Leaf Cells Research Articles

Nanoceria-induced variations in leaf anatomy and cell wall composition drive the increase in mesophyll conductance of salt-stressed cotton leaves

Nanomaterials as an emerging tool are being used to improve plant′s net photosynthetic rate (AN) when suffering salt stress, but the underlying mechanisms remain unclear. To clarify this, a hydroponic experiment was conducted to study the effects of polyacrylic acid coated nanoceria (PNC) on the AN of salt-stressed cotton and related intrinsic mechanisms. Results showed that the PNC-induced AN enhancement of salt-stressed leaves was strongly facilitated by the mesophyll conductance to CO2 (gm). Further analysis showed that the PNC-induced improvement of gm was related to the increased chloroplast surface area exposed to intercellular airspaces, which was attribute to the increased mesophyll surface area exposed to intercellular airspaces and chloroplast number due to the increased K+ content and decreased reactive oxygen species level in salt-stressed leaves. Interestingly, our results also showed that PNC-induced variations in cell wall composition of salt-stressed cotton leaves strongly influenced gm, especially, hemicellulose and pectin. Moreover, the proportion of pectin in cell wall composition played a more important role in determining gm. Our study demonstrated for the first time that nanoceria, through alterations to anatomical traits and cell wall composition, drove gm enhancement, which ultimately increased AN of salt-stressed leaves.

Rising temperature impacts the trace metal uptake and toxicity in aquatic plants - A case study of Ni and Co in Elodea canadensis Michx.

The global warming and environmental pollution are two crucial contemporary concerns. As both are strongly connected with urbanisation and anthropogenic impact on the environment, they often affect the ecosystem simultaneously. Aquatic habitats are particularly susceptible to thermal and chemical pollution. Temperature influences nearly all physical and chemical features of water bodies and trace metals are known for their toxicity to aquatic organisms. However, effects of multiple stressors, cumulative effects as well as response and possible adaptations of organisms are still open questions. Thus, the aim of this study was to characterize the combined effect of temperature and two trace metals (Co and Ni) on the metal bioaccumulation and viability of a model aquatic macrophyte Elodea canadensis Michx. We exposed shoots of E. canadensis to three temperatures and four metal concentrations (together and separately) applied at environmentally relevant levels. Shoot growth and metal concentration in plants were measured after 120 h. Moreover, after 24, 72 and 120 h the changes in leaf cell morphology and viability were analysed. The results showed that metal accumulation was dose-dependent and was not affected by temperature. The growth of plants was not affected by temperature nor metals. On the other hand, the exposure to Co and Ni and the elevated temperature negatively affected cell viability of E. canadensis leaves which manifested by increased permeability of plasma membranes and visible necroses. The greatest damaged leaf areas were determined after 120 h in the highest concentration of both metals and the highest temperature which indicates synergistic impact of trace metals and temperature on performance of macrohydrophytes. The observed phenomena suggest that global warming and/or thermal pollution may have implications for the performance of aquatic macrophytes in chemically polluted waters, their ability to spread and colonize polluted habitats and their suitability in phytoremediation.

Differential effects of pH on cadmium accumulation in Artemisia argyi growing in low and moderately cadmium-contaminated paddy soils

BackgroundPhytoremediation is affected by physical and chemical properties of the soil such as soil pH, moisture, and nutrient content. Soil pH is a key element influencing Cd bioavailability and can be easily adjusted in agricultural practices. The soil pH level may relate to the effectiveness of phytoremediation; however, this has not been extensively investigated. In the current study, we evaluated the effect of Cd contamination level (0.56 and 0.92 mg/kg) and soil pH (5, 6, and 7) on Cd accumulation and allocation in Artemisia argyi, a fast-growing perennial crop.ResultsOur results indicated that higher soil Cd concentrations reduce A. argyi biomass, and the loss of the root mass was particularly significant. Higher soil pH decreased Cd content in stems and roots of A. argyi cultivated in moderately Cd-polluted soil, and increased Cd content in stems and roots of the plant grown in low Cd-polluted soil. Higher soil pH decreased the percentage of Cd distributed in the soluble fraction and cell walls and increased the percentage of Cd in the organelles of leaf cells for moderate soil Cd levels. The bioconcentration and translocation factor exceeded 4.0 and 1.0, respectively, across all tested treatments, indicating that A. argyi is a promising candidate for phytoremediation. Notably, the effects of soil pH on Cd accumulation and subcellular distribution in A. argyi differed between low and moderately Cd-contaminated soils.ConclusionAdjustments to soil pH based on the degree of Cd contamination can enhance Cd extraction by A. argyi, thereby reducing the overall remediation cycle of cadmium-polluted paddy fields of South China.Graphical

