Development Of Stomata Research Articles

A Electron micrograph of the leaf epidermal structure of legumes

Our goal was to find morphological features that can help us identify or describe the stomata ontogeny and epidermal structures. Our team got seeds of two types of leguminous plants—Arachis hypogaea L. groundnuts and Vigna subterranean L. bambaranuts—from the Kano State Agricultural and Rural Development Authority and the Yankaba market in Nassarawa, which is in Kano State. The study specifically evaluated the leaf epidermal studies, stomata development (ontogeny), types of stomata, stomata size, pore length, pore width, and stomata index in both the surfaces of the leaves. We conducted ontogenetic studies using safety razor blades on the epidermal layers. We determined the stomata index by studying the type of stomata, the number of stomata, and the number of epidermal cells. We subjected the obtained data to a one-way analysis of variance. All the studied varieties/species exhibited amphistomatic stomata on both surfaces, with a higher density on the lower surface. In SAMNUT 23, we found the paracytic type of stomata, which is perigynous and has an irregular anticlinal cell wall. In Dandakar, we found the tetracyclic type, which is mesogynous and has a pentagonal epidermal cell shape and a slightly straight anticlinal cell wall. Finally, in Bambara nuts, we found the endocytic type, which is polygonal with a curved anticlinal wall and a mesoperigynous ontogeny.

Tolerance to mild shading levels in cattail as related to increased photosynthesis and changes in its leaf area and anatomy.

Shading is an environmental factor that has been little investigated regarding its effects on emergent aquatic plants. Typha domingensis Pers. is an emergent macrophyte that demonstrates some plasticity for self-shading, and as it can shade other species in the same area, the effect of shading on its traits deserves further investigation. The objective of the present study was to evaluate the gas exchange, leaf anatomy, and growth of T. domingensis cultivated under increasing shading intensities. The plants were collected and propagated in a greenhouse, and the clones were subjected to four shading intensities: 0% (unshaded), 35%, 73%, and 83% shading created by black nets. Growth traits, clonal production, photosynthesis, transpiration, and leaf anatomy were evaluated. The 73% and 83% shading promoted the death of all plants, but all plants survived in the 35% and unshaded treatments. Compared with the unshaded treatment, the 35% shading treatment promoted a higher photosynthetic rate and greater transpiration, supporting increased growth and production of clones. The increase in the photosynthetic rate in the 35% shading was related to the increase in leaf area which increased the photosynthesis of the whole plant. The 73% and 83% treatments inhibited the development of photosynthetic parenchyma and stomata in T. domingensis, leading to a drastic reduction in photosynthesis and energy depletion. Therefore, T. domingensis does not tolerate intense shading, but its photosynthetic characteristics and growth are favored by mild shading, a factor that may be of great importance for its competitiveness and invasive behavior.

Genome-wide analysis of the TIFY family in Lycium and the negative regulation of stomatal development by LrJAZ2 gene

Stomata are ports that facilitate gas and water vapor exchange during plant photosynthesis and transpiration. Stomatal development is strictly regulated by endogenous hormone. Jasmonate, an important signal that modulates multiple physiological processes in plants, has been found to negatively regulate stomatal development in Arabidopsis thaliana, yet the molecular mechanisms underlying stomata development signaling remain to be understood. Jasmonate ZIM-domain (JAZ) proteins are the members of TIFY family and the key component of JA signaling pathway. Its function in stomatal development is unclear to data. Here, we screened out 24 TIFY family members against the genome of Lycium, and identified a JAZ member by combination analyses of evolutionary tree, cis-elements in promoter and gene expression patterns. Overexpression of this gene (LrJAZ2) in Lycium ruthenicum and Arabidopsis thaliana indicated LrJAZ2 negatively regulates stomatal development. Microscopic observations revealed that overexpression of LrJAZ2 negatively regulated stomatal development by decreasing stomatal density and index, which may lead to lower leaf transpiration rates. Transcriptome data indicated the overexpression of LrJAZ2 up-regulated the stomatal related genes such as LrERL2, LrPYL4, and down-regulated the LrSPCH. Collectively, our study found that LrJAZ2 is a key gene in stomatal development regulation in L. ruthenicum and provided new insights into the regulation of stomatal development.

