查看更多>>摘要：? 2022Excessive N deposition leads to the conversion of previously N limited to N saturated forest ecosystems. The input of N can result in severe N/P imbalance and N-induced P deficiency. The present study investigates whether N addition induces P deficiency in beech saplings or if this can be counteracted by enhanced internal P (re)cycling. Furthermore, it was tested whether addition of P can mitigate N induced P deficiency. In addition, higher need of P due to enhanced growth may be realized either by enhanced P uptake or by improved internal P (re)cycling. This assumption was tested with beech saplings growing at higher light intensity. Therefore, a mesocosm approach with beech saplings and soil (O and A horizon) originating from a P-poor forest was conducted. Mesocosms were cultivated for two growing seasons in a garden. Addition of N, P, or combined addition of N and P took place during the first year and another group of saplings was exposed to higher light intensity to enhance CO2 assimilation and growth. Soil horizons and beech saplings were harvested during the second year of growth in spring, summer, autumn, and winter. The results show that internal (re)cycling of N and P is different and mostly determined by the season. The seasonal (re)cycling of P was driven by the metabolic P demand of tissues/organs characterized by shifting P between the perennial tissues bark and wood of branches and coarse roots and deciduous leaves, fine roots and long-distance transport paths without using major storage resources. In contrast, seasonal (re)cycling of N is characterized by N storage in perennial tissues during dormancy and by N mobilization from the entire trunk, i.e. branch, stem and coarse roots, in spring. Furthermore, these seasonal dynamics were found to be independent of the treatment.
查看更多>>摘要：? 2022 Elsevier B.V.The NF-YA transcription factor in plants is a subunit of the NF-Y (NUCLEAR FACTOR-Y) complex, which plays important roles in plant stress responses and development. The transcripts of genes encoding NF-YA are predicted to be cleaved by members of the miR169 family. We previously identified several miR169s from rapeseed (Brassica napus) based on high-throughput sequencing. In this study, by using 5′ RACE and transient expression in Nicotiana benthamiana, we established that Bna-MIR169m, Bna-MIR169n, Bna-MIR169t (newly identified in this study) cleave target BnaNF-YAs. Quantitative PCR analysis revealed that most Bna-MIR169s detected in the leaves and roots were responsive to salinity, drought, and abscisic acid (ABA) treatment. To examine that these regulations are delivered to downstream of NF-YA, Bna-MI169n and BnaNF-YA9 were heterologously expressed in Arabidopsis thaliana plants. Bna-MI169n exhibited delayed seed germination and root elongation, oppositely, those expressing BnaNF-YA9 had higher rates of seed germination and root elongation under abiotic stress compared to untransformed Arabidopsis. Furthermore, through digital gene expression profiling, we identified several downstream genes co-regulated by Bna-miR169n and BnaNF-YA9. All these results point out that Bna-miR169n and BnaNF-YA9 form a cascade regulates plant abiotic stress responses.
查看更多>>摘要：? 2022 Elsevier B.V.Cyclic nucleotide-gated channels (CNGCs) in plants are nonselective Ca2+-permeable cationic channel proteins, that are part of the signal transduction cascade system and are involved in the physiological regulation of plant responses to adverse environments. This study firstly showed that the stronger submergence tolerance of G. soja P18B seedlings compared to the G. max cultivar KF1, might be related to the enhanced processes of Ca2+ signal cascade (higher Ca2+ content), anaerobic metabolism (higher activities of PDC and ADH), and energy reserves (higher ATP level) in the leaves during submergence. Then, the potential submergence-responsive differentially expressed genes (DEGs) enriched in voltage-gated potassium channel activity, such as GsCNGC20-f and GsCNGC20-g, and those enriched in calcium ion binding, i.e. GsCaML, GsCAM4, GsCML41, and GsCML45 were identified through leaf transcriptomic analysis of P18B and KF1 under submergence. The qRT-PCR, tobacco leaf transient expression and GUS staining displayed a more obviously induced upregulation of GsCNGC20-f and GsCNGC20-g by submergence stress. BiFC and Y2H assays showed that plasma membrane-located GsCNGC-f could interact with GsCaM4 or GsCaML. Finally, overexpression of GsCNGC20-f could alleviate submergence injury in hairy-root composite soybean plants or transgenic Arabidopsis seedlings by maintaining a higher content of Ca2+ and activities of PDC and ADH (associated with upregulated gene expression of PDCs and ADHs), and thereafter enhancing ATP levels in the leaves via improved anaerobic respiration under hypoxic conditions. The functions of GsCNGC20-f involving in the adaptation and survival of G. soja P18B seedlings under submergence stress can provide new perspectives for the molecular breeding of flooding-tolerant soybeans or other crops.
