and WRKY53, in which WRKY25 is a positive and WRKY18 is a negative regulator of WRKY53 expression. All three WRKY factors are influencing senescence and moreover, H2O2 treatment enhanced expression of all three factors. In DPI-ELISAs we showed that binding of WRKY25 to the WRKY53 promoter is redox-sensitive. However, even though WRKY25 is a positive regulator of WRKY53, it is a negative regulator of leaf senescence, pointing to a more complex regulatory network with more and still unknown factors. Furthermore, the mitogen-activated kinase kinase kinase 1 (MEKK1) was found to bind to the promoter of WKRY53 and influence its expression most likely via phosphorylation of WRKY proteins. By reporter gene assays I confirmed that MEKK1 increased the effect of WRKY53 protein on the promotor activity of its own gene and I could show that MEKK1 also enhanced the positive effect of WRKY25 protein on WKRY53 driven gene expression. Moreover, MEKK1 turned the negative effect of WKRY18 on WRKY53 expression into a positive one. Taken together, this indicates that MEKK1 does not specifically interact with WRKY53 but also with other WRKY proteins. It is noteworthy, that it exhibited a positive effect on the expression of all three WRKYs. By characterizing an inducible knockdown line for MEKK1, a clear role of MEKK1 in senescence regulation was observed. ERF4 exists in two different isoforms due to alternative polyadenylation: ERF4-R, which contains an ERF-associated amphiphilic repression (EAR) motif and ERF4-A, which lacks this motif. By a reverse genetics approach, in which I analyzed the phenotype, I could show that ERF4 isoforms are both involved in leaf senescence regulation. By subsequent molecular and biochemical assays, I gained an understanding of the mode of action of ERF4 isoforms and how they possibly affect leaf senescence. Both isoforms bind to the promoter of the CATALASE3 (CAT3) gene and have antagonistic effects on CAT3 gene expression. The ratio of ERF4-A to ERF4-R changed over time. Together with visualization of CAT3 activity on native gels, this hints at a function of the ERF4 isoforms as an activator of CAT3 in earlier and as a repressor of CAT3 expression in later stages. This could foster an increase of H2O2 in later stages, which induces expression of many SAGs and contributes to degradation processes. Lastly, by analysis of transcriptome data, seed storage proteins (SSPs) were found to be expressed in vegetative tissues of Brassica napus L. (cv. Mozart). I confirmed NAPIN and CRUCIFERIN expression in leaves via quantitative real-time PCR and found a correlation between intracellular H2O2 and SSP accumulation. Moreover, their expression depended on the nitrogen (N)-supply. In addition, N-starvation induced senescence differed from developmental senescence, since H2O2 levels were not increased but reduced in these plants. This work reveals new insights in senescence regulation. It contributes to the general endeavor, to gain an understanding of the complex molecular network underlying leaf senescence regulation

Celebrating 25 Years of World Wetlands Day

The purpose of this Special Issue is to celebrate 25 years of “World Wetlands Day”. There is no other ecosystem that has its very own Ramsar Convention or such a challenge impacting ecosystem sustainability. Papers for this Special Issue provide an overview of wetland status and function within different regions of the world. The papers in this Special Issue of Land consist of three review papers, ten research articles and one perspective paper. Edward Maltby’s review paper provides us with an overview of the paradigm shift of how we value and assess wetlands over time. Ballut-Dajud et al. provide us with a worldwide perspective on factors affecting wetland loss. Finally, Jan Vymazal provides us with a historical overview of the development of water quality treatment wetlands in Europe and North America. The research papers can be grouped into four groups: 1) use of remote sensing to analyze stability and dynamic factors affecting wetlands; 2) factors affecting the wetlands’ ability to store carbon; 3) assessment of wetlands effect on water quality; and 4) understanding historical use and value of wetlands, farmer’s attitudes about wetland management, and how we can value wetland ecosystem services. Finally, Bryzek et al. remind us that, as wetland researchers and managers, we should minimize damage to wetlands even through field monitoring work

Book of abstracts, 4th World Congress on Agroforestry

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Agroforestry-Based Ecosystem Services

As a dynamic interface between agriculture and forestry, agroforestry has only recently been formally recognized as a relevant part of land use with ‘trees outside forest’ in important parts of the world—but not everywhere yet. The Sustainable Development Goals have called attention to the need for the multifunctionality of landscapes that simultaneously contribute to multiple goals. In the UN decade of landscape restoration, as well as in response to the climate change urgency and biodiversity extinction crisis, an increase in global tree cover is widely seen as desirable, but its management by farmers or forest managers remains contested. Agroforestry research relates tree–soil–crop–livestock interactions at the plot level with landscape-level analysis of social-ecological systems and efforts to transcend the historical dichotomy between forest and agriculture as separate policy domains. An ‘ecosystem services’ perspective quantifies land productivity, flows of water, net greenhouse gas emissions, and biodiversity conservation, and combines an ‘actor’ perspective (farmer, landscape manager) with that of ‘downstream’ stakeholders (in the same watershed, ecologically conscious consumers elsewhere, global citizens) and higher-level regulators designing land-use policies and spatial zoning

Dipterocarps protected by Jering local wisdom in Jering Menduyung Nature Recreational Park, Bangka Island, Indonesia

