Plant Body Research Articles

The Role of Sulfur in Agronomic Biofortification with Essential Micronutrients.

Sulfur (S) is an essential macronutrient for plants, being necessary for their growth and metabolism and exhibiting diverse roles throughout their life cycles. Inside the plant body, S is present either in one of its inorganic forms or incorporated in an organic compound. Moreover, organic S compounds may contain S in its reduced or oxidized form. Among others, S plays roles in maintaining the homeostasis of essential micronutrients, e.g., iron (Fe), copper (Cu), zinc (Zn), and manganese (Mn). One of the most well-known connections is homeostasis between S and Fe, mainly in terms of the role of S in uptake, transportation, and distribution of Fe, as well as the functional interactions of S with Fe in the Fe-S clusters. This review reports the available information describing the connections between the homeostasis of S and Fe, Cu, Zn, and Mn in plants. The roles of S- or sulfur-derived organic ligands in metal uptake and translocation within the plant are highlighted. Moreover, the roles of these micronutrients in S homeostasis are also discussed.

Molecular framework integrating nitrate sensing in root and auxin-guided shoot adaptive responses

Mineral nutrition is one of the key environmental factors determining plant development and growth. Nitrate is the major form of macronutrient nitrogen that plants take up from the soil. Fluctuating availability or deficiency of this element severely limits plant growth and negatively affects crop production in the agricultural system. To cope with the heterogeneity of nitrate distribution in soil, plants evolved a complex regulatory mechanism that allows rapid adjustment of physiological and developmental processes to the status of this nutrient. The root, as a major exploitation organ that controls the uptake of nitrate to the plant body, acts as a regulatory hub that, according to nitrate availability, coordinates the growth and development of other plant organs. Here, we identified a regulatory framework, where cytokinin response factors (CRFs) play a central role as a molecular readout of the nitrate status in roots to guide shoot adaptive developmental response. We show that nitrate-driven activation of NLP7, a master regulator of nitrate response in plants, fine tunes biosynthesis of cytokinin in roots and its translocation to shoots where it enhances expression of CRFs. CRFs, through direct transcriptional regulation of PIN auxin transporters, promote the flow of auxin and thereby stimulate the development of shoot organs.

The plant TOR kinase tunes autophagy and meristem activity for nutrient stress-induced developmental plasticity.

Plants, unlike animals, respond to environmental challenges with comprehensive developmental transitions that allow them to cope with these stresses. Here we discovered that antagonistic activation of the Target of Rapamycin (TOR) kinase in Arabidopsis thaliana roots and shoots is essential for the nutrient deprivation-induced increase in the root-to-shoot ratio to improve foraging for mineral ions. We demonstrate that sulfate limitation-induced downregulation of TOR in shoots activates autophagy, resulting in enhanced carbon allocation to the root. The allocation of carbon to the roots is facilitated by the specific upregulation of the sucrose-transporter genes SWEET11/12 in shoots. SWEET11/12 activation is indispensable for enabling sucrose to act as a carbon source for growth and as a signal for tuning root apical meristem activity via glucose-TOR signaling. The sugar-stimulated TOR activity in the root suppresses autophagy and maintains root apical meristem activity to support root growth to enhance mining for new sulfate resources in the soil. We provide direct evidence that the organ-specific regulation of autophagy is essential for the increased root-to-shoot ratio in response to sulfur limitation. These findings uncover how sulfur limitation controls the central sensor kinase TOR to enable nutrient recycling for stress-induced morphological adaptation of the plant body.

