Ethylene Synthesis Research Articles

Acetylsalicylic acid and salicylic acid alleviate postharvest leaf senescence in Chinese flowering cabbage (Brassica rapa var. parachinensis)

The leaves of ‘Ningxia Chinese flowering cabbage’ readily become yellow and senesce after harvest. To test the effects of acetylsalicylic acid (ASA) and salicylic acid (SA) on postharvest leafy vegetables, Chinese flowering cabbages were sprayed with 2 mmol L−1 ASA and 1.5 mmol L−1 SA, and stored at 15 °C. Compared with the controls, during storage, ASA- and SA-treated cabbages retained higher levels of total chlorophyll (Chl), Chl a, and Chl b, and lower activities of chlorophyllase, Mg dechelatase, pheophytinase, and Chl-degrading peroxidase, and had more intact chloroplasts. Furthermore, ASA and SA repressed respiration intensity, ethylene rate, the activities of 1-aminocyclopropane-1-carboxylic acid (ACC) synthase and ACC oxidase, and ACC content, decreased reactive oxygen species (ROS) levels, and increased the activities of superoxide dismutase, catalase, ascorbate peroxidase, peroxidase, phenylalanine ammonia lyase, cinnamate 4-hydroxylase, 4-coumarate-CoA ligase, chalcone synthase, chalcone isomerase, and cinnamyl alcohol dehydrogenase, promoting the accumulation of phenolics and flavonoids. Using principal component and hierarchical clustering analyses, leaf senescence was attributed to higher respiration, ethylene synthesis, and ROS levels, while the delay of senescence in treated cabbages resulted from the cooperation of ROS metabolism and the phenylpropanoid pathway. ASA and SA slowed leaf degreening and senescence. Between the two treatments, 2 mmol L−1 ASA was the most effective.

Label-Free Quantitative Proteomics Reveal the Involvement of PRT6 in Arabidopsis thaliana Seed Responsiveness to Ethylene

In Arabidopsis thaliana, the breaking of seed dormancy in wild type (Col-0) by ethylene at 100 μL L−1 required at least 30 h application. A mutant of the proteolytic N-degron pathway, lacking the E3 ligase PROTEOLYSIS 6 (PRT6), was investigated for its role in ethylene-triggered changes in proteomes during seed germination. Label-free quantitative proteomics was carried out on dormant wild type Col-0 and prt6 seeds treated with (+) or without (−) ethylene. After 16 h, 1737 proteins were identified, but none was significantly different in protein levels in response to ethylene. After longer ethylene treatment (30 h), 2552 proteins were identified, and 619 Differentially Expressed Proteins (DEPs) had significant differences in protein abundances between ethylene treatments and genotypes. In Col, 587 DEPs were enriched for those involved in signal perception and transduction, reserve mobilization and new material generation, which potentially contributed to seed germination. DEPs up-regulated by ethylene in Col included S-adenosylmethionine synthase 1, methionine adenosyltransferase 3 and ACC oxidase involved in ethylene synthesis and of Pyrabactin Resistance1 acting as an ABA receptor, while DEPs down-regulated by ethylene in Col included aldehyde oxidase 4 involved in ABA synthesis. In contrast, in prt6 seeds, ethylene did not result in strong proteomic changes with only 30 DEPs. Taken together, the present work demonstrates that the proteolytic N-degron pathway is essential for ethylene-mediated reprogramming of seed proteomes during germination.