查看更多>>摘要：? 2022 Elsevier B.V.Salicylic acid (SA) plays an important role in regulating leaf senescence. However, the molecular mechanism of leaf senescence of safflower (Carthamus tinctorius) is still elusive. In this study, we found that the bHLH transcription factor (TF) CtbHLH41 in Carthamus tinctorius significantly delayed leaf senescence and inhibited the expression of senescence-related genes. In order to explore how CtbHLH41 promotes leaf senescence, we carried out yeast two-hybrid screening. In this study, by exploring the mechanism of CtbHLH41 regulating CtCP1, it was found that CtCP1 promoted the hydrolysis of CtbHLH41 protein, accelerated the transcriptional activities of salicylic acid-mediated senescence-related genes CtSAG12 and CtSAG29, chlorophyll degradation genes CtNYC1 and CtNYE1, and accelerated leaf senescence. We found a negative SA regulator CtANS1, which interacted with CtbHLH41 and regulated its stability, thereby inhibiting CtCP1-mediated leaf senescence. In short, our results provide a new insight into the mechanism of CtbHLH41 actively regulating the senescence of safflower leaves induced by SA.
查看更多>>摘要：? 2022 Elsevier B.V.Metallothioneins (MTs) are diverse class of cysteine-rich proteins having metal-chelation properties. The role of MTs has been demonstrated in different abiotic stresses and MTs have been designated as biomolecular stress markers. Chickpea is an important legume crop supplying proteins to humans, as well as acting as great soil-binders along with nitrogen-fixation capability. The present research deals with the development of transgenic chickpea overexpressing metallothionein type-1 (CarMT1) gene for analyzing its role in stress tolerance against drought and heavy metals. The overexpression construct was designed using binary expression vector, pBI121 and transformed in chickpea desi cultivar, Pusa-362 for functional validation by using sonication-assisted Agrobacterium-mediated transformation. The results indicated high transcript levels under the drought (22-folds) and changes in physiological (photosynthesis rate, transpiration rate, stomatal conductance, water-use efficiency) and biochemical (antioxidant enzymes and compatible solutes) parameters suggesting stress-mitigating roles of CarMT1. The transgenic seeds were evaluated for heavy metal stress adaptation that resulted in better seed survival efficiency under different heavy metal stresses. The results indicated beneficial roles of MT gene in transgenic lines of chickpea in presence of different abiotic stresses, which could pave the way for multi-stress tolerant crop development.
查看更多>>摘要：? 2022 Elsevier B.V.Drought is a major adverse environmental factor that limits plant productivity. Concomitant assimilation of carbon (C) and nitrogen (N) in illuminated leaves requires the regulated partitioning of reductant and photosynthate to sustain the demands of amino acid and carbohydrate biosynthesis. The short-term exposure to drought and its responses of photosynthesis and photosynthate partitioning to N enrichment was studied in Cyamopsis tetragonoloba (L.) Taub (guar). Four contrasting varieties of guar, HG-563, RGC-986 (drought-tolerant) and RGC-471, Varsha (drought-sensitive) were subjected to 15 days water stress and leaf tissues were studied in order to contemplate the counter strategy engaged under drought conditions. In guar plants, sensors trigger a signalling cascade that activates numerous proteins to induce the expression of certain genes involved in carbon and nitrogen metabolism.The levels of glucose, starch, and Glutamate dehydrogenase (GDH), Aspartate aminotransferase (AspAT), isocitrate dehydrogenase (ICDH), Nitrate Reductase (NR), and Nitrite reductase (NiR) activities were determined biochemically during 15 days drought treatment, at three stages. Further, the carbon (oxidative phosphorylation and TCA cycle) - nitrogen metabolic pathway interaction was studied at the molecular level. The respiratory pathway genes were upregulated, while the nitrogen metabolic pathway genes were downregulated under all stages of drought in guar plants. The physiological, biochemical and molecular data suggests that the high rates of dark respiration was insufficient to provide extra carbon required to assist amino acid synthesis but rather sufficed by a rapid metamorphosis in the photosynthetic carbon partitioning to amino acid metabolism via the nitrogen metabolism.
查看更多>>摘要：? 2022The effects of enhanced ultraviolet-B (UV-B, 280–320 nm) radiation reaching the Earth's surface has become an important issue in terrestrial and marine ecosystems. Living in the land–marine boundary, intertidal macroalgae have various adaptive strategies to resist drastic environmental changes. In this study, we investigated the effects of enhanced UV-B radiation on the photosynthetic performance and photoprotective mechanisms of the red macroalgae Neoporphyra haitanensis. Our results showed that increasing UV-B radiation inhibited growth, damaged chloroplast structures and photosynthetic pigments, and reduced PSII activity and recovery ability in N. haitanensis. UV-B radiation significantly increased non-photochemical quenching (NPQ), indicating that NPQ is an effective photoprotection strategy in N. haitanensis. The transthylakoid proton gradient (ΔpH) uncoupler ammonium chloride (NH4Cl) significantly inhibited NPQ induction, showing that the induction of NPQ in N. haitanensis was dependent on ΔpH. Furthermore, violaxanthin and antheraxanthin, essential components of the xanthophyll cycle for modulating NPQ, were not detected in N. haitanensis, indicating the absence of the xanthophyll cycle in N. haitanensis. However, the increased NPQ under UV-B radiation was still associated with the accumulation of zeaxanthin. These findings will be useful for revealing adaptive strategies of intertidal macroalgae to cope with increasing UV-B radiation in the future.
