Wall Growth Research Articles

MaPom1, a Dual-Specificity Tyrosine Phosphorylation-Regulated Kinase, Positively Regulates Thermal and UV-B Tolerance in Metarhizium acridum

Fungi play irreplaceable roles in the functioning of natural ecosystems, but global warming poses a significant threat to them. However, the mechanisms underlying fungal tolerance to thermal and UV-B stresses remain largely unknown. Dual-specificity tyrosine phosphorylation-regulated kinase (DYRK) Pom1 is crucial for fungal growth, conidiation, and virulence. However, its role in stress tolerance within kingdom fungi has not been explored. In this study, we analyzed the function of MaPom1 (a Pom1 homologous gene) in the entomopathogenic fungus Metarhizium acridum and its regulatory roles in stress tolerance. Conidial thermal and UV-B tolerance significantly decreased in the MaPom1 disruption strain (ΔMaPom1), whereas conidial yield and virulence were unaffected. RNA-Seq analysis indicated that the differentially expressed genes (DEGs) were primarily related to amino sugar, nucleotide sugar metabolism, cell wall components, growth and development, and stress response pathways. Under heat shock treatment, the expression levels of heat shock protein genes decreased significantly, leading to reduced thermotolerance. Moreover, under UV-B treatment, MaPom1 expression and the enzyme activity significantly changed, indicating its involvement in regulating UV-B tolerance. The percentage of nuclear damage in ΔMaPom1 under UV-B treatment was higher than that in the wild-type strain (WT) and the complementary strain (CP). Additionally, the transcription levels of DNA damage-related genes significantly decreased, whereas those of several genes involved in the DNA damage repair response increased significantly. Overall, MaPom1 contributed to thermal and UV-B tolerance by regulating the expression of heat shock protein genes and DNA damage repair genes.

LD-transpeptidation is crucial for fitness and polar growth in Agrobacterium tumefaciens.

Peptidoglycan (PG), a mesh-like structure which is the primary component of the bacterial cell wall, is crucial to maintain cell integrity and shape. While most bacteria rely on penicillin binding proteins (PBPs) for crosslinking, some species also employ LD-transpeptidases (LDTs). Unlike PBPs, the essentiality and biological functions of LDTs remain largely unclear. The Hyphomicrobiales order of the Alphaproteobacteria, known for their polar growth, have PG which is unusually rich in LD-crosslinks, suggesting that LDTs may play a more significant role in PG synthesis in these bacteria. Here, we investigated LDTs in the plant pathogen Agrobacterium tumefaciens and found that LD-transpeptidation, resulting from at least one of 14 putative LDTs present in this bacterium, is essential for its survival. Notably, a mutant lacking a distinctive group of 7 LDTs which are broadly conserved among the Hyphomicrobiales exhibited reduced LD-crosslinking and tethering of PG to outer membrane β-barrel proteins. Consequently, this mutant suffered severe fitness loss and cell shape rounding, underscoring the critical role played by these Hyphomicrobiales-specific LDTs in maintaining cell wall integrity and promoting elongation. Tn-sequencing screens further revealed non-redundant functions for A. tumefaciens LDTs. Specifically, Hyphomicrobiales-specific LDTs exhibited synthetic genetic interactions with division and cell cycle proteins, and a single LDT from another group. Additionally, our findings demonstrate that strains lacking all LDTs except one displayed distinctive phenotypic profiles and genetic interactions. Collectively, our work emphasizes the critical role of LD-crosslinking in A. tumefaciens cell wall integrity and growth and provides insights into the functional specialization of these crosslinking activities.

Rhodopseudomonas palustris Atp2 Protein Exerts Antifungal Effects by Targeting the Ribosomal Protein MoRpl12 in Magnaporthe oryzae.