Apart of the oil palm plantation expansion, the Jering Menduyung Nature Recreational Park has relatively diverse plants. The 3,538 ha park is located at the north west of Bangka Island, Indonesia. The minimum species-area curve was 0.82 ha which is just below Dalil conservation forest that is 1.2 ha, but it is much higher than measurements of several secondary forests in the Island that are 0.2 ha. The plot is inhabited by more than 50 plant species. Of 22 tree species, there are 40 individual poles with the average diameter of 15.3 cm, and 64 individual trees with the average diameter of 48.9 cm. The density of Dipterocarpus grandiflorus (Blanco) Blanco or kruing, is 20.7 individual/ha with the diameter ranges of 12.1 – 212.7 cm or with the average diameter of 69.0 cm. The relatively intact park is supported by the local wisdom of Jering tribe, one of indigenous tribes in the island. People has regulated in cutting trees especially in the cape. The conservation agency designates the park as one of the kruing propagules sources in the province. The growing oil palm plantation and the less adoption of local wisdom among the youth is a challenge to forest conservation in the province where tin mining activities have been the economic driver for decades. More socialization from the conservation agency and the involvement of university students in raising environmental awareness is important to be done

Advances in Food, Bioproducts and Natural Byproducts for a Sustainable Future: From Conventional to Innovative Processes

The world population is expected to reach almost 10,000 million in 2050, so, it is necessary to use our resources efficiently: to produce more food using less land and pollute less, to optimize the production and use of biomass from diversified resources. For this, new approaches and processes, with special emphasis from a biotechnological perspective, may need to be implemented to move towards a circular model that will confer environmental sustainability. In this book, the analysis and optimization of some examples of food and bioproduct processes, as well as development of innovative and emerging food and byproducts processing methods, are considered. Valorization, bioprocessing, and biorefining of food-industry-based streams, the role of industrial microorganisms, the isolation of high added-value compounds, applications of the resulting bio-based chemicals in food manufacturing, novel food formulations, among others, are addressed

Advances in Food, Bioproducts and Natural Byproducts for a Sustainable Future: From Conventional to Innovative Processes

The world population is expected to reach almost 10,000 million in 2050, which entails the need to focus on sustainability and its three pillars: the economy, the environment, and society. Within this context, it is necessary to use our resources efficiently; for instance, we will need to produce much more food using less land and while polluting less to optimize the production of biomass from diversified resources, along with its subsequent conversion, fractionation, and processing. To achieve this, new approaches and processes, with special emphasis from a biotechnological perspective, may need to be implemented to move towards a circular model that will confer environmental sustainability. Global projections of food losses constitute an abundant pool of complex carbohydrates, proteins, lipids, and functional compounds. Hence, the deployment of food waste streams as raw materials will encompass the formulation of added-value products that will be ideally reintroduced in the food supply chain to close the loop. Therefore, the analysis and optimization of any food and bioproduct process, as well as the development of innovative and emerging food and by-product processing methods, are important as a necessity for the sustainable transition to a bioeconomy era. The valorization, bioprocessing, and biorefining of food-industry-based streams, the role of industrial microorganisms, the isolation of high-added-value compounds, applications of the resulting bio-based chemicals in food manufacturing, novel food formulations, economic policies for food waste management, along with sustainability or techno-economic assessment of processing methods constitute subject areas that need to be addressed. More specifically, bioprocess design to valorize food-industry waste and by-product streams should be initiated by characterizing the composition of the onset raw material with the aim of identifying the target end-products, whereas the generation of multiple high-added-value products is a prerequisite for cost-effective processes to establish economic sustainability. On top of that, the feasibility of innovative processes could be sustained by encompassing food applications, driven by the constantly emerging consumers’ demand for functional foods and beverages with enhanced nutritional value. Equally, a growing awareness for bio-based and natural food components is being developed, thereby imposing challenges on the substitution of chemically derived ingredients with their natural counterparts

Healing Through Caring and Knowledge-Making in Everyday Food Practices Among LGBTQ+ Black, Indigenous, People of Colour

Three different models are used in this study to understand how everyday food practices carry healing potential through the interwoven process of caring and knowledge-making. Daily food practices reflect a mixture of tradition and modernity— borne out of our roots and our contexts. Anzaldúa’s (1987) Borderland Theory helps us understand how this mixture is made by people who straddle two borders or worlds and contest those confines. Chavez-Dueñas et al.’s (2019) HEART model names strengthening our cultural and familial traditions and roots as part of the broader processes of building cultural consciousness and connection, and engaging in collective healing. Finally, Galliher et al.’s (2017) Integrated Identity Development maps our identities and deep interconnectedness with one another, observed in daily food behaviours like cooking, eating, and sharing. This study uses food photos and interviews of 14 Black, Indigenous, People of Color (BIPOC) individuals, who are Lesbian, Gay, Bisexual, Transgender, Queer (LGBTQ+) from United States and Canada, to explore how they heal, learn, and make meaning of their food practices. Participants photographed food moments across two weeks, brought these photos during a semi-structured interview at four weeks, and responded to a follow-up after eight months. Participants’ daily food moments reflected their personal, social, and cultural contexts. Individually, participants shared definitions of healing, and intentionality and gratitude as important wellness attitudes. They experienced caring and connection through social aspects of sharing and receiving food, particularly individualizing food to express care and connecting to a sense of togetherness. Participants connected to food on a cultural level by engaging with values such as resourcefulness and marking special occasions. Participants experienced food’s historical memory by connecting with ancestry, land, and the sacred, acknowledging oppression, and creating memories. Lastly, food is a landscape of contradictory notions of authenticity and hybridity, and an arena to develop new family traditions, given caregivers’ roles as knowledge keepers. Seven participants endorsed increased mindfulness around food practices and seven participants reported increased awareness and connection to their background, loved ones, and communities at the eight-month follow-up. Deepening our knowledges about our home and remaining flexible with tradition helps us keep intergenerational teachings