Fourier-transform infrared spectroscopy (FTIR) with the attenuated total reflectance technique was used to identify Rhodobryum roseum from its four adulterants. The FTIR spectra of six samples in the ...range from 4000 cm-1 to 600 cm-1 were obtained. The second-derivative transformation test was used to identify the small and nearby absorption peaks. A cluster analysis was performed to classify the spectra in a dendrogram based on the spectral similarity. Principal component analysis (PCA) was used to classify the species of six moss samples. A cluster analysis with PCA was used to identify different genera. However, some species of the same genus exhibited highly similar chemical components and FTIR spectra. Fourier self-deconvolution and discrete wavelet transform (DWT) were used to enhance the differences among the species with similar chemical components and FTIR spectra. Three scales were selected as the feature-extracting space in the DWT domain. The results show that FTIR spectroscopy with chemometrics is suitable for identifying Rhodobryum roseum and its adulterants.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Summary
An increased concentration of cytosolic calcium ions (Ca2+) is an early response by plant cells to heat shock. However, the molecular mechanism underlying the heat‐induced initial Ca2+ ...response in plants is unclear. In this study, we identified and characterized a heat‐activated Ca2+‐permeable channel in the plasma membrane of Arabidopsis thaliana root protoplasts using reverse genetic analysis and the whole‐cell patch‐clamp technique. The results indicated that A. thaliana cyclic nucleotide‐gated ion channel 6 (CNGC6) mediates heat‐induced Ca2+ influx and facilitates expression of heat shock protein (HSP) genes and the acquisition of thermotolerance. GUS and GFP reporter assays showed that CNGC6 expression is ubiquitous in A. thaliana, and the protein is localized to the plasma membrane of cells. Furthermore, it was found that the level of cytosolic cAMP was increased by a mild heat shock, that CNGC6 was activated by cytosolic cAMP, and that exogenous cAMP promoted the expression of HSP genes. The results reveal the role of cAMP in transduction of heat shock signals in plants. The correlation of an increased level of cytosolic cAMP in a heat‐shocked plant with activation of the Ca2+ channels and downstream expression of HSP genes sheds some light on how plants transduce a heat stimulus into a signal cascade that leads to a heat shock response.
Red-skinned pears are favored by people for their attractive appearance and abundance of anthocyanins. However, the molecular basis of anthocyanin biosynthesis in red pears remains elusive. Here, a ...comprehensive transcriptome analysis was conducted to explore the potential regulatory mechanism of anthocyanin biosynthesis in 'Red Zaosu' pear (
×
). Gene co-expression analysis and transcription factor mining identified 263 transcription factors, which accounted for 6.59% of the total number of transcription factors in the pear genome in two gene modules that are highly correlated with anthocyanin biosynthesis. Clustering, gene network modeling with STRING-DB, and local motif enrichment analysis (CentriMo) analysis suggested that PpPIF8 may play a role in anthocyanin biosynthesis. Furthermore, eight PIFs were identified in the pear genome, of which only
was rapidly induced by light. Functional studies showed that PpPIF8 localizes in the nucleus and is preferentially expressed in the tissue of higher levels of anthocyanin. The overexpression of PpPIF8 in pear peel and pear calli promotes anthocyanin biosynthesis and upregulates the expression of anthocyanin biosynthesis genes. Yeast-one hybrid and transgenic analyses indicated that PpPIF8 binds to the
promoter to induce
expression. The positive effect of PpPIF8 on anthocyanin biosynthesis is different from previously identified negative regulators of PyPIF5 and MdPIF7 in pear and apple. Taken together, our data not only provide a comprehensive view of transcription events during the coloration of pear peel, but also resolved the regulatory role of PpPIF8 in the anthocyanin biosynthesis pathway.
