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1.
Carbon dioxide enhances the development of the ethylene forming enzyme in tobacco leaf discs 总被引:2,自引:1,他引:1
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Since CO2 is known to stimulate ethylene production by promoting the conversion of 1-aminocyclopropane-1-carboxylic acid (ACC) to ethylene, the effect of CO2 on the activity and the development of the ethylene forming enzyme (EFE) was studied in tobacco (Nicotiana tabacum L. cv Havana 425 and Xanthi) leaf discs. In addition to previous observations that EFE activity is dependent on CO2 concentration and is saturable with 2% CO2, present data show two saturation curves at 2% and 10% CO2. Promotion of EFE development was dependent also on CO2 concentration (saturated at 2% CO2) and duration (maximum at 24 in the dark), and was abolished by 20 micromolar cycloheximide. Application of exogenous ethylene (20 microliters per liter) or light treatment further increased the CO2-enhanced development of EFE, implying that these two factors can also affect EFE development via interaction with CO2. The results suggest that CO2 exerts its stimulatory effect on the conversion of ACC to ethylene by enhancing not only the activity but also the synthesis of EFE in leaf discs. 相似文献
2.
Shimon Meir Sonia Philosoph-Hadas Nehemia Aharoni 《Journal of Plant Growth Regulation》1984,3(1-3):169-181
Indole-3-acetic acid (IAA) labeled in its carboxyl group was metabolized by tobacco leaf discs (Nicotiana tabacum L. cv. Xanthi) into three metabolites, two of which were preliminarily characterized as a peptide and an ester-conjugated IAA. Reapplication of each of the three metabolites (at 10 M) resulted in a marked stimulation of ethylene production and decarboxylation by the leaf discs. Similarly, these three IAA metab olites could induce elongation of wheat coleoptile segments, which was accompanied by decarboxylation. Both the exogenously supplied esteric and peptidic IAA conjugates were converted by the leaf discs into the same metabolites as free IAA. (1-14C)IAA, applied to an isolated epidermis tissue, was completely metabolized to the esteric and peptidic IAA conjugates. This epidermis tissue showed much higher ethylene production rates and lower decarboxylation rates than did the whole leaf disc.The results suggest that the participation of IAA conjugates in the regulation of various physiological processes depends on the release of free IAA, which is obtained by enzymatic hydrolysis of the conjugates in the tissue. The present study demonstrates biological activity of endogenous IAA conjugates that were synthesized by tobacco leaf discs in response to exogenously supplied IAA.Contribution No. 952-E, 1983 series, from the Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel. 相似文献
3.
Changes in the patterns of ethylene production, chlorophyll content, and respiration were studied in relation to the senescence of intact leaves and leaf discs. The primary leaves of pinto bean, which abscise readily during natural senescence, and tobacco and sugar beet leaves, which do not abscise, were used. A decrease in the rate of ethylene production and respiration, during the slow phase of chlorophyll degradation, was observed in leaf-blade discs cut from mature leaves and aged in the dark. During rapid chlorophyll loss both ethylene production and respiration increased and then decreased. These climacteric-like patterns were shown by leaf discs of all three species. Discs taken from leaves that had been senescing on the plant also showed a climacteric-like rise in ethylene production but not in respiration, which decreased continuously with leaf age. Climacteric-like patterns in the rise of ethylene and respiration for leaf discs were also shown by the petioles of both bean and tobacco leaves. This indicates that the rise of ethylene and respiration is characteristic of the general process of senescence in leaves and is not restricted to the abscission process. In contrast to the ethylene-forming systems in climacteric fruits and many flowers, the one in leaves declines sharply in the early stages of senescence. The subsequent rise of ethylene production appears to be associated with the rapid phase of chlorophyll breakdown, and may indicate the final stage of the senescence process during which ethylene could be actively involved in inducing leaf abscission. 相似文献
4.