Rice blast is one of the most hazardous diseases affecting rice production. Previously, we discovered that the Atp2 protein of Rhodopseudomonas palustris could significantly inhibit the appressorium formation and pathogenicity of Magnaporthe oryzae. However, the molecular mechanism of this fungus has remained unknown. This study revealed that Atp2 can enter the cell and interact with the ribosomal protein MoRpl12 of M. oryzae, directly affecting the expression of the MoRpl12 protein. Silencing the MoRPL12 gene can affect cell wall integrity, growth, conidiogenesis, and fungal pathogenicity. The quantitative reverse transcription PCR results showed significant changes in the expression of conidiation-related genes in the MoRPL12 gene-silenced mutants or in the Atp2 protein-treated plants. We further found that Atp2 treatment can influence the expression of ribosomal-related genes, such as RPL, in M. oryzae. Our study revealed a novel antifungal mechanism by which the Atp2 protein binds to the ribosomal protein MoRpl12 and inhibits the pathogenicity of rice blast fungus, providing a new potential target for rice blast prevention and control.

Fuel fumes and foliage: the fate of speciated gasoline VOCs during phytoremediation and their impact on the bacterial phenotype

The capacity of indoor plants including green walls to capture, deposit and remediate individual volatile organic compounds (VOCs) has been well documented. However, in realistic settings, plant systems are exposed to a complex mixture of VOCs from highly varied various emission sources. Gasoline vapour is one of the major sources of these emissions, containing high concentrations of the carcinogens benzene, toluene, ethylbenzene and xylene (BTEX). Using both solid phase micro extraction (SPME) and quick, easy, cheap, effective, rugged and safe (QuEChERS) sampling techniques, we assessed the dynamics of individual speciated gasoline VOC phytoremediation from the air and uptake within green wall plant species and growth substrates within a small passive green wall system, along with quantifying the phenotypic changes within the plant-associated bacterial communities resulting from gasoline exposure. Over 8 hours the green wall system achieved 100% removal of atmospheric benzene, 1,2,3-trimethyl, eicosane and hexadecane, benzene 1,3-diethyl-; 1,3,5 cycloheptatriene,7- ethyl and carbonic acid eicosyl vinyl ester. All plant species tested demonstrated the accumulation 45 petrochemical VOCs (pVOCs) with Spathiphyllum wallisii successfully accumulating the majority of pVOC functional groups after 24 h of gasoline exposure. Within the plants phyllospheric bacterial communities, changes in both cellular complexity and granularity appeared to increase as a result of gasoline exposure, while cell size diminished. This work provides novel findings on the VOC removal processes of botanical systems for realistic and highly toxic VOC profiles.

Central Actions of Leptin Induce an Atrophic Pattern and Improves Heart Function in Lean Normoleptinemic Rats via PPARβ/δ Activation.

Leptin, acting centrally or peripherally, has complex effects on cardiac remodeling and heart function. We previously reported that central leptin exerts an anti-hypertrophic effect in the heart via cardiac PPARβ/δ activation. Here, we assessed the impact of central leptin administration and PPARβ/δ inhibition on cardiac function. Various cardiac properties, including QRS duration, R wave amplitude, heart rate (HR), ejection fraction (EF), end-diastolic left ventricular mass (EDLVM), end-diastolic volume (EDV), and cardiac output (CO) were analyzed. Central leptin infusion increased cardiac PPARβ/δ protein content and decreased HR, QRS duration, and R wave amplitude. These changes induced by central leptin suggested a decrease in the ventricular wall growth, which was confirmed by MRI. In fact, the EDLVM was reduced by central leptin while increased in rats co-treated with leptin and GSK0660, a selective antagonist of PPARβ/δ activity. In summary, central leptin plays a dual role in cardiac health, potentially leading to ventricular atrophy and improving heart function when PPARβ/δ signaling is intact. The protective effects of leptin are lost by PPARβ/δ inhibition, underscoring the importance of this pathway. These findings highlight the therapeutic potential of targeting leptin and PPARβ/δ pathways to combat cardiac alterations and heart failure, particularly in the context of obesity.

