In recent years salicylic acid (SA) has been the focus of intensive research due to its function as an endogenous signal mediating local and systemic plant defence responses against pathogens. It has ...also been found that SA plays a role during the plant response to abiotic stresses such as drought, chilling, heavy metal toxicity, heat, and osmotic stress. In this sense, SA appears to be, just like in mammals, an 'effective therapeutic agent' for plants. Besides this function during biotic and abiotic stress, SA plays a crucial role in the regulation of physiological and biochemical processes during the entire lifespan of the plant. The discovery of its targets and the understanding of its molecular modes of action in physiological processes could help in the dissection of the complex SA signalling network, confirming its important role in both plant health and disease. Here, the evidence that supports the role of SA during plant growth and development is reviewed by comparing experiments performed by exogenous application of SA with analysis of genotypes affected by SA levels and/or perception.
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Biostimulants are natural organic compounds that can be applied to plants, so that they can modify plant physiology, stimulate growth and increase response to biotic and abiotic stresses. ...Biostimulants must have good solubility in suitable solvents. The research about the Effect of Centella (Centella asiatica (L.) Urb.) Extract with Several Types of Solvents as a Biostimulant on the Growth of Pagoda Mustard (Brassica rapa var. narinosa L.) was conducted from March to June 2022 at the Plant Physiology Laboratory and Greenhouse, Department of Biology, Faculty of Mathematics and Natural Sciences, Andalas University, Padang. The research aims to determine the effect of C. asiatica extract with several types of solvents as a biostimulant and to determine the best type of solvent to extract C. asiatica as a biostimulant in increasing the growth of Pagoda mustard. This study used a completely randomized design (CRD) consisting of 5 treatments with 6 replications. The treatment consist of control, distilled water, methanol, ethanol and acetone. The results obtained in this study were C. asiatica extract with several types of solvents gave significantly different effects on the parameters of leaf number, leaf area and leaf chlorophyll content. The results of this study indicate that methanol and ethanol are the best solvents for making C. asiatica extract as a biostimulant that can increase the growth of Pagoda mustard.
The COsub.2 fertilization effect (CFE) plays a crucial role in the amelioration of climate change. Many physiological and environmental factors, such as stand age, stand type, and site conditions, ...may affect the extent of the CFE. However, the relationship between the CFE and these factors remains elusive. In this study, we used the emerging gross primary production (GPP) remote sensing products, with GPP predicted using eddy covariance–light use efficiency models (EC-LUE GPP) based on satellite near-infrared reflectance of vegetation (NIRv GPP) and assessed with a random forest model to explore the CFE trends with stand age in a coniferous forest and a broad-leaved forest in Heilongjiang Province, China. We additionally compared the differences among the CFEs under different site conditions. The CFEs in coniferous forests and broad-leaved forests both showed a rapid increase in stands of 10 to 20 years of age, followed by a decline after reaching a maximum, with the rate of decline reducing with age. Eventually, CFE remained stable in stands near 100 years of age. However, the CFE in coniferous forests exhibited more extended periods of rapid increase and a higher maximum than in broad-leaved forests. Moreover, in this study, we used the site class index (SCI) to grade site conditions. The results demonstrate that the CFE differed significantly under different levels of site conditions, and these differences gradually decreased with age. The site with the highest SCI had fewer environmental restrictions on the CFE, and consequently, the CFE rate of decline was faster. Our results are of significance in understanding the CFE and adapting to future changes in atmospheric COsub.2 concentration.
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5.
First off the mark: early seed germination Weitbrecht, Karin; Müller, Kerstin; Leubner-Metzger, Gerhard
Journal of experimental botany,
06/2011, Volume:
62, Issue:
10
Journal Article
Peer reviewed
Open access
Most plant seeds are dispersed in a dry, mature state. If these seeds are non-dormant and the environmental conditions are favourable, they will pass through the complex process of germination. In ...this review, recent progress made with state-of-the-art techniques including genome-wide gene expression analyses that provided deeper insight into the early phase of seed germination, which includes imbibition and the subsequent plateau phase of water uptake in which metabolism is reactivated, is summarized. The physiological state of a seed is determined, at least in part, by the stored mRNAs that are translated upon imbibition. Very early upon imbibition massive transcriptome changes occur, which are regulated by ambient temperature, light conditions, and plant hormones. The hormones abscisic acid and gibberellins play a major role in regulating early seed germination. The early germination phase of Arabidopsis thaliana culminates in testa rupture, which is followed by the late germination phase and endosperm rupture. An integrated view on the early phase of seed germination is provided and it is shown that it is characterized by dynamic biomechanical changes together with very early alterations in transcript, protein, and hormone levels that set the stage for the later events. Early seed germination thereby contributes to seed and seedling performance important for plant establishment in the natural and agricultural ecosystem.
