Environmental Stress and Plants 2.0

Following the success of our previous edition [1], this Special Issue ‘Environmental Stress and Plants 2.0’ includes 23 original articles and 3 reviews. The high level of participation and the large number of reports show that plant researchers are interested in this topic. We provide a brief overview of the papers, which include original articles (categorized by stress type) as well as reviews

Drought Stress Affects the Response of Italian Local Tomato (Solanum lycopersicum L.) Varieties in a Genotype-Dependent Manner

Drought stress is one of the most severe conditions for plants, especially in the face of the emerging problem of global warming. This issue is important when considering economically relevant crops, including the tomato. For these plants, a promising solution is the valorization of local agrobiodiversity as a source of genetic variability. In this paper we investigated how six Italian tomato varieties react to a prolonged period of water depletion. We used a multidisciplinary approach, from genetics to plant physiology and cytology, to provide a detailed overview of the response of plants to stress. The varieties analyzed, each characterized by a specific genetic profile, showed a genotype-specific response with the variety 'Fragola' being the most resistant and the variety 'Pisanello' the most susceptible. For all the parameters evaluated, 'Fragola' performed in a manner comparable to that of control plants. On the contrary, 'Pisanello' appeared to be more affected and showed an increase in the number of stomata and a drastic increase in antioxidants, a symptom of acute oxidative stress. Our work suggests the existence of a valuable reservoir of genetic biodiversity with more drought-tolerant tomato genotypes opening the way to further exploitation and use of local germplasm in breeding programs

Biochemical and cytological interactions between callose synthase and microtubules in the tobacco pollen tube

Key message: The article concerns the association between callose synthase and cytoskeleton by biochemical and ultrastructural analyses in the pollen tube. Results confirmed this association and immunogold labeling showed a colocalization. Abstract: Callose is a cell wall polysaccharide involved in fundamental biological processes, from plant development to the response to abiotic and biotic stress. To gain insight into the deposition pattern of callose, it is important to know how the enzyme callose synthase is regulated through the interaction with the vesicle-cytoskeletal system. Actin filaments likely determine the long-range distribution of callose synthase through transport vesicles but the spatial/biochemical relationships between callose synthase and microtubules are poorly understood, although experimental evidence supports the association between callose synthase and tubulin. In this manuscript, we further investigated the association between callose synthase and microtubules through biochemical and ultrastructural analyses in the pollen tube model system, where callose is an essential component of the cell wall. Results by native 2-D electrophoresis, isolation of callose synthase complex and far-western blot confirmed that callose synthase is associated with tubulin and can therefore interface with cortical microtubules. In contrast, actin and sucrose synthase were not permanently associated with callose synthase. Immunogold labeling showed colocalization between the enzyme and microtubules, occasionally mediated by vesicles. Overall, the data indicate that pollen tube callose synthase exerts its activity in cooperation with the microtubular cytoskeleton

Expression of clementine asp-rich proteins (CcASP-RICH) in tobacco plants interferes with the mechanism of pollen tube growth

Low-molecular-weight, aspartic-acid-rich proteins (ASP-RICH) have been assumed to be involved in the self-incompatibility process of clementine. The role of ASP-RICH is not known, but hypothetically they could sequester calcium ions (Ca2+) and affect Ca2+-dependent mechanisms. In this article, we analyzed the effects induced by clementine ASP-RICH proteins (CcASP-RICH) when expressed in the tobacco heterologous system, focusing on the male gametophyte. The aim was to gain insight into the mechanism of action of ASP-RICH in a well-known cellular system, i.e., the pollen tube. Pollen tubes of tobacco transgenic lines expressing CcASP-RICH were analyzed for Ca2+ distribution, ROS, proton gradient, as well as cytoskeleton and cell wall. CcASP-RICH modulated Ca2+ content and consequently affected cytoskeleton organization and the deposition of cell wall components. In turn, this affected the growth pattern of pollen tubes. Although the expression of CcASP-RICH did not exert a remarkable effect on the growth rate of pollen tubes, effects at the level of growth pattern suggest that the expression of ASP-RICH may exert a regulatory action on the mechanism of plant cell growth

Herpesvirus-Associated Acute Urticaria: An Age Matched Case-Control Study

Background Acute and recurrent acute urticaria are often associated with multiple factors including infections and recent data suggest a role for herpesviruses. Objective To test the null hypothesis, that is, there is no association of herpesvirus infections with urticaria. Methods Thirty-seven patients between one month and 15 years of age were age matched to 37 controls who were healthy or had mild acute respiratory infections but without urticaria. Patients and controls were followed for 1 to 6 years. Diagnostic studies included DNA detection by real-time PCR for herpes simplex virus (HSV) types 1 and 2, Epstein-Barr virus (EBV), cytomegalovirus (CMV) and human herpesvirus-6 (HHV-6). Tests for other infections included adenovirus, parvovirus B 19, respiratory syncytial virus, influenza A, Group A streptococci, rotavirus, and parasites. Results Specific infections were diagnosed in 26 of 37 cases and among 9 of 37 control children (P=0.0002). Single or concomitant herpesvirus infections occurred in 24 cases and in 4 controls (65% vs 11 %, p=0.0003). Cases had 10 HHV-6 infections, 8 CMV infections, 5 EBV infections, and 4 HSV-1 infections. Conclusion Herpesvirus infections are associated with acute or recurrent acute urticaria