Spraying KH2PO4 Alleviates the Damage of Spring Low-Temperature Stress by Improving the Physiological Characteristics of Wheat Flag Leaves

The low-temperature stress (LTS) in spring results in tremendous yield loss in wheat production, and the application of potassium dihydrogen phosphate (KH2PO4) can alleviate stress-induced damage. However, the underlying effect of spraying KH2PO4 on the physiological characteristics of wheat flag leaves under spring LTS remains unclear. In this study, we investigated the effect of spraying KH2PO4 on flag leaf physiological traits and yield under spring LTS, including treatments at 15 °C and spraying H2O (CK), treatment at −4 °C and spraying H2O (LT1), and treatment at −4 °C and spraying KH2PO4 (LT2). The results showed that spraying KH2PO4 significantly increased the activities of the superoxide dismutase (SOD), the peroxidase (POD), and the catalase (CAT), and reduced malondialdehyde (MDA) content in the flag leaves. Compared to LT1, the SOD, POD, and CAT activities in the flag leaves of the Yangnong19 (YN19) and Xinmai26 (XM26) via LT2 increased by 5.5%, 10.9%, and 3.9%, and 5.4%, 9.2%, and 4.4%, respectively, and the MDA content of the YN19 and XM26 decreased by 10.5% and 9.1%, respectively, at 0–12 d after low temperature treatment (DALTT). Spraying KH2PO4 appreciably alleviated damage to the leaf cell morphology and tissue integrity, and increased the accumulation of proline and soluble protein, the chlorophyll content, and the activities of Ribulose–1,5–bisphosphate carboxylase and phosphoenolpyruvate carboxykinase. The net photosynthetic rate in the flag leaves of the YN19 and XM26 via LT2 increased by 37.9% and 35.9%, respectively, at 0–12 DALTT, compared to LT1. Moreover, spraying KH2PO4 reduced the yield loss rate of the YN19 and XM26 by 13.06% and 16.72%, respectively. The present study demonstrates that spraying KH2PO4 can enhance wheat resistance to spring LTS and maintain the photosynthetic capacity of flag leaves, alleviating the negative effects of LTS on grain yield.

Impact of saflufenacil and glyphosate-based herbicides on the morphoanatomical and development of Enterolobium contortisiliquum (Vell.) Morong (Fabaceae): new insights into a non-target tropical tree species.

The unregulated use and improper management of herbicides can cause negative effects on non-target species and promote changes in biological communities. Therefore, the current study is aimed at understanding morphoanatomical responses and effects on seedling development induced by the herbicides glyphosate and saflufenacil in Enterolobium contortisiliquum, a non-target tropical species. The plants were cultivated in a greenhouse and subjected to herbicides at doses of 0, 160, 480, and 1440g a.e ha-1 for glyphosate, and 0, 25, 50, and 100g a.i ha-1 for saflufenacil. We conducted visual and morphological assessments over 90days post-application. Leaf samples were collected 12days after the application for anatomical analysis, and we also performed a micromorphometric analysis of the leaf tissues. Biomarkers of phytotoxicity were identified in plants exposed to both herbicides, even at the lowest doses, including in leaves without visual symptoms. The main morphological alterations were the decrease in growth, stem diameter, and dry mass. Furthermore, the leaves and stems visually exhibited chlorosis and necrosis. Both herbicides triggered anatomical modifications such as significant changes (p < 0.05) in the thickness of leaf tissues, hypertrophy, cell collapse, and changes in epicuticular waxes. However, the alterations induced by glyphosate were more widespread compared to saflufenacil, encompassing alterations in the root system. We confirmed that the different mechanisms of action of each herbicide and the existence of an underground reserve system in this species are intrinsically linked to the morphological and developmental responses described. Our findings suggest that E. contortisiliquum could be a potential bioindicator species for these herbicides in the environment, even at concentrations lower than those typically recommended for field application.

