Ethylene Synthesis Research Articles

Optimization of parameters in using two different approaches for palladium-based spent catalysts (ethylene synthesis process) regeneration: supercritical carbon dioxide based extraction process and thermal process

ABSTRACT The application of supercritical fluid (SF)-based technologies for catalyst activation has gained increased attention during the past two decades. Respecting this attention, the current investigation seeks to find the optimum operating conditions for activation of Palladium- based spent catalysts. The results indicate that the optimum operating conditions, based on changing one factor at a time (design of experiment approach), are: 45°C and 220 bar for, respectively, extraction temperature and pressure, 80 min for static time and 0.14 cm3/s for CO2 flow rate leading catalyst activation up to 97.62% (active area of regenerated catalyst/ active area of fresh catalyst) based on BET analysis. Additionally, the thermal process including heated nitrogen, steam, and a combination of air and steam were examined to find whether or not it is possible to regenerate the deactivated catalyst. The results reveal the optimum conditions of 2.5 bar and 550°C for pressure and temperature with regeneration efficiency of 97.46% (active area of regenerated catalyst/active area of fresh catalyst) based on BET analysis. Finally, the regenerated catalysts were further analyzed by BET, SEM, XRD, and XRF analyses which revealed the efficiency of both SC-CO2 and optimized thermal methods for catalyst activation through industrial purposes.

Ethylene regulates aerenchyma formation in cotton under hypoxia stress by inducing the accumulation of reactive oxygen species

Aerenchyma formation is one of the most effective mechanisms adapted by plants to cope with waterlogging (WL). It which reduces the negative effects of WL by facilitating gas diffusion within roots. To understand the response of cotton roots to WL, hypoxia-tolerant genotype Cx094 and hypoxia-sensitive genotype Wang18 were used in this study. The seedlings of two varieties were treated by three methods: flooding in pots as Treatment 1 (flooding), low oxygen with agar solution as Treatment 2 (flooding + agar) and hypoxia with agar solution and nitrogen gas as Treatment 3 (flooding + agar + N 2 ). The results showed that in Cx094, the highest proportion of aerenchyma was found in Treatment 2, with no corresponding aerenchyma formation in Wang18. Further studies were carried out in Treatment 2 to check the aerenchyma formation in six cotton accessions and the results showed that aerenchyma only formed in hypoxia-tolerance genotypes, confirming the important role of aerenchyma formation in WL-tolerant genotypes. The unique characteristic of cotton is that four symmetrical aerenchyma were formed under WL stress, and they appeared one by one. We also showed that hypoxia signal induced expression of ACS and ACO genes, resulting more ethylene synthesis in hypoxia-tolerant genotypes. Moreover, ethylene induced reactive oxygen species (ROS) accumulated by up-regulation of RBOHs expression and down-regulation of MT-3a expression. Finally, ROS caused up-regulation of CEL and XET expressions to induce programmed cell death, and result in lysigenous aerenchyma. Exogenous ethylene inhibitor decreased the formation of aerenchyma in Cx094, while ethephon, an ethylene precursor, promote the formation of aerenchyma in Wang18, signifying the important role of ethylene in the formation of aerenchyma in cotton. • The first time to report aerenchyma in cotton. • Ethylene induced ROS accumulation. • ROS promotes PCD occurrence. • Ethylene promotes aerenchyma formation in cotton.

SAMS1 stimulates tomato root growth and P availability via activating polyamines and ethylene synergetic signaling under low-P condition

Phosphorus (P) utilization by plants is low, which limits crop yields and causes environmental pollution. SAMS1 controls polyamines and ethylene synthesis, and actively responds to various biotic and abiotic stresses. However, how SAMS1 regulates plant P efficiency remains unclear. This study showed that SAMS1-overexpressing improves tomato P efficiency. As a result, overexpression of SAMS1 reduced the accumulation of putrescine and, which induced H2O2 by promoting the conversion of putrescine to spermidine/spermine. This not only facilitated the occurrence of lateral roots under low-P conditions but also promoted the continuous elongation of lateral roots, forming the low-P adaptive root morphological characteristics in tomato plants. In addition to morphological regulation, SAMS1 also promoted root H+-ATPase activity and H+ secretion through polyamines and ethylene signals, enhancing P absorption. However, the phosphatase activity, reutilization of cell wall P, and its distribution to the root was only induced by SAMS1-mediated ethylene signal. Field experiments showed that using SAMS1-overexpressing transgenic rootstocks significantly reduced the input of P fertilizer, promoted plant growth and yield. Together, SAMS1 can promote tomato root growth and P utilization by activating synergistic signals of PAs and Eth.