Cell water permeability and cell wall properties are critical to survival of plant cells during freezing, however the underlying molecular mechanisms remain elusive. Here, we report that a ...specifically cold-induced nuclear protein, Tolerant to Chilling and Freezing 1 (TCF1), interacts with histones H3 and H4 and associates with chromatin containing a target gene, blue-copper-binding protein (BCB), encoding a glycosylphosphatidylinositol-anchored protein that regulates lignin biosynthesis. Loss of TCF1 function leads to reduced BCB transcription through affecting H3K4me2 and H3K27me3 levels within the BCB gene, resulting in reduced lignin content and enhanced freezing tolerance. Furthermore, plants with knocked-down BCB expression (amiRNA-BCB) under cold acclimation had reduced lignin accumulation and increased freezing tolerance. The pal1pal2 double mutant (lignin content reduced by 30% compared with WT) also showed the freezing tolerant phenotype, and TCF1 and BCB act upstream of PALs to regulate lignin content. In addition, TCF1 acts independently of the CBF (C-repeat binding factor) pathway. Our findings delineate a novel molecular pathway linking the TCF1-mediated cold-specific transcriptional program to lignin biosynthesis, thus achieving cell wall remodeling with increased freezing tolerance.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The surface wax of fruit has a significant effect on abiotic stress and fruit quality. In this study, the composition of the waxes found on fruit surfaces and the related gene expression of three ...different pear cultivars (Xuehua, Yali, and Yuluxiang) were investigated during cold storage. The results showed that 35 wax compositions were found on the surfaces of the three pear cultivars, mainly including C
alkane, three fatty acids, two esters, three aldehydes, three fatty alcohols, and three triterpenoids. The largest amount of C
alkane, three fatty acids and two esters were found in Yuluxiang (YLX) on day 90, while aldehydes with carbons of C
and C
were the highest in Yali (YL). Xuehua (XH) showed the largest amount of C
fatty alcohol on day 180 compared to YLX and YL. Larger amounts of triterpenoids were found in XH and YL when compared to YLX. The expression levels of fifteen wax related genes (
,
,
,
,
,
,
,
,
,
,
,
,
,
, and
) reached their peak at day 45 in YLX, compared to XH and YL, their expression levels in YLX were higher to different degrees. These results suggest that the different expression patterns of wax-related genes may be closely related to the difference in wax compositions of the surface wax of three pear cultivars.
Salinity (NaCl) stress impairs plant growth and inflicts severe crop losses. In roots, increasing extracellular NaCl causes Ca²⁺ influx to elevate cytosolic free Ca²⁺ (Ca²⁺(cyt)) as a second ...messenger for adaptive signaling. Amplification of the signal involves plasma membrane reduced nicotinamide adenine dinucleotide phosphate oxidase activation, with the resultant reactive oxygen species triggering Ca²⁺ influx. The genetic identities of the Ca²⁺-permeable channels involved in generating the Ca²⁺(cyt) signal are unknown. Potential candidates in the model plant Arabidopsis (Arabidopsis thaliana) include annexin1 (AtANN1). Here, luminescent detection of Ca²⁺(cyt) showed that AtANN1 responds to high extracellular NaCl by mediating reactive oxygen species-activated Ca²⁺ influx across the plasma membrane of root epidermal protoplasts. Electrophysiological analysis revealed that root epidermal plasma membrane Ca²⁺ influx currents activated by NaCl are absent from the Atann1 loss-of-function mutant. Both adaptive signaling and salt-responsive production of secondary roots are impaired in the loss-of-function mutant, thus identifying AtANN1 as a key component of root cell adaptation to salinity.
The ethylene-regulated hypocotyl elongation of Arabidopsis thaliana involves many transcription factors. The specific role of MYC transcription factors in ethylene signal transduction is not ...completely understood. The results here revealed that two MYCs, MYC2 and MYC3, act as negative regulators in ethylene-suppressed hypocotyl elongation. Etiolated seedlings of the loss-of-function mutant of MYC2 or MYC3 were significantly longer than wild-type seedlings. Single- or double-null mutants of MYC2 and MYC3 displayed remarkably enhanced response to ACC(1-aminocyclopropane-1-carboxylate), the ethylene precursor, compared to wild-type seedlings. MYC2 and MYC3 directly bind to the promoter zone of ERF1, strongly suppressing its expression. Additionally, EIN3, a key component in ethylene signaling, interacts with MYC2 or MYC3 and significantly suppresses their binding to ERF1’s promoter. MYC2 and MYC3 play crucial roles in the ethylene-regulated expression of functional genes. The results revealed the novel role and functional mechanism of these transcription factors in ethylene signal transduction. The findings provide valuable information for deepening our understanding of their role in regulating plant growth and responding to stress.
