Guard Cells
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2021 ◽  
Vol 12 ◽  
Author(s):  
Chuanlei Xiao ◽  
Huimin Guo ◽  
Jing Tang ◽  
Jiaying Li ◽  
Xuan Yao ◽  
...  

There are more than 100 GDSL lipases in Arabidopsis, but only a few members have been functionally investigated. Moreover, no reports have ever given a comprehensive analysis of GDSLs in stomatal biology. Here, we systematically investigated the expression patterns of 19 putative Guard-cell-enriched GDSL Lipases (GGLs) at various developmental stages and in response to hormone and abiotic stress treatments. Gene expression analyses showed that these GGLs had diverse expression patterns. Fifteen GGLs were highly expressed in guard cells, with seven preferentially in guard cells. Most GGLs were localized in endoplasmic reticulum, and some were also localized in lipid droplets and nucleus. Some closely homologous GGLs exhibited similar expression patterns at various tissues and in response to hormone and abiotic stresses, or similar subcellular localization, suggesting the correlation of expression pattern and biological function, and the functional redundancy of GGLs in plant development and environmental adaptations. Further phenotypic identification of ggl mutants revealed that GGL7, GGL14, GGL22, and GGL26 played unique and redundant roles in stomatal dynamics, stomatal density and morphology, and plant water relation. The present study provides unique resources for functional insights into these GGLs to control stomatal dynamics and development, plant growth, and adaptation to the environment.


2021 ◽  
Author(s):  
Li Qin ◽  
Ling-hui Tang ◽  
Jia-shu Xu ◽  
Xian-hui Zhang ◽  
Yun Zhu ◽  
...  

SUMMARYThe rapid (R)-type anion channel plays a central role in controlling stomatal closure in plant guard cells, thus regulating the exchange of water and photosynthetic gas (CO2) in response to environmental stimuli. The activity of the R- type anion channel is regulated by malate. However, the molecular basis of the R-type anion channel activity remains elusive. Here, we describe the first cryo-EM structure of the R-type anion channel QUAC1 at 3.5 Å resolution in the presence of malate. The structure reveals that the QUAC1 is a symmetrical dimer, forming a single electropositive T-shaped pore for passing anions across the membrane. The transmembrane and cytoplasmic domains are assembled into a twisted bi-layer architecture, with the associated dimeric interfaces nearly perpendicular. Our structural and functional analyses reveal that QUAC1 functions as an inward rectifying anion channel and suggests a mechanism for malate-mediated channel activation. Altogether, our study uncovers the molecular basis for a novel class of anion channels and provides insights into the gating and modulation of the R-type anion channel.


2021 ◽  
Vol 12 ◽  
Author(s):  
Tenghua Wang ◽  
Wenxiu Ye ◽  
Yin Wang ◽  
Maoxing Zhang ◽  
Yusuke Aihara ◽  
...  

Stomata in the epidermis of plants play essential roles in the regulation of photosynthesis and transpiration. Stomata open in response to blue light (BL) by phosphorylation-dependent activation of the plasma membrane (PM) H+-ATPase in guard cells. Under water stress, the plant hormone abscisic acid (ABA) promotes stomatal closure via the ABA-signaling pathway to reduce water loss. We established a chemical screening method to identify compounds that affect stomatal movements in Commelina benghalensis. We performed chemical screening using a protease inhibitor (PI) library of 130 inhibitors to identify inhibitors of stomatal movement. We discovered 17 PIs that inhibited light-induced stomatal opening by more than 50%. Further analysis of the top three inhibitors (PI1, PI2, and PI3; inhibitors of ubiquitin-specific protease 1, membrane type-1 matrix metalloproteinase, and matrix metalloproteinase-2, respectively) revealed that these inhibitors suppressed BL-induced phosphorylation of the PM H+-ATPase but had no effect on the activity of phototropins or ABA-dependent responses. The results suggest that these PIs suppress BL-induced stomatal opening at least in part by inhibiting PM H+-ATPase activity but not the ABA-signaling pathway. The targets of PI1, PI2, and PI3 were predicted by bioinformatics analyses, which provided insight into factors involved in BL-induced stomatal opening.


2021 ◽  
pp. 1-16
Author(s):  
Felipe Górski ◽  
Geysiane Moreira Gerotti ◽  
Hélida Mara Magalhães

The in vitro development of a plant is controlled by factors that promote a series of plant responses, which interfere with tissue organogenesis and morphology. For plants of the family Lamiaceae, these factors remain unknown or poorly understood, hindering in vitro cultivation of these plants. The basil cultivar ‘Grecco a palla’ has attractive chemical properties for medicinal, pharmaceutical, and cosmetic industries; however, its production is limited due to the lack of appropriate cultivation conditions. Two types of explants of this species (nodal segments and stem apexes) were grown in culture media with auxin and cytokinin, and their development was followed for 60 days. During in vitro cultivation, both explants were subjected to higher concentrations of plant growth regulators (PGRs) produced only calluses, without induction of shoots. Small amounts of regulators favored hyperhydricity as nodal segments or stem apexes in the absence of PGRs produced plants with disturbances, including brittle, light green, and thick leaves. In this case, there was an increase in the cell layers of palisade parenchyma, which had large cell spaces and larger cells. This tissue also advanced to spongy parenchyma and compressed it. The stomatal density was low; however, the stomata were larger with additions mainly in the guard cells and the stomatic opening. Therefore, stem apexes in the absence of PGRs produced more vigorous plants, whereas nodal segments with low amounts of cytokinins and auxins developed a well-branched and abundant root system.