Integrated Transcriptomics and Nontargeted Metabolomics Analysis Reveal Key Metabolic Pathways in Ganoderma lucidum in Response to Ethylene.

Ganoderic acid (GA) is an important secondary metabolite of Ganoderma lucidum with a diverse array of pharmacological properties. In this study, we found that exogenous ethylene increased the production of endogenous ethylene and ganoderic acid in G. lucidum. However, the mechanism by which ethylene is regulated remains unclear. As a result, we performed a combined transcriptomics and nontargeted metabolomics analysis to evaluate the regulatory mechanism of ethylene. A total of 4070 differentially expressed genes (1835 up-regulated and 2235 down-regulated) and 378 differentially accumulated metabolites (289 up-regulated and 89 down-regulated) were identified in all groups. The transcriptomics and nontargeted metabolomics data revealed that genes involved in the tricarboxylic acid (TCA) cycle, polyamine metabolic pathway, acetyl-CoA carboxylase (ACC) pathway, and triterpenoid metabolism were up-regulated, whereas the metabolic intermediates involved in these metabolic pathways were down-regulated. These findings imply that ethylene potentially accelerates normal glucose metabolism, hence increasing the number of intermediates available for downstream biological processes, including polyamine metabolism, ethylene synthesis pathway, and ganoderic acid biosynthesis. The findings will contribute significantly to our understanding of secondary metabolites biosynthesis in fungi.

Effect of Glycine Betaine Treatment on Aroma Production of ‘Nanguo’ Pears After Long-Term Cold Storage–Possible Involvement of Ethylene Synthesis and Signal Transduction Pathways

Effect of Glycine Betaine Treatment on Aroma Production of ‘Nanguo’ Pears After Long-Term Cold Storage–Possible Involvement of Ethylene Synthesis and Signal Transduction Pathways

Proteomics analysis reveals new insights into surface pitting of sweet cherry cultivars displaying contrasting susceptibility

ABSTRACT Surface pitting in sweet cherry (Prunus avium L.) is characterised by depressions development on the skin surface. Pitting damage happens during harvest and postharvest handling and develops during cold storage. This study compared two cultivars with contrasting susceptibility to pitting (Kordia: tolerant; Sweetheart: susceptible) using a LC-MS/MS proteomic approach to identify key metabolic and signalling pathways related to this disorder during ripening and postharvest storage. The variability observed in the principal component analysis was driven by the cultivars suggesting that surface pitting susceptibility is triggered by the inherent differences between cultivars. Proteins involved in anthocyanin biosynthesis were more abundant in Kordia. Moreover, CCR (cinnamoyl-CoA reductase) and FLS (flavonol synthase) proteins showed higher abundance in Sweetheart. An overexpression in enzymes related to the synthesis of abscisic acid (ABA), jasmonic acid (JA) and ethylene were found in Kordia. A higher abundance of sucrose synthase (SUS), UDP-glycosyltransferases (UDP-GT) and polygalacturonase-inhibiting proteins (PGIP) were observed in Kordia, while a higher content of invertase (INV) was observed in Sweetheart. The overexpression of the studied pathways suggests that tolerance to surface pitting could be correlated to one or more of these factors, and susceptibility might be given by the inherent differences in the metabolic processes of each cultivar.

Sugarcane plant growth promoting rhizo bacterial interaction for enhanced salinity tolerance