Standardization of Crop Geometry and Major Nutrients for Enhancing the Growth, Yield and Quality of Davana (Artemisia pallens Wall) cv. Theni under Northern Dry Zone of Karnataka, India

The study was conducted on the effect of spacing and fertilizers on growth, quality and yield of Artemisia pallens Wall. cv. Theni in northern Karnataka (Zone III) for two consecutive years in rabi 2021 and 2022. The research was set out in a factorial RCBD and replicated thrice in nine treatment combinations, that is three levels of spacing (S1: 15 x 7.5 cm, S2: 20 x 10 cm and S3: 30 x 10 cm) and three fertilizer levels (F1: 60:30:20 N, P2O5, K2O kg ha-1, F2: 90:30:30 N, P2O5, K2O kg ha-1 and F3: 120:40:40 N, P2O5, K2O kg ha-1). The pooled data of two years was statistically analysed using the Fisher's method of "Analysis of variance". Among the spacing levels, 20 x 10 cm spacing was noticed the maximum inflorescences plant-1 (87.40), hundred flower weight (3.83 g), fresh herbage yield (11.29 t ha-1), dry herbage yield (2.83 t ha-1) & essential oil yield (13.23 kg ha-1). Among various fertilizer doses application of F3 (120:40:40 N, P2O5, K2O kg ha-1) was noticed economically feasible, it has obtained maximal growth and yield parameters. The highest fresh herb yield (12.78 t ha-1), dry herbage yield (3.16 t ha-1) and essential oil yield of (15.46 kg ha-1) were noticed with 120:40:40 N, P2O5, K2O kg ha-1 (F3) application. Spacing of 20 x 10 cm (S2) and application of 120:40:40 N N, P2O5, K2O kg ha-1 (F3) found to be economical with highest benefit cost ratio of 4.08.

Enhanced lignin and cellulose metabolism promote cell wall synthesis and growth of wild soybean HRA under alkali stress.

Soil salinization adversely threatens plant survival and food production globally. The mobilization of storage reserves in cotyledons and establishment of the hypocotyl/root axis (HRA) structure and function are crucial to the growth of dicotyledonous plants during the post-germination growth period. Here, we report the adaptive mechanisms of wild and cultivated soybeans in response to alkali stress in soil during the post-germination growth period. Diferences in physiological parameters, microstructure, and the types, amounts and metabolic pathways of small molecule metabolites and gene expression were compared and multi-omics integration analysis was performed between wild and cultivated soybean under sufcient and artifcially simulated alkali stress during the post-germination growth period in this study. Structural analysis showed that the cell wall thickness of wild soybean under alkali stress increased, whereas cultivated soybeans were severely damaged. A comprehensive analysis of small molecule metabolites and gene expression revealed that protein breakdown in wild soybean cotyledons under alkali stress was enhanced, and transport of amino acids and sucrose increased. Additionally, lignin and cellulose synthesis in wild soybean HRA under alkali stress were enhanced. verall, protein decomposition and transport of amino acids and sucrose increased in wild soybean cotyledons under alkali stress, which in turn, promotes HRA growth. Similarly, lignin and cellulose synthesis in wild soybean HRA enhanced, which subsequently, enhanced cell wall synthesis, thereby maintaining the stability and functionality of HRA under alkali stress. This study presents important practical implications for the utilization of wild plant resources and sustainable development of agriculture.

Sur7 mediates a novel pathway for PI4,5P2 regulation in C. albicans that promotes stress resistance and cell wall morphogenesis.