Update on stomata development and action under abiotic stress.

Stomata, key gatekeepers of plant hydration, have long been known to play a pivotal role in mitigating the impacts of abiotic stressors. However, the complex molecular mechanisms underscoring this role remain unresolved fully and continue to be the subject of research. In the context of water-use efficiency (WUE), a key indicator of a plant's ability to conserve water, this aspect links intrinsically with stomatal behavior. Given the pivotal role of stomata in modulating water loss, it can be argued that the complex mechanisms governing stomatal development and function will significantly influence a plant's WUE under different abiotic stress conditions. Addressing these calls for a concerted effort to strengthen plant adaptability through advanced, targeted research. In this vein, recent studies have illuminated how specific stressors trigger alterations in gene expression, orchestrating changes in stomatal pattern, structure, and opening. This reveals a complex interplay between stress stimuli and regulatory sequences of essential genes implicated in stomatal development, such as MUTE, SPCH, and FAMA. This review synthesizes current discoveries on the molecular foundations of stomatal development and behavior in various stress conditions and their implications for WUE. It highlights the imperative for continued exploration, as understanding and leveraging these mechanisms guarantee enhanced plant resilience amid an ever-changing climatic landscape.

Epidermal and subepidermal changes during the formation of hairy galls induced by Eriophyidae on Avicennia schaueriana leaves.

Leaf-galling Eriophyidae (Acarina) may promote simple or complex alterations in the organs of their host plants, such as an increase in indumentum density or the reorganization of epidermis and ground system tissue patterns. To test if hairy galls of Eriophyidae on Avicennia schaueriana (Acanthaceae) are related to complex changes, leaf galls in distinct developmental phases were compared to non-galled leaves using anatomical, histochemical, and histometric analyses. Quantitative comparisons of preferential gall induction sites and gall area according to distinct leaf portions were made to evaluate if the impacts of gall formation can be related to the distinct potentialities of leaf microsites. The apical portion of the leaves and leaf margins were the sites with the highest occurrence of galls, but no relationship was detected between gall area and induction site. The gall anatomy revealed that epidermal features are influenced the most with the development of abnormal stomata and projected or sunken salt glands. The most striking change is the neoformation of elongated filiform trichomes on the abaxial surface (where the mites occur) that accumulate reducing sugars and proteins. The filiform trichomes may protect the inducers against abiotic stressors and enemies, and the primary metabolites that accumulate are important foods for mites. The mesophyll has simple alterations, only in the spongy parenchyma. Complex alterations occur only in abaxial epidermal cells close to feeding sites of the inducer. The number of inducers per gall seems to be the most important influence on gall size, since gall area is not related to the position in the leaves.

A non-canonical function of Arabidopsis ERECTA proteins and a role of the SWI3B subunit of the SWI/SNF chromatin remodeling complex in gibberellin signaling.

The Arabidopsis ERECTA family (ERf) of leucine-rich repeat receptor-like kinases (LRR-RLKs) comprising ERECTA (ER), ERECTA-LIKE 1 (ERL1), and ERECTA-LIKE 2 (ERL2) controls epidermal patterning, inflorescence architecture, and stomata development and patterning. These proteins are reported to be plasma membrane associated. Here we show that the er/erl1/erl2 mutant exhibits impaired gibberellin (GA) biosynthesis and perception alongside broad transcriptional changes. The ERf kinase domains were found to localize to the nucleus where they interact with the SWI3B subunit of the SWI/SNF chromatin remodeling complex (CRCs). The er/erl1/erl2 mutant exhibits reduced SWI3B protein level and affected nucleosomal chromatin structure. Similar to swi3c and brm plants with inactivated subunits of SWI/SNF CRCs, it also does not accumulate DELLA RGA and GAI proteins. The ER kinase phosphorylates SWI3B in vitro, and the inactivation of all ERf proteins leads to the decreased phosphorylation of SWI3B protein in vivo. The identified correlation between DELLA overaccumulation and SWI3B proteasomal degradation, and the physical interaction of SWI3B with DELLA proteins indicate an important role of SWI3B-containing SWI/SNF CRCs in gibberellin signaling. Co-localization of ER and SWI3B on GID1 (GIBBERELLIN INSENSITIVE DWARF 1) DELLA target gene promoter regions and abolished SWI3B binding to GID1 promoters in er/erl1/erl2 plants supports the conclusion that ERf-SWI/SNF CRC interaction is important for transcriptional control of GA receptors. Thus, the involvement of ERf proteins in the transcriptional control of gene expression, and observed similar features for human HER2 (epidermal growth family receptor member), indicate an exciting target for further studies of evolutionarily conserved non-canonical functions of eukaryotic membrane receptors.