Establishment and application of novel culture methods in Marchantia polymorpha: persistent tip growth is required for substrate penetration by rhizoids

ABSTRACT A NIMA-related protein kinase, MpNEK1, directs tip growth of rhizoids through microtubule depolymerization in a liverwort Marchantia polymorpha. The Mpnek1 knockouts were shown to develop curly and spiral rhizoids due to the fluctuated direction of growth. Still, physiological roles and mechanisms of MpNEK1-dependent rhizoid tip growth remain to be clarified. Here, we developed novel culture methods to further study rhizoid growth of M. polymorpha, in which plants were grown on vertical plates. We applied the established methods to investigate MpNEK1 function in rhizoid growth. Rhizoids of the wild-type and Mpnek1 plants grew toward the gravity. The aerial rhizoids were longer in Mpnek1 than in the wild type. When the rhizoids were grown on the surface of a cellophane sheet, rhizoid length was comparable between the wild type and Mpnek1, whereas Mpnek1 developed more rhizoids compared to the wild type. We also applied gellan gum, which is more transparent than agar, to analyze rhizoids grown in the medium. Rhizoids of Mpnek1 displayed defect on entering into the solid medium. These results suggest that Mpnek1 rhizoids have the deficiency in invasive tip growth. Thus, stable directional growth is important for rhizoids to get into the soil to anchor plant body and to adsorb water and nutrients. Collectively, our newly designed growth systems are valuable for analyzing rhizoid growth.

PERANGKAT PEMBELAJARAN BIOLOGI BERNUANSA KARAKTER MELALUI INQUIRY DALAM PEMBELAJARAN DARING

<p><em>Preliminary studies of needs analysis on the development of biology learning tools show the low learning outcomes of students' cognitive and behavioral characteristics. Therefore, it is necessary to develop learning instruments that aim to develop character-based biology learning tools through inquiry during online learning that achieve valid, useful, and efficient benchmarks. The device consists of four components, namely: lesson plans (RPP), student books (BPD), student worksheets (LKPD), and assessment instruments. This type of research is developmental research by using the 4-D model (four D), which has 4 stages, namely the defining stage, the design stage, the develop stage, and the last stage of dissemination. The final score of the analysis of the validity of the learning instrument states that the biology learning tool with character nuances through inquiry for the sake of improving cognitive and character learning achievement in the online learning period for the subject of plant and animal body structure and function in class XI high school that was developed is suitable to be applied based on the final validation score from validator. Biology learning instruments with character nuances through inquiry so that cognitive and character learning outcomes during the online learning period that are developed are practical and effectively implemented in class XI of high school on the material structure and function of the body of plants and animals have increased. Therefore, biology learning tools with character nuances through inquiry are appropriate to be applied because they have met the practical, valid and effective criteria.</em></p>

Heavy Metal Pollution in Iraqi Rivers and Impact on Human and Fish Health: A Review

The Euphrates and Tigris rivers are the main vital water sources in Iraq, and therefore many studies have been conducted on them to find out the reasons for their pollution, and the most important sources of pollution are heavy metals. Heavy metals are usually present in nature. Some of them are necessary for life, but they can become toxic through their accumulation in living organisms, as they cannot be eliminated in ecosystems through natural processes, unlike most organic pollutants, where these elements are one of the dangerous pollutants that enter the freshwater environment and cause an imbalance in the ecological system. This is directly or indirectly reflected on the human beings. These elements enter the plant and animal bodies through the soil, water and air which have been categorized by their ability to bio-accumulate in the tissues of animals and elevate their concentration in the tissue and body fluids. Such bioaccumulation causes toxicity to living organisms and may affect human public health. Fishes are the most susceptible among the aquatic animals to the toxicity of heavy metals. They are a basic food source and animal protein, cheap and economical, with a high nutritional value and the human body needs them on a permanent and continuous basis. Fishes are also commonly used in assessing the health of aquatic organisms. This review is focused on the pathological effects of heavy metals in both fishes and humans.

Technology of growing Bog blueberry (Vaccinium uliginosum L.) seedlings from green cuttings in Tashkent province, Uzbekistan

Blueberry (Vaccinium uliginosum L.) is one of the most popular fruit plants in the world consumer market. In North America, cultivars of blueberry are widely used as a valuable food and medicinal plant. Blueberries are widely used in both folk medicine and official medicine. This research was aimed at researching different technology use in growing Bog blueberry seedling using its green cuttings in Tashkent province, Uzbekistan. During the experiments, phenological observations and statistical analysis method Dospekhov were employed to analyze growth Bog blueberry in different treatment options. The results showed that the effect of plant concentration on the diameter of the young plant body was recorded at indolyl butyric acid-80 mg/l and Indolyl butyric acid-100 mg/l at plant concentration. In this variant, too, the effect of the concentration of the growing substance on the body diameter of the plants was positive, and it was found that the Duke variety was in the range of 7.5-7.1 mm and the Patriot variety in the range of 6.5-6.4 mm. The highest rate of total average leaf level of plants (360.8-359.7 cm2) was recorded in plants developed from green cuttings of the Duke variety.