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Plants commonly live in a symbiotic association with arbuscular mycorrhizal fungi (AMF). They invest photosynthetic products to feed their fungal partners, which, in return, provide mineral nutrients ...foraged in the soil by their intricate hyphal networks. Intriguingly, AMF can link neighboring plants, forming common mycorrhizal networks (CMNs). What are the terms of trade in such CMNs between plants and their shared fungal partners? To address this question, we set up microcosms containing a pair of test plants, interlinked by a CMN of Glomus intraradices or Glomus mosseae. The plants were flax (Linum usitatissimum; a C₃ plant) and sorghum (Sorghum bicolor; a C₄ plant), which display distinctly different ¹³C/¹²C isotope compositions. This allowed us to differentially assess the carbon investment of the two plants into the CMN through stable isotope tracing. In parallel, we determined the plants' "return of investment" (i.e. the acquisition of nutrients via CMN) using ¹⁵N and ³³P as tracers. Depending on the AMF species, we found a strong asymmetry in the terms of trade: flax invested little carbon but gained up to 94% of the nitrogen and phosphorus provided by the CMN, which highly facilitated growth, whereas the neighboring sorghum invested massive amounts of carbon with little return but was barely affected in growth. Overall biomass production in the mixed culture surpassed the mean of the two monocultures. Thus, CMNs may contribute to interplant facilitation and the productivity boosts often found with intercropping compared with conventional monocropping.
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Polyploidy is generally not tolerated in animals, but is widespread in plant genomes and may result in extensive genetic redundancy. The fate of duplicated genes is poorly understood, both ...functionally and evolutionarily. Soybean (Glycine max L.) has undergone two separate polyploidy events (13 and 59 million years ago) that have resulted in 75% of its genes being present in multiple copies. It therefore constitutes a good model to study the impact of whole‐genome duplication on gene expression. Using RNA‐seq, we tested the functional fate of a set of approximately 18 000 duplicated genes. Across seven tissues tested, approximately 50% of paralogs were differentially expressed and thus had undergone expression sub‐functionalization. Based on gene ontology and expression data, our analysis also revealed that only a small proportion of the duplicated genes have been neo‐functionalized or non‐functionalized. In addition, duplicated genes were often found in collinear blocks, and several blocks of duplicated genes were co‐regulated, suggesting some type of epigenetic or positional regulation. We also found that transcription factors and ribosomal protein genes were differentially expressed in many tissues, suggesting that the main consequence of polyploidy in soybean may be at the regulatory level.
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Dear Editor,
Transcription factors （TFs） are proteins that regulate the expression of target genes by binding to specific cis-elements in pro-moter regions. Transcriptional regulators （TRs） a）so ...regulate the expression of target genes; however, they operate indirectly via interaction with the basal transcription apparatus （e.g., TFs）, or by altering the accessibility of DNA to TFs via chromatin remodeling. Another type of regulatory proteins, protein kinases （PKs）,
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Green plants are all around us. We are totally dependent on them for food; we cultivate them for our pleasure; and we have used them in a vast number of ways down the centuries to our advantage. But ...have you ever wondered how plants work? Where do trees get the material to make wood? How does a bulb 'know' to sprout in the spring? Why are flowers different colours and why do they smell? This book answers these questions in a charming and accessible way. From their ability to take energy from sunlight to make their own food to their amazing range of life-sustaining, death-defying strategies, John King explains why plants dominate our planet. Plants might live life at a different pace from animals but they are just as fascinating. This is not just a book for keen gardeners and naturalists. This is a book for anyone who wants to understand why the earth is green.
Symbiotic root nodules in leguminous plants result from interaction between the plant and nitrogen-fixing rhizobia bacteria. There are two major types of legume nodules, determinate and ...indeterminate. Determinate nodules do not have a persistent meristem, while indeterminate nodules have a persistent meristem. Auxin is thought to play a role in the development of both these types of nodules. However, inhibition of rootward auxin transport at the site of nodule initiation is crucial for the development of indeterminate nodules but not determinate nodules. Using the synthetic auxin-responsive DR5 promoter in soybean (Glycine max), we show that there is relatively low auxin activity during determinate nodule initiation and that it is restricted to the nodule periphery subsequently during development. To examine if and what role auxin plays in determinate nodule development, we generated soybean composite plants with altered sensitivity to auxin. We overexpressed microRNA393 to silence the auxin receptor gene family, and these roots were hyposensitive to auxin. These roots nodulated normally, suggesting that only minimal/reduced auxin signaling is required for determinate nodule development. We overexpressed microRNA160 to silence a set of repressor auxin response factor transcription factors, and these roots were hypersensitive to auxin. These roots were not impaired in epidermal responses to rhizobia but had significantly reduced nodule primordium formation, suggesting that auxin hypersensitivity inhibits nodule development. These roots were also hyposensitive to cytokinin and had attenuated expression of key nodulation-associated transcription factors known to be regulated by cytokinin. We propose a regulatory feedback loop involving auxin and cytokinin during nodulation.
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