An R2R3 MYB transcription factor PsFLP regulates the symmetric division of guard mother cells during stomatal development in Pisum sativum.

MYB transcriptional regulators belong to one of the most significant transcription factors families in plants, among which R2R3-MYB transcription factors are involved in plant growth and development, hormone signal transduction, and stress response. Two R2R3-MYB transcription factors, FLP and its paralogous AtMYB88, redundantly regulate the symmetrical division of guard mother cells (GMCs), and abiotic stress response in Arabidopsis thaliana. Only one orthologue gene of FLP was identified in pea (Pisum sativum FLP; PsFLP). In this study, we explored the gene function of PsFLP by virus-induced gene silencing (VIGS) technology. The phenotypic analysis displayed that the silencing of PsFLP expression led to the abnormal development of stomata and the emergence of multiple guard cells tightly united. In addition, the abnormal stomata of flp could be fully rescued by PsFLP driven by the FLP promoter. In conclusion, the results showed that PsFLP plays a conservative negative role in regulating the symmetric division of GMC during stomatal development. Based on real-time quantitative PCR, the relative expressions of AAO3, NCED3, and SnRK2.3 significantly increased in the flp pFLP::PsFLP plants compared to mutant, indicating that PsFLP might be involved in drought stress response. Thus, PsFLP regulates the genes related to cell cycle division during the stomatal development of peas and participates in response to drought stress. The study provides a basis for further research on its function and application in leguminous crop breeding.

Post-embryonic function of GLOBULAR EMBRYO 4 (GLE4)/OsMPK6 in rice development.

In plants, mitogen activated protein kinases (MPKs) are involved in various signaling pathways that lead to biotic and abiotic responses as well as that regulate developmental processes. Among them, MPK6 and its closely related homologue, MPK3, act redundantly and are known to be involved in asymmetric cell divisions of meristemoid mother cells in stomata development and of zygotes in Arabidopsis. Loss-of-function mutants of GLE4/OsMPK6, which is an orthologue of MPK6 in rice, showed a defect in polarity establishment in early stage of embryogenesis. However, because of the embryo lethality of the mutations, the function of GLE4/OsMPK6 in post-embryonic development is not clarified. Here, we report the analysis of post embryonic function of GLE4/OsMPK6 in vegetative stage of rice using regenerated gle4/osmpk6 homozygous plants from tissue culture. The regenerated plants are dwarf and produce multiple shoots with small leaves. These shoots never develop into reproductive stage, instead, proliferate vegetative shoots repeatedly. Leaves of gle4/osmpk6 have small leaf blade at the tip and blade-sheath boundary become obscure. Stomata arrangement is also disturbed in gle4/osmpk6 leaf blade. The shape of shoot apical meristem of gle4/osmpk6 become disorganized. Thus, GLE4/OsMPK6 functions in shoot organization and stomata patterning in the post embryonic development in rice.