Etnobotani Tumbuhan Berkhasiat Obat pada Masyarakat Karang Bayan Kabupaten Lombok Barat

Each region has a unique medical culture. The traditional culture of the Sasaknese on Lombok Island has been accustomed to using various types of plants in their traditional medical culture. Those who known to have knowledge and abilities about traditional medicine known as Belian. Knowledge about the types of medicinal plants and the methods and techniques of treatment are generally passed down in the kinship hierarchy.One group of people who are still attached to the tradition of traditional medicine is the special Sasak tribe of the Karang Bayan community, West Lombok. The elders believe that the origin of these communities is from the Bayan region, North Lombok, which is known as a wetu telu area with unique cultural characteristics and relatively preserved local cultural knowledge. Observations, interviews and collection of medicinal plant specimens were carried out in Karang Bayan. Determination of the samples using the snowball method. Data were analyzed descriptively qualitatively by summarizing the results of interviews and parsing various medicinal plants and diseases that are believed to be cured. Furthermore, the data generated and then triangulated (comparing the data obtained with books or journals relating to the research). A total of 47 types of medicinal plants are used to treat 33 types of diseases and symptoms of certain diseases by the Karang Bayan community. Plant parts such as roots, stems, bark, leaves, fruit, seeds, sap, and even the whole plant body are used in medicine. During the compounding process until the application of drugs using certain, Belian (healers) believe that if the procedure is ignored then the patient will not get a cure. This resulted in the formation of strong suggestions in maintaining the traditional treatment procedures for both traditional healers and the patient.

A Review of Endophytes\' Ability to Promote Plant Development on Medicinal Herbs

Abstract: Countless microbes live in the bodies of animals and plants. Plant growth is aided by the interaction between microbes and plants. They can be used as bio-fertilizers because of their nutrient intake and nitrogen-fixing capacity. These bacteria produce important metabolites and secondary metabolites that can be used to treat cancer and other chronic human diseases. They play a key role in the decomposition of heavy metals in the soil. In other words, they have a positive impact on agriculture, medicine, biotechnology, and food science. Plant growth-promoting rhizobacteria (PGPR) are commonly used to improve the growth of a wide range of crops, such as seed germination, plant weight, and harvest yields. Plant development is triggered by PGPR colonization because bacteria produce plant hormones such as indole-3-acetic acid, cytokinin, and gibberellins, as well as enhanced mineral and nitrogen availability in the soil. They are also known to defend their host plants from harmful bacteria in some cases. The role of PGPR in connection to medicinal plants and their impact on the development of botanicals is an area where there is still a lot of research to be done. This review highlights the potential PGPR–medicinal plant interactions that could boost the medicinal plant's effectiveness, particularly in farmed plants. The significance of medicinal plant endophytic microbes for bioactive potentials.

Versatile roles of sorbitol in higher plants: luxury resource, effective defender or something else?