Developmentally controlled subcellular remodeling and VND-initiated vacuole-executed PCD module shape xylem-like cells in peat moss

Peat moss (Sphagnum) is a non-vascular higher plant with unique xylem-like hyaline (H) cells that are accompanied by photosynthetic chlorophyllous cells. These cellular structures play crucial roles in water storage and carbon sequestration. However, it is largely unknown how peat moss develops the H cells. This study systematically explored the Sphagnum Developmental Cell Atlas and Lineage and classified leaf cell development into two lineages with six stages (S0-S5) based on changes in key cellular traits, including the formation of spiral secondary cell walls (S4) and the presence of water pores (S5). Cell lineage-specific subcellular remodeling was transcriptionally regulated during leaf development, and vacuole-mediated clearance of organelles and cell death led to mature dead H cells. Interestingly, expression of land plant conserved Vascular-related NAC Domain (VND) genes correlated with H cell formation. Overall, these results suggest that the origination of xylem-like H cells is related to VND, likely through the neofunctionalization of vacuole-mediated cell death to attempt xylem formation in peat moss, suggesting potential uncoupling of xylem and phloem cell origins. This study positions peat moss as a potential model organism for studying integrative evolutionary cell biology.

Diethyl aminoethyl hexanoate reprogramed accumulations of organic metabolites associated with water balance and metabolic homeostasis in white clover under drought stress.

Diethyl aminoethyl hexanoate (DA-6) serving as a non-toxic and low-cost plant growth regulator is used for improving plant growth and stress tolerance, but the DA-6-mediated organic metabolites remodeling in relation to drought tolerance is not well documented in crops. The aims of the present study were to evaluate impacts of DA-6 on physiological functions including osmotic adjustment, photochemical efficiency, oxidative damage, and cell membrane stability as well as organic metabolites remodeling in white clover (Trifolium repens) leaves based on the analysis of metabolomics. Plants were foliarly treated with or without DA-6 and subsequently exposed to drought stress for 8 days. Results demonstrated that foliar application of DA-6 (1.5 mM) could significantly ameliorate drought tolerance, which was linked with better leaf water status, photosynthetic performance, and cell membrane stability as well as lower oxidative injury in leaves. Metabolic profiling of organic metabolites identified a total of 59 metabolites including 17 organic acids, 20 sugars, 12 alcohols, and 10 other metabolites. In response to drought stress, the DA-6 induced accumulations of many sugars and sugar alcohols (erythrulose, arabinose, xylose, inosose, galactose, talopyranose, fucose, erythritol, and ribitol), organic acids (propanoic acid, 2,3-dihydroxybutanoic acid, palmitic acid, linolenic acid, and galacturonic acid), and other metabolites (2-oxazoline, silane, and glycine) in white clover. These altered metabolites induced by the DA-6 could perform critical functions in maintenances of osmo-protection, osmotic adjustment, redox homeostasis, cell wall structure and membrane stability when white clover suffered from water deficit. In addition, the campesterol and stigmasterol significantly accumulated in all plants in spite of the DA-6 pretreatment under drought stress, which could be an important adaptive response to water deficit due to beneficial roles of those two metabolites in regulating cell membrane stability and antioxidant defense. Present findings provide new evidence of DA-6-regulated metabolic homeostasis contributing to drought tolerance in leguminous plants.