Improvement of salt tolerance of Arabidopsis thaliana seedlings inoculated with endophytic Bacillus cereus KP120

ABSTRACT In our previous reports, an endophytic bacterium, Bacillus cereus KP120 was isolated from the halophyte species Kosteletzkya virginica. In this study, the effect of KP120 colonization on Arabidopsis thaliana seedlings was investigated. Our results showed that inoculation with KP120 could promote the growth of A. thaliana seedlings plants under salt-stress conditions, compared with uninoculated controls. After salt treatment, chlorophyll, proline, the activity of antioxidant enzymes, Indole-3-acetic acid and 1-aminocyclopropane-1-carboxylate-deaminase in plants inoculated were increased significantly but malondialdehyde content was decreased compared with the plants under salt stress lonely. Similarly, under non-salt stress, physiological indices above except for MDA in plants inoculated with KP120 were increased compared with control. B. cereus also induced the up-regulation of key genes involved in IAA biosynthesis, responses, transport, down-regulated expression of genes related with ethylene synthesis and response. Our work principally demonstrates that Bacillus cereus KP120 significantly enhances plant growth and increases plant tolerance to salt stress.

The molecular mechanism on suppression of climacteric fruit ripening with postharvest wax coating treatment via transcriptome.

Wax coating is an important means to maintain fruit quality and extend fruit shelf life, especially for climacteric fruits, such as apples (Malus domestica). Here, we found that wax coating could inhibit ethylene production, chlorophyll degradation, and carotenoid synthesis, but the molecular mechanism remains unclear. The regulatory mechanism of wax coating on apple fruit ripening was determined by subjecting wax-treated apple fruits to transcriptome analysis. RNA-seq revealed that 1,137 and 1,398 genes were upregulated and downregulated, respectively. These differentially expressed genes (DEGs) were shown to be related to plant hormones, such as ethylene, auxin, abscisic acid, and gibberellin, as well as genes involved in chlorophyll degradation and carotenoid biosynthesis. Moreover, we found that some genes related to the wax synthesis process also showed differential expression after the wax coating treatment. Among the DEGs obtained from RNA-seq analysis, 15 were validated by quantitative RT-PCR, confirming the results from RNA-seq analysis. RNA-seq and qRT-PCR of pear (Pyrus ussuriensis) showed similar changes after wax treatment. Our data suggest that wax coating treatment inhibits fruit ripening through ethylene synthesis and signal transduction, chlorophyll metabolism, and carotenoid synthesis pathways and that waxing inhibits endogenous wax production. These results provide new insights into the inhibition of fruit ripening by wax coating.

Phosphine Fumigation Followed by Cold Treatment to Control Peach Fruit Moth, Carposina sasakii, Larvae on “Fuji” Apples Intended for Export

The fumigation of apples using methyl bromide (MeBr) can cause severe deterioration in fruit quality. Moreover, maintaining the quality of apples during postharvest storage and eradicating pests, especially those involved in quarantine issues, are important for facilitating the export of apples, including the “Fuji” apple (Malus pumila var. “Fuji”) in South Korea. In the present study, phosphine (PH3) fumigation as an alternative to MeBr was found to be more effective for the control of peach fruit moth larvae (Carposina sasakii), which had naturally infested Fuji apples, at a high temperature (25 °C) rather than at a low temperature (5 °C). To achieve the industry requirement of better-quality perishable commodities and meet quarantine guidelines for export, PH3 fumigation at the low temperature (5 °C) was followed by cold treatments at 3 ± 2 °C for 2 and 4 weeks, which led to higher efficacy than was achieved using PH3 at 5 °C alone. Given that chemical treatments, such as treatment with 1-methylcyclopropene, can inhibit ethylene synthesis, low-temperature PH3 fumigation for 72 h followed by 4 weeks of cold treatment could also extend the shelf life of apples and resolve known quarantine issues when used as an alternative to MeBr treatment.

An Insight of Quinclorac Resistance Mechanism in Early Watergrass ( Echinochloa oryzoides )

Background Quinclorac- main herbicide targeting to barnyard grass, has been used for decades in rice fields. Echinochloa species have been reported evolving into quinclorac resistance.Objective: Quinclorac resistance and its mechanism remain undisclosed in Echinochloa oryzoides (Ard.) Fritsch that needs to be uncovered. Methods Dose-response assays were performed, followed by ethylene synthesis, and related enzyme activities along with gene transcription were studied. β-CAS activity and its molecular docking were investigated. Results E. oryzoides evolved into 21 times resistance to quinclorac [...]