An Analysis of the factors that would influence investment in infrastructure assets by managers of pension funds in Kenya

Submitted in partial fulfilment of the requirements for the degree of Master in Public Policy and Management at Strathmore University.Infrastructure investments have traditionally been financed by governments but competing needs for limited resources has seen an increase in private sector funding of infrastructure projects. Given the large capital requirements needed for infrastructure investments, pooled savings such as those held by pension funds, insurance companies and endowments funds have been identified as potential sources of funding. The unique characteristics of infrastructure assets such as the long term horizon, stable, predictable and inflation linked cash flows match the liability profile of pension funds making them an ideal potential source of funding for infrastructure. In developed and emerging countries, pension funds have invested in infrastructure assets notwithstanding various barriers that exist. This study sought to analyze the factors that would influence investment in infrastructure assets by pension funds in Kenya. The review of theoretical and empirical literature identified nine factors that could influence investments in infrastructure assets. Questionnaires were issued to managers of pension funds in Kenya and 48 responses out of a targeted 66 respondents were received attaining a 73% response rate. The extent of influence of these factors on investment in infrastructure assets by managers of pension funds in Kenya was measured using an ordinal Likert scale and this was corroborated by a question that asked them to rank the relative importance of each of the factors. Factor analysis was then carried out to reduce the factors. The findings showed that the main factors that would influence the investments in infrastructure assets in Kenya were: the structure and investment characteristics of infrastructure assets, the expected return, governance of pension schemes and risk and regulation. Policy makers in Kenya should engage with the pension industry and address the potential impact these factors would have on attracting private capital as they structure infrastructure assets. Further research can be conducted on the feasibility of Public Private Partnerships in Kenya that require user fees on public utilities to be charged in the long term to meet the asset-liability match required by pension funds

Arabinogalactan proteins: actors or spectators during abiotic and biotic stress in plants?

Arabinogalactan proteins (AGPs) are a family of hydroxyproline-rich glycoproteins (HRGP) ubiquitous in the plant kingdom. They are probably one of the most heterogeneous and complex families of macromolecules, making them able to perform different and multiple functions. Located at the plasma membrane–cell wall interface, AGPs are involved in several processes, from plant growth and development to reproduction. An additional function of AGPs in response to biotic and abiotic stress has been suggested by several studies. The purpose of this review is to summarize critically and analytically the available knowledge on the effects of abiotic stress (low and high temperatures, drought, flooding, anoxia and metal deficiency/toxicity) and biotic stress (bacteria, fungi, nematodes and viruses) on AGPs. A deeper understanding of the role of AGPs during these conditions can be an important tool for understanding AGP biology and for the possible development of efficient breeding strategies

Immunohistochemical analyses on two distinct internodes of stinging nettle show different distribution of polysaccharides and proteins in the cell walls of bast fibers

Stinging nettle is a perennial herbaceous species holding value as a multi-purpose plant. Indeed, its leaves and roots are phytofactories providing functional ingredients of medicinal interest and its stems produce silky and resistant extraxylary fibers (a.k.a. bast fibers) valued in the biocomposite sector. Similarly to what is reported in other fiber crops, the stem of nettle contains both lignified and hypolignified fibers in the core and cortex, respectively, and it is therefore a useful model for cell wall research. Indeed, data on nettle stem tissues can be compared to those obtained in other models, such as hemp and flax, to support hypotheses on the differentiation and development of bast fibers. The suitability of the nettle stem as model for cell wall-related research was already validated using a transcriptomics and biochemical approach focused on internodes at different developmental stages sampled at the top, middle, and bottom of the stem. We here sought to complement and enrich these data by providing immunohistochemical and ultrastructural details on young and older stem internodes. Antibodies recognizing non-cellulosic polysaccharides (galactans, arabinans, rhamnogalacturonans) and arabinogalactan proteins were here investigated with the goal of understanding whether their distribution changes in the stem tissues in relation to the bast fiber and vascular tissue development. The results obtained indicate that the occurrence and distribution of cell wall polysaccharides and proteins differ between young and older internodes and that these changes are particularly evident in the bast fibers

Active distribution grids. Observability and RES-based DG forecasting

There are many reasons that have led to the penetration of Renewable Energy Sources based (RES-based) generation plants in the Italian power systems, i.e. the sensitivity to environmental issues, the presence of massive economic incentives and the development of technology. This, with the evolution of electricity markets, introduced new problems in the operation of the transmission and distribution grids. In particular, coordination actions between the Transmission System Operator (TSO) and the Distribution System Operator (DSO) became mandatory for guaranteeing a good operation of the whole power system. A series of resolutions, by the Italian Regulatory Authority for Energy, Networks and Environment (ARERA), has been published, aimed at tracing guidelines and indications to build and to grow the necessary collaboration between TSO and DSO. Areti, DSO in Rome metropolitan area, has decided to participate, in collaboration with Italian TSO, TERNA, in the first forms of experimentation in the field of observability of power flows and the state of RES-based resources spread over the Medium Voltage (MV) networks, as defined in the Authority documents. A system based on models, using neural networks, is proposed for reproducing the behaviour of the RES-based generation plants monitored. The paper presents it, verifying whether the application to cases of real plants is able to produce results compatible with the indications given to achieve the success of the tests