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Plant cells withstand mechanical stress originating from turgor pressure by robustly maintaining the mechanical properties of the cell wall. This applies at the organ scale as well; many plant stems act as pressurized cylinders, where the epidermis is under tension and inner tissues are under compression. The clavata3 de-etiolated3 (clv3-8 det3-1) double mutant of Arabidopsis thaliana displays cracks in its stems because of a conflict between the mechanical properties of the weak epidermis and over-proliferation of inner stem tissues. In this work, we conducted three-point bending tests on various Arabidopsis thaliana mutants, including those displaying the stem cracking phenotype, to examine the differences in their mechanical properties. The clv3-8 det3-1 double mutant exhibited reduced stem stiffness, consistent with reduced differentiation due to the clv3-8 mutation. Yet, in clv3-8, stem cross-sectional area was increased associating with the increase in vascular bundle number, and stem cross-sections displayed various shapes. To uncouple the contribution of geometry and cell-wall differentiation to the mechanical properties of the whole stems, we tested the contribution of lignified fibers to stem stiffness. In order to suppress lignin deposition in stems genetically, we generated multiple higher-order mutants by crossing clv3-8 and/or det3-1 with nst1-1 nst3-1, in which lignin deposition is suppressed. Stem stiffness was reduced markedly in all nst1-1 nst3-1 mutant backgrounds. Overall, our results suggest that stem stiffness relies on the presence of differentiated, lignified, fiber tissue as well as on the alignment or spatial distribution of vascular bundles within the stem organ. [ABSTRACT FROM AUTHOR]

Base-cutting is essential in sugarcane harvesting, and violent collisions between the base-cutter and stalk can cause stubble damage. Therefore, it is necessary to study the base-cutting mechanism to reduce stubble damage. Based on the mechanical analysis method, this study analysed the base-cutting process of sugarcane vascular bundles and stems from fibber and macro perspectives, respectively. In addition, the base-cutting process was simulated based on Discrete Element Method, and field experiments were conducted to validate the analysis results. The tensile length function L (z) of the vascular bundle was derived from a fibber perspective. A mechanical model of the cutting force on the entire stem was obtained from a macro perspective. From the equations, it can be found that the kinematic parameters of the base-cutter have a significant influence on the cutting force. The simulation test revealed that the cutting force increased sharply when the blade was cut into stems, and the maximum cutting force reached 146.9N. Field tests were conducted to explore the relationship between these factors and the stubble damage rate. To decrease the damage rate to a smaller level, the single-factor test results showed that the forward speed of harvester, rotational speed of disc, and cutting depth should be controlled in the range of 0.8–1.4 m s−1, 600–1000 r·min−1, and 60–120 mm, respectively. The response surface test showed that the order of the effect of each factor on stubble damage was forward speed > rotational speed > cutting depth. The lowest stubble damage rate was 6.20% when the forward speed, rotational speed of disc, and cutting depth were 1.4 m s−1, 800 r·min−1, and 79.07 mm, respectively. After experimental field verification, the damage rate met the harvesting standard. • Under-the-ground base-cutting mechanism and processes were revealed in this study. • Tensile length function and mechanical model were got in different perspectives. • The soil around root-soil composite can decrease damage of stubble during cutting. • The maximum cutting force reached to 146.9N when blade completely cut into stem. • The optimal parameters of factors and interaction were explored by field tests. [ABSTRACT FROM AUTHOR]

SUMMARY: Proline metabolism plays a crucial role in both environmental stress responses and plant growth. However, the specific mechanism by which proline contributes to abiotic stress processes remains to be elucidated. In this study, we utilized atrzf1 (Arabidopsis thaliana ring zinc finger 1) as a parental line for T‐DNA tagging mutagenesis and identified a suppressor mutant of atrzf1, designated proline content alterative 31 (pca31). The pca31 mutant suppressed the insensitivity of atrzf1 to dehydration stress during early seedling growth. Using Thermal Asymmetric Interlaced‐PCR, we found that the T‐DNA of pca31 was inserted into the promoter region of the At2g22620 gene, which encodes the cell wall enzyme rhamnogalacturonan lyase 1 (RGL1). Enzymatic assays indicated that RGL1 exhibited rhamnogalacturonan lyase activity, influencing cell wall pectin composition. The decrease in RGL1 gene expression suppressed the transcriptomic perturbation of the atrzf1 mutant. Silencing of the RGL1 gene in atrzf1 resulted in a sensitive phenotype similar to pca31 under osmotic stress conditions. Treatment with mannitol, salt, hydrogen peroxide, and abscisic acid induced RGL1 expression. Furthermore, we uncovered that RGL1 plays a role in modulating root growth and vascular tissue development. Molecular, physiological, and genetic experiments revealed that the positive modulation of RGL1 during abiotic stress was linked to the AtRZF1 pathway. Taken together, these findings establish that pca31 acts as a suppressor of atrzf1 in abiotic stress responses through proline and cell wall metabolisms. Significance Statement: RGL1 exhibits rhamnogalacturonan lyase activity, which contributes to the modulation of pectin composition, vascular tissue development, and root growth. RGL1, as a suppressor of E3 ubiquitin ligase AtRZF1, functions as a positive modulator in proline synthesis and cell wall metabolism under osmotic stress conditions. [ABSTRACT FROM AUTHOR]

Exogenous gibberellic acid was applied to regulate fruit growth of grapes to acquire high quality seedless berries. The vascular bundles provide the pathway of water and nutrient transport into the fruit and play an important role in berry growth and sugar accumulation. Therefore, changes in berry size and quality are closely related to the structure and function of the vascular tissue. In this study, 10-year-old “Shine Muscat” grape vines were treated with GA3 in grapevine production. Based on previous research and experimental environmental conditions, four treatments were applied: elongating cluster（5 mg L−1 GA3 on Apr. 28）+ seedless（25 mg L−1 GA3 on May. 24）+ expanding（50 mg L−1 GA3 on Jun. 7） (T1), seedless（25 mg L−1 GA3 on May. 24）+ expanding（50 mg L−1 GA3 on Jun. 7） (T2), expanding（50 mg L−1 GA3 on Jun. 7） (T3) and water (CK). Compared to CK, all fruits treated with GA3 had greater berry size. In addition, GA3 treated grapes had greater vascular bundle areas, including the areas of both phloem and xylem, as well as a greater number of vessels compared to control fruit. During the first rapid growth stage, water transport into the grape was rapid and did not differ among treatments. During veraison, the water transport rate among the four treatments differed, and the rank of speed was T2>T3>CK>T1. Therefore, we found that GA3 treatment can significantly promote the differentiation of vascular tissues and improve water transport capacity and phloem sugar unloading; T2 promoted the development of vascular bundles, enhanced water transport speed and phloem sugar unloading of fruit after veraison, and increased berry size.

Recently developed ‘super’ rice cultivars with greater yield potentials often suffer from the problem of poor grain filling, especially in inferior spikelets. Here, we studied the activities of enzymes related to starch metabolism in rice stems and grains, and the microstructures related to carbohydrate accumulation and transportation to investigate the effects of different water regimes on grain filling. Two ‘super’ rice cultivars were grown under two irrigation regimes of well-watered (WW) and alternate wetting and moderate soil drying (AWMD). Compared with the WW treatment, the activities of ADP glucose pyrophosphorylase (AGPase), starch synthase (StSase) and starch branching enzyme (SBE), and the accumulation of non-structural carbohydrates (NSCs) in the stems before heading were significantly improved, and more starch granules were stored in the stems in the AWMD treatment. After heading, the activities of α-amylase, β-amylase, sucrose phosphate synthase (SPS) and sucrose synthase in the synthetic direction (SSs) were increased in the stems to promote the remobilization of NSCs for grain filling under AWMD. During grain filling, the enzymatic activities of sucrose synthase in the cleavage direction (SSc), AGPase, StSase and SBE in the inferior spikelets were increased, which promoted grain filling, especially for the inferior spikelets under AWMD. However, there were no significant differences in vascular microstructures. The grain yield and grain weight could be improved by 13.1 and 7.5%, respectively, by optimizing of the irrigation regime. We concluded that the low activities of key enzymes in carbon metabolism is the key limitation for the poor grain filling, as opposed to the vascular microstructures, and AWMD can increase the amount of NSC accumulation in the stems before heading, improve the utilization rate of NSCs after heading, and increase the grain filling, especially in the inferior spikelets, by altering the activities of key enzymes in carbon metabolism.