Reducing plant-derived ethylene concentrations increases the resistance of temperate grassland to drought

Model predictions indicate that extreme drought events will occur more frequently by the end of this century, with major implications for terrestrial ecosystem functions such as plant productivity and soil respiration. Previous studies have shown that drought-induced ethylene produced by plants is a key factor affecting plant growth and development, but the impact of drought-induced ethylene on ecosystem functions in natural settings has not yet been tested. Here, we reduced the amount of plant-derived ethylene concentrations by adding the ethylene inhibitor aminoethoxyvinylglycine (AVG), and investigated in situ plant productivity, soil respiration and ethylene concentrations for two years in a semi-arid temperate grassland in Inner Mongolia, China. Drought significantly reduced plant productivity and soil respiration, but the application of AVG reduced ethylene concentrations and significantly increased aboveground plant productivity and soil respiration, effectively enhancing resistance to drought. The reason for this could be that AVG application increased the activity of 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase and abundance of the acdS gene (the key gene for ACC deaminase), facilitating reduced ACC concentrations in the plant tissue and reduced in planta ethylene synthesis. In addition, there was a significant correlation between soil ACC deaminase activity and plant productivity. Given the global distribution of arid and semi-arid areas, and the expected increases in the frequency and intensity of drought stress, this is a significant concern. These results provide novel evidence of the impact of drought-induced plant ethylene production on ecosystem functions in semi-arid temperate grassland ecosystems.

Comparative Transcriptome and Pigment Analyses Reveal Changes in Gene Expression Associated with Flavonol Metabolism in Yellow Camellia

The accumulation of various pigments leads to the formation of different flower colors in plants. However, the regulation mechanism of yellow flower formation and flower color differences between Camellia nitidssima C.W.Chi (CN) and its hybrids C. ‘Zhenghuangqi’ (ZHQ), C. ‘Huangxuanlv’ (HXL), and C. ‘Xinshiji’ (XSJ), remains largely unknown. Here, we showed that the content of two flavonols, quercetin-7-O-glucoside (Qu7G) and quercetin-3-O-glucoside (Qu3G), was positively correlated with the yellow degree of petals in CN and its three hybrids. Additionally, we performed a comparative transcriptomic analysis of petals of the four yellow camellia plants, which revealed 322 common upregulated and 866 common downregulated DEGs (differentially expressed genes) in the CN vs. ZHQ, CN vs. HXL, and CN vs. XSJ comparison groups. Their regulatory pathway analysis showed that flavonol biosynthesis genes (FLSs and GTs) and transcriptional regulatory genes MYBs were all expressed higher in CN than its three hybrids, which corresponded to differences in the flavonol content among the four yellow camellias. Further, two ethylene synthesis genes (ACSs, ACO) and three ethylene signaling genes (EIN2s, EIN3, ERFs) were all upregulated in the yellow petals of CN. In conclusion, the expression of flavonol-related genes and flavonols (Qu7G and Qu3G) accumulation could play a key role in the formation of yellow flowers in camellia, and the ethylene pathway might be involved in the regulation of yellow flower formation of camellias. This work describes the possible regulatory pathway of yellow camellia, thereby laying a foundation for future verification of genes linked to flower coloring and the breeding of yellow camellia.

Determination of Optimum PGPB-Priming Protocol on Germination and Seedling Growth in Lentil