The human fungal pathogen Candida albicans can cause lethal systemic infections due to its ability to resist stress from the host and to undergo invasive hyphal growth. Previous studies showed that plasma membrane MCC/eisosome domains were important for virulence by promoting the ability of Sur7 to mediate normal cell wall morphogenesis and stress resistance. The sur7Δ mutant displayed abnormal clusters of PI4,5P2, suggesting that misregulation of this lipid underlies the sur7Δ phenotype. To test this, we increased PI4,5P2 levels by deleting combinations of the three PI4,5P2 5' phosphatase genes (INP51, INP52, and INP54) and found that some combinations, such as inp51Δ inp52Δ, gave phenotypes similar the sur7Δ mutant. In contrast, deleting one copy of MSS4, the gene that encodes the 5' kinase needed to create PI4,5P2, reduced the abnormal PI4,5P2 clusters and also decreased the abnormal cell wall and stress sensitive phenotypes of the sur7Δ mutant. Additional studies support a model that the abnormal PI4,5P2 patches recruit septin proteins, which in turn promote aberrant cell wall growth. These results identify Sur7 as a novel regulator of PI4,5P2 and highlight the critical role of PI4,5P2 in the regulation of C. albicans virulence properties.

Fibromuscular Dysplasia: Renal Artery Dissection and Infarction in a Young Male

Fibromuscular dysplasia is an abnormal cell growth of the arterial wall that usually affects the renal and carotid arteries. It may lead to stenosis, tortuosity, aneurysm, or dissection of the artery and can potentially compromise the circulation from ensuing total occlusion and infarction of the recipient area. We report a case of a young male who presented with severe acute abdominal pain in the right side of the abdomen associated with nausea, vomiting, and constipation. Computed tomography of the abdomen with intravenous contrast showed acute renal infarction of a focal area at the lower pole of the right kidney, subsequent computed angiography showed dissection of a segmental branch of the right renal artery associated with fibromuscular dysplasia and beading appearance of the right renal artery. The renal function test and urinalysis were both normal. The patient was treated with unfractionated heparin infusion, with the resolution of abdominal pain, he was subsequently discharged home uneventfully on oral aspirin.

Acellular Bovine Pericardial Patch for Difficult Abdominal Closure in the Pediatric Population: Our Experience with Review of Literature.

Closure of congenital body wall defects in children can be a challenging task for the pediatric Surgeon. Biological prosthesis has been increasingly used for high-risk wound closure in adult patients with excellent outcomes and use in the pediatric population has also been reported. Here, we aim to study the outcome of abdominal wound repair with a tissue-engineered acellular bovine pericardial patch. Over a period of 21 months, a total of 15 children had undergone abdominal wound repair with bioprostheses, i.e., bovine pericardial patch at our institute. Patient demographics, cause of defect, an indication of patch use, rate of infection, postoperative recovery, recurrence, and outcome were studied. A total of 15 patients underwent abdominal wall closure with acellular bovine pericardial patch. Nine out of 15 patients were neonates, of whom five had gastroschisis, two had a congenital diaphragmatic hernia, and two had ruptured omphalocele major. Of the rest 6 patients, 2 were patients of bladder exstrophy, 2 were older children of congenital diaphragmatic hernia with incisional hernias, and 2 were older children with omphalocele major. Out of the five patients with gastroschisis, two died during the early postoperative period due to sepsis. The wound healed in the rest 13 patients with mild skin dehiscence in two patients. Only one child had a recurrence. Reconstruction with acellular bovine pericardial patch is a viable option in children with high-risk abdominal wounds as it allows tensionless repair with excellent healing and minimal complications. Recurrence, if any, may disappear with time as remodeling of the prosthesis occurs along with the growth of the body wall of the child.

Unravelling the biostimulant activity of a protein hydrolysate in lettuce plants under optimal and low N availability: a multi-omics approach.