Sorbitol metabolism plays multiple roles in many plants, including energy and carbon enrichment, effective defence against various stresses and other emerging specific roles. The underlying mechanisms are, however, incompletely understood. This review provides the current state-of-the-art, highlights missing knowledge and poses several remaining questions. The basic properties of sugar alcohols are summarised and pathways of sorbitol metabolism, including biosynthesis, degradation and key enzymes are described. Sorbitol transport within the plant body is discussed and individual roles of sorbitol in different organs, specific cells or even cellular compartments, are elaborated, clarifying the critical importance of sorbitol allocation and distribution. In addition to plants that accumulate and transport significant quantities of sorbitol (usual producers), there are some that synthesize small amounts of sorbitol or only possess sorbitol metabolising enzymes (non-usual producers). Modern analytical methods have recently enabled large amounts of data to be acquired on this topic, although numerous uncertainties and questions remain. For a long time, it has been clear that enriching carbohydrate metabolism with a sorbitol branch improves plant fitness under stress. Nevertheless, this is probably valid only when appropriate growth and defence trade-offs are ensured. Information on the ectopic expression of sorbitol metabolism genes has contributed substantially to our understanding of the sorbitol roles and raises new questions regarding sorbitol signalling potential. We finally examine strategies in plants producing sorbitol compared with those producing mannitol. Providing an in-depth understanding of sugar alcohol metabolism is essential for the progress in plant physiology as well as in targeted, knowledge-based crop breeding.

Foliar application of mepiquat chloride and nitrogen improves yield and fiber quality traits of cotton (Gossypium hirsutum L.).

Cotton (Gossypium hirsutum L.) is one of the most important cash crops primarily grown for fiber. It is a perennial crop with indeterminate growth pattern. Nitrogen (N) is extremely important for vegetative growth as balanced N-nutrition improves photosynthesis, resulting in better vegetative growth. Excessive N-supply results in more vegetative growth, which increases the incidence of insect pest and diseases’ infestation, pollute surface and ground water, delays maturity and produces low crop yield with poor quality. The use of plant growth regulators (PGRs) is an emerging option to control excessive vegetative growth. The PGRs help in improving plant architecture, boll retention, boll opening, yield and quality by altering growth and physiological processes such as photosynthesis, assimilate partitioning and nutrients dynamic inside the plant body. Mepiquat chloride (1,1-dimethylpiperidinum chloride) is globally used PGR for canopy development and control of excessive vegetative growth in cotton. This study investigated the effect of mepiquat chloride (MC) and N application on yield and yield components of transgenic cotton variety ‘BT-FSH-326’. Two N rates (0, 198 kg ha-1) and five MC rates (0, 30,60, 90 and 120 g ha-1) were included in the study. Results revealed that MC and N application improved boll weight, number of bolls per plant, and seed cotton and lint yields. The highest seed cotton and lint yields (3595 kg ha-1 and 1701 kg ha-1, respectively) were observed under foliar application of 198 kg ha-1 N and 120 g ha-1 MC. Fiber length, fiber strength, micronaire and uniformity were significantly improved with foliar application of MC and N. In conclusion, foliar application of MC and N could be helpful in improving yield and fiber quality of cotton.

The greenest revolution – harnessing the power of plants to help combat climate change

As we continue searching for the technologies that will halt global warming, let us take a moment to think about plants. A key contributor to our climate crisis is the accumulation of carbon dioxide in the atmosphere. Plants have been capturing carbon dioxide for billions of years, making them the most tried and tested carbon capture machinery on the planet. Plants fix carbon dioxide as part of photosynthesis. After years of research, we now know the key regulators of this process and have the knowledge to start engineering plants with increased photosynthetic capacity. In addition to improving the efficiency of carbon fixation, we must also find a way to stably store the carbon captured by plants. To achieve this, we can look to the below-ground part of the plant body – the root system. Plant roots are packed full of carbon and also exude carbon-rich molecules into the soil. Engineering future plants with deeper, more extensive root systems, with enhanced chemical composition that increases carbon content and reduces the rate of biodegradation, offers a way to store atmospheric carbon fixed by plants below ground for years to come. With optimized root systems, these plants would also be better equipped to explore their surrounding soils for water and nutrients, which would ultimately improve plant performance. This approach also offers a way to replenish our carbon-depleted soils, which would increase soil quality by improving water and nutrient retention. Harnessing the plants' natural ability to capture carbon, thus provides a way to not only restore balance to the carbon cycle, but also improve soil quality and future crop performance.