'Candidatus Phytoplasma solani' Predicted Effector SAP11-like Alters Morphology of Transformed Arabidopsis Plants and Interacts with AtTCP2 and AtTCP4 Plant Transcription Factors.

Phytoplasmas are obligate intracellular pathogens that profoundly modify the development, physiology and behavior of their hosts by secreting effector proteins that disturb signal pathways and interactions both in plant and insect hosts. The characterization of effectors and their host-cell targets was performed for only a few phytoplasma species where it was shown that the SAP11 effector alters plant morphology by destabilizing plant transcription factors: TEOSINTE BRANCHED 1-CYCLOIDEA-PROLIFERATING CELL FACTOR (TCPs). To explore the possible role of the SAP11-like effector from 'Ca. P. solani', we used Arabidopsis thaliana as a model plant. The SAP11-like effector gene from 'Ca. P. solani' was introduced into arabidopsis by floral dip and transgenic lines were regenerated. In planta bimolecular fluorescence complementation (BIFC) assays in agroinfiltrated Nicotiana benthamiana leaf cells were conducted to detect interactions between SAP11-like and AtTCP2 and AtTCP4 using confocal microscopy. SAP11-like from 'Ca. P. solani' induced significant phenotypic changes in arabidopsis, including crinkled leaves with reduced size, lower biomass, more axillary branches, changes in root morphology, and crinkled and smaller siliques. The BIFC assays proved in planta interaction of SAP11-like effector with AtTCP2 and AtTCP4. To our knowledge, this is the first characterization of the interaction between the 'Ca. P. solani' effector and plant transcription factors, suggesting a potential mechanism of modulating plant development and induction of characteristic symptoms in 'Ca. P. solani'-infected plants.

An integrative taxonomic study of the genus Lethocolea (Marchantiophyta: Acrobolbaceae)

Background and aims – Lethocolea (Acrobolbaceae) is a small liverwort genus of seven species distributed in temperate regions of the Southern Hemisphere and on tropical mountains. The taxonomic history of the genus has been chaotic, the species were described under many different names and have been distinguished mainly based on geography. Here, we undertook a taxonomic revision of the genus based on a reassessment of morphological characters and a molecular analysis. Material and methods – Type material and additional collections from 17 herbaria were examined in the morphological study. Sequences of the rps4 chloroplast region and maximum likelihood analyses were used to reconstruct the phylogeny. Key results and conclusions – Two fully supported clades were resolved within Lethocolea lending support to the recognition of two subgenera, subgen. Lethocolea and subgen. Symphyomitra. Lethocolea congesta from Africa, and L. glossophylla and L. radicosa from America exhibited considerable morphological overlap and were not distinguishable based on rps4 sequences. The latter two species are reduced into synonymy with L. congesta, whose range spans across Africa, the Neotropics and southern South America. In Australasia, where only one species, L. pansa, is recognized, two morphotypes were found. The first one, with a smooth cuticle, wingless gemmae, and leaf cells without trigones, is identical to the type of L. pansa and occurs in Australia and New Zealand. In addition, the species is newly reported from South Africa. The second morphotype has a papillose cuticle, winged gemmae, and leaf cells with distinct trigones, and is assigned to L. javanica, which ranges across Australasia and furthermore occurs in Java and India. The recognition of these two species is supported by molecular analysis. Altogether, we recognize four species within Lethocolea, which are thoroughly described, illustrated, and keyed. We present 12 new lectotypifications.