Bamboo is a typical natural fiber-reinforced composite with excellent mechanical properties, which are determined by its special micro-structure. As the reinforcing phase, the vascular bundles play a central role in the control of the mechanical properties of bamboo macro-structure. To find the exact gradient variation of the mechanical properties of these continuously distributed vascular bundles within the bamboo culm, 4-year-old Moso bamboo was chosen to investigate the variation of locate-distribution, cross-section area, and mechanical properties of single vascular bundles along the longitudinal and radial directions with respect to their location from the base, middle, and top sections of bamboo culm, respectively. It shows that the spatial distribution of vascular bundles along the column is distributed exponentially from the inside to the outside of the culm. The cross-section area of the vascular bundles decreased exponentially from the inside to the outside along the radial direction. All the vascular bundles were then carefully separated from bamboo strips and tested via the tensile tests. Test results show that the longitudinal tensile strengths of vascular bundles ranged from 180.44 to 774.10 MPa, and the longitudinal Young's modulus ranged from 9.00 to 44.76 GPa. The tensile strength of vascular bundles at the outer side was three times higher than that of the inner side, while Young's modulus at the outer side was three to four times higher than that of the inner side. For all three height positions, the strengths and Young's modulus of vascular bundles are all exponentially increased from the inner side to the outer side along the radial direction. This work will provide a basis for the highly processed product's application of bamboo resources and a reference for further study on the trans-scale analysis of the mechanical properties of bamboo. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the gradient properties of bamboo at the microscopic level and provide a basis for improving the utilization rate of bamboo. Using moso bamboo (Phyllostachys edulis (Carrière) J. Houz.) as a research subject, the variation of vascular bundle area percentage, chemical content, relative crystallinity (CR), mechanical properties of different bamboo slivers, and correlation between those parameters were analyzed. From the bamboo green layer (BGL) to the bamboo yellow layer (BYL), the distribution of vascular bundles changed from dense to sparse. Cellulose and lignin mass content decreased gently, and hemicellulose mass content showed gradual increases. The CR showed an order of bamboo middle layer (BML) > BGL > BYL. The tensile modulus of elasticity, tensile strength, bending modulus of elasticity, and bending strength decreased from BGL to BYL. The order of influence degree on mechanical properties of moso bamboo was vascular bundle area, hemicellulose content, lignin mass content, density, and CR, and these factors correlated with mechanical properties at a significant level (p < 0.05). Vascular bundle area had a decisive effect on the mechanical properties of bamboo. The vascular bundle area and density were linearly correlated with mechanical properties, while the lignin mass content and CR were curve-linearly correlated with mechanical properties. [ABSTRACT FROM AUTHOR]

The unique zigzag-patterned tea plant is a rare germplasm resource. However, the molecular mechanism behind the formation of zigzag stems remains unclear. To address this, a BC1 genetic population of tea plants with zigzag stems was studied using histological observation and bulked segregant RNA-seq. The analysis revealed 1494 differentially expressed genes (DEGs) between the upright and zigzag stem groups. These DEGs may regulate the transduction and biosynthesis of plant hormones, and the effects on the phenylpropane biosynthesis pathways may cause the accumulation of lignin. Tissue sections further supported this finding, showing differences in cell wall thickness between upright and curved stems, potentially due to lignin accumulation. Additionally, 262 single-nucleotide polymorphisms (SNPs) across 38 genes were identified as key SNPs, and 5 genes related to zigzag stems were identified through homologous gene function annotation. Mutations in these genes may impact auxin distribution and content, resulting in the asymmetric development of vascular bundles in curved stems. In summary, we identified the key genes associated with the tortuous phenotype by using BSR-seq on a BC1 population to minimize genetic background noise. [ABSTRACT FROM AUTHOR]

Ferns are primitive vascular plants with diverse morphologies and structures. Plant anatomical traits and their linkages can reflect adaptation to the environment; however, these remain are still poorly understood in ferns. The main objective of this study was to explore whether there was structural coordination among and within organs in fern species. We measured 16 hydraulically related anatomical traits of pinnae, petioles, and roots of 24 representative fern species from the tropical and subtropical forest understory and analyzed trait correlation networks. In addition, we examined phylogenetic signals for the anatomical traits and analyzed co-evolutionary relationships. These results indicated that stomatal density and all petiole anatomical traits exhibited significant phylogenetic signals. Evolutionary correlations were observed between the tracheid diameter and wall thickness of the petiole and between the water transport capacity of the petiole and stomatal density. Conversely, anatomical traits of roots (e.g., root diameter) showed no phylogenetic signals and were not significantly correlated with those of the pinnae and petioles, indicating a lack of structural coordination between the below- and above-ground organs. Unlike angiosperms, vein density is unrelated to stomatal density or pinna thickness in ferns. As root diameter decreased, the cortex-to-stele diameter ratio decreased significantly (enhanced water absorption) in angiosperms but remained unchanged in ferns. These differences lead to different responses of ferns to climate change and improve our knowledge of the water adaptation strategies of ferns. [ABSTRACT FROM AUTHOR]

This article explores a unique characteristic of the tree fern species Cyathea rojasiana found in a tropical montane forest in Panama. The senescent leaves of this fern bend downwards and touch the ground, where they decompose and transform into living roots that provide nutrients to the rest of the plant. This adaptation has not been observed in other tree ferns and may have been overlooked in other species as well. The article also provides information about the distribution and habitat of C. rojasiana. The text raises questions about the ecological significance of this adaptation and suggests that there may be more undiscovered nutrient uptake adaptations in plants living in nutrient-poor environments. [Extracted from the article]

Cork spot-like physiological disorder (CSPD) is a newly identified issue in 'Kurenainoyume' apples, yet its mechanism remains unclear. To investigate CSPD, we conducted morphological observations on 'Kurenainoyume' apples with and without pre-harvest fruit-bagging treatment using light-impermeable paper bags. Non-bagged fruit developed CSPD in mid-August, while no CSPD symptoms were observed in bagged fruit. The bagging treatment significantly reduced the proportion of opened lenticels, with only 17.9% in bagged fruit compared to 52.0% in non-bagged fruits. In non-bagged fruit, CSPD spots tended to increase from the lenticels, growing in size during fruit development. The cuticular thickness and cross-sectional area of fresh cells in CSPD spots were approximately 16 µm and 1600 µm², respectively. Healthy non-bagged fruit reached these values around 100 to 115 days after full bloom from mid- to late August. Microscopic and computerized tomography scanning observations revealed that many CSPD spots developed at the tips of vascular bundles. Therefore, CSPD initiation between opened lenticels and vascular bundle tips may be influenced by water stress, which is potentially caused by water loss, leading to cell death and the formation of CSPD spots. [ABSTRACT FROM AUTHOR]