Influence of Salinity with Different Cl-:SO42- Ratios on Wheat (Triticum aestivum L.) Growth

A major threat for sustainable agriculture is the continuous increase in salt-affected area. Salt stress causes the land degradation, ecological imbalance, Environmental pollution and reduce the crop production. It changes different physical and chemical processes taking place in plant body such as seed germination and uptake of different nutrients and water. Wheat is the main cereal crop and primary diet for one third population of the humans. It can tolerate the salinity effect to some extent but at higher level of salinity, its production reduces significantly. Salt-affected soils have relatively more number of salts which are easily solubilize in water and exchangeable sodium as compared to the normal soil. These salts are ionized and produce different types of cations (Mg2+, Ca2+ and Na+) and anions (Cl-, CO32-, SO42-, and HCO3-). Sulphate salinity is also toxic for plant growth as chloride salinity. The objective of this research is to assess the effect of salinity with various Cl-:SO42- ratios on wheat growth. A pot trial was conducted on wheat by creating salinity with different levels of chloride and sulphate (4:1, 3:1, 2:1, 1:1, 1:2, 1:3 and 1:4). Experimental design was complete randomized design (CRD). Different physiochemical parameters of soil before and after harvesting of the crop and also growth parameters were determined. Data was analysed using statistical software. On the basis of these results, it was determined that both types of salinity reduced the wheat growth significantly, but chloride type salinity has more injurious effect than sulphate salinity. It was concluded that chloride ion has more toxic effect than sulphate ion for wheat growth and development.

Characterizing Mechanical Properties of Primary Cell Wall in Living Plant Organs Using Atomic Force Microscopy

The mechanical properties of the primary cell walls determine the direction and rate of plant cell growth and, therefore, the future size and shape of the plant. Many sophisticated techniques have been developed to measure these properties; however, atomic force microscopy (AFM) remains the most convenient for studying cell wall elasticity at the cellular level. One of the most important limitations of this technique has been that only superficial or isolated living cells can be studied. Here, the use of atomic force microscopy to investigate the mechanical properties of primary cell walls belonging to the internal tissues of a plant body is presented. This protocol describes measurements of the apparent Young's modulus of cell walls in roots, but the method can also be applied to other plant organs. The measurements are performed on vibratome-derived sections of plant material in a liquid cell, which allows (i) avoiding the use of plasmolyzing solutions or sample impregnation with wax or resin, (ii) making the experiments fast, and (iii) preventing dehydration of the sample. Both anticlinal and periclinal cell walls can be studied, depending on how the specimen was sectioned. Differences in the mechanical properties of different tissues can be investigated in a single section. The protocol describes the principles of study planning, issues with specimen preparation and measurements, as well as the method of selecting force-deformation curves to avoid the influence of topography on the obtained values of elastic modulus. The method is not limited by sample size but is sensitive to cell size (i.e., cells with a large lumen are difficult to examine).

Synthesis of γ-Aminobutyric Acid-Modified Chitooligosaccharide Derivative and Enhancing Salt Resistance of Wheat Seedlings.

Salinity is one of the major abiotic stresses limiting crop growth and productivity worldwide. Salt stress during germination degenerates crop establishment and declines yield in wheat, therefore alleviating the damage of salt stress to wheat seedlings is crucial. Chitooligosaccharide (COS) was grafted with γ-aminobutyric acid based on the idea of bioactive molecular splicing, and the differences in salt resistance before and after grafting were compared. The expected derivative was successfully synthesized and exhibited better salt resistance-inducing activity than the raw materials. By activating antioxidant enzymes such as superoxide dismutases (SOD), catalase (CAT) and phenylalanine ammonia-lyase (PAL) and subsequently eliminating reactive oxygen species (ROS) in a timely manner, the rate of O−2 production and H2O2 content of wheat seedlings were reduced, and the dynamic balance of free radical metabolism in the plant body was maintained. A significantly reduced MDA content, reduced relative permeability of the cell membrane, and decreased degree of damage to the cell membrane were observed. A significant increase in the content of soluble sugar, maintenance of osmotic regulation and the stability of the cell membrane structure, effective reduction in the salt stress-induced damage to wheat, and the induction of wheat seedling growth were also observed, thereby improving the salt tolerance of wheat seedlings.