Yield, cell structure and physiological and biochemical characteristics of rapeseed under waterlogging stress

Rapeseed (Brassica napus L.) is a major oilseed crop in the middle and lower reaches of the Yangtze River in China. However, it is susceptible to waterlogging stress. This study aimed to investigate the physiological characteristics, cellular changes, and gene expression patterns of rapeseed under waterlogging stress, with the goal of providing a foundation for breeding waterlogging-tolerant rapeseed. The results revealed that waterlogging-tolerant rapeseed exhibited higher levels of soluble sugars and antioxidant enzyme activity, particularly in the roots. Conversely, waterlogging-sensitive rapeseed displayed greater changes in malondialdehyde, proline, and hydrogen peroxide levels. Cellular observations showed that after experiencing waterlogging stress, the intercellular space of rapeseed leaf cells expanded, leading to disintegration of mitochondria and chloroplasts. Moreover, the area of the root xylem increased, the number of vessels grew, and there were signs of mitochondrial disintegration and vacuole shrinkage, with more pronounced changes observed in waterlogging-sensitive rapeseed. Furthermore, significant differences were found in the transcription levels of genes related to anaerobic respiration and flavonoid biosynthesis, and different varieties demonstrated varied responses to waterlogging stress. In conclusion, there are differences in the response of different varieties to waterlogging stress at the levels of morphology, physiological characteristics, cell structure, and gene transcription. Waterlogging-tolerant rapeseed responds to waterlogging stress by regulating its antioxidant defense system. This study provides valuable insights for the development of waterlogging-tolerant rapeseed varieties.

Anatomical Responses of Two Species under Controlled Water Restriction.

Quillay (Quillaja saponaria Molina) and peumo (Cryptocarya alba [Molina] Looser) are two tree species endemic to Chile that grow in Mediterranean climate zones, characterized by a summer season with high temperatures, high solar radiation, and low soil water availability. A study was conducted with 2-year-old Q. saponaria and C. alba plants and two substrate water conditions: well-watered and controlled water restriction. At the end of the study, anatomical leaf modifications were analyzed. The tissues were anatomically described in transverse sections of juvenile and adult leaves, measuring leaf thickness, cuticle thickness, and cell density of the mesophyll parenchymal tissues. In the young leaves of Q. saponaria plants undergoing water restriction treatment, an increase in cuticle and leaf thickness and a decrease in the density of the palisade and spongy parenchyma were observed. In contrast, a significant reduction in leaf thickness was observed in adult leaves of both species with water restriction treatment. The anatomical changes in the leaves of Q. saponaria and C. alba suggest an adaptation to adverse environmental conditions, such as water restriction.

Salinity-Induced Photorespiration in Populus Vascular Tissues Facilitate Nitrogen Reallocation.

Adaptation to abiotic stress is critical for the survival of perennial tree species. Salinity affects plant growth and productivity by interfering with major biosynthetic processes. Detrimental effects of salinity may vary between different plant tissues and cell types. However, spatial molecular mechanisms controlling plant responses to salinity stress are not yet thoroughly understood in perennial trees. We used laser capture microdissection in clones of Populus tremula x alba to isolate palisade and vascular cells of intermediary leaf from plants exposed to 150 mM NaCl for 10 days, followed by a recovery period. Cell-specific changes in proteins and metabolites were determined. Salinity induced a vascular-specific accumulation of proteins associated with photorespiration, and the accumulation of serine, 3-phosphoglycerate and NH4 + suggesting changes in N metabolism. Accumulation of the GLUTAMINE SYNTHETASE 2 protein, and increased GS1.1 gene expression, indicated that NH4 + produced in photorespiration was assimilated to glutamine, the main amino acid translocated in Populus trees. Further analysis of total soluble proteins in stems and roots showed the accumulation of bark storage proteins induced by the salinity treatments. Collectively, our results suggest that the salt-induced photorespiration in vascular cells mediates N-reallocation in Populus, an essential process for the adaptation of trees to adverse conditions.