查看更多>>摘要：? 2022 Elsevier B.V.Plants are continuously challenged by several environmental stresses that impair their growth and production performances. Stresses encountered by plants can be caused by biotic agents (e.g., herbivores, parasitic microorganisms, weeds) and abiotic factors (e.g., cold, drought, soil and water salinity). Despite these differences, plants respond to biotic and abiotic stresses with shared adaptive mechanisms resulting in complex and interlinked cross-talks. Systemin is a hormone peptide, playing a central role in the regulation of plant response against a wide range of stress agents, including wound, phytopathogenic fungi and phytophagous and sucking insects. It has also been shown that upregulation of prosystemin, the precursor protein of systemin, enhanced the tolerance of tomato plants to salt stress, indicating that systemin induced molecular adaptations to biotic stress can also be beneficial to plants exposed to salt stress. Considering that systemin is a small peptide that can be sensed by plants both as soil drench and foliar applications, we hypothesized that exogenous applications of systemin may increase salt stress tolerance in tomato plants through the activation of multiple adaptation mechanisms. Here we report that a soil drench picomolar solution of systemin increases tomato salt stress tolerance by i) activating of SOS1, NHX and HKT Na+ transporters in leaves ii) enhancing the cellular antioxidant power, and iii) balancing the protease activity induced by salt stress. Activation of these responses upon exogeneous application of systemin was highly correlated to an improved tomato growth under salt stress, suggesting that systemin may represent an important component of the crosstalk between biotic and abiotic stress responses in plants.
查看更多>>摘要：? 2022 Elsevier B.V.Low temperature stress limits the geographical distribution of tea plants (Camellia sinensis) and the yield and quality of tea. CsICE1 is a crucial regulator of tea plant's cold signaling pathway; however, the regulatory mechanism of CsICE1 is still unclear. In this study, we found that the N-terminus of CsICE1 contains a transcriptional activation domain and a region of protein interaction. Yeast two-hybrid and bimolecular fluorescence complementation experiments confirmed that CsWRKY4 and CsOCP3 interacted with CsICE1 in the nucleus. Like CsICE1, CsWRKY4 and CsOCP3 were localized in the nucleus, and CsOCP3 was also targeted to the chloroplast. The expression of CsWRKY4 and CsOCP3 was downregulated under cold stress, unlike that of CsICE1. Under biotic stresses and salicylic acid treatment, the expression of all three genes was increased, whereas jasmonic acid treatment resulted in decreased expression of all three genes. Dual-luciferase transient assays revealed that CsICE1 promoted the expression of CsCBF1 and CsCBF3, whereas CsWRKY4 and CsOCP3 inhibited the expression of CsCBF1 and CsCBF3 and attenuated their induction by CsICE1. Taken together, these results suggest that CsWRKY4 and CsOCP3 interact with CsICE1 and regulate CsCBF1/3, thus mediating the stress response in tea plant. Furthermore, these results highlight that CsICE1 is not only a key component in the low temperature signal response pathway, but it may also serve as a point of confluence for cold and other signaling pathways.
查看更多>>摘要：? 2022 Elsevier B.V.The ocean's microplastic (MP) burden reflects the ultimate sink, yet plants are the key receivers of all sizes. However, just a few studies have been published so far have solely examined single-sized commercial PS, PE, and PET. Furthermore, commercially available disposable plastic petri usage and autoclave-sterilization of polymers with plant growth medium might affect the results when testing the premises. Here we show in-vitro phenotypic, metabolic, and transcriptional change schemes in the Arabidopsis under ozone sterilized individual polymer types of varying sizes (75–150 and 150–212 μm) using authentic macro-plastic pieces in the environment. PS, PP and, PE exposed photosynthetically active young seedlings outperformed both sizes of PVC and PET. MP reformed transcriptional expression of functional protein families regulating redox and energy status, DNA synthesis, cell division/repair. Both PET sizes yielded more than 6–17-fold transcripts of one helix protein2 (OHP2) and A-type cyclins (CYCA3;2). While not a significant interaction between MP types and sizes was detected for pigments (p = 0.118), osmoprotectants (p = 0.979), reactive oxygen species (p = 0.065), cell membrane strength (p = 0.0850), and biomass (p = 0.115); the effect of different polymer types was found positively responsive on the root architecture (p < 0.001) and depending on what level of particle size is present, showing a significant interaction between polymers and their dimensions in triggered OHP2 and CYCA3;2 transcript abundance (p = 0.001). Changes in root structure, germination, osmotic balance, and redox status might be attributed to the strong release of chemical additives on plastics. Despite our limited understanding of how MPs impact the overall defense network, the findings provided here may be beneficial for future plant-MP interaction research at the gene and protein level.
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