The present investigation was meted out on two promising sugarcane genotypes CoN-13072 and CoN-13073, were exposed to different NaCl levels to assess rhizobacterial interaction for salinity tolerance. From the shoot apex portion of two sugarcane genotypes tissue culture plantlets were developed. From that regenerated plantlets shifted to polyhouse and exposed to different NaCl levels to assess rhizobacterial interaction for salinity tolerance. Maximum shoot length (25.40 cm) was observed in genotype CoN-13073 under rhizobacterial inoculum at 2.0% NaCl concentration and maximum root length (12.40 cm) was observed at 0.0% and 1.5% NaCl concentration under rhizobacterial inoculum in genotype CoN-13072 and CoN-13073 respectively. Maximum shoot root ratio (2.60) and (2.40) was observed at 0.0% NaCl concentration with rhizobacterial inoculum within the rooting mixture of both the genotypes CoN-13073 and CoN-13072 respectively. High chlorophyll content index (5.48) and leaf area (41.20 cm2/plant) was observed in genotype CoN-13073 at 0.0% NaCl concentration under rhizobacterial inoculum. In genotypes CoN-13073 and CoN-13072, with a rise in NaCl concentration upto 2.0% and 1.5% respectively, increase in shoot length, leaf area and chlorophyll content index was observed as a result of increase in ACC deaminase activity. ACC deaminase activity and ethylene content within the plant body are negatively correlated. Increase in ACC deaminase activity results decrease in ethylene synthesis in plant body to avoid stress. Among the 2 genotypes, CoN-13073 found to be more salt tolerant at higher NaCl levels with the exhibition of low osmotic conductance, maximum leaf area with high chlorophyll content index.

Transcriptome and DNA methylome analysis reveal new insights into methyl jasmonate-alleviated chilling injury of peach fruit after cold storage

Methyl jasmonate (MeJA) has been used to alleviate the chilling injury (CI) caused by postharvest cold storage of horticultural crops involving peach fruit. However, the molecular mechanism remains largely unknown. Here, we treated melting peach fruit (Prunus persica L. Batsch., cv. Hujingmilu) with different concentrations of MeJA, followed by storage at 0 °C up to 28 d. Peach fruit treated with 1 mM MeJA delayed the development of CI during 3 d shelf-life followed by 28 d cold after storage (C28dS3). The alleviated CI was associated with significant higher content of JA-Ile in peach fruit after MeJA treatment than controls. RNA-Seq revealed significant alternations in expression of genes related to ethylene synthesis, fruit softening, flesh browning and aroma-related volatile synthesis. Transcription factors associated with fruit ripening such as PpNAC1 and JA signaling such as PpMYC2.2 showed higher transcript levels in MeJA treated peach fruit than controls. Peach fruit with CI symptom had higher genome methylation level than MeJA treated fruit after cold storage at C28dS3. Reverse patterns between transcript abundance and DNA methylation in promoter were observed for transcription factor PpNAC1 and downstream PpACS1 for ethylene synthesis, PpExp1 for softening, and PpAAT1 for volatile ester and lactone production. Overall, in addition to providing new insights into the regulatory mechanism for MeJA in alleviating fruit chilling injury through integration of transcriptome and DNA methylome, our study also establishes a foundation for fruit quality maintaining after cold storage of peach fruit.

Identification of genes and metabolic pathways involved in wounding-induced kiwifruit ripening

Fruit is constantly challenged by wounding events, inducing accelerated ripening and irreversible metabolic changes. However, cognate mechanisms that regulate this process are little known. To expand our knowledge of ripening metabolism induced by wounding, an artificial-wound global transcriptome investigation combined with metabolite profiling study was conducted in postharvest kiwifruit (Actinidia chinensis var. deliciosa (A. Chev.) A. Chev. ‘Hayward’). Wounding treatment promoted fruit ripening, as demonstrated by changes in fruit firmness, ethylene production and respiration activity determined periodically during a ripening period of 8 d at room temperature. Calcium imaging using fluorescent probe Fluo-3 AM revealed spatial dynamics of Ca2+ signaling in the wounding area following 8d ripening. Several sugars including fructose, glucose, and sucrose as well as organic acids such as citric, succinic and galacturonic acid were increased by wounding. Changes of various amino acids in wounded-treated fruit, especially 5-oxoproline and valine along with alternations of soluble alcohols, like myo-inositol were detected. Gene expression analysis of the wounded fruit showed increased expression of genes that are mainly involved in defense response (e.g., AdTLP.1-3, AdPP2C.1-2, AdMALD1), calcium ion binding (e.g., AdCbEFh, AdCLR, AdANX), TCA cycle (e.g., AdMDH.1, AdMDH.2, AdCS), sugars (e.g., AdSUSA.1, AdSPS4, AdABFr), secondary metabolism (e.g., AdPAL.1-3, AdCCR, AdHCT.1-2), lipid processing (e.g., AdGELP.1-4, AdGELP) and pectin degradation (e.g., AdPE.1-2, AdPAE.1-2, AdPG.1-2) as well as in ethylene (AdERF7, AdERF1B, AdACO.1-4) and auxin (AdICE, AdAEFc, AdASII) synthesis and perception. Moreover, genes related to aquaporins, such as AdAQP2, AdAQP4 and AdAQP7 were down-regulated in fruit exposed to wounding. These results demonstrate multiple metabolic points of wounding regulatory control during kiwifruit ripening and provide insights into the molecular basis of wounding-mediated ripening.