Chronic mild cadmium exposure increases the vulnerability of tomato plants to dehydration

Heavy metal contamination increases plant susceptibility to both biotic and abiotic stresses. However, the comprehensive impact of heavy metal pollution on plant hydraulics, which is crucial for plant productivity, and the interaction between heavy metal stress and environmental factors on plant health are not yet fully understood. In this study, we investigated the effects of cadmium exposure on plant-water relations and hydraulics of Solanum lycopersicum L., cultivar Piccadilly. Particular attention was given to leaf hydraulic conductance (KL) in response to cadmium pollution and dehydration.Cadmium exposure exhibited negligible impacts on tomato productivity but resulted in significant differences in pressure-volume derived traits. Leaves and roots of Cd-treated plants showed reduced wall stiffness compared to control samples. However, Cd-treated leaves had a less negative turgor loss point (Ψtlp), whereas Cd-treated roots exhibited more negative Ψtlp values due to lower osmotic potential at full turgor compared to control samples.Leaves and root cells of Cd-treated plants showed higher values of saturated water content compared to control plants, along with a distinct mineral profile between the two experimental groups. Despite similar leaf water potential thresholds for 50% and 80% loss of KL in control and cadmium-treated leaves, plants grown in cadmium-polluted soil showed higher leaf cell damages even under well watered conditions. This, in turn, affected the plant ability to recover from drought upon rehydration by compromising cell rehydration ability.Overall, the present findings suggest that under conditions of low water availability, cadmium pollution increases the risk of leaf hydraulic failure.

Cyto-architecture of Byblis glands and leaf cells based on freeze-substitution and conventional TEM.

Byblis liniflora (Byblidaceae) is a carnivorous plant that has developed sticky fly paper traps with two types of glandular trichomes producing digestive enzymes and sticky mucilage. This study aimed to analyze the ultrastructure of these glandular leaf trichomes based on rapid freeze fixation and conventional chemical fixation in the attempt to understand their functional contribution to the carnivorous performance of the plants. The Byblis cells were studied in TEM, SEM and STEM using cryo techniques for fixation and substitution in addition to conventional chemical fixation. We show in detail the architecture of both the digestive glands and the mucilage glands with their relevant sets of organelles. Both mitochondria and plastids have a conspicuous plasticity, with branches and constrictions, and they associate to form clusters. The glandular cells appear to be transfer cells with cell wall ingrowths. Digestive glands occur in different states of development. Their cuticle forms discontinuities which are unique among glands of carnivorous plants. They look like cuticular holes -- the cuticle separates from the cell wall in only one spot and then ruptures. Cuticular discontinuities thus differ from cuticular gaps and cuticular pores so far described in carnivorous plants. We therefore propose for them the term cuticular holes. Application of cryo-techniques made it possible to show the true structure of the cell wall and the relationship between cell wall ingrowths and organelles, as well as the morphology and structure of organelles and their associations.

SUPERMAN Targets PHRAGMOPLAST ORIENTING KINESIN to Negatively Regulate Leaf Cell Division in Poplar

ABSTRACTPlant organs achieve their specific size and shape through the coordination of cell division and cell expansion, processes that are profoundly influenced by environmental cues. Cytokinesis during cell division depends on the position of the cytokinetic wall, but how this process responses to environment fluctuations remains underexplored. Here, we investigated a regulatory module involving C2H2‐type zinc finger protein (C2H2‐ZFP) in leaf morphology during drought stress. A total of 123 C2H2‐ZFP members were identified through a comparative genome survey in Populus alba × P. glandulosa ‘84K’. Among them, PagSUPa, an orthologous gene of Arabidopsis SUPERMAN, was selected due to its responsiveness to drought stress and was further confirmed to play a role in leaf development. Phenotypic characterization and cellular analysis revealed that PagSUPa fine‐tunes the duration of cell proliferation in the adaxial epidermis, thereby influencing leaf morphology by modulating leaf adaxial‐abaxial polarity. Additionally, we found that PagSUPa directly suppresses the expression of PHRAGMOPLAST ORIENTING KINESIN1 (PagPOK1) and PagPOK2, genes encoding proteins involved in phragmoplast orientation and position, which results in impaired cytokinesis and cell wall organization. This study provides novel insights into the regulatory network governed by the SUP gene during leaf development, specifically in relation to cell division.