Seismic stress-mediated improvements in morphometry, foliar anatomy and biochemistry of in vitro grown plants of Gardenia jasminoides J. Ellis

ABSTRACT Gardenia jasminoides J. Ellis (Cape jasmine) is a horticultural plant. It is difficult to cultivate species due to pathogen sensitivity; hence, the demand for this species is gradually increasing. Thus, micropropagation would be a convenient tool to produce quality planting material, but the higher rate of mortality constitutes a constraint to large-scale propagation. Seismic stress is one of the abiotic stresses that promote growth, structural stability, and positively affect plantlet development. The objective of the present study was to evaluate the effect of moderate seismic stress under in vitro conditions on the proliferation of shoots, biochemical attributes (photosynthetic pigments, carbohydrates constituents, free amino acids, etc.), and foliar anatomical stability of plantlets G. jasminoides. Results showed the superiority of moderate seismic stress (75 rpm for 10 min) in the improved proliferation of shoots, development of functional stomata, elimination of anatomical abnormalities, improved photosynthetic pigments and rooting efficiency, and finally increased survival percentage of plantlets after transplantation into field conditions. These findings provided evidence for the positive role of the optimised seismic stress in regulating the morpho-anatomical and biochemical traits in G. jasminoides which is an indication of the development of diverse adaptive strategies by the micropropagated plantlets to abiotic stress.

Study of Camellia sinensis diploid and triploid leaf development mechanism based on transcriptome and leaf characteristics.

Polyploidization results in significant changes in the morphology and physiology of plants, with increased growth rate and genetic gains as the number of chromosomes increases. In this study, the leaf functional traits, photosynthetic characteristics, leaf cell structure and transcriptome of Camellia sinensis were analyzed. The results showed that triploid tea had a significant growth advantage over diploid tea, the leaf area was 59.81% larger, and the photosynthetic capacity was greater. The morphological structure of triploid leaves was significantly different, the xylem of the veins was more developed, the cell gap between the palisade tissue and the sponge tissue was larger and the stomata of the triploid leaves were also larger. Transcriptome sequencing analysis revealed that in triploid tea, the changes in leaf morphology and physiological characteristics were affected by the expression of certain key regulatory genes. We identified a large number of genes that may play important roles in leaf development, especially genes involved in photosynthesis, cell division, hormone synthesis and stomata development. This research will enhance our understanding of the molecular mechanism underlying tea and stomata development and provide a basis for molecular breeding of high-quality and high-yield tea varieties.

Intercellular Communication during Stomatal Development with a Focus on the Role of Symplastic Connection.

Stomata are microscopic pores on the plant epidermis that serve as a major passage for the gas and water exchange between a plant and the atmosphere. The formation of stomata requires a series of cell division and cell-fate transitions and some key regulators including transcription factors and peptides. Monocots have different stomatal patterning and a specific subsidiary cell formation process compared with dicots. Cell-to-cell symplastic trafficking mediated by plasmodesmata (PD) allows molecules including proteins, RNAs and hormones to function in neighboring cells by moving through the channels. During stomatal developmental process, the intercellular communication between stomata complex and adjacent epidermal cells are finely controlled at different stages. Thus, the stomata cells are isolated or connected with others to facilitate their formation or movement. In the review, we summarize the main regulation mechanism underlying stomata development in both dicots and monocots and especially the specific regulation of subsidiary cell formation in monocots. We aim to highlight the important role of symplastic connection modulation during stomata development, including the status of PD presence at different cell-cell interfaces and the function of relevant mobile factors in both dicots and monocots.

Observation of the development of leaf vein and stomata and identification candidate transcription factors related to vein/stoma development in grapevine leaf (Vitis vinifera L.)