The regulatory role of ethylene in leaf senescence was studied with excised tobacco leaf discs which were allowed to senesce in darkness. Exogenous ethylene, applied during the first 24 hours of senescence, enhanced chlorophyll loss without accelerating the climacteric-like pattern of rise in both ethylene and CO2, which occurred in the advanced stage of leaf senescence. Rates of both ethylene and CO2 evolution increased in the ethylene-treated leaf discs, especially during the first 3 days of senescence. The rhizobitoxine analog, aminoethoxy vinyl glycine, markedly inhibited ethylene production and reduced respiration and chlorophyll loss. Pretreatment of leaf discs with Ag+ or enrichment of the atmosphere with 5 to 10% CO2 reduced chlorophyll loss, reduced rate of respiration, and delayed the climacteric-like rise in both ethylene and respiration. Ag+ was much more effective than CO2 in retarding leaf senescence. Despite their senescence-retarding effect, Ag+ and CO2, which are known to block ethylene action, stimulated ethylene production by the leaf discs during the first 3 days of the senescing period; Ag+ was more effective than CO2. The results suggest that although ethylene production decreases prior to the climacteric-like rise during the later stages of senescence, endogenous ethylene plays a considerable role throughout the senescence process, presumably by interacting with other hormones participating in leaf senescence. 相似文献
5.
Production and action of ethylene in senescing leaf discs: effect of indoleacetic Acid, kinetin, silver ion, and carbon dioxide
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Supraoptimal concentrations of indoleacetic acid (IAA) stimulated ethylene production, which in turn appeared to oppose the senescence-retarding effect of IAA in tobacco leaf discs. Kinetin acted synergistically with IAA in stimulating ethylene production, but it inhibited senescence. Silver ion and CO(2), which are believed to block ethylene binding to its receptor sites, delayed senescence in terms of chlorophyll loss and stimulated ethylene production. Both effects of Ag(+) were considerably greater than those of CO(2). IAA, kinetin, CO(2), and Ag(+), combined, acted to increase ethylene production further. Although this combination increased ethylene production about 160-fold over that of the control, it inhibited senescence. Treatment with 25 mul/l of ethylene in the presence of IAA enhanced chlorophyll loss in leaf discs and inhibited by about 90% the conversion of l-[3,4-(14)C] methionine to (14)C(2)H(4) suggesting autoinhibition of ethylene production.The results suggest that ethylene biosynthesis in leaves is controlled by hormones, especially auxin, and possibly the rate of ethylene production depends, via a feedback control system, on the rates of ethylene binding at its receptor sites. 相似文献
6.
Relationship between Leaf Water Status and Endogenous Ethylene in Detached Leaves 总被引:10,自引:5,他引:5
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Aharoni N 《Plant physiology》1978,61(4):658-662
The pattern of changes in the internal concentration of ethylene in response to water stress was investigated in species with leaves that do abscise and leaves that do not abscise. When leaves which abscise were detached and exposed to dry air for up to 6 hours, a continuous increase of internal ethylene was observed. In water-stressed leaves which do not abscise only a transient rise in ethylene occurred. The peak, which was attained after 30 to 120 minutes, depending on the species studied, was followed by a sharp decline to the initial level. The principal site of ethylene production in response to a short period of water stress was in the blades rather than the petioles in both types of leaves. The internal ethylene level in leaves was reduced by pretreatment with the ethoxy analog of rhizobitoxine (an inhibitor of ethylene biosynthesis) or by maintaining the leaves under subatmospheric pressure. The results obtained by these methods showed that ethylene was not involved in the mechanism of stomatal movement in either turgid or in stressed leaves. Also, the increase in leaf abscisic acid content and the depletion of gibberellins induced by water stress were not related to the internal concentration of ethylene in the detached leaf. The different patterns of drought-induced ethylene production observed in the blades of leaves which exhibit abscission compared with those which do not exhibit abscission may indicate the involvement of ethylene in a primary event in the process of leaf abscission induced by water stress. 相似文献
7.
CO2对离体欧芹叶片中蛋白质代谢的影响 总被引:5,自引:0,他引:5
以离体欧芹叶片为实验系统,研究了CO2对叶片中蛋白质降解的影响。对离体欧芹叶片中游离氨基酸含量及可溶蛋白含量的分析结果表明:CO2具有抑制离体欧芹叶片中蛋白质降解的作用,这为进一步了解CO2延缓叶片衰老的作用机理很有意义。 相似文献
8.