Critical roles of the activation of ethylene pathway genes mediated by DNA demethylation in Arabidopsis hyperhydricity.

Hyperhydricity (HH) often occurs in plant tissue culture, seriously influencing the commercial micropropagation and genetic improvement. DNA methylation has been studied for its function in plant development and stress responses. However, its potential role in HH is unknown. In this study, we report the first comparative DNA methylome analysis of normal and hyperhydric Arabidopsis thaliana (L.) Heynh. seedlings using whole-genome bisulfite sequencing (BS-seq). We found that the global methylation level decreased in hyperhydric seedlings, and most of the differentially methylated genes were CHH hypomethylated genes. Moreover, the bisulfite sequencing results showed that hyperhydric seedlings displayed CHH demethylation patterns in the promoter of the ACS1 and ETR1 genes, resulting in upregulated expression of both genes and increased ethylene accumulation. Furthermore, hyperhydric seedling displayed reduced stomatal aperture accompanied by decreased water loss and increased phosphorylation of aquaporins accompanied by increased water uptake. While silver nitrate (AgNO3 ) prevented HH by maintained the degree of methylation in the promoter regions of ACS1 and ETR1 and downregulated the transcription of both genes. AgNO3 also reduced the content of ethylene together with the phosphorylation of aquaporins and water uptake. Taken together, this study suggested that DNA demethylation is a key switch that activates ethylene pathway genes to enable ethylene synthesis and signal transduction, which may subsequently influence aquaporin phosphorylation and stomatal aperture, eventually causing HH; thus, DNA demethylation plays a crucial role in HH. These results provide insights into the epigenetic regulation mechanism of HH and confirm the role of ethylene and AgNO3 in hyperhydricity control.

Bacterial Modulation of the Plant Ethylene Signaling Pathway Improves Tolerance to Salt Stress in Lettuce (Lactuca sativa L.)

Salinity has extensive adverse effects on plant growth and the development of new agronomic strategies to improve crop salt tolerance is becoming necessary. Currently, the use of plant growth promoting rhizobacteria (PGPR) to mitigate abiotic stress in crops is of increasing interest. The most analyzed mechanism is based on ACC deaminase activity, an enzyme that decreases the ethylene synthesis, an important phytohormone in plant stress response. We aimed to identify other PGPR mediated mechanisms involved in the regulation of salt stress in plant. We used three PGPR strains (ESL001, ESL007, SH31), of which only ESL007 demonstrated ACC deaminase activity, to evaluate their effect on lettuce plants under salt stress (100 mM NaCl). We measured growth and biochemical parameters (e.g., proline content, lipid peroxidation and ROS degradation), as well as expression levels of genes involved in ethylene signaling (CTR1, EBF1) and transcription factors induced by ethylene (ERF5, ERF13). All bacterial strains enhanced growth on salt-stressed lettuce plants and modulated the proline levels. Strains ESL007 and SH31 triggered a higher catalase and ascorbate-peroxidase activity, compared to non-stressed plants. Differential expression of ethylene-related genes in inoculated plants subjected to salinity was observed. We gained consistent evidence for the existence of alternative mechanisms to ethylene modulation, which probably rely on bacterial IAA production and other chemical signals. These mechanisms modify the expression of genes associated with ethylene signaling and regulation, complementarily to the ACC deaminase model to diminish abiotic stress responses.

Ethylene works as a possible regulator for the rootlet elongation and transcription of genes for phosphorus acquisition in cluster roots of Lupinus albus L.