Plant growth regulators are synthetic compounds that have become a significant and technical guarantee for agricultural productivity. In China, ''Jindeli'', which contains active elements of ethephon and cycocel (EC), has been proven to prevent maize stem elongation, improve maize stem thickness, stem morphology and mechanical strength, root growth, lodging resistance, and yield under various cultivation models. Diethyl aminoethyl hexanoate (DA-6) can promote cell division and growth. From 2020–2021, four growth regulators sprays were used to conduct a field experiment; G1: water spraying; G2: EC spraying; G3: DA-6 spraying; G4: EC+DA-6 spraying under two cultivation models; R: ridge covered with plastic film mulching and T: traditional flat planting without plastic mulching. The results indicated that RG4 treatment considerably decreased plant height, internode length, ear height, lodging rate, and center of gravity height, while improved the internode bending strength, cross-sectional area, cortical thickness, and stem vascular bundles as compared with rest of all other treatments. RG4 treatment considerably improved internode diameter, stem mechanical strength, filling degree, root growth, mean tilt angle, and lignin content, while significantly reducing LAI. In addition, RG4 considerably enhanced the quality of corn stems, such as increasing mechanical properties and enhancing the compressive strength of corn stalks that content of hemicellulose, cellulose, and lignin has been increased. Furthermore, RG4 treatment significantly improved grain yield by optimizing leaf layer structure and increasing bleeding saps levels, increasing the grains per row and ear. Thus, under the RG4 treatment maize lodging rate was decreased 72.1%, and increased WUE (52.8%), and grain yield (46.6%). In conclusion, the results clearly demonstrate that in the semi-arid regions risk of lodging can be avoided by spraying EC+DA-6 with ridge covered plastic film mulching to the enriched stalk quality, shaping plant morphological characteristics, and proving a stable cultivation model to improving maize productivity.

With growing concerns over global warming, cultivating heat-tolerant crops has become paramount to prepare for the anticipated warmer climate. Cassava (Manihot esculenta Crantz), a vital tropical crop, demonstrates exceptional growth and productivity under high-temperature (HT) conditions. Yet, studies elucidating HT resistance mechanisms in cassava, particularly within vascular tissues, are rare. We dissected the leaf mid-vein from leaf, and did the comparative transcriptome profiling between mid-vein and leaf to figure out the cassava vasculature HT resistance molecular mechanism. Anatomical microscopy revealed that cassava leaf veins predominantly consisted of vasculature. A thermal imaging analysis indicated that cassava experienced elevated temperatures, coinciding with a reduction in photosynthesis. Transcriptome sequencing produced clean reads in total of 89.17G. Using Venn enrichment, there were 65 differentially expressed genes (DEGs) and 93 DEGs had been found highly specifically expressed in leaf and mid-vein. Further investigation disclosed that leaves enhanced pyruvate synthesis as a strategy to withstand high temperatures, while mid-veins fortified themselves by bolstering lignin synthesis by comprehensive GO and KEGG analysis of DEGs. The identified genes in these metabolic pathways were corroborated through quantity PCR (QPCR), with results aligning with the transcriptomic data. To verify the expression localization of DEGs, we used in situ hybridization experiments to identify the expression of MeCCoAMT(caffeoyl-coenzyme A-3-O-methyltransferase) in the lignin synthesis pathway in cassava leaf veins xylem. These findings unravel the disparate thermotolerance mechanisms exhibited by cassava leaves and mid-veins, offering insights that could potentially inform strategies for enhancing thermotolerance in other crops. [ABSTRACT FROM AUTHOR]

We present anatomical imaging techniques and measurements that are useful additions to the existing morphological toolbox for the identification of seven coastal grasses and one rush. Our method is simple and inexpensive and requires the removal of only one leaf, which prevents removal of plants from their habitats. This method can also be used in seasons when reproductive structures (important for current morphological ID efforts) are not present. We find significant quantitative differences in leaf width, adaxial to abaxial ratios (ADAB ratio, which we introduce as a new parameter), vascular bundle cross-sectional areas, and interveinal distances, as well as providing images for qualitative analysis of these plants' anatomies; including differences in bundle sheath structures, fiber distributions, epidermal and cuticular properties, and chloroplast positioning. [ABSTRACT FROM AUTHOR]

Bamboo is a natural vascular bundle (VB) reinforced composite material used in more than 10 fields such as construction and furniture. The nodes in bamboo are crucial to its mechanical properties, but understanding of its performance is limited by lack of knowledge about the three-dimensional (3D) structure of the node. This work aimed to non-destructively identify the multi-dimensional characteristics of the VB in a bamboo branched node (BN) using X-ray microtomography (μCT). The VB was segmented from the BN using deep learning combined with the Watershed algorithm. The 3D model reconstruction and characterization of the VB were also conducted. It was found that the structure of VBs showed significant changes along the height of the BN. The VBs formed a complex 3D structure, VBs of the culm are connected with those of the branch, and the connectivity of the conducting tissue and fibers was 88.91% and 99.95%, respectively. The conducting tissue and the fibers had similar shapes but varying thicknesses, which enabled VBs to perform both water transport and mechanical support functions. The volumes fraction of parenchyma, fibers, and conducting tissue in the BN were 61.3%, 35.3%, and 3.4%, respectively, but the tissue proportion of the different heights of the BN varied from each other. The nodal ridge was a mechanical weak point of the BN, with a maximum fibers proportion of 43.8%. This study contributes to understanding the relationship of VBs between the branch and the culm. It provides a structural perspective for understanding the mechanical properties of BN and a theoretical basis for optimizing bamboo utilization efficiency. [ABSTRACT FROM AUTHOR]

Bamboo is a typical natural fiber-reinforced composite with excellent mechanical properties, which are determined by its special micro-structure. As the reinforcing phase, the vascular bundles play a central role in the control of the mechanical properties of bamboo macro-structure. To find the exact gradient variation of the mechanical properties of these continuously distributed vascular bundles within the bamboo culm, 4-year-old Moso bamboo was chosen to investigate the variation of locate-distribution, cross-section area, and mechanical properties of single vascular bundles along the longitudinal and radial directions with respect to their location from the base, middle, and top sections of bamboo culm, respectively. It shows that the spatial distribution of vascular bundles along the column is distributed exponentially from the inside to the outside of the culm. The cross-section area of the vascular bundles decreased exponentially from the inside to the outside along the radial direction. All the vascular bundles were then carefully separated from bamboo strips and tested via the tensile tests. Test results show that the longitudinal tensile strengths of vascular bundles ranged from 180.44 to 774.10 MPa, and the longitudinal Young’s modulus ranged from 9.00 to 44.76 GPa. The tensile strength of vascular bundles at the outer side was three times higher than that of the inner side, while Young’s modulus at the outer side was three to four times higher than that of the inner side. For all three height positions, the strengths and Young’s modulus of vascular bundles are all exponentially increased from the inner side to the outer side along the radial direction. This work will provide a basis for the highly processed product’s application of bamboo resources and a reference for further study on the trans-scale analysis of the mechanical properties of bamboo.

This study aimed to investigate the gradient properties of bamboo at the microscopic level and provide a basis for improving the utilization rate of bamboo. Using moso bamboo (Phyllostachys edulis (Carrière) J. Houz.) as a research subject, the variation of vascular bundle area percentage, chemical content, relative crystallinity (CR), mechanical properties of different bamboo slivers, and correlation between those parameters were analyzed. From the bamboo green layer (BGL) to the bamboo yellow layer (BYL), the distribution of vascular bundles changed from dense to sparse. Cellulose and lignin mass content decreased gently, and hemicellulose mass content showed gradual increases. The CR showed an order of bamboo middle layer (BML) > BGL > BYL. The tensile modulus of elasticity, tensile strength, bending modulus of elasticity, and bending strength decreased from BGL to BYL. The order of influence degree on mechanical properties of moso bamboo was vascular bundle area, hemicellulose content, lignin mass content, density, and CR, and these factors correlated with mechanical properties at a significant level (p < 0.05). Vascular bundle area had a decisive effect on the mechanical properties of bamboo. The vascular bundle area and density were linearly correlated with mechanical properties, while the lignin mass content and CR were curve-linearly correlated with mechanical properties.