Plant growth promoting bacterias (PGPBs) can be described as bacterial strains increasing water and nutrient uptake, gaining nitrogen and phosphorus to plants by biological nitrogen fixation and phosphate mineralization, promoting plant growth and enabling to improve the tolerance to stress factors due to mechanisms as secretion of various phytohormones, vitamins and growth regulators, restriction of ethylene synthesis with ACC deaminase activity, decreasing of pathogen damage by the secret of antibiotic and fungicidal compounds. This study was carried out in a laboratory of Field crops in Siirt University under controlled conditions. The 2 original bacterial strains (KF3B and KF63C) and 5 different priming times (control, 1, 2, 4 and 6 h) were applied on the Fırat-87 lentil variety. The study was laid out in a completely randomized design with 3 replications. It was aimed with this study that investigating effects based on bacterial biodiversity and priming time on germination characteristics and seedling growth in lentils. According to results, biodiversity-induced differences were observed in germination percentage, seedling fresh weight, seedling dry weight, seedling length and seedling vigor index while priming time significantly affected all investigated parameters except for germination percentage. However, the interaction of strains and priming times did not lead to any significant differences in traits. In conclusion, microbial diversity and priming time have a critical role on successful of the priming technique. Optimum priming time for lentils was determined as 4 hours. Besides, the strain of KF63C had a noteworthy stimulative effect on especially seedling growth in the experiment.

S-Assimilation Influences in Carrageenan Biosynthesis Genes during Ethylene-Induced Carposporogenesis in Red Seaweed Grateloupia imbricata.

The synthesis of cell-wall sulfated galactans proceeds through UDP galactose, a major nucleotide sugar in red seaweed, whilst sulfate is transported through S-transporters into algae. Moreover, synthesis of ethylene, a volatile plant growth regulator that plays an important role in red seaweed reproduction, occurs through S-adenosyl methionine. This means that sulfur metabolism is involved in reproduction events as well as sulfated galactan synthesis of red seaweed. In this work we study the effects of methionine and MgSO4 on gene expression of polygalactan synthesis through phosphoglucomutase (PGM) and galactose 1 phosphate uridyltransferase (GALT) and of sulfate assimilation (S-transporter and sulfate adenylyltransferase, SAT) using treatment of ethylene for 15 min, which elicited cystocarp development in Grateloupia imbricata. Also, expressions of carbohydrate sulfotransferase and galactose-6-sulfurylase in charge of the addition and removal of sulfate groups to galactans backbone were examined. Outstanding results occurred in the presence of methionine, which provoked an increment in transcript number of genes encoding S-transporter and assimilation compared to controls regardless of the development stage of thalli. Otherwise, methionine diminished the transcript levels of PGM and GALT and expressions are associated with the fertilization stage of thalli of G. imbricata. As opposite, methionine and MgSO4 did not affect the transcript number of carbohydrate sulfotransferase and galactose-6-sulfurylase. Nonetheless, differential expression was obtained for sulfurylases according to the development stages of thalli of G. imbricata.

Metabolome Analysis under Aluminum Toxicity between Aluminum-Tolerant and -Sensitive Rice (Oryza sativa L.).

Aluminum (Al) solubilizes into trivalent ions (Al3+) on acidic soils, inhibiting root growth. Since about 13% of global rice cultivation is grown on acidic soils, improving Al tolerance in rice may significantly increase yields. In the present study, metabolome analysis under Al toxicity between the Al-tolerant variety Nipponbare and the Al-sensitive variety H570 were performed. There were 45 and 83 differential metabolites which were specifically detected in Nipponbare and H570 under Al toxicity, respectively. Furthermore, the results showed that 16 lipids out of 45 total metabolites were down-regulated, and 7 phenolic acids as well as 4 alkaloids of 45 metabolites were up-regulated in Nipponbare, while 12 amino acids and their derivatives were specifically detected in H570, of which 11 amino acids increased, including L-homoserine and L-methionine, which are involved in cysteine synthesis, L-ornithine and L-proline, which are associated with putrescine synthesis, and 1-aminocyclopropane-1-carboxylate, which is associated with ethylene synthesis. The contents of cysteine and s-(methyl) glutathione, which were reported to be related to Al detoxification in rice, decreased significantly. Meanwhile, putrescine was accumulated in H570, while there was no significant change in Nipponbare, so we speculated that it might be an intermediate product of Al detoxification in rice. The differential metabolites detected between Al-tolerant and -sensitive rice variants in the present study might play important roles in Al tolerance. These results provide new insights in the mechanisms of Al tolerance in rice.