Nitrogen fixation and other biogeochemically important features of Atacama Desert giant horsetail plant microbiomes inferred from metagenomic contig analysis.

Background and AimsCanyon stream beds in the hyperarid Atacama Desert surprisingly harbour magnificent groves of endemic giant horsetail wetland plants, Equisetum xylochaetum. Our previous metagenomic study of eukaryotes closely associated with this plant indicated that the microbiome included prokaryotes that might likewise influence host success and environment. We explored this possibility by using the metagenomic sequence to characterize prokaryote taxa and functional genes present in the microbiome of E. xylochaetum sampled from remote sites differing in the degree of anthropogenic disturbance. We focused on biogeochemical functions known to be important in wetland ecosystems.MethodsTo ensure that analyses were conducted on microbes most closely associated with plants, we extracted DNA from well-washed plant organs whose microbial biofilms were revealed with scanning electron microscopy. To assess the benefits of longer sequences for taxonomic and gene classifications, results of analyses performed using contigs were compared with those obtained with unassembled reads. We employed methods widely used to estimate genomic coverage of single taxa for genomic analysis to infer relative abundances of taxa and functional genes.Key ResultsKey functional bacterial genera (e.g. Hydrogenophaga, Sulfuritalea and Rhodoferax) inferred from taxonomic and functional gene analysis of contigs – but not unassembled reads – to occur on surfaces of (or within) plants at relatively high abundance (>50× genomic coverage) indicated roles in nitrogen, sulfur and other mineral cycling processes. Comparison between sites revealed impacts on biogeochemical functions, e.g. reduced levels of the nifH gene marker under disturbance. Vanadium nitrogenases were more important than molybdenum nitrogenases, indicated by both functional genes and taxa such as Rhodomicrobium and Phaeospirillum inferred from contigs but not unassembled reads.ConclusionsOur contig-based metagenomic analyses revealed that microbes performing key wetland biogeochemical functions occur as tightly adherent biofilms on the plant body, not just in water or sediments, and that disturbance reduces such functions, providing arguments for conservation efforts.

Monitoring SARS-CoV-2 in the Wastewater and Rivers of Tapachula, a Migratory Hub in Southern Mexico.

The COVID-19 pandemic has been monitored by applying different strategies, including SARS-CoV-2 detection with clinical testing or through wastewater-based epidemiology (WBE). We used the latter approach to follow SARS-CoV-2 dispersion in Tapachula city, located in Mexico’s tropical southern border region. Tapachula is a dynamic entry point for people seeking asylum in Mexico or traveling to the USA. Clinical testing facilities for SARS-CoV-2 monitoring are limited in the city. A total of eighty water samples were collected from urban and suburban rivers and sewage and a wastewater treatment plant over 4 months in Tapachula. We concentrated viral particles with a PEG-8000-based method, performed RNA extraction, and detected SARS-CoV-2 particles through RT-PCR. We considered the pepper mild mottle virus as a fecal water pollution biomarker and analytical control. SARS-CoV-2 viral loads (N1 and N2 markers) were quantified and correlated with official regional statistics of COVID-19 bed occupancy and confirmed cases (r > 91%). Our results concluded that WBE proved a valuable tool for tracing and tracking the COVID-19 pandemic in tropical countries with similar water temperatures (21–29 °C). Monitoring SARS-CoV-2 through urban and suburban river water sampling would be helpful in places lacking a wastewater treatment plant or water bodies with sewage discharges.Supplementary InformationThe online version contains supplementary material available at 10.1007/s12560-022-09523-2.

Evolution of osmosensing OSCA1 Ca2+ channel family coincident with plant transition from water to land.