The unique zigzag-patterned tea plant is a rare germplasm resource. However, the molecular mechanism behind the formation of zigzag stems remains unclear. To address this, a BC1 genetic population of tea plants with zigzag stems was studied using histological observation and bulked segregant RNA-seq. The analysis revealed 1494 differentially expressed genes (DEGs) between the upright and zigzag stem groups. These DEGs may regulate the transduction and biosynthesis of plant hormones, and the effects on the phenylpropane biosynthesis pathways may cause the accumulation of lignin. Tissue sections further supported this finding, showing differences in cell wall thickness between upright and curved stems, potentially due to lignin accumulation. Additionally, 262 single-nucleotide polymorphisms (SNPs) across 38 genes were identified as key SNPs, and 5 genes related to zigzag stems were identified through homologous gene function annotation. Mutations in these genes may impact auxin distribution and content, resulting in the asymmetric development of vascular bundles in curved stems. In summary, we identified the key genes associated with the tortuous phenotype by using BSR-seq on a BC1 population to minimize genetic background noise.

The visualization and evaluation of fruit vascular bundles in grape are indispensable for understanding the development and growth of the fruit. The vascular bundles in grape are as thin as human hair, and strongly adhere to flesh cells, making it difficult to isolate individual intact vessel elements. Currently there is little information about methods to characterize grape vascular tissue. In this study, we describe an easy and effective technique to visualize the xylem cell structure of the ‘Red Globe’ grape (Vitis L.). The intact vascular bundles of the grape were isolated through enzymatic degradation of flesh cells by hydrolases which were effective in removing flesh cells from vascular bundles. This enabled the illustration of the fine surface structure of vessel elements and their arrangement in the vascular bundles of the grape. This modified method to separate the vascular bundles into individual vessel elements was more effective than former methods of manually shaking to isolate individual vessels. Clear images of xylem vessel arrangement and structural characteristics of individual vessel element were acquired by light microscopy (BX51, Olympus, Tokyo, Japan), transmission electron microscopy (Tecnai 12, Philips, Netherlands) and scanning electron microscopy (GeminiSEM 300, Carl Zeiss, Germany). In addition, the 3D structure of vessel elements was observed using confocal laser scanning microscopy (Zeiss: model: LSM-880, Oberkochen, Germany). The imaging techniques for visualizing and analyzing the structure of xylem vessels in grape described in this study are an improvement of past methods. An effective method to isolate grape vascular bundles from flesh cells was also developed, which enables the imaging of the fine surface structure of vessel elements and their arrangement in grape vascular bundles. By adjusting the process of maceration of vascular bundles, an easy and effective method was developed to gently disrupt the plant tissue and isolate individual vessel elements. These improved techniques are suitable to observe the intact morphology of vascular bundles in the grape, improve experimental efficiency and accelerate new discoveries on the anatomical structure of the grape.

The vascular anatomy and morphology structure of the Allium sativum flower were studied. New morphological features were investigated for taxonomy in Amaryllidaceae. 15 flowers of Allium sativum were sectioned using standard methods of Paraplast embedding and serial sectioning at 20 mm thickness. Sections were stained with Safranin and Astra Blau and mounted in Eukitt. We find three vertical zones in the Allium sativum gynoecium: synascidiate, symplicate and hemisymplicate. The micromorphology and vascular flower anatomy were described by using flowers transverse sections. The Allium sativum peduncle contains 6 vascular bundles - three large and three small ones, which branch out and form a circle of vascular bundles - a vascular cylinder, from which at the level of the peduncle they depart six pairs of vascular bundles, traces of tepals, traces of stamens and above - traces of dorsal carpel bundles. Stamens depart from the ovary wall. In the center of the ovary, there remains a circle of small vascular bundles- the roots of the ventral complex, which were reorganized above, with the appearance of locules, into ventral carpel bundles, which supplied ovules and end blindly. In the same way, the dorsal carpel bundles also end blindly. The trace of the ovules was single-bundle. The traces of the dorsal carpel bundles were single-bundled. There were 6 ovules, 2 ovules in each locule. Traces of stamens and traces of inner and outer tepals were single-bundled. The study of new features of vascular anatomy and flower morphology will make a significant contribution to the taxonomy of the Amaryllidaceae family. [ABSTRACT FROM AUTHOR]

A large vascular bundle number (VBN) in the panicle neck in rice (Oryza sativa L.) is related to the ability to transport assimilates from stem and leaf to reproductive organs during seed maturation. Several quantitative trait loci (QTLs) for VBN have been identified by using segregating populations derived from a cross between indica and japonica rice cultivars. However, the detailed location, effect, and interaction of QTLs for VBN were not understood well. Here, to elucidate the genetic basis of VBN, we identified three stable QTLs for VBN--qVBN5, qVBN6 and qVBN11--by using 71 recombinant inbred lines derived from a cross between indica 'IR24' and japonica 'Asominori'. We confirmed their positions and characterized their effects by using chromosome segment substitution lines (CSSLs) with an 'IR24' genetic background. qVBN6 had the most substantial effect on VBN, followed by qVBN11 and qVBN5. We developed pyramided lines carrying two QTLs for VBN to estimate their interaction. The combination of qVBN6 and qVBN11 accumulated VBN negatively in the pyramided lines owing to the independent actions of each QTL. The QTLs detected for VBN will enhance our understanding of genetic mechanisms of VBN and can be used in rice breeding. [ABSTRACT FROM AUTHOR]

The stems of six species of Bromus (B. scoparius L., B. lanceolatus Roth., B. sterilis L., B. madritensis L., B. squarrosus L. and B. danthoniae Trin.) which belongs to Poaceae family grown in Duhok province, Kurdistan region, Iraq were examined anatomically. The samples of Bromus species have been collected from Duhok city in spring 2022. The research was carried out at Biology department, Faculty of science, University of Zakho. The study aims to distinguish between the anatomical differences among the Bromus species since they share phenotypic traits that make it difficult to distinguish them apart. The samples were fixed in formalin-acetic-acid alcohol (FAA) and cross sections were prepared, examined using compound light microscope and photographed at different power. The highest number and measures of the vascular bundles, thicknesses of cuticle, epidermis, hypodermis, and the diameters of the minor and major vascular bundles (stele) were recorded in the B. danthoniae. while, the highest dimeters of metaxylem and cross section of stem were appeared in B. scoparius and B. sterilis, respectively. On the other hand, the lowest number and measures of the above-mentioned features were fluctuated among the Bromus sterilis, B. lanceolatus, B. madritensis. The cross sections indicated that there were valuable differences in both qualitative and quantitative values of the anatomical features among the species. [ABSTRACT FROM AUTHOR]

The stems of six species of Bromus (B. scoparius L., B. lanceolatus Roth., B. sterilis L., B. madritensis L., B. squarrosus L. and B. danthoniae Trin.) which belongs to Poaceae family grown in Duhok province, Kurdistan region, Iraq were examined anatomically. The samples of Bromus species have been collected from Duhok city in spring 2022. The research was carried out at Biology department, Faculty of science, University of Zakho. The study aims to distinguish between the anatomical differences among the Bromus species since they share phenotypic traits that make it difficult to distinguish them apart. The samples were fixed in formalin- acetic-acid alcohol (FAA) and cross sections were prepared, examined using compound light microscope and photographed at different power. The highest number and measures of the vascular bundles, thicknesses of cuticle, epidermis, hypodermis, and the diameters of the minor and major vascular bundles (stele) were recorded in the B. danthoniae. while, the highest dimeters of metaxylem and cross section of stem were appeared in B. scoparius and B. sterilis, respectively. On the other hand, the lowest number and measures of the above-mentioned features were fluctuated among the Bromus sterilis, B. lanceolatus, B. madritensis. The cross sections indicated that there were valuable differences in both qualitative and quantitative values of the anatomical features among the species.