The application of protein hydrolysates (PH) biostimulants is considered a promising approach to promote crop growth and resilience against abiotic stresses. Nevertheless, PHs bioactivity depends on both the raw material used for their preparation and the molecular fraction applied. The present research aimed at investigating the molecular mechanisms triggered by applying a PH and its fractions on plants subjected to nitrogen limitations. To this objective, an integrated transcriptomic-metabolomic approach was used to assess lettuce plants grown under different nitrogen levels and treated with either the commercial PH Vegamin® or its molecular fractions PH1(>10 kDa), PH2 (1-10 kDa) and PH3 (<1 kDa). Regardless of nitrogen provision, biostimulant application enhanced lettuce biomass, likely through a hormone-like activity. This was confirmed by the modulation of genes involved in auxin and cytokinin synthesis, mirrored by an increase in the metabolic levels of these hormones. Consistently, PH and PH3 upregulated genes involved in cell wall growth and plasticity. Furthermore, the accumulation of specific metabolites suggested the activation of a multifaceted antioxidant machinery. Notwithstanding, the modulation of stress-response transcription factors and genes involved in detoxification processes was observed. The coordinated action of these molecular entities might underpin the increased resilience of lettuce plants against nitrogen-limiting conditions. In conclusion, integrating omics techniques allowed the elucidation of mechanistic aspects underlying PH bioactivity in crops. Most importantly, the comparison of PH with its fraction PH3 showed that, except for a few peculiarities, the effects induced were equivalent, suggesting that the highest bioactivity was ascribable to the lightest molecular fraction.

Effect of Different Shading Color on Growth and Yield Performance of (Black Ginger) Kaempferia parviflora Wall. ex Baker

A study was conducted to investigate the impact of different shading colors on the growth and yield performance of (black ginger) Kaempferia parviflora Wall. ex Baker. The experiment was conducted in a glasshouse at MARDI Jerangau, Terengganu, from September 2022 to May 2023. The experiment followed a randomized complete block design (RCBD) with three replications. The shade treatments consisted of non-shade (T1), green shade (T2), yellow shade (T3), and red shade (T4). The results revealed that the application of colored shading significantly enhanced both the growth and yield of K. parviflora. Notably, the growth performance at the 5-month after planting (MAP) stage was crucial for rhizome yield, with any decrease in plant height potentially leading to diminished rhizome weight measurements. Among the shading colors, green shade emerged as the most effective, boosting total rhizome weight compared to non-shaded conditions. Correlation analysis between yield components demonstrated a strong positive relationship between rhizome length and rhizome weight (0.894), followed by rhizome weight and root weight (0.835). In conclusion, the study highlights the beneficial effects of colored shading on the yield components of K. parviflora, emphasizing the potential for optimized cultivation practices to enhance crop productivity.

Dynamic relationship among extracellular matrix and body wall cells in Hirudo verbana morphogenesis

A great bulk of recent experimental evidence suggests the key role of the complex crosstalk between the extracellular matrix (ECM) and the cellular component of tissues during morphogenesis and embryogenesis. In particular, remodeling of the ECM and of its physical interactions pattern with surrounding cells represent two crucial processes that might be involved in muscle development. However, little information is available on this topic, especially on invertebrate species. To obtain new insights on how tuning the ECM microenvironment might drive cellular fate during embryonic development, we used the invertebrate medicinal leech Hirudo verbana as a valuable experimental model, due to its simple anatomy and the recapitulation of many aspects of the basic biological processes of vertebrates. Our previous studies on leech post-embryonic development have already shown the pivotal role of ECM changes during the growth of the body wall and the role of Yes-associated protein 1 (YAP1) in mechanotransduction. Here, we suggest that the interactions between stromal cell telocytes and ECM might be crucial in driving the organization of muscle layers during embryogenesis. Furthermore, we propose a possible role of the pleiotropic enzyme HvRNASET2 as a possible modulator of collagen deposition and ECM remodeling not only during regenerative processes (as previously demonstrated) but also in embryogenesis.

Dynamics of cell wall-binding proteins at a single molecule level: B. subtilis autolysins show different kinds of motion.