The ε-amino group of lysine residues may be mono-, di- or tri-methylated by protein lysine methyltransferases. In the past few years it has been highly considered that methylation of both histone and non-histone proteins has fundamental role in development and progression of various human diseases. Thus, the establishment of tools to study lysine methylation that will distinguish between the different states of methylation is required to elucidate their cellular functions. The 3X malignant brain tumor domain (3XMBT) repeats of the Lethal(3)malignant brain tumor-like protein 1 (L3MBTL1) have been utilized in the past as an affinity reagent for the identification of mono- and di-methylated lysine residues on individual proteins and on a proteomic scale. Here, we have utilized the 3XMBT domain to develop an enzyme-linked immunosorbent assay (ELISA) that allows the high-throughput detection of 3XMBT binding to methylated lysines. We demonstrated that this system allows the detection of methylated peptides, methylated proteins and PKMT activity on both peptides and proteins. We also optimized the assay to detect 3XMBT binding in crude E. coli lysates which facilitated the high throughput screening of 3XMBT mutant libraries. We have utilized protein engineering tools and generated a double site saturation 3XMBT library of residues 361 and 411 that were shown before to be important for binding mono and di-methylated substrates and identified variants that can exclusively recognize only di-methylated peptides. Together, our results demonstrate a powerful new approach that will contribute to deeper understanding of lysine methylation biology and that can be utilized for the engineering of domains for specific binders of other post-translational modifications. 相似文献
9.
Dario A. Breitel Louise Chappell-Maor Sagit Meir Irina Panizel Clara Pons Puig Yanwei Hao Tamar Yifhar Hagai Yasuor Mohamed Zouine Mondher Bouzayen Antonio Granell Richart Ilana Rogachev Asaph Aharoni 《PLoS genetics》2016,12(3)
The involvement of ethylene in fruit ripening is well documented, though knowledge regarding the crosstalk between ethylene and other hormones in ripening is lacking. We discovered that AUXIN RESPONSE FACTOR 2A (ARF2A), a recognized auxin signaling component, functions in the control of ripening. ARF2A expression is ripening regulated and reduced in the rin, nor and nr ripening mutants. It is also responsive to exogenous application of ethylene, auxin and abscisic acid (ABA). Over-expressing ARF2A in tomato resulted in blotchy ripening in which certain fruit regions turn red and possess accelerated ripening. ARF2A over-expressing fruit displayed early ethylene emission and ethylene signaling inhibition delayed their ripening phenotype, suggesting ethylene dependency. Both green and red fruit regions showed the induction of ethylene signaling components and master regulators of ripening. Comprehensive hormone profiling revealed that altered ARF2A expression in fruit significantly modified abscisates, cytokinins and salicylic acid while gibberellic acid and auxin metabolites were unaffected. Silencing of ARF2A further validated these observations as reducing ARF2A expression let to retarded fruit ripening, parthenocarpy and a disturbed hormonal profile. Finally, we show that ARF2A both homodimerizes and interacts with the ABA STRESS RIPENING (ASR1) protein, suggesting that ASR1 might be linking ABA and ethylene-dependent ripening. These results revealed that ARF2A interconnects signals of ethylene and additional hormones to co-ordinate the capacity of fruit tissue to initiate the complex ripening process. 相似文献
10.
Xu Chen Lei Shi Yuqin Chen Lu Zhu Dasheng Zhang Shi Xiao Asaph Aharoni Jianxin Shi Jie Xu 《Plant, cell & environment》2019,42(4):1190-1204
Sepals play important roles in protecting inner floral organs from various stresses and in guaranteeing timely flower opening. However, the exact role of sepals in coordinating interior and exterior signals remains elusive. In this study, we functionally characterized a heat shock protein gene, Arabidopsis HSP70‐16, in flower opening and mild heat stress response, using combined genetics with anatomic, physiological, chemical, and molecular analyses. We showed that HSP70‐16 is required for flower opening and mild heat response. Mutation of HSP70‐16 led to a significant reduction in seed setting rate under 22°C, which was more severe at 27°C. Mutation of HSP70‐16 also caused postgenital fusion at overlapping tips of two lateral sepals, leading to failed flower opening, abnormal floral organ formation, and impaired fertilization and seed setting. Chemical and anatomic analyses confirmed specific chemical and morphological changes of cuticle property in mutant lateral sepals, and qRT‐PCR data indicated that expression levels of different sets of cuticle regulatory and biosynthetic genes were altered in mutants grown at both 22°C and 27°C temperatures. This study provides a link between thermal and developmental perception signals and expands the understanding of the roles of sepal in plant development and heat response. 相似文献