The leaf functions through photosynthesis and determines the yield and quality of the grape (Vitis vinifera L.). Understanding the morphology, anatomy, and molecular regulation of leaf development can provide insight into the function of the leaf. In the present study, the microstructure of the vein and stomata was observed using an improved tissue clearing method, and differently expressed transcription factors (TFs) underlying leaf development were determined by transcriptome analysis in the ‘Pinot Noir’ grape. The process of stomata development from a single epidermal cell to a mature stomata cell was observed clearly under light microscopy by improving the method of tissue clearing. The onset of stomata formation in the leaf tip occurred prior to that in the central leaf, and developing stomata were observed in the center of the leaves at different development stages except for L5, when only mature stomata were present. The major vein was initiated before leaf unfolding (L1) and numbers of vessels increased underlying leaf growth. The shape of the vessel presented tapering. Freely ending veins were not observed until stages L4 and L5, and the vessels were different from other order veins in shape and ways of connection. Development-dependent differences between stomata and vein suggested differences in function during leaf development. A total of 445 TFs involved in leaf morphology and anatomy were identified. The members of the bHLH family (SCRM) and MYB family (MYB88) can contribute to stomata patterning during leaf development. Members of the TF families of ARF (ARF5), Dof (TMO6 and HCA2), HD-Zip III (HB14), and GRAS (SCR, SCL14, and SCL28) were potential regulators involved in vein development. The grape orthologs of WOX9, TCP4, and GRF1-9 can participate in leaf outgrowth and expansion. These results will be helpful for our further study of the molecular regulation of leaf development and the relation between leaf structure and function, which can be applied to improve grape production.

Variations of stomata development in tea plant (Camellia sinensis) leaves in different light and temperature environments and genetic backgrounds.

Stomata perform important functions in plant photosynthesis, respiration, gas exchange, and interactions with environments. However, tea plant stomata development and functions are not known. Here, we show morphological changes during stomata development and genetic dissection of stomata lineage genes regulating stomata formation in tea developing leaves. Different tea plant cultivars displayed clear variations in the stomata development rate, density and size, which are closely related to their tolerance against dehydration capabilities. Whole sets of stomata lineage genes were identified to display predicted functions in regulating stomatal development and formation. The stomata development and lineage genes were tightly regulated by light intensities and high or low temperature stresses, which affected stomata density and function. Furthermore, lower stomatal density and larger size were observed in triploid tea varieties as compared to those in diploid plant. Key stomata lineage genes such as CsSPCHs, CsSCRM, and CsFAMA showed much lower expression levels, whereas negative regulators CsEPF1 and CsYODAs had higher expression levels in triploid than in diploid tea varieties. Our study provides new insight into tea plant stomatal morphological development and the genetic regulatory mechanisms on stomata development under abiotic stresses and genetic backgrounds. The study lays a foundation for future exploring of the genetic improvement of water use efficiency in tea plants for living up to the challenge of global climate change.

Stu-miR827-Targeted StWRKY48 Transcription Factor Negatively Regulates Drought Tolerance of Potato by Increasing Leaf Stomatal Density

Stomata are specialized portals in plant leaves to modulate water loss from plants to the atmosphere by control of the transpiration, thereby determining the water-use efficiency and drought resistance of plants. Despite that the stomata developmental progression is well-understood at the molecular level, the experimental evidence that miRNA regulates stomata development is still lacking, and the underlying mechanism remains elusive. This study demonstrates the involvement of stu-miR827 in regulating the drought tolerance of potato due to its control over the leaf stomatal density. The expression analysis showed that stu-miR827 was obviously repressed by drought stresses and then rapidly increased after rewatering. Suppressing the expression of stu-miR827 transgenic potato lines showed an increase in stomatal density, correlating with a weaker drought resistance compared with wildtype potato lines. In addition, StWRKY48 was identified as the target gene of stu-miR827, and the expression of StWRKY48 was obviously induced by drought stresses and was greatly upregulated in stu-miR827 knockdown transgenic potato lines, suggesting its involvement in the drought stress response. Importantly, the expression of genes associated with stomata development, such as SDD (stomatal density and distribution) and TMM (too many mouths), was seriously suppressed in transgenic lines. Altogether, these observations demonstrated that suppression of stu-miR827 might lead to overexpression of StWRKY48, which may contribute to negatively regulating the drought adaptation of potato by increasing the stomatal density. The results may facilitate functional studies of miRNAs in the process of drought tolerance in plants.