The bacterial cell wall is a meshwork of crosslinked peptidoglycan strands, with a thickness of up to 50 nm in Firmicutes. Little is known about how proteins move through the cell wall to find sites of enzymatic activity. Cell wall synthesis for cell elongation involves the integration of new peptidoglycan strands by integral membrane proteins, as well as the degradation of existing strands by so-called autolysins, soluble proteins that are secreted through the cell membrane. Autolysins comprise different classes of proteases and glucanases and mostly contain cell-wall binding domains in addition to their catalytic domain. We have studied dynamics of Bacillus subtilis autolysins LytC, a major endopeptidase required for lateral cell wall growth, and LytF, a peptidase acting at the newly formed division site in order to achieve separation of daughter cells. We show that both proteins, fused to moxVenus are present as three distinct populations of different diffusion constants. The fastest population is compatible with free diffusion in a crowded liquid environment, that is similar to that of cytosolic enzymes, likely reflecting autolysins diffusing through the periplasm. The medium mobile fraction can be explained by constrained motion through a polymeric substance, indicating mobility of autolysins through the wall similar to that of DNA-binding proteins within the nucleoid. The slow-mobile fraction are most likely autolysins bound to their specific substrate sites. We show that LytF is more static during exponential phase, while LytC appears to be more active during the transition to stationary phase. Both autolysins became more static in backgrounds lacking redundant other autolysins, suggesting stochastic competition for binding sites. On the other hand, lack of inhibitor IseA or autolysin CwlS lead to an altered preference for polar localization of LytF within the cell wall, revealing that inhibitors and autolysins also affect each other's pattern of localization, in addition to their activity.

Integrated physiological, transcriptomic, and metabolomic analyses of drought stress alleviation in Ehretia macrophylla Wall. seedlings by SiO2 NPs (silica nanoparticles).

With environmental problems such as climate global warming, drought has become one of the major stress factors, because it severely affects the plant growth and development. Silicon dioxide nanoparticles (SiO2 NPs) are crucial for mitigating abiotic stresses suffered by plants in unfavorable environmental conditions and further promoting plant growth, such as drought. This study aimed to investigate the effect of different concentrations of SiO2 NPs on the growth of the Ehretia macrophylla Wall. seedlings under severe drought stress (water content in soil, 30-35%). The treatment was started by starting spraying different concentrations of SiO2 NPs on seedlings of Ehretia macrophyla, which were consistently under normal and severe drought conditions (soil moisture content 30-35%), respectively, at the seedling stage, followed by physiological and biochemical measurements, transcriptomics and metabolomics analyses. SiO2 NPs (100 mg·L-1) treatment reduced malondialdehyde and hydrogen peroxide content and enhanced the activity of antioxidant enzymes under drought stress. Transcriptomic analysis showed that 1451 differentially expressed genes (DEGs) in the leaves of E. macrophylla seedlings were regulated by SiO2 NPs under drought stress, and these genes mainly participate in auxin signal transduction and mitogen-activated protein kinase signaling pathways. This study also found that the metabolism of fatty acids and α-linolenic acids may play a key role in the enhancement of drought tolerance in SiO2 NP-treated E. macrophylla seedlings. Metabolomics studies indicated that the accumulation level of secondary metabolites related to drought tolerance was higher after SiO2 NPs treatment. This study revealed insights into the physiological mechanisms induced by SiO2 NPs for enhancing the drought tolerance of plants.

The changing morphology of the ventricular walls of mouse and human with increasing gestation.

That the highly trabeculated ventricular walls of the developing embryos transform to the arrangement during the fetal stages, when the mural architecture is dominated by the thickness of the compact myocardium, has been explained by the coalescence of trabeculations, often erroneously described as 'compaction'. Recent data, however, support differential rates of growth of the trabecular and compact layers as the major driver of change. Here, these processes were assessed quantitatively and visualized in standardized views. We used a larger dataset than has previously been available of mouse hearts, covering the period from embryonic day 10.5 to postnatal day 3, supported by images from human hearts. The volume of the trabecular layer increased throughout development, in contrast to what would be expected had there been 'compaction'. During the transition from embryonic to fetal life, the rapid growth of the compact layer diminished the proportion of trabeculations. Similarly, great expansion of the central cavity reduced the proportion of the total cavity made up of intertrabecular recesses. Illustrations of the hearts with the median value of left ventricular trabeculation confirm a pronounced growth of the compact wall, with prominence of the central cavity. This corresponds, in morphological terms, to a reduction in the extent of the trabecular layer. Similar observations were made in the human hearts. We conclude that it is a period of comparatively slow growth of the trabecular layer, rather than so-called compaction, that is the major determinant of the changing morphology of the ventricular walls of both mouse and human hearts.