Aims: In this study, a novel plant growth regulator 2,4-dichloroformamide cyclopropane acid (B2) was used to explore its effects on wheat stalk morphology, chemical composition, anatomical structure, crushing strength and their relationship with lodging resistance. The effects of stem quality change on grain filling and yield were further discussed. Methods: We conducted a series of experiments, including determinations of internode morphology and breaking resistance, analyses of chemical composition and hormone content, observation of internode anatomy, and measurement of grain filling rate, to explore the effects of internode developmental changes induced by B2 treatment on grain filling. Results: Spraying 150 μmol·L−1 B2 at jointing stage significantly decreased plant height, height of center of gravity, basal internode and cell length, while increased stem diameter, wall thickness of basal second internode, cortex thickness, vascular bundle transverse section area and cell cross-sectional area, which resulted in higher breaking strength and culm lodging resistance index. B2 also significantly reduced the content of gibberellin in the second basal internode, and increased the accumulation of lignin and cellulose, thus forming a shorter and stronger stalk. Correlation analysis showed that stem outer diameter, stem wall thickness, cellulose and lignin content were significantly and positively correlated with stem breaking strength. The improvement of stalk structure, especially vascular bundle area, increased bleeding sap, which contributed to grain filling and final yield formation. Conclusions: Lodging resistance and average grain-filling rate can be enhanced by spraying B2 at wheat jointing stage due to the improvement of culm structure, which is conducive to further increase of yield. [ABSTRACT FROM AUTHOR]

Variation in anatomical features of the culm wall namely the shape and size distributions of vascular bundles between different genera and species of bamboo is not well understood due to the cumbersome task of manual measurements. Using machine learning methodology, this work presents a universal vascular bundle detection model for rapid, reliable, and automatic characterization of vascular bundles in culm cross sections of 213 species across 23 genera of Chinese bamboos. The number of vascular bundles and the fiber sheath area have positive linear correlations with the outer circumference and the wall thickness, respectively. The distribution density of vascular bundles has a decay exponential correlation with the outer circumference and the wall thickness. The average fiber volume fraction was 35.2 % ± 7 % with relatively small variation between species. Bamboo species could be grouped into three categories based the endodermis to epidermis distribution pattern of radial and tangential length of vascular bundles, two categories of radial-to-tangential ratio and four categories of fiber sheath area distribution pattern. Implications on bamboo classification, structural and pulp/paper applications were discussed. The findings from this study provide groundwork for the establishment of a unified, authoritative and objective bamboo classification system based on the vascular tissue morphology. [ABSTRACT FROM AUTHOR]

The structure of the bamboo node obviously differs from that of the internode and largely affects the mechanical properties of bamboo. However, the node structure of moso bamboo, an important economic and ecologic bamboo species, was still unclear. Thus, in this study, the 3D structural changes of the vascular bundle (VB) in the moso bamboo node were visualized and quantified. The compressive properties and failure mechanisms of the bamboo node were discussed based on the structural changes. The results showed that the horizontal VB in bamboo node was classified into three types: branching, cross-linking, and thickening. The cross-sectional area of the vertical VB in bamboo node increased, and the vertical VBs shifted to the outer side after passing through the node. Due to the "wire hoop" effect of the horizontal VBs, the longitudinal compressive strength of the node was greater than that of the internode. The deflection of VBs caused slippage between VBs and resulted in the decrease of the node's transversal compressive strength. This research provided key information for a deeper understanding of the structure and mechanical properties of bamboo for potential applications. [ABSTRACT FROM AUTHOR]

BackgroundMaize stover is an important source of crop residues and a promising sustainable energy source in the United States. Stalk is the main component of stover, representing about half of stover dry weight. Characterization of genetic determinants of stalk traits provide a foundation to optimize maize stover as a biofuel feedstock. We investigated maize natural genetic variation in genome-wide association studies (GWAS) to detect candidate genes associated with traits related to stalk biomass (stalk diameter and plant height) and stalk anatomy (rind thickness, vascular bundle density and area).ResultsUsing a panel of 942 diverse inbred lines, 899,784 RNA-Seq derived single nucleotide polymorphism (SNP) markers were identified. Stalk traits were measured on 800 members of the panel in replicated field trials across years. GWAS revealed 16 candidate genes associated with four stalk traits. Most of the detected candidate genes were involved in fundamental cellular functions, such as regulation of gene expression and cell cycle progression. Two of the regulatory genes (Zmm22 and an ortholog of Fpa) that were associated with plant height were previously shown to be involved in regulating the vegetative to floral transition. The association of Zmm22 with plant height was confirmed using a transgenic approach. Transgenic lines with increased expression of Zmm22 showed a significant decrease in plant height as well as tassel branch number, indicating a pleiotropic effect of Zmm22.ConclusionSubstantial heritable variation was observed in the association panel for stalk traits, indicating a large potential for improving useful stalk traits in breeding programs. Genome-wide association analyses detected several candidate genes associated with multiple traits, suggesting common regulatory elements underlie various stalk traits. Results of this study provide insights into the genetic control of maize stalk anatomy and biomass.

Plant vascular bundles are responsible for water and material transportation, and their quantitative and functional evaluation is desirable in plant research. At the single-plant level, the number, size, and distribution of vascular bundles vary widely, posing a challenge to automatically and accurately identifying and quantifying them. In this study, a deep learning-integrated phenotyping pipeline was developed to robustly and accurately detect vascular bundles in Computed Tomography (CT) images of stem internodes. Two semantic indicators were used to evaluate and identify a suitable feature extraction network for semantic segmentation models. The epidermis thickness of maize stem was evaluated for the first time and adjacent vascular bundles were improved using an adaptive watershed-based approach. The counting accuracy (R2) of vascular bundles was 0.997 for all types of stem internodes, and the measured accuracy of size traits was over 0.98. Combining sap flow experiments, multiscale traits of vascular bundles were evaluated at the single-plant level, which provided an insight into the water use efficiency of the maize plant.

Zingiberaceae is the largest family in order Zingiberales and commonly known as aromatic rhizomatous herbs. Few earlier studies recorded the successful adaptation of wild gingers in limestone area. The preliminary study was carried out to investigate the difference in the anatomical characters between limestone and non-limestone ginger species. A total of four wild ginger species from limestone and non-limestone area were selected and the leaf surfaces, pseudostem, rhizome and root were used in this study. Qualitative study revealed different concentration of vascular bundle in vegetative parts between limestone and non-limestone species meanwhile quantitative study exhibited the differences in sizes of veins on leaf epidermis. The anatomy changes in the studied samples were mainly influenced by the differences of nutrients concentration in limestone and non-limestone areas due to their adaptations on different habitats. [ABSTRACT FROM AUTHOR]

Bamboo is susceptible to moisture-induced dimensional instability and cracking. Combining traditional methods with vascular bundle detection, the coordinates and fiber sheath area of each vascular bundle was determined accurately. Based on data fitting, the change in the shape of cross-section was quantified and analyzed based on parameters such as radius, radian, and arc length. The changes in the total area and the areas of different types of fiber sheath, as well as the changes in the arrangement of vascular bundles were studied. The results showed that when the moisture content was reduced from 64% to 0%, the radius of the cross section was increased by 21%, while the radian and arc length decreased by 22% and 6%, respectively. The fibers shrunk by 15%, which was greater than that of the other tissues except bamboo fibers (9%). The gradient distribution of the fiber volume fraction contributed to its asynchronous dry shrinkage. Significant radial and tangential displacements were found in vascular bundles. This work further elucidated the dry shrinkage mechanism of bamboo, and was of great significance for the quantitative analysis of changes in bamboo structure from a combination of micro and macro perspectives. [ABSTRACT FROM AUTHOR]