Comparison of Stomatal Structure and Distribution between Ovules and Leaves in Ginkgo biloba

Stomata are plant epidermal structures that play essential roles in photosynthesis, respiration, and transpiration. Although stomata on plant leaves have been extensively studied, their structure and distribution on other organs remain poorly understood. The “living fossil “, Ginkgo biloba, has naked ovules that are thought to be primitive reproductive structures in ancient seed plants. Therefore, we hypothesized that there are some distinct stoma features in G. biloba ovules that have not been reported. In this study, we investigated the morphological development of stomata on ovules and leaves of Ginkgo biloba using scanning electron microscopy, then examined the anatomical characteristics of the general stalk and petiole using semi-thin sectioning. We found that stomata were distributed on the epidermis of the whole ovule, except near the micropyle; these stomata persisted until harvest, indicating that ovules perform gross photosynthesis to an extent similar to the photosynthesis observed in leaves, which is beneficial to ovule development. Ovule and leaf stomata share similar orientation, composition, and development; however, their distribution and subsidiary cell morphology significantly differ. The morphology of the general stalk was similar to the morphology of the petiole, but xylem cell development was minimal, and no sclerenchyma cells were present beneath the epidermis; these findings suggested that the general stalk is biomechanically weaker than the petiole. Overall, these results suggest that despite their differences, G. biloba ovules and leaves share many morphological and anatomical similarities in terms of stomatal architecture and stalk anatomy. These findings will help to elucidate the leaf origins of “flowers” in ancient plants.

Vapour Pressure Deficit (VPD) Drives the Balance of Hydraulic-Related Anatomical Traits in Lettuce Leaves.

The coordination of leaf hydraulic-related traits with leaf size is influenced by environmental conditions and especially by VPD. Water and gas flows are guided by leaf anatomical and physiological traits, whose plasticity is crucial for plants to face environmental changes. Only a few studies have analysed how variations in VPD levels influence stomatal and vein development and their correlation with leaf size, reporting contrasting results. Thus, we applied microscopy techniques to evaluate the effect of low and high VPDs on the development of stomata and veins, also analysing leaf functional traits. We hypothesized that leaves under high VPD with a modified balance between veins and stomata face higher transpiration. We also explored the variability of stomata and vein density across the leaf lamina. From the results, it was evident that under both VPDs, plants maintained a coordinated development of stomata and veins, with a higher density at low VPD. Moreover, more stomata but fewer veins developed in the parts of the lettuce head exposed to light, suggesting that their differentiation during leaf expansion is strictly dependent on the microclimatic conditions. Knowing the plasticity of hydraulic-related morpho-functional traits and its intra-leaf variability is timely for their impact on water and gas fluxes, thus helping to evaluate the impact of environmental-driven anatomical variations on productivity of natural ecosystems and crops, in a climate change scenario.

Stomatal Development and Gene Expression in Rice Florets.

Stomata play a fundamental role in modulating the exchange of gases between plants and the atmosphere. These microscopic structures form in high numbers on the leaf epidermis and are also present on flowers. Although leaf stomata are well studied, little attention has been paid to the development or function of floral stomata. Here, we characterize in detail the spatial distribution and development of the floral stomata of the indica rice variety IR64. We show that stomatal complexes are present at low density on specific areas of the lemma, palea and anthers and are morphologically different compared to stomata found on leaves. We reveal that in the bract-like organs, stomatal development follows the same cell lineage transitions as in rice leaves and demonstrate that the overexpression of the stomatal development regulators OsEPFL9-1 and OsEPF1 leads to dramatic changes in stomatal density in rice floral organs, producing lemma with approximately twice as many stomata (OsEPFL9-1_oe) or lemma where stomata are practically absent (OsEPF1_oe). Transcriptomic analysis of developing florets also indicates that the cellular transitions during the development of floral stomata are regulated by the same genetic network used in rice leaves. Finally, although we were unable to detect an impact on plant reproduction linked to changes in the density of floral stomata, we report alterations in global gene expression in lines overexpressing OsEPF1 and discuss how our results reflect on the possible role(s) of floral stomata.