Water is crucial to plant growth, development, and environmental adaptation. Water stress triggers cytosolic Ca2+ ([Ca2+ ]i ) increases, and the osmosensor OSCA1 (REDUCED-HYPEROSMOLALITY-INDUCED-[Ca2+ ]i -INCREASE 1), a member of the OSCA family, perceives the initial water stress and governs its downstream responses. OSCA homologs exist in eukaryotes and largely radiate in higher plants. However, it is enigmatic whether the OSCA family is crucial for plant evolution from aqueous to terrestrial environments and for the subsequent adaptation on land. Here, we carried out the first phylogenetic and molecular evolutionary analyses of the OSCA family. The family originated and diversified during the early evolution of protists, and three more lineages were established (a) in plants, (b) in fungi, and (c) in a complex clade of several major eukaryotic lineages. The chlorophyte algal cluster is directly basal to streptophyte-specific Clades 1-3, consistent with plant transition from water to land. The Clades 1-3 present different gene expansion pattern and together with previous functional analysis of OSCAs reveal that they probably have evolved diverse functions in respond to various mechanical stresses during the independent evolution of land plant clades. Moreover, variable selection pressures on different land plant lineages were explored. OSCAs in early land plants (mosses and lycophytes) were under decelerated evolution, whereas OSCAs in seed plants showed accelerated evolution. Together, we hypothesize OSCAs have evolved to sense water stress in the ancestor of euphyllophytes, which occupies typical leaves, typical roots, and phloem tissues, all of which require osmosensors to maintain water balance and food conduction through plant bodies.

Secondary cell wall patterning-connecting the dots, pits and helices.

All plant cells are encased in primary cell walls that determine plant morphology, but also protect the cells against the environment. Certain cells also produce a secondary wall that supports mechanically demanding processes, such as maintaining plant body stature and water transport inside plants. Both these walls are primarily composed of polysaccharides that are arranged in certain patterns to support cell functions. A key requisite for patterned cell walls is the arrangement of cortical microtubules that may direct the delivery of wall polymers and/or cell wall producing enzymes to certain plasma membrane locations. Microtubules also steer the synthesis of cellulose-the load-bearing structure in cell walls-at the plasma membrane. The organization and behaviour of the microtubule array are thus of fundamental importance to cell wall patterns. These aspects are controlled by the coordinated effort of small GTPases that probably coordinate a Turing's reaction-diffusion mechanism to drive microtubule patterns. Here, we give an overview on how wall patterns form in the water-transporting xylem vessels of plants. We discuss systems that have been used to dissect mechanisms that underpin the xylem wall patterns, emphasizing the VND6 and VND7 inducible systems, and outline challenges that lay ahead in this field.

A modeling framework for predicting the effect of the operating conditions and component sizing on fuel cell degradation and performance for automotive applications

In this study, durability and performance prediction were integrated in the sizing process of the FC stack of a fuel cell range-extender (FCREx) vehicle together with the design of a dynamics-limited control strategy. For that purpose, a FCREx vehicle model integrating a FC stack, balance of plant, battery, H2 tank and vehicle body (C-class SUV) validated in previous studies was used. To predict FC stack degradation rate, a novel semi-empirical multi-layered degradation modeling framework for automotive application is proposed and developed. Degradation rates are calculated based on reference degradation rates measured at reference and known conditions (1st layer) and scaled with the electrochemical phenomena (2nd layer) and the operating conditions (3rd layer) through scaling functions based on physical tendencies. Results show how increasing the FC stack power decreases H2 consumption but increases durability, while increasing the dynamic limitations on the control strategy increases both H2 consumption and durability. The isolated effect of sizing implied a decrease in H2 consumption of ∼3% and an increase in FC stack durability of ∼53% when comparing the 40 kW and 100 kW designs. In contrast, the effect of dynamic limitations was significantly perceived in the 40 kW design which implied an increase in H2 consumption close to 8% and an increase in durability of 294% when comparing the infinite dynamics and the highest dynamically restricted cases. Nevertheless, the effect of sizing is neglected under high dynamic limitation and limiting the current density change rate to 0.001 A/cm2s may prevent the control strategy from fulfilling the charge sustaining mode in aggressive driving. Based on these results, a set of recommendations were elaborated for FC stack and FCV manufacturers aiming to apply FCREx architecture to passenger car vehicles.