Background The Masquelet method has become increasingly popular for the treatment of bone defects in recent years. In this method, an induced membrane (IM) with abundant blood circulation, stem cells, and osteogenesis-promoting factors is formed by implanting bone cement during the first surgery. This IM stimulates bone formation in the bone defect after implantation of the bone graft during the second surgery. However, the Masquelet method requires two surgeries and thus a longer treatment period. In the present study, we investigated whether bone defects could be reconstructed in a single surgery by introducing a vascular bundle into the bone defect as an alternative to the IM, in addition to bone grafting. Methods Thirty-six 12-week-old female Sprague-Dawley rats were used. After creating a 5-mm long bone defect in the femur, a mixture of autologous and artificial bone was grafted into the defect, and a saphenous arteriovenous vascular bundle was introduced. The animals were divided into three groups: the control group (bone defect only), the BG group (bone grafting only), and the BG + V group (bone grafting + vascular bundle introduction). After surgery, radiological and histological evaluations were performed to assess osteogenesis and angiogenesis in bone defects. Results In the BG + V group, significant bone formation was observed in the bone defect on radiological and histological evaluations, and the amount of bone formation was significantly higher than that in the other two groups. Furthermore, cortical bone continuity was observed in many specimens in the BG + V group. On histological evaluation, the number of blood vessels was also significantly higher in the BG + V group than in the other two groups. Conclusion Our results suggest that the introduction of a vascular bundle in addition to bone grafting can promote bone formation in bone defects and allow for complete bone defect reconstruction in a single surgery. [ABSTRACT FROM AUTHOR]

The need to produce crops with higher yields is critical due to a growing global population, depletion of agricultural land, and severe climate change. Compared with the "source" and "sink" transport systems that have been studied a lot, the development and utilization of vascular bundles (conducting vessels in plants) are increasingly important. Due to the complexity of the vascular system, its structure, and its delicate and deep position in the plant body, the current research on model plants remains basic knowledge and has not been repeated for crops and applied to field production. In this review, we aim to summarize the current knowledge regarding biomolecular strategies of vascular bundles in transport systems (source-flow-sink), allocation, helping crop architecture establishment, and influence of the external environment. It is expected to help understand how to use sophisticated and advancing genetic engineering technology to improve the vascular system of crops to increase yield. [ABSTRACT FROM AUTHOR]

In the developing wheat grain, nutrients from the spikelet axis are delivered to the endosperm via the nutrient transfer tissues (NTTs). Knowledge of the NTTs development is paramount to understanding the accumulation of starch and protein in wheat grain. In this study, two near-isogenic lines including 'Shimai19-P' and 'Shimai19-N' and a wheat cultivar 'Shimai19' were used to analyze the anatomical structure of the large vascular bundle, chalaza, nucellar projection, and the small vascular bundle in wheat grains at 0–20 days after pollination (DAP) using paraffin sectioning and semi-thin sectioning techniques. The phloem sieve tubes reached the maximal number at 4 DAP in 'Shimai19-P' and 'Shimai19'; however, phloem sieve tubes of 'Shimai19-N' reached the maximum number at 6 DAP. The transverse section areas of the small vascular bundles of 'Shimai19-N' and 'Shimai19-P' reached the highest value at 8 DAP, while the sieve tubes and parenchyma cells in the small vascular vessels decreased significantly. At 12 DAP, nuclei of the chalazal cells in the three wheat varieties began gradually disappearing, with the most apparent changes reported in 'Shimai19-N'. In conclusion, there was significant variation in the formation of sieve tubes and vessels in large vascular bundles, the disappearance of chalazal cell nuclei, and the transverse section area of small vascular bundles in different waxy wheat grains, which is considered as the important morphological and anatomical basis for the difference of wheat starch and nutrients accumulation. [ABSTRACT FROM AUTHOR]

Iron nanomaterials are widely present in the environment and their concentrations are increasing day by day. In many applications, iron nanomaterials are included, but the minimum and maximum concentrations that are not harmful to plants are not yet known. Effect of F3O4(NPs) on Peganum harmala plants for the purpose of showing anatomical responses as effective biomarkers for increasing the concentration of nanomaterials in the ecosystem. Electron microscopy to determine the effect of different doses of F3O4(NPs) ranging from (0-600 mg / L) were used. The cross-sections of leaves were compared in terms of epidermis, parenchyma cells, vascular cylinder, especially xylem and phloem vessels. Epidermal variations were studied stomata, guard cells and normal cells of the epidermis. The laboratories of the Department of Environmental Sciences and Pollution at the College of Science, University of Kufa for the year 2022 were used to conduct experiments. The anatomical results of the studied plants showed that the largest effect was on the epidermis of the plants, especially on the stomata system, where the stomata were closed and decreased in number, while the vascular system was less affected by the variation in the concentration of F3O4(NPs) compared to the rest anatomical indicators. The severity effect was proportional to the increase in concentration. The results indicate that an insufficient supply of F3O4(NPs) (150 mg / L) can be a plant growth stimulator and the results can be used in practical applications to increase production and improve crops as a fertilizer. Whereas, treatments with high concentrations inhibit antioxidants, causing a deficiency of growth activity in plants. [ABSTRACT FROM AUTHOR]

Bamboos are treated to boost their shelf life from the degrading activity of fungal microbes and other insects and to increase their longevity in use and durability by using various chemicals. The present study is vis-a-vis the standardization of two bamboo species Dendrocalamus strictus and Thyrostachys siamensis for a comparative analysis of the mechanical and anatomical properties of samples treated with CCB (Copper Chrome Boron), and BBA (Borax Boric Acid) as well as untreated samples. Samples were tested for both bending and compression; and the parameters such as MOE (Modulus of Elasticity), MOI (Moment of Inertia), Maximum compressive strength, and ultimate strength were analyzed. The anatomical variations arising in the top and bottom sections were also investigated and it has found that the mechanical properties of the species treated with CCB solutions yield a better result in maximum compressive strength and high value of MOI as compared to BBA whereas the samples treated with BBA provides superior performance with respect to MOE. Anatomical examination revealed that the cellular structure and arrangement of vascular bundles are responsible for the increase in time taken for the rate of penetration of chemicals in D.strictus i.e one-half hour as compared to T.siamensis which got treated in 20 minutes. In D.strictus the density of vascular bundles is high so it takes time to get it treated completely as compared to T. siamensis. [ABSTRACT FROM AUTHOR]

Summary: The peduncle vascular system of maize is critical for the transport of photosynthetic products, nutrients, and water from the roots and leaves to the ear. Accordingly, it positively affects the grain yield. However, the genetic basis of peduncle vascular bundle (PVB)‐related traits in maize remains unknown. Thus, 15 PVB‐related traits of 386 maize inbred lines were investigated at three locations (Yongcheng, 17YC; Kaifeng, 20KF; and Yuanyang, 20YY). The repeatability for the 15 traits ranged from 35.53% to 92.13%. A genome‐wide association study was performed and 69 non‐redundant quantitative trait loci (QTL) were detected, including 9, 41, and 27 QTL identified at 17YC, 20KF, and 20YY, respectively. These QTL jointly explained 4.72% (SLL) to 37.30% (NSVB) of the phenotypic variation. Eight QTL were associated with the same trait at two locations. Furthermore, four pleiotropic QTL were identified. Moreover, one QTL (qPVB44), associated with NSVB_20KF, was co‐localized with a previously reported locus related to kernel width, implying qPVB44 may affect the kernel width by modulating the number of small vascular bundles. Examinations of the 69 QTL identified 348 candidate genes that were classified in five groups. Additionally, 26 known VB‐related homologous genes (e.g. VLN2, KNOX1, and UGT72B3) were detected in 20 of the 69 QTL. A comparison of the NSVB between a Zmvln2 EMS mutant and its wild type elucidated the function of the candidate gene ZmVLN2. These results are important for clarifying the genetic basis of PVB‐related traits and may be useful for breeding new high‐yielding maize cultivars. [ABSTRACT FROM AUTHOR]