ICE‐SCREAM comes in different flavors: Angiosperms encode two types of ICE proteins predicted to differ in their regulation by OST1 and MPK3/6

AbstractINDUCER OF CBF EXPRESSION (ICE) proteins reportedly have a role in cold acclimation and stomata development, but the former has recently been questioned. Our aim was to analyze ICE, OPEN STOMATA 1 (OST1) and MITOGEN ACTIVATED PROTEIN KINASE 3/6 (MPK3/6) protein data and place the results in context with reports in the literature. Orthologous protein sequences from species representative of different plant lineages were retrieved via BLAST searches and assembled into multiple sequence alignments for a comprehensive comparison of key features. We identified one type of ICE protein in bryophytes, lycophytes, ferns and angiosperms, and a second type of ICE protein in angiosperms only, each with characteristic interaction domains. Due to the higher observed similarity of the identified orthologs to proteins from Vitis riparia than to those from Arabidopsis, they were referred to as VrICE2L and VrICE4L, respectively. Regulatory sequence motifs for the kinase OST1 were present in the VrICE2L proteins although less conserved in the non‐angiosperms, whereas OST1 orthologs could be identified in all plant species, including algae. Interestingly, MPK3/6 motifs were most clearly conserved in the VrICE2L and VrICE4L proteins of the more evolved angiosperms, at a time that the A subtype of MPK3/6 kinases and the CRT‐BINDING FACTOR (CBF)‐encoding genes first appeared in the plant lineages. These data are intended to stimulate further investigations of VrICE4L proteins in non‐model plants and provide some evolutionary context into the overlap between stomatal function and regulation, and the cold acclimation pathway.

Acidic and Alkaline Conditions Affect the Growth of Tree Peony Plants via Altering Photosynthetic Characteristics, Limiting Nutrient Assimilation, and Impairing ROS Balance.

Exposure to acidic and alkaline conditions were found to cause the excess accumulation of reactive oxygen species in tree peony, thereby causing damage and inhibiting plant growth and development. The activities of antioxidant enzymes were also found to be significantly up-regulated, especially under alkaline conditions; this explained why tree peony is better adapted to alkaline than to acidic conditions. Through pairwise comparisons, 144 differentially expressed genes (DEGs) associated with plant growth, photosynthesis, and stress were identified. The DEGs related to stress were up-regulated, whereas the remaining DEGs were almost all down-regulated after acid and alkaline treatments. The nutrient assimilation was greatly inhibited. Chlorophyll synthesis genes were suppressed, and chlorophyll content was reduced. The development and structures of stomata and chloroplasts and the transcription of related genes were also influenced. Among photosynthesis-related DEGs, electron transport chains were the most sensitive. The suppressed expression of photosynthesis genes and the reduced light-harvesting capacity, together with the impairment of chloroplasts and stomata, finally led to a sharp decrease in the net photosynthetic rate. Carbohydrate accumulation and plant biomass were also reduced. The present study provides a theoretical basis for the response mechanisms of tree peony to adverse pH conditions and enriches knowledge of plant adaptation to alkaline conditions.

Impact of culture vessels on micro-morphological features of in vitro Dendrobium Sabin Blue orchid.

Different designs of the plant tissue culture vessel, such as size, material, and shape, may alter its microenvironment atmosphere. The present study was conducted on protocorm-like bodies (PLBs) of Dendrobium Sabin Blue orchid to determine the development of PLBs on plastic and glass culture vessels of different sizes. PLBs were cultured in half-strength Murashige and Skoog (MS) medium with the same initial weight of 0.5 g in 10 replicates. The growth index of the PLBs was calculated after 11 weeks to study their growth in every vessel; additionally, biochemical analysis was performed to determine carbohydrate content, proline concentration, and photosynthesis pigments in the PLBs. Scanning electron microscopy (SEM) was performed to study stomata development on PLBs in each vessel, and histological analyses were conducted to study the cell structure. Overall, the PLBs cultured in a large 470 ml plastic vessel showed successful growth with a high growth index, high carbohydrate content, low-stress condition, and high chlorophyll content. SEM confirmed that the presence of trichome and rhizoid in PLBs cultured in the 470 ml plastic vessel. Histological analysis showed the formation of the shoot on the PLBs and the presence of starch granules. Thus, the use of plastic as a culture vessel provides a good impact for culturing PLBs and has low cost.