Spermidine (Spd) has been correlated with various physiological and developmental processes in plants, including pollen tube growth. In this work, we show that Spd induces an increase in the ...cytosolic Ca²⁺ concentration that accompanies pollen tube growth. Using the whole-cell patch clamp and outside-out single-channel patch clamp configurations, we show that exogenous Spd induces a hyperpolarization-activated Ca²⁺ current: the addition of Spd cannot induce the channel open probability increase in excised outside-out patches, indicating that the effect of Spd in the induction of Ca²⁺ currents is exerted via a second messenger. This messenger is hydrogen peroxide (H₂O₂), and is generated during Spd oxidation, a reaction mediated by polyamine oxidase (PAO). These reactive oxygen species trigger the opening of the hyperpolarization-activated Ca²⁺-permeable channels in pollen. To provide further evidence that PAO is in fact responsible for the effect of Spd on the Ca²⁺-permeable channels, two Arabidopsis mutants lacking expression of the peroxisomal-encoding AtPAO3 gene, were isolated and characterized. Pollen from these mutants was unable to induce the opening of the Ca²⁺-permeable channels in the presence of Spd, resulting in reduced pollen tube growth and seed number. However, a high Spd concentration triggers a Ca²⁺ influx beyond the optimal, which has a deleterious effect. These findings strongly suggest that the Spd-derived H₂O₂ signals Ca²⁺ influx, thereby regulating pollen tube growth.
Plant cell growth and stress signaling require Ca²⁺ influx through plasma membrane transport proteins that are regulated by reactive oxygen species. In root cell growth, adaptation to salinity ...stress, and stomatal closure, such proteins operate downstream of the plasma membrane NADPH oxidases that produce extracellular Superoxide anion, a reactive oxygen species that is readily converted to extracellular hydrogen peroxide and hydroxyl radicals, OH˙ In root cells, extracellular OH˙ activates a plasma membrane Ca²⁺ -permeable conductance that permits Ca²⁺ influx. In Arabidopsis thaliana, distribution of this conductance resembles that of annexin1 (ANN1). Annexins are membrane binding proteins that can form Ca²⁺ -permeable conductances in vitro. Here, the Arabidopsis loss-of-function mutant for annexin1 (Atann1) was found to lack the root hair and epidermal OH˙-activated Ca²⁺ -and K⁺ -permeable conductance. This manifests in both impaired root cell growth and ability to elevate root cell cytosolic free Ca²⁺ in response to OH˙. An OH˙-activated Ca²⁺ conductance is reconstituted by recombinant ANN1 in planar lipid bilayers. ANN1 therefore presents as a novel Ca²⁺-permeable transporter providing a molecular link between reactive oxygen species and cytosolic Ca²⁺ in plants.
Extracellular ATP regulates higher plant growth and adaptation. The signalling events may be unique to higher plants, as they lack animal purinoceptor homologues. Although it is known that plant ...cytosolic free Ca²⁺ can be elevated by extracellular ATP, the mechanism is unknown. Here, we have studied roots of Arabidopsis thaliana to determine the events that lead to the transcriptional stress response evoked by extracellular ATP. Root cell protoplasts were used to demonstrate that signalling to elevate cytosolic free Ca²⁺ is determined by ATP perception at the plasma membrane, and not at the cell wall. Imaging revealed that extracellular ATP causes the production of reactive oxygen species in intact roots, with the plasma membrane NADPH oxidase AtRBOHC being the major contributor. This resulted in the stimulation of plasma membrane Ca²⁺-permeable channels (determined using patch-clamp electrophysiology), which contribute to the elevation of cytosolic free Ca²⁺. Disruption of this pathway in the AtrbohC mutant impaired the extracellular ATP-induced increase in reactive oxygen species (ROS), the activation of Ca²⁺ channels, and the transcription of the MAP kinase3 gene that is known to be involved in stress responses. This study shows that higher plants, although bereft of purinoceptor homologues, could have evolved a distinct mechanism to transduce the ATP signal at the plasma membrane.
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