Combined Toxic Effects and Mechanisms of Chloroacetic Acid and N-Nitrosodimethylamine on Submerged Macrophytes

Disinfection by-products (DBPs) such as chloroacetic acids (CAAs) and N-Nitrosodimethylamine (NDMA) are prevalent pollutants in surface waters, particularly with the increasing use of chlorine-based disinfectants. The entry of these DBPs into water bodies may increase accordingly, posing ecological risks to aquatic life. To assess the toxic effects of CAAs and NDMA on submerged macrophytes, Vallisneria natans was exposed to different concentrations of CAAs (1.0, 10.0, and 100.0 μg L−1) and NDMA (0.1, 1.0, and 10.0 μg L−1). A RI value of &lt;1 indicates that simultaneous exposure to CAAs and NDMA can produce an antagonistic effect. Both CAAs and NDMA adversely affect the photosynthetic system of plants. In the NDMA treatment group, chlorophyll a content decreases with increasing concentration, accounting for 96.03%, 60.80%, and 58.67% of the CT group, respectively. Additionally, it effectively triggers the plant’s antioxidant response, with significant increases in SOD, POD, and GSH levels. Among these, the combined treatment group AN2 (10 + 1 μg L−1) showed the most significant change in SOD activity, reaching 3.57 times that of the CT group. Ultrastructural changes also revealed stress responses in leaf cells and damage to organelles. Furthermore, metabolomics provided insights into the metabolic responses induced by CAAs or NDMA in V. natans leaves, where the composition and metabolism of lipids, fatty acids, cofactors and vitamins, amino acids, nucleotides, and some antioxidants were regulated, affecting plant growth. This study provides preliminary information for the ecological risk assessment of submerged plants by complex contamination with the disinfection by-products CAA and NDMA.

Identification of a highly efficient chloroplast-targeting peptide for plastid engineering.

Plastids are pivotal target organelles for comprehensively enhancing photosynthetic and metabolic traits in plants via plastid engineering. Plastidial proteins predominantly originate in the nucleus and must traverse membrane-bound multiprotein translocons to access these organelles. This import process is meticulously regulated by chloroplast-targeting peptides (cTPs). Whereas many cTPs have been employed to guide recombinantly expressed functional proteins to chloroplasts, there is a critical need for more efficient cTPs. Here, we performed a comprehensive exploration and comparative assessment of an advanced suite of cTPs exhibiting superior targeting capabilities. We employed a multifaceted approach encompassing computational prediction, in planta expression, fluorescence tracking, and in vitro chloroplast import studies to identify and analyze 88 cTPs associated with Arabidopsis thaliana mutants with phenotypes linked to chloroplast function. These polypeptides exhibited distinct abilities to transport green fluorescent protein (GFP) to various compartments within leaf cells, particularly chloroplasts. A highly efficient cTP derived from Arabidopsis plastid ribosomal protein L35 (At2g24090) displayed remarkable effectiveness in chloroplast localization. This cTP facilitated the activities of chloroplast-targeted RNA-processing proteins and metabolic enzymes within plastids. This cTP could serve as an ideal transit peptide for precisely targeting biomolecules to plastids, leading to advancements in plastid engineering.

High photosynthesis rates in Brassiceae species are mediated by leaf anatomy enabling high biochemical capacity, rapid CO2 diffusion and efficient light use.

Certain species in the Brassicaceae family exhibit high photosynthesis rates, potentially providing a valuable route toward improving agricultural productivity. However, factors contributing to their high photosynthesis rates are still unknown. We compared Hirschfeldia incana, Brassica nigra, Brassica rapa and Arabidopsis thaliana, grown under two contrasting light intensities. Hirschfeldia incana matched B. nigra and B. rapa in achieving very high photosynthesis rates under high growth-light condition, outperforming A. thaliana. Photosynthesis was relatively more limited by maximum photosynthesis capacity in H. incana and B. rapa and by mesophyll conductance in A. thaliana and B. nigra. Leaf traits such as greater exposed mesophyll specific surface enabled by thicker leaf or high-density small palisade cells contributed to the variation in mesophyll conductance among the species. The species exhibited contrasting leaf construction strategies and acclimation responses to low light intensity. High-light plants distributed Chl deeper in leaf tissue, ensuring even distribution of photosynthesis capacity, unlike low-light plants. Leaf anatomy of H. incana, B. nigra and B. rapa facilitated effective CO2 diffusion, efficient light use and provided ample volume for their high maximum photosynthetic capacity, indicating that a combination of adaptations is required to increase CO2-assimilation rates in plants.