ABSTRACT White lupin (Lupinus albus L.) plants are tolerant plants under phosphorus (P)deficiency. They form unique morphological roots, so-called cluster roots (CRs) under P deficiency. CRs contribute to P absorption by the expansion of the root surface area and P mobilization activities. Previous research has implied the involvement of several hormonal functions in CR formation. Ethylene is a key regulator responsible for the modification of root architecture and P acquisition in response to low P in plants. However, understanding the effect of ethylene on CR morphogenesis is not enough. Here, the focus was on the effects of ethylene on CR morphology and gene expression for P acquisition. First, a reanalysis of public RNA-Seq data indicated that the gene expression for ethylene synthesis was induced during CR maturation. In turn, the 10-days application of an ethylene synthesis inhibitor, CoCl2, and an ethylene precursor, ACC, to CR formed in hydroponic culture without P was performed. CR morphology, transcript levels of the genes related to P acquisition, and citrate concentration in roots were determined. The results indicated that the elongation of rootlets in CR was promoted in a Co2+ concentration-dependent manner, suggesting that ethylene is responsible for the arrest of rootlet elongation. mRNA accumulation for acid phosphatases, phosphate transporters, citrate synthases, and a putative citrate transporter increased in ACC-treated immature CR, suggesting that ethylene induces the transcription of genes for P acquisition. Additionally, the trend of citrate concentration in roots among treatments was similar to that in the expression of citrate synthases, supporting that ethylene accumulation promotes citrate synthesis. The roles of the arrest of rootlet elongation and regulation of gene expressions for P acquisition are considered independent functions of ethylene. It was concluded that ethylene works as a possible regulator for the rootlet elongation and transcription of genes for P acquisition in CRs, although further studies are required to elucidate the molecular mechanisms of the arrest of rootlet elongation and transcriptional regulation.

Drought Stress Interacts With Powdery Mildew Infection in Tomato.

Under field conditions, plants are often exposed to more than one stress factor at the same time, and therefore need to adapt to different combinations of stresses. Crosstalk between responses to abiotic and biotic stresses is known to occur, and the interaction between stress responses can be positive or negative. We studied the interaction of drought stress and powdery mildew (PM) infection in tomatoes using near-isogenic tomato lines (NILs) carrying the Ol-1, ol-2, or Ol-4 gene that confers resistance to tomato PM caused by Oidium neolycopersici. Our study demonstrated that drought-induced growth reduction was not further reduced by powdery mildew infection. Drought stress, however, decreased fungal infection in the susceptible genotype Moneymaker (MM) with fungal biomass tending to decrease further as the drought severity increased. Drought stress did not affect PM resistance levels of resistant NIL carrying ol-2 (a mutant of the tomato susceptibility Mlo gene) and Ol-4 an NLR (nucleotide-binding site-LRR) R gene associated with a fast hypersensitivity response (HR) but tended to slightly decrease disease levels of NIL-Ol-1 (no gene characterized yet, associated with a slow HR following PM infection). At the molecular level, genes involved in abscisic acid (ABA), salicylic acid (SA), and ethylene pathways were highly induced under combined stress indicating the involvement of ABA, SA, and ethylene in the crosstalk between abiotic and biotic stress. Messenger RNA expression of the ABA-responsive dehydrin SlTAS14 was induced under drought and combined stress with the highest induction under combined stress, and resistant NIL lines showed higher expression levels than MM. The expression of SlNCED (involved in ABA synthesis) was also upregulated under drought and highly induced under combined stress. Expression levels of pathogen responsive gene SlPR1 (an indicator of the SA pathway) and SlACS (involved in ethylene synthesis) were highly induced under powdery mildew infection in MM and the Ol-1 and were induced the most under combined stress in these lines. Taken together, these findings indicate that drought stress can interact with and influence PM infection in tomatoes in a resistance type-dependent manner. The role of hormonal signaling pathways in the crosstalk between drought stress and PM infection is further discussed.

Role of Melatonin in Apple Fruit during Growth and Ripening: Possible Interaction with Ethylene.

The role of melatonin during the growth and ripening of apple fruit was studied using local varieties. The evolution of the growth and ripening parameters, including fruit size and weight, firmness, color change, sugar content, and ethylene production, was different in the five varieties studied, with yellow apples (Reineta and Golden) initiating the ripening process earlier than reddish ones (Teórica, Sanroqueña, and Caguleira). Changes in the melatonin and melatonin isomer 2 contents during growth and ripening were studied in Golden apples, as was the effect of the melatonin treatment (500 µM, day 124 post-anthesis) on the apple tree. Melatonin content varied greatly, with higher value in the skin than in the flesh. In the skin, melatonin increased at day 132 post-anthesis, when ethylene synthesis started. In the flesh, melatonin levels were high at the beginning of the growth phase and at the end of ripening. Melatonin isomer 2 was also higher once the ripening started and when ethylene began to increase. The melatonin treatment significantly advanced the ethylene production and increased the fruit size, weight, sugar content, and firmness. The data suggest that melatonin stimulates fruit ripening through the induction of ethylene synthesis, while melatonin treatments before ripening improve the final fruit quality.