Attenuation of ethylene signaling increases cotton resistance to a defoliating strain of Verticillium dahliae

The severity of Verticillium wilt on cotton caused by defoliating strains of Verticillium dahliae has gradually increased and threatens production worldwide. Identification of the molecular components of leaf defoliation may increase cotton tolerance to V. dahliae. Ethylene, a major player in plant physiological processes, is often associated with senescence and defoliation of plants. We investigated the cotton–V. dahliae interaction with a focus on the role of ethylene in defoliation and defense against V. dahliae. Cotton plants inoculated with V. dahliae isolate V991, a defoliating strain, accumulated more ethylene and showed increased disease symptoms than those inoculated with a non-defoliating strain. In cotton with a transiently silenced ethylene synthesis gene (GhACOs) and signaling gene (GhEINs) during cotton–V. dahliae interaction, ethylene produced was derived from cotton and more ethylene increased cotton susceptibility and defoliation rate. Overexpression of AtCTR1, a negative regulator in ethylene signaling, in cotton reduced sensitivity to ethylene and increased plant resistance to V. dahliae. Collectively, the results indicated precise regulation of ethylene synthesis or signaling pathways improve cotton resistant to Verticillium wilt.

High light stress induces H2O2 production and accelerates fruit ripening in tomato

Increased synthesis of H2O2 is observed during the initiation of fruit ripening. However, its association with plant cell processes triggering the maturation of fruit has not yet been demonstrated. The aim of this work is to investigate whether H2O2 participates in the tomato ripening process and particularly through its association with the ethylene signaling pathway. The experiments were carried out with two ethyl methanesulfonate mutant lines of Micro-Tom tomato deficient in GDP-L-galactose phosphorylase activity and displaying lower ascorbic acid content than the corresponding parental genotype (i.e. wild type). Plants were subjected to a high irradiance (HI) treatment to stimulate H2O2 synthesis. HI treatment enhanced H2O2 production and reduced the timing of fruit ripening in both mutants and wild-type fruits. These results could be linked to an increase of the expression of H2O2-related genes and changes in the expression of ethylene-related genes. The fruit H2O2 production increased or decreased after applying the treatments that induced ethylene synthesis or blocked its action, respectively. The results presented in this work give an evidence of the association of redox and hormonal components during fruit ripening in which H2O2 participates downstream in the events regulated by ethylene.

The miR164a-NAM3 module confers cold tolerance by inducing ethylene production in tomato.

Because of a high sensitivity to cold, both the yield and quality of tomato (Solanum lycopersicum L.) are severely restricted by cold stress. The NAC transcription factor (TF) family has been characterized as an important player in plant growth, development, and the stress response, but the role of NAC TFs in cold stress and their interaction with other post-transcriptional regulators such as microRNAs in cold tolerance remains elusive. Here, we demonstrated that SlNAM3, the predicted target of Sl-miR164a/b-5p, improved cold tolerance as indicated by a higher maximum quantum efficiency of photosystem II (Fv/Fm), lower relative electrolyte leakage, and less wilting in SlNAM3-overexpression plants compared to wild-type. Further genetic and molecular confirmation revealed that Sl-miR164a/b-5p functioned upstream of SlNAM3 by inhibiting the expression of the latter, thus playing a negative role in cold tolerance. Interestingly, this role is partially mediated by an ethylene-dependent pathway because either Sl-miR164a/b-5p silencing or SlNAM3 overexpression improved cold tolerance in the transgenic lines by promoting ethylene production. Moreover, silencing of the ethylene synthesis genes, SlACS1A, SlACS1B, SlACO1, and SlACO4, resulted in a significant decrease in cold tolerance. Further experiments demonstrated that NAM3 activates SlACS1A, SlACS1B, SlACO1, and SlACO4 transcription by directly binding to their promoters. Taken together, the present study identified the miR164a-NAM3 module conferring cold tolerance in tomato plants via the direct regulation of SlACS1A, SlACS1B, SlACO1, and SlACO4 expression to induce ethylene synthesis.