Stratigraphic evolution of a salt-walled basin: the influence of diapirism and compressional tectonics on the sedimentary record of the Estopanyà syncline (South-Central Pyrenees)

This contribution describes the influence of diapirism and compressional tectonics in the sedimentary record of the Estopanyà and Boix synclines (salt-walled basins) in the South-Central Pyrenees (NE Spain). Based on mapping and logging of five stratigraphic sections, two lithostratigraphic units (LU-1 and 2) along the eastern diapir margin of these synclines and five more (LU-3 to 7) in their inner parts are defined. LU-1 and 2 consist of monomictic breccias deposited probably during the Upper Triassic-Oligocene and the Upper Cretaceous, respectively. LU-3 to 7 constitute a marine to fluvial succession of the Tremp Group deposited during the Upper Cretaceous to Paleocene. The stratigraphic and sedimentological record indicates that the topography, position, and accommodation space of the Estopanyà and Boix synclines was actively controlled by the evolution of salt structures from the Late Cretaceous to the Oligocene in response to the advance of the Alpine compression in the South-Central Pyrenees. The growth of salt-inflated ridges with a near parallel orientation to the axis of the studied synclines since the Upper Cretaceous, progressively compartmentalized the Boix syncline until inhibiting sedimentation during the lower Paleocene. In the upper Paleocene, the Alpine compression approached the study area increasing salt evacuation and the subsidence of the Estopanyà and Boix synclines. During the early to middle Ypresian, onset of compression led to salt expulsion by piercing the sedimentary roof of the inherited salt-inflated ridges and forming two salt walls at the eastern margin of the Estopanyà and Boix synclines that were squeezed and welded (possibly through secondary welds) due to tectonic compression during the Oligocene. This contribution provides a new interpretation of the structural and stratigraphic evolution of the Estopanyà and Boix synclines, proposing an evolutionary model that includes the rejuvenation, growth, and extrusion of salt walls as deciphered from the stratigraphy, sedimentology, and petrology of the diapir margin breccias and the sedimentary succession of the adjoining salt-embedded basins. Hence, it provides a new analogue study for understanding the interplay between compressional tectonics, diapirism, and sedimentation to other inverted salt basins with precursor salt walls worldwide.

A continuum mechanics model of the plant cell wall reveals interplay between enzyme action and cell wall structure

Plant cell growth is regulated through manipulation of the cell wall network, which consists of oriented cellulose microfibrils embedded within a ground matrix incorporating pectin and hemicellulose components. There remain many unknowns as to how this manipulation occurs. Experiments have shown that cellulose reorients in cell walls as the cell expands, while recent data suggest that growth is controlled by distinct collections of hemicellulose called biomechanical hotspots, which join the cellulose molecule together. The enzymes expansin and Cel12A have both been shown to induce growth of the cell wall; however, while Cel12A’s wall-loosening action leads to a reduction in the cell wall strength, expansin’s has been shown to increase the strength of the cell wall. In contrast, members of the XTH enzyme family hydrolyse hemicellulose but do not appear to cause wall creep. This experimentally observed behaviour still awaits a full explanation. We derive and analyse a mathematical model for the effective mechanical properties of the evolving cell wall network, incorporating cellulose microfibrils, which reorient with cell growth and are linked via biomechanical hotspots made up of regions of crosslinking hemicellulose. Assuming a visco-elastic response for the cell wall and using a continuum approach, we calculate the total stress resultant of the cell wall for a given overall growth rate. By changing appropriate parameters affecting breakage rate and viscous properties, we provide evidence for the biomechanical hotspot hypothesis and develop mechanistic understanding of the growth-inducing enzymes.Graphic