Lily scale-explants cultured in vitro regenerate adventitious bulblets at their base. Large scale-explants (6 × 18 mm; the basal side is 6 mm) yielded more (26%) bulblet growth than small ones (6 × 6 mm). The beneficial effect of the scale was also clear when bulblets excised from scale explants were transferred to fresh medium for additional growth. When a small piece of the original scale was left attached to these bulblets, growth increased by 33%. The growth of bulblets was highest in explants cut from the middle of a scale as opposed to the edge, and in explants cut from the basal half as opposed to the apical half. We examined the development of the scale-explants during the period of bulblet regeneration in vitro and the scale explants were physiologically very active as judged by the decrease in the amount of polysaccharides in the explant (ca.70%) and the increase in total amount of soluble sugars in the explant (ca. 40%). In the basal scale explants, the number of starch granules was far higher than in apical scale explants. During culture, the number of vascular bundles increased in basal and apical scale explants from 6 to 3.3 to 8 and 4 bundles, respectively. Key Message: Explants excised from different parts of lily bulb scales exhibit a different growth in vitro dependent on their amount of storage starch and vascular bundle intensity. [ABSTRACT FROM AUTHOR]

The vascular bundle plays a vital role in photoassimilates transportation in rice. However, the vascular bundle characteristics of basal internode and its relationship with stem assimilates allocation and yield remain unclear. In this study, experiments with four different types of rice varieties subjected to three nitrogen application levels were conducted. The results showed that large vascular bundles (LVB) and small vascular bundles (SVB)-related traits of basal internode exhibited genotypic differences. Indica-japonica hybrid varieties had the highest number of cross sectional areas and phloem areas of LVB and SVB, thus the highest stem nonstructural carbohydrates (NSC) translocation, grain filling percentage and grain yield, followed by indica hybrid varieties and indica conventional varieties, and those were the lowest in japonica conventional varieties. The LVB and SVB related traits were significantly and positively correlated with stem NSC translocation, grain filling percentage and grain yield, respectively These results suggested that improving the characteristics of basal internodes was beneficial to enhance stem NSC translocation and consequently increase grain yield. Nitrogen application increased LVB and SVB related traits. Therefore, varieties with developed vascular bundles of basal internodes and cultivation techniques for improving vascular bundle related traits should be considered as the effective route for increasing grain yield. [ABSTRACT FROM AUTHOR]

The vascular bundle of the shank is an important 'flow' organ for transforming maize biological yield to grain yield, and its microscopic phenotypic characteristics and genetic analysis are of great significance for promoting the breeding of new varieties with high yield and good quality. In this study, shank CT images were obtained using the standard process for stem micro-CT data acquisition at resolutions up to 13.5 μm. Moreover, five categories and 36 phenotypic traits of the shank including related to the cross-section, epidermis zone, periphery zone, inner zone and vascular bundle were analyzed through an automatic CT image process pipeline based on the functional zones. Next, we analyzed the phenotypic variations in vascular bundles at the base of the shank among a group of 202 inbred lines based on comprehensive phenotypic information for two environments. It was found that the number of vascular bundles in the inner zone (IZ_VB_N) and the area of the inner zone (IZ_A) varied the most among the different subgroups. Combined with genome-wide association studies (GWAS), 806 significant single nucleotide polymorphisms (SNPs) were identified, and 1245 unique candidate genes for 30 key traits were detected, including the total area of vascular bundles (VB_A), the total number of vascular bundles (VB_N), the density of the vascular bundles (VB_D), etc. These candidate genes encode proteins involved in lignin, cellulose synthesis, transcription factors, material transportation and plant development. The results presented here will improve the understanding of the phenotypic traits of maize shank and provide an important phenotypic basis for high-throughput identification of vascular bundle functional genes of maize shank and promoting the breeding of new varieties with high yield and good quality. [ABSTRACT FROM AUTHOR]

Little is known on how karst plants adapt to highly heterogeneous habitats via adjusting leaf anatomical structures. Phyllostachys glauca McClure is a dominant species that grow across different microhabitats in the limestone mountains of Jiangxi Province, China. We investigated the leaf anatomical structures, plant biomass, soil water content, soil total nitrogen (TN), and soil total phosphorus (TP) from three habitats characterized by different rock exposure, including high rock exposure (HRE), medium rock exposure (MRE) and low rock exposure (LRE), and aimed to discern the relationships between the leaf anatomical plasticity and edaphic factors. The leaves of P. glauca in different habitats showed significant anatomical plasticity in two aspects. First, the leaves adjusted cuticle thickness, papillae length, bulliform cell size and mesophyll thickness to lower water loss and then adapt to the water-deficient habitats (HRE). Second, the leaves enlarged vessels and vascular bundles (first-order and second-order parallel veins) to improve water and nutrient transportation and then enhance plant growth in nitrogen-rich habitats (HRE). Soil water and soil nutrients purely explained the total variation of leaf anatomical traits by 21.7% and 15.7%, respectively, and had a shared proportion of 15.8%. Our results indicated that the leaf anatomical variations in different habitats were associated with both soil water and soil nutrients. Moreover, we found that leaf anatomical structures were more affected by TN than TP. The present study advanced the current understanding of the strategies employed by karst plants to cope with highly heterogeneous habitats via leaf anatomical plasticity. [ABSTRACT FROM AUTHOR]

Laminated veneer bamboo is a green and sustainable building material with better mechanical properties and lower discreteness than raw bamboo. Normal laminated veneer bamboo (NLVB) is usually made of flat-sawn bamboo strips, which needs to slice the curved cross-sectional bamboo strips into rectangular section. Nevertheless, the outer bamboo wall with rich vascular bundles is cut off, reducing the mechanical properties of laminated veneer bamboo. In this regard, a novel curved laminated veneer bamboo (CLVB), directly using curved cross-sectional bamboo strips, was investigated in this work. The failure modes, stress-strain relationships and load-displacement curves of CLVB material were studied and compared with NLVB material through tensile, compressive, shear and bending tests. Otsu algorithm was used to identify the proportion of vascular bundles. In addition, the microscopic morphology of the adhesive layer and vascular bundle was observed by scanning electron microscope (SEM). Finally, the energy consumption of the specimen was calculated to compare the differences of large deformation in bending test. The results showed that the CLVB and NLVB exhibited similar failure modes in tensile, shear and bending tests, but had different failure modes in compressive test. It was demonstrated that the CLVB showed significant enhancements in the strength and modulus when compared to the NLVB. Specifically, the proportion of cross-sectional vascular bundles in the CLVB was 1.22 times larger than that of the NLVB, contributing to the better mechanical performance of fiber-loaded specimens. In addition, the CLVB had superior bonding performance with a continuous and obvious adhesive layer in the SEM observation, while the adhesive layer of NLVB was discontinuous and irregular. Compared with CLVB, NLVB consumed more energy consumption due to the extra fiber dissociation of bending specimens. In short, CLVB performed better mechanical properties, showing its great potential as an alternative material to engineered bamboo. [Display omitted] • A novel curved laminated veneer bamboo (CLVB) was investigated. • Comprehensive tests were carried out to evaluate the mechanical properties. • The results were analyzed based on the vascular bundles and SEM observations. • Failure mode and mechanism were analyzed from macro and micro perspectives. • CLVB exhibits better mechanical property than that of normal LVB. [ABSTRACT FROM AUTHOR]