TaMYC8 regulates TaERF6 and inhibits ethylene synthesis to confer Cd tolerance in wheat

Cadmium (Cd) is a toxic, nonessential heavy metal; its accumulation in plants alters metabolism and limits productivity. Although various studies have addressed the Cd stress response in various species, the detailed molecular mechanisms remain unknown. Therefore, the present work investigated the influence of the TaMYC8 transcription factor (TF) on the Cd-induced stress response in wheat. The present study found that TaMYC8 is a nuclear protein highly induced in the roots under Cd stress. Overexpression of TaMYC8 in the wheat cultivar ‘Bobwhite’ increased sensitivity to Cd stress, probably due to the increased levels of superoxide (O 2 .- ), malonaldehyde (MDA), jasmonic acid (JA), and Cd, and reduced the proline content and antioxidant enzyme activity. In contrast, silencing TaMYC8 via RNA interference (RNAi) significantly lowered Cd accumulation and improved Cd tolerance. Using the yeast one-hybrid assay (Y1H), chromatin immunoprecipitation-quantitative polymerase chain reaction (ChIP–qPCR), electrophoretic mobility shift assay (EMSA), and dual luciferase reporter assay, it was found that TaMYC8 could physically bind to the TaERF6 promoter and activate TaERF6 transcription. More importantly, knockdown of TaMYC8 by RNAi inhibited the activities of 1-aminocyclopropane-1-carboxylic (ACC) acid synthase (ACS) and ACC oxidase (ACO) of the ethylene biosynthetic pathway. In conclusion, TaMYC8 promotes TaERF6 transcription and affects the ethylene biosynthetic pathway. These findings provide a theoretical basis for breeding low-Cd-accumulating wheat cultivars. • TaMYC8 decreased Cd tolerance of transgenic wheat . • TaMYC8 binds to the promoter of TaERF6 as well as regulating the transcription of TaERF6 . • TaMYC8 affects Cd tolerance of wheat by regulating ethylene synthesis .

Hypobaric treatment augments the efficacy of 1-MCP in apple fruit.

This research aimed to extend the postharvest shelf life of Royal Gala apple during cold storage and maintain its market value in simulated retail conditions. Apples were treated with hypobaric pressure (50kPa for 4h) followed by 1-MCP (0.5µL L-1, 0.7µL L-1, and 1.0µL L-1) treatment for 24h individually and in combinations, stored at (1 ± 1°C, 85 ± 3% RH) for 120d and analyzed for different quality parameters (Peel color, firmness, weight loss, TSS, acidity, ethylene production rate, and respiration rate) at each 30 d interval, followed by a 20 d simulated retail condition at 20 ± 3°C with 4 d interval. Results indicated that all 1-MCP concentrations were more effective in retaining quality compared to individual hypobaric treatment. However, a synergistic effect was observed by combining 1-MCP with hypobaric treatment. Among the combined treatments, 1.0µL L-11-MCP + 50kPa more effectively and significantly retained quality during cold storage. Furthermore, the apples were more juicy, tasty, and attractive in color than others in simulated conditions. Addition of hypobaric treatment to 1-MCP might reduce endogenous ethylene in fruit by outward diffusion and blocking further ethylene synthesis by the action of 1-MCP. However, in-depth study is required for further understanding the phenomena.

Ultra-Low Oxygen and Preconditioning Storage Regulate Ethylene Synthesis to Prevent Corky Disorders in 'Fuji' Apple.