Synthesis of thermoplastic polyethylene elastomers and ethylene–methyl acrylate copolymers using methylene-bridged binuclear bulky dibenzhydryl α-diimine Ni(II) and Pd(II) catalysts

Binuclear olefin polymerization catalysts have recently attracted extensive interest in the field of polyolefin synthesis due to their excellent catalytic performance. In this work, we designed and synthesized a class of methylene-bridged binuclear bulky dibenzhydryl α-diimine Ni(II) and Pd(II) catalysts and applied them to ethylene polymerization and copolymerization. The Ni(II) complexes exhibited high activities (ca. 106 g·mol−1·h−1) and yielded highly branched (79–92/1000C) polyethylenes with very high molecular weights (Mn up to 44.57 × 104 g/mol) in ethylene polymerization. The obtained polyethylene products demonstrated excellent strain recovery (SR up to 84%). Meanwhile, the corresponding Pd(II) complexes also displayed high activities (well above 105 g·mol−1·h−1), and generated highly branched (90–92/1000C) polyethylene with high molecular weights (Mn up to 27 × 104 g/mol) in ethylene polymerization. More importantly, these Pd(II) complexes led to generating highly branched (93–101/1000C) polar functional copolymers with moderate molecular weights (Mn up to 6 × 104 g/mol) and moderate incorporation ratios (ca. 1 mol%) in ethylene–methyl acrylate copolymerization. Compared with mononuclear α-diimine Ni(II) and Pd(II) catalysts, the binuclear catalysts possessed higher thermal stability and activity, generated higher molecular weights polyethylene.

Thermal crosslinking synthesis of ethylene-vinyl acetate copolymer supported floating TiO2 photocatalyst: characterization and photocatalytic performance.

Floating photocatalyst is of extensive interest due to easy recovery and efficient light harvest. Support materials largely determine the stability of floating photocatalysts and their synthesis complexity. Thus, finding proper floating supports is very important. Herein, ethylene-vinyl acetate copolymer (EVA) was investigated as a support to prepare floating TiO2/EVA using a simple thermal crosslinking procedure. Multiple characterization analyses demonstrated that TiO2 was anchored onto EVA surface evenly via hydrogen-bond-enhanced physical crosslinking and remained its virgin crystal structure. Photocatalytic experiments showed that the removal efficiency of Rhodamine B (RhB) by floating TiO2/EVA increased by 33.8% as compared to suspended particle TiO2. The h+ and ·O2- played dominant roles in TiO2/EVA-driven RhB degradation. A 30-day stability test demonstrated that TiO2/EVA had a high thermal, pH, and photo- stability. The three-run reuse test proved that TiO2/EVA exhibited satisfactory reusability. This study provides a new option for floating photocatalyst synthesis.

The NAC factor LpNAL delays leaf senescence by repressing two chlorophyll catabolic genes in perennial ryegrass.

Expression of chlorophyll (Chl) catabolic genes during leaf senescence is tightly controlled at the transcriptional level. Here, we identified a NAC family transcription factor, LpNAL, involved in regulating Chl catabolic genes via the yeast one-hybrid system based on truncated promoter analysis of STAYGREEN (LpSGR) in perennial ryegrass (Lolium perenne L.). LpNAL was found to be a transcriptional repressor, directly repressing LpSGR as well as the Chl b reductase gene, NONYELLOWING COLORING1. Perennial ryegrass plants over-expressing LpNAL exhibited delayed leaf senescence or stay-green phenotypes, whereas knocking down LpNAL using RNA interference accelerated leaf senescence. Comparative transcriptome analysis of leaves at 30 d after emergence in wild-type, LpNAL-overexpression, and knock-down transgenic plants revealed that LpNAL-regulated stay-green phenotypes possess altered light reactions of photosynthesis, antioxidant metabolism, ABA and ethylene synthesis and signaling, and Chl catabolism. Collectively, the transcriptional repressor LpNAL targets both Chl a and Chl b catabolic genes and acts as a brake to fine-tune the rate of Chl degradation during leaf senescence in perennial ryegrass.

A long noncoding RNA functions in high-light-induced anthocyanin accumulation in apple by activating ethylene synthesis.