Multistability of roller structures under parametric excitation of capillary waves in a square cell with a round protrusion in the center

In nonlinear systems with instability, multistability often occurs. When studying processes occurring in real environments, the problem arises of finding paths leading to any state of equilibrium and searching for new stable states. In two-dimensional systems, they can consist of domains and differ in orientation in space. The goal of the work is to experimentally determine the features of the generation of multidomain structures in a two-dimensional system in the presence of complex boundaries of a liquid layer that experiences periodic vertical oscillations. The paper presents the results of an experimental study of the dynamics of roller domains of parametrically excited capillary waves in a square cell with a round insert in the center of the cell. In different domains, the rollers were oriented parallel and perpendicular to the boundaries of the cuvette and the boundaries of the circular insert. It was found that the dynamics of domains is determined by the movement of their fronts, and depending on the initial and boundary conditions, stable two-dimensional roller structures can appear at the edges of a square cell with a round protrusion in the center of the cell. In different domains, the rollers had different orientations. In this case, roundings with a large radius had the strongest effect on the dynamics of defects. Multistability of equilibrium states of roller structures was discovered, characterized by the fact that, with constant system parameters, various scenarios of domain competition arose, leading to 11 different stable equilibrium states, which differed in the number of domains, their shape and the presence of spatial symmetry. It turned out that during the occurrence of defects and the growth of domain walls, slow liquid flows arise near the boundaries of the cuvette and the circular insert. The rollers begin to move, and then a new stable equilibrium state is established in the form of a single domain containing one or two domain walls. It has been experimentally shown that the most stable equilibrium states of domains arise when the circular protrusion is symmetrically positioned relative to the sides of the cuvette. The results obtained may be of interest when studying the processes of establishing stable regimes in active media under strong competition and when studying the formation of two-dimensional structures from conducting particles capable of scattering electromagnetic waves.

Comparative transcriptome analysis of resistant and susceptible watermelon genotypes reveals the role of RNAi, callose, proteinase, and cell wall in squash vein yellowing virus resistance.

Watermelon (Citrullus lanatus) is the third largest fruit crop in the world in term of production. However, it is susceptible to several viruses. Watermelon vine decline (WVD), caused by whitefly-transmitted squash vein yellowing virus (SqVYV), is a disease that has caused over $60 million in losses in the US and continues to occur regularly in southeastern states. Understanding the molecular mechanisms underlying resistance to SqVYV is important for effective disease management. A time-course transcriptomic analysis was conducted on resistant (392291-VDR) and susceptible (Crimson Sweet) watermelon genotypes inoculated with SqVYV. Significantly higher levels of SqVYV were observed over time in the susceptible compared to the resistant genotype. The plasmodesmata callose binding protein (PDCB) gene, which is responsible for increased callose deposition in the plasmodesmata, was more highly expressed in the resistant genotype than in the susceptible genotype before and after inoculation, suggesting the inhibition of cell-to-cell movement of SqVYV. The potential role of the RNA interference (RNAi) pathway was observed in the resistant genotype based on differential expression of eukaryotic initiation factor (eIF), translin, DICER, ribosome inactivating proteins, RNA-dependent RNA polymerase (RDR), and Argonaute (AGO) genes after inoculation. The significant differential expression of hormone-related genes, including those involved in the ethylene, jasmonic acid, auxin, cytokinin, gibberellin, and salicylic acid signaling pathways, was observed, emphasizing their regulatory roles in the defense response. Genes regulating pectin metabolism, cellulose synthesis, cell growth and development, xenobiotic metabolism, and lignin biosynthesis were overexpressed in the susceptible genotype, suggesting that alterations in cell wall integrity and growth processes result in disease symptom development. These findings will be helpful for further functional studies and the development of SqVYV-resistant watermelon cultivars.