Corky disorders in apples represent a significant problem for long-term storage where controlled atmosphere (CA) is mainly used. Ultra-low oxygen (ULO) is an alternative to CA, which consists of low partial pressure of O2 to maintain a low metabolism in the apple fruit, achieving an effective decrease in the ethylene production and physiological disorders. The aim of this research was to study the effectiveness of a short hypoxia period on the development of cork physiological disorders during the storage of apple. ‘Fuji’ apples were prestored under ULO (0.5 kPa O2) for two periods of time (15 and 30 days) and at two temperatures (0 or 5°C). Corky physiological disorders increased at 5°C prestorage temperature; however, ULO treatments for 15 or 30 days at 0 or 5°C achieved a significant reduction in corky disorders near to 1%, compared with control treatments. In addition, a considerable reduction in ethylene production for up to 30 days was observed in ULO-treated fruit at 0 and 5°C. ULO for 30 days at 0 and 5°C increased the internal production of ethanol and acetaldehyde, causing a lower sensory quality due to the presence of fermentative flavors in fruit stored at 5°C. ULO of 15 days of conditioning decreased the relative expression of ethylene biosynthesis genes MdACS1 and MdACO1, resulting in lower ethylene production.

Synthesis and Characterization of Ethylene Glycol-Polydimethylsiloxane-Polybutyl Methacrylate Copolymer

Synthesis and Characterization of Ethylene Glycol-Polydimethylsiloxane-Polybutyl Methacrylate Copolymer

The involvement of nitric oxide and ethylene on the formation of endodermal barriers in response to Cd in hyperaccumulator Sedum alfredii

Nitric oxide (NO) and ethylene are both important signaling molecules which participate in numerous plant development processes and environmental stress resistance. Here, we investigate whether and how NO interacts with ethylene during the development of endodermal barriers that have major consequences for the apoplastic uptake of cadmium (Cd) in the hyperaccumulator Sedum alfredii. In response to Cd, an increased NO accumulation, while a decrease in ethylene production was observed in the roots of S. alfredii. Exogenous supplementation of NO donor SNP (sodium nitroprusside) decreased the ethylene production in roots, while NO scavenger cPTIO (2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide) had the opposite effect. The exogenous addition of NO affected the ethylene production through regulating the expression of genes related to ethylene synthesis. However, upon exogenous ethylene addition, roots retained their NO accumulation. The abovementioned results suggest that ethylene is downstream of the NO signaling pathway in S. alfredii. Regardless of Cd, addition of SNP promoted the deposition of endodermal barriers via regulating the genes related to Casparian strips deposition and suberization. Correlation analyses indicate that NO positively modifies the formation of endodermal barriers via the NO-ethylene signaling pathway, Cd-induced NO accumulation interferes with the synthesis of ethylene, leading to a deposition of endodermal barriers in S. alfredii.

BpEIN3.1 represses leaf senescence by inhibiting synthesis of ethylene and abscisic acid in Betula platyphylla

Leaf senescence and abscission play crucial role in annual plant adapting to seasonal alteration and climate changes by shortening life cycle and development process in response to abiotic and/or biotic stressors underlying phytohormones and environmental signals. Ethylene and abscisic acid are the major phytohormones that promotes leaf senescence, involving various transcription factors, such as EIN3 (ethylene-insensitive 3) and EIL (ethylene-insensitive 3-like) gene family, controlling leaf senescence through metabolite biosynthesis and signal transduction pathways. However, the roles of EIN3 regulating leaf senescence responding to environmental changes in perennial plant, especially forestry tree, remain unclear. In this study, we found that BpEIN3.1 from a subordinated to EIL3 subclade, is a transcription repressor and regulated light-dependent premature leaf senescence in birch (Betula platyphylla). BpEIN3.1 might inhibits the transcription of BpATPS1 by binding to its promoter. Shading suppressed premature leaf senescence in birch ein3.1 mutant line. Ethylene and abscisic acid biosynthesis were also reduced. In addition, abscisic acid positively regulated the expression of BpEIN3.1. This was demonstrated by the hormone-response element analysis of BpEIN3.1 promoter and its gene expression after the hormone treatments. Moreover, our results showed that abscisic acid is also involved in maintaining homeostasis. The molecular mechanism of leaf senescence provides a possibility to increasing wood production by delaying of leaf senescence.