Anthocyanin production in apple (Malus domestica) fruit and their consequent coloration can be induced by high-light treatment. The hormone ethylene is also essential for this coloration, but the regulatory relationships that link ethylene and light with anthocyanin-associated coloration are not well defined. In this study, we observed that high-light treatment of apple fruit increased anthocyanin accumulation more than moderate-light treatment did and was the main contributor of induced ethylene production and activation of anthocyanin biosynthesis. A transcriptome study of light-treated apple fruit suggested that a long noncoding RNA (lncRNA), MdLNC610, the corresponding gene of which is physically located downstream from the 1-aminocyclopropane-1-carboxylate oxygenase (ACO) ethylene biosynthesis gene MdACO1, likely affects anthocyanin biosynthesis under high-light treatment. Expression and promoter β-glucuronidase reporter analyses further showed that MdLNC610 upregulates expression of MdACO1 and so likely participates in high-light-induced ethylene biosynthesis. Overexpression of MdACO1 and MdLNC610 in apple fruit and calli indicated that a major increase in MdLNC610 expression activates MdACO1 expression, thereby causing an increase in ethylene production and anthocyanin levels. These results suggest that MdLNC610 participates in the regulation of high-light-induced anthocyanin production by functioning as a positive regulator to promote MdACO1 expression and ethylene biosynthesis. Our study provides insights into the relationship between mRNA and lncRNA networks in the ethylene biosynthetic pathway and anthocyanin accumulation in apple fruit.

Relatively Low Light Intensity Promotes Phosphorus Absorption and Enhances the Ethylene Signaling Component EIN3 in Maize, Wheat, and Oilseed Rape

Previous studies have found that once seedlings break the soil, light can induce the degradation of the key ethylene signaling element ethylene insensitive 3 (EIN3), so as to indirectly inhibit the synthesis of ethylene. Ethylene is the most important hormone in phosphorus absorption by plants, which induces the expression of acid phosphatase (APase) and phosphorus starvation response genes. Therefore, it might be speculated that changes in light intensity could regulate phosphorus absorption to some degree. However, there are few reports on the mechanism by which light intensity regulates phosphorus metabolism. In this study, the effects of different light intensities on phosphorus assimilation and metabolism in plants were studied. The results showed that relatively low light intensity could promote the secretion of APase, so as to increase the concentration of plant total phosphorus and cellular Pi. However, the low light intensity may also inhibit plant growth. Among the three species, oilseed rape was the most sensitive to the low light intensity. The steady-state level of the EIN3 protein decreased significantly under a relatively high light intensity; while the ethylene level also decreased under the high light intensity. Therefore, appropriate reductions in light intensity may simultaneously promote phosphorus assimilation and maintain plant growth.

Identification of key proteins related to high-quality fiber in Upland cotton via proteomics analysis.

The dynamics of cotton fiber elongation and microfibirl deposition orientation were delineated; advanced ethylene synthesis and redox reaction homeostasis may be crucial for high-quality fiber formation. Fiber length, strength, and fineness determine the use and commercial value of cotton fiber, but their underlying molecular mechanisms remain obscure. We compared the dynamic change trajectories of length, diameter and microfibril orientation angle of the fibers produced by an introgression line SY6167 which generates high-quality fibers even better than Sea island cotton with those of the common-quality fibers from TM-1 across 5 to 30days post anthesis (DPA). The proteomes were profiled and compared at six representative time points using 2-DE and MS/MS. 14 proteins differentially expressed inside each of cotton line temporally and significantly different tween the two lines were identified. The dynamic change trajectories of fiber length and microfibril angle are close to "s" and reverse "s" growth curves, respectively. SY6167 and TM-1 fibers entered the logarithmic elongation phase simultaneously at 10 DPA, and SY6167 kept elongating logarithmically for 2 more days than TM-1. In parallel to logarithmic elongation, microfibril orientation angles dived sharply, and SY6167 declined faster for a shorter duration than TM-1. 53% of the identified proteins are related to redox homeostasis, and most of them are expressed at higher levels in SY6167 during logarithmic elongation. 1-Aminocyclopropane-1-Carboxylic Acid Oxidase (ACO) started to accumulate at 16 DPA in SY6167, and its encoding genes were highly expressed at this stage, with a much higher level than TM-1. These findings suggest high-quality fibers are associated with high expression of the proteins related to stress and redox homeostasis, the continuously elevated expression of ethylene synthesis ACO gene may play an essential role.