• GA 3 and CPPU, either alone or in combination, caused an increase in berry size, area of berry vascular bundles, relative vessel number, and water transport in grape berry. • The CPPU treatment showed a preference for increasing phloem area of berry vascular bundles, whereas GA 3 primarily increased the xylem area. • The GA 3 treatment impacted specific transcription factors associated with xylem differentiation, whereas CPPU and the combined treatment triggered a diverse set of genes linked to the initiation, proliferation, and differentiation of vascular bundles. Fruit vascular bundles play a critical role in transporting water and nutrients within fruit, ultimately impacting fruit size and quality. Gibberellic acid (GA) and the synthetic cytokinin forchlorfenuron (CPPU) are commonly used to enhance grape berry size. Understanding their effects on the structure and function of berry vascular bundles could provide new information on the regulatory mechanism of these hormones on grapevine expansion and quality. In this study, the fruitlets of 'Pinot Noir' and 'Einset Seedless' grape varieties were treated by GA 3 , CPPU, and a combination of both at two weeks after full bloom. The samples were collected at 20, 40 and 70 days post-treatment. The results showed that all treatments led to an increase in berry size, xylem area, phloem area, the relative abundance of large-diameter grade vessels (>6 μm), the corresponding xylem area-specific hydraulic conductivity, and water absorption in both grape varieties. Specifically, CPPU favored an increase in phloem area, while GA 3 primarily increased the xylem area. The combined application had a strong effect on both xylem and phloem area. RNA-seq analysis revealed that all treatments induced variations in the expression levels of multiple hormone signal components and genes related to vascular development. GA 3 treatment mainly influenced some specific transcription factors involved in xylem differentiation, while CPPU and the combination treatment induced a wide range of genes related to vascular cambium initiation, proliferation, and differentiation of phloem and xylem vessels. Overall, our findings suggest that GA 3 played a significant role in xylem differentiation, whereas CPPU had a major impact on both phloem and xylem differentiation in grape berries. These results lay the groundwork for further research the precise regulation of fruit vascular development under GA 3 and CPPU treatments. [ABSTRACT FROM AUTHOR]

Unraveling the characteristics of bamboo vascular bundles is critical for understanding their physiology and mechanical properties. However, different bamboo species have different vascular bundles, leading to significant variations in their industrial applications. In this paper, the You Only Look Once algorithm was applied to examine the vascular bundles of several species representatives within Dendrocalamus (Dendrocalamus farinosus , Dendrocalamus asper , and Dendrocalamus latiflorus) and Bambusa (Bambusa pervariabilis , Bambusa textilis , and Bambusa arundinacea), considering their economic and ecological importance. The analysis included the classifications of vascular bundles, their dimensions, and the areas of fiber sheaths. The results showed that the vascular bundles of Dendrocalamus and Bambusa were mainly broken-waist type. Along the radial direction, both Dendrocalamus and Bambusa exhibited gradient variability in vascular bundles, suggesting a similar underlying structural pattern. Quadratic functions could be employed to represent the radial distributions of vascular bundle size and fiber sheath area. Statistically, the fiber sheath area was positively correlated with vascular bundle size (P <0.05). In addition, significant differences in vascular bundles were detected among different bamboo species, which may lead to substantial variations in their mechanical properties. In particular, Bambusa arundinacea had the highest vascular bundle length (724.57 μm) and length/width ratio (1.69), while Dendrocalamus asper had the highest vascular bundle width (552.20 μm) and fiber sheath area (0.22 mm2). Nevertheless, principal component analysis indicated substantial similarity in the vascular bundles of Dendrocalamus and Bambusa. Moreover, the interspecific variations in vascular bundles were notably more pronounced within Dendrocalamus compared to those observed within Bambusa. Overall, our study examined the variations in vascular bundles between Dendrocalamus and Bambusa , offering insights that hold significant potential for bamboo taxonomy and the design of bio-inspired materials. • Bamboo exhibited radial gradient variability in vascular bundles. • Fiber sheath area was positively correlated with vascular bundle size. • Vascular bundles were different among different bamboo species. • PCA indicated similarity between Dendrocalamus and Bambusa. • Different bamboo genera are distinguished by diverse vascular bundles. [ABSTRACT FROM AUTHOR]

Plant stem is essential for the delivery of resources and has a great impact on plant lodging resistance and yield. However, how to accurately and efficiently extract structural information from crop stems is a big headache. In this study, we first established a Maize Stalk Cross-section Phenotype (MSCP) dataset containing anatomical information of 990 images from hand-cut transections of stalks. Then, to large-scale measure the stalk anatomy features, we developed a Maize Stalk Cross-section Phenotyping Network (MSCP-Net) which integrated a convolutional neural network and the methods of instance segmentation and key point detection. A total of 14 stalk anatomical parameters (traits) can be automatically produced with high mAP@.5 (0.907) for the parameter "vascular bundles segmentation" and high DICE (0.864) for the parameter "functional zones segmentation". The cross-validation with the MSCP dataset indicated the good performance of MSCP-Net in predicting anatomical traits. On this basis, the correlation analysis across 14 anatomical traits and 12 agronomic importance traits in 110 maize inbred-lines was conducted and revealed that the stalk related traits (stem cross-section, large vascular bundles, fiber contents, and aerial roots) are key indicators for lodging resistance and grain yield of maize. In addition, the maize inbred-lines were classified into two groups, and the higher value of group II compared with group I in breeding hybrid varieties was discussed. The results demonstrated that the MSCP-Net is expected to be a useful tool to rapidly obtain stem anatomical traits which are agronomic important in maize genetic improvement. [Display omitted] • A high-quality MSCP dataset containing anatomical information of 990 images from hand-cut transections of maize stalks was established. • A high-performance MSCP-Net was developed to automatically and accurately produce 14 maize stalk anatomical traits. • It was demonstrated that stem anatomical traits are agronomic important in germplasm evaluation and crop breeding. [ABSTRACT FROM AUTHOR]

The swelling/shrinking behavior is a complex process of interactions between multiscale structures, and it is also a major problem affecting the processing and utilization of bamboo. As an important structure connecting macroscopic and cellular scales in bamboo, the analysis of vascular bundles' swelling/shrinking behaviors is important for revealing the swelling/shrinking laws of bamboo. In this study, in-situ observation technique was used to characterize the swelling/shrinking behaviors of open vascular bundles, open fibers, semi-open vascular bundles and semi-open fibers, and further analyzed the area change and location change of open vascular bundles (OV) and its fibers (OF), semi-open vascular bundles (HOV) and its fibers (HOF), and then analyzed the area and position change. During the swelling/shrinking cycle, the area change patterns of HOV was similar. The shrinkage rate of OV varied little, with a range of 1–0.74 %. The shrinkage rate of HOV was 1–0.18 %. The shrinkage ranges for OF and HOF fibers were closer, 1–0.2 % and 1–0.18 %, respectively. Swelling/shrinking was accompanied by movement of vascular bundles and fiber, with HOV moving in a radial direction and OV moving in a definite direction. Random forest simulations reveal that the effect of different fiber sheaths on the shrinkage area of the vascular bundle varies, and the HOV is more affected by the fiber sheath，its factor importance is 0.47. The importance of the fibrous sheath "a" to the OV area is only 0.24. This provides an important reference for the subsequent establishment of multiscale swelling/shrinking relationships for bamboo. • The influence of the vascular bundle morphology on its shrinkage /swelling behavior. • There were differences in displacement direction of different types of vascular bundles. • The effect of fiber sheath, humidity on the vascular bundles swelling area was analyzed using a random forest algorithm. [ABSTRACT FROM AUTHOR]