2021 ◽  
Author(s):  
Changzheng Song ◽  
Jiao Zhao ◽  
Marjorie Guichard ◽  
Dongbo Shi ◽  
Guido Grossmann ◽  
...  

Strigolactones (SLs) are a class of plant hormones modulating developmental programs in response to endogenous and exogenous stimuli and mediating biotic interactions. However, a comprehensive view on the spatio-temporal pattern of SL signaling has not been established and tools for a systematic in planta analysis do not exist. Here, we present Strigo-D2, a genetically encoded ratiometric SL signaling sensor, allowing the examination of SL signaling distribution with cellular resolution and its rapid response to altered SL levels in intact plants. By monitoring the abundance of a truncated and fluorescently labeled SUPPRESSOR OF MAX2 1-LIKE 6 (SMXL6) protein, a proteolytic target of the SL signaling machinery, we show that all cell types investigated have the capacity to respond to changes in SL levels but with very different dynamics. In particular, SL signaling is pronounced in vascular cells but low in guard cells and the meristematic region of the root. We also show that other hormones leave Strigo-D2 activity unchanged indicating that initial SL signaling steps work in isolation from other hormonal signaling pathways. Specificity and spatio-temporal resolution of Strigo-D2 underline the value of the sensor for monitoring SL signaling in a broad range of biological contexts and with highly instructive analytical depth.


2021 ◽  
Vol 63 ◽  
pp. 102090
Author(s):  
Roxane P. Spiegelhalder ◽  
Michael T. Raissig

2021 ◽  
Vol 12 ◽  
Author(s):  
Li-Na Yang ◽  
Hao Liu ◽  
Yan-Ping Wang ◽  
Jenifer Seematti ◽  
Laura J. Grenville-Briggs ◽  
...  

Phytophthora infestans, the most damaging oomycete pathogen of potato, is specialized to grow sporangiophore through opened stomata for secondary inoculum production. However, it is still unclear which metabolic pathways in potato are manipulated by P. infestans in the guard cell–pathogen interactions to open the stomata. Here microscopic observations and cell biology were used to investigate antagonistic interactions between guard cells and the oomycete pathogen. We observed that the antagonistic interactions started at the very beginning of infection. Stomatal movement is an important part of the immune response of potato to P. infestans infection and this occurs through guard cell death and stomatal closure. We observed that P. infestans appeared to manipulate metabolic processes in guard cells, such as triacylglycerol (TAG) breakdown, starch degradation, H2O2 scavenging, and NO catabolism, which are involved in stomatal movement, to evade these stomatal defense responses. The signal transduction pathway of P. infestans-induced stomatal opening likely starts from H2O2 and NO scavenging, along with TAG breakdown while the subsequent starch degradation reinforces the opening process by strengthening guard cell turgor and opening the stomata to their maximum aperture. These results suggest that stomata are a barrier stopping P. infestans from completing its life cycle, but this host defense system can be bypassed through the manipulation of diverse metabolic pathways that may be induced by P. infestans effector proteins.


2021 ◽  
Author(s):  
Hongliang Wang ◽  
Rongxia Li ◽  
Jingkai Rong ◽  
Tian Sang ◽  
Chanhong Kim ◽  
...  

Multicellular organisms such as plants contain different types of cells with specialized functions. Analyzing the characteristics of each type of cells will reveal specific cell functions and enhance understanding of how an organism organizes and works. Due to the lack of a method to enrich the particular type of cells and the limited sensitivity and capability of mass spectrometry-based technologies, comprehensive analyses of the global proteome in a single plant cell are still impossible. Here we report a high-sensitive and efficient single-cell-proteomic pipeline, combining simplified flow cytometry-based fluorescent cell-sorting for fluorescent protoplasts and an optimized nano-scale proteomics method, which allows us to identify more than 1,000 unique proteins from 500 guard cell protoplasts. This method was applied to profile the proteome of guard cells and mesophyll cells in Arabidopsis leaves, and epidermal cells in root tips of Arabidopsis and rice seedlings. We also performed an in-depth, quantitative comparison between the proteomics of guard cells and mesophyll cells and revealed that the enrichment of signal transduction-related proteins enables guard cells to respond to various environmental stimuli quickly. This method is applicable to other types of cells in plant or non-plant systems to acquire systemic knowledge of how cells work specifically and in highly organized multiple cell organisms.


Complexity ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Abdul Razzaq ◽  
Sharaiz Shahid ◽  
Muhammad Akram ◽  
Muhammad Ashraf ◽  
Shahid Iqbal ◽  
...  

Stomata are the main medium of plants for the trade of water, regulate the gas exchange, and are responsible for the process of photosynthesis and transpiration. The stomata are surrounded by guard cells, which help to control the rate of transpiration by opening and closing the stomata. The stomata states (open and close) play a significant role in describing the plant’s health. Moreover, stomata counting is important for scientists to investigate the numbers of stomata that are open and those that are closed to measure their density and distribution on the surface of leaves through different sampling techniques. Although a few techniques for stomata counting have been proposed, these approaches do not identify and classify the stomata based on their states in leaves. In this research, we have developed an automatic system for stomata state identification and counting in quinoa leaf images through the transformed learning (neural network model Single Shot Detector) approach. In leaf imprint, the state of stomata has been determined by measuring the correlation between the area of stomata and the aperture of each detected stoma in the image. The stomata states have been classified through the Support Vector Machine (SVM) algorithm. The overall identification and classification accuracy of the proposed system are 98.6% and 97%, respectively, helping researchers to obtain accurate stomatal state information for leaves in an efficient and simple way.


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