Montmorillonite nanoclay triggers immunity responses in wheat against Puccinia striiformis f. sp. tritici, and suppresses uredospore germination

Puccinia striiformis f. sp. tritici causes the important disease, yellow rust of wheat (Triticum aestivum). Montmorillonite nanoclay (MNC) is naturally occurring and biodegradable. This study assessed in vitro anti-germination effects of MNC on P. striiformis uredospores. Application of MNC at 150 mg L-1 completely inhibited uredospore germination, and MNC at 100 mg L-1 reduced yellow rust severity in wheat plants by 89%. Expression of defense-related genes was increased after MNC treatment at 100 mg L-1, by 5.23-fold for jasmonate and ethylene-responsive factor 3 (JERF3), 4.89-fold for chitinase class II (CHI II), and 2.37-fold for pathogenesis-related protein 1 (PR1). Applying MNC at 100 mg L-1 also activated the antioxidant enzymes POD to 62.1 unit min-1 g-1 fresh wt, PPO to 21.6 units min-1 g-1 fresh wt, and CAT to 36.6 units min-1 g-1 fresh wt. MNC also enhanced phenolic content in wheat leaves (to 1489.53 mg 100 g-1 f. wt), and reduced lipid oxidation levels (to 5.6 μmol MDA g-1 fresh wt). MNC at 100 mg L-1 also mitigated damaging effects of P. striiformis infections on host leaf cell ultrastructure, increased leaf photosynthetic pigments, and increased wheat plant growth. These results show that MNC has potential as a natural control agent for yellow rust of wheat, although field testing of MNC is necessary before this material can be recommended for wheat production.

GhPME36 aggravates susceptibility to Liriomyza sativae by affecting cell wall biosynthesis in cotton leaves

BackgroundCotton is an important economic crop and a host of Liriomyza sativae. Pectin methylesterase (PME)-mediated pectin metabolism plays an indispensable role in multiple biological processes in planta. However, the pleiotropic functions of PME often lead to unpredictable effects on crop resistance to pests. Additionally, whether and how PME affects susceptibility to Liriomyza sativae remain unclear.ResultsHere, we isolated GhPME36, which is located in the cell wall, from upland cotton (Gossypium hirsutum L.). Interestingly, the overexpression of GhPME36 in cotton caused severe susceptibility to Liriomyza sativae but increased leaf biomass in Arabidopsis. Cytological observations revealed that the cell wall was thinner with more demethylesterified pectins in GhPME36-OE cotton leaves than in WT leaves, whereas the soluble sugar content of GhPME36-OE cotton leaf cell walls was accordingly higher; both factors attracted Liriomyza sativae to feed on GhPME36-OE cotton leaves. Metabolomic analysis demonstrated that glucose was significantly differentially accumulated. Transcriptomic analysis further revealed DEGs enriched in glucose metabolic pathways when GhPME36 was overexpressed, suggesting that GhPME36 aggravates susceptibility to Liriomyza sativae by affecting both the structure and components of cell wall biosynthesis. Moreover, GhPME36 interacts with another pectin-modifying enzyme, GhC/VIF1, to maintain the dynamic stability of pectin methyl esterification.ConclusionsTaken together, our results reveal the cytological and molecular mechanisms by which GhPME36 aggravates susceptibility to Liriomyza sativae. This study broadens the knowledge of PME function and provides new insights into plant resistance to pests and the safety of genetically modified plants.