植物逆境胁迫耐受性启动子的研究进展

逆境胁迫如干旱、极端温度、损伤等非生物胁迫和病虫害等生物胁迫严重影响植物的生长发育及产量。逆境胁迫耐受性启动子能够接受逆境条件下的诱导信号,激活植物体内胁迫应答基因的表达,使植物感知并适应逆境。本文对逆境胁迫耐受性启动子的克隆及功能研究情况进行综合分析,主要包括抗旱、耐盐、耐高温、抗冻、耐损伤、抗病和抗虫基因启动子。     

河南省植物逆境生物学重点实验室简介

河南省植物逆境生物学实验室为教育部重点实验室,拥有植物学博士学位授予权点。在实验室主任宋纯鹏教授的带领下,利用基因组学、细胞生物学、分子遗传学和农业生态学等实验技术,建立了有特色的实验模式体系,系统开展植物对环境因子应答的分子机理及其调控技术的研究。探讨在干旱、盐害和低温等逆境条件下,植物生长发育和逆境适应的分子遗传基础和细胞信号转导机制;提出了与逆境反应密切相关的H2O2作为信号分子参与了ABA诱导的气孔关闭过程;分析和鉴定与植物抗盐、抗旱等相关特异基因;阐明作物适应“多变低水”的生理及生态机制等。     

细胞程序性死亡在植物适应逆境中的意义

细胞程序性死亡是近年来生命科学的研究热点之一,它不仅在植物生长发育中起重要作用,而且与植物适应逆境也密切相关。本文就细胞程序性死亡在植物适应逆境中的重要作用进行了综述,以期对细胞程序性死亡的研究进一步深入和对植物适应逆境的潜力有新的认识。     

蛋白质组学在研究植物响应逆境机理上的应用

逆境条件下植物可以通过改变其基因表达和相关代谢活动来适应,探讨植物基因和蛋白表达谱的变化就成为植物逆境响应机制研究中的重要内容,蛋白质表达谱反映了植物细胞和组织的实际状态,是植物基因表达和最终代谢的关键环节。随着蛋白质分离技术、质谱鉴定技术和植物生物信息学的迅速发展,蛋白质组学在植物响应逆境方面的研究中的应用已经比较成功,加深了人们对植物响应逆境机制的认识,并为人们提供了新的线索和思维。本文主要对蛋白质组学在植物响应非生物逆境(干旱、盐胁迫、低温胁迫、高温胁迫等)和生物逆境(病虫害)的机制研究的应用上进行了综述。     

逆境胁迫下ABA与钙信号转导途径之间的相互调控机制

Ca2+信号是植物应答各种逆境胁迫响应的一个重要组分,它在植物抗病、抗虫及适应非生物胁迫反应中起着重要的作用.Caz+信号作为第二信使在激素信号转导尤其是ABA信号转导过程中发挥着重要作用.研究表明,当植物受到如干旱、低温、盐害等环境胁迫时,细胞迅速积累ABA,胞内钙离子浓度瞬间升高,然后钙离子浓度呈现忽高忽低的震荡现象.在植物细胞中发现Caz+/CDPK、Caz+/CaM和Caz+/CBL三类钙信号系统,它们与逆境胁迫信号转导密切相关.本文通过综述植物在逆境条件下,ABA与钙信号的产生、转导及产生适应性和抗性等方面,介绍了ABA与钙信号之间的相互调节机制.     

植物逆境miRNA研究进展

包括生物和非生物在内的多种逆境胁迫是植物正常生长和作物产量提高的重要限制性因素。植物在长期的进化过程中, 通过诱导表达某些抵御或防卫途径的关键基因来实现对胁迫的响应。研究表明, 逆境胁迫不仅会诱导植物蛋白质编码基因的表达, 也会诱导一些非蛋白质编码基因的表达, 这类非蛋白质编码基因的表达产物在植物的生长、发育和应对逆境胁迫等过程中起到重要的调控作用。miRNA(小分子RNA)就是这类非蛋白质编码基因产物中的重要类群, 研究发现, 多种逆境均会诱导miRNA的产生, 其作用是通过引导目的基因mRNA的降解和阻止翻译过程来调控靶基因, 最终通过形态或生理上的变化达到对逆境的适应。文章主要对植物逆境胁迫下miRNA的研究, 特别是逆境胁迫诱导miRNA的产生、靶基因调控以及miRNA在植物适应逆境胁迫过程中的作用进行了综述, 同时, 文章还对在逆境胁迫下植物miRNA的研究方法进行了初步的探讨。     

钙信使在植物适应非生物逆境中的作用

综述了非生物逆境胁迫下植物体内钙信号的产生,特点及植物在适应逆境中钙信使系统的可能作用。     

生物逆境和共生状态下植物的蛋白质组学研究

蛋白质组技术已广泛应用于植物遗传、发育和生理生态等诸多生物学领域,主要研究植物的遗传多样性、植物发育、组织分化、植物对非生物逆境(包括高温、低温、高盐和干旱等)和生物逆境(病虫害)的适应机制和植物与微生物(根瘤共生体)相互作用机制。本文综述了微生物与植物互作的蛋白质组研究进展,包括有害和有益的相互作用,同时对植物蛋白质组学的发展前景进行了讨论。     

逆境诱导植物开花的研究进展

植物在长期的进化过程中形成了对环境改变的适应机制。在逆境条件下,例如干旱、高盐、低温、强光、弱光、紫外线等,植物会提前开花结实以尽早完成其生命周期,这种生物学现象被称为"逆境诱导的开花"。植物的这种避逆应激反应不但在进化上具有非常重要的生物学意义,而且对农业生产也具有重要的指导意义。逆境诱导植物开花与光周期、春化、环境温度、自主途径、赤霉素和年龄等开花途径的分子调控机制不同,有其自身的特点。文中对逆境诱导植物开花的研究历史、代谢调控以及分子机制等进行了阐述,并展望了未来的研究方向。     

植物脯氨酸合成酶基因工程研究进展

逆境条件下植物细胞积累脯氨酸是植物适应逆境的一种反应,有利于减轻逆境对植物的伤害。简要回顾了生物体脯氨酸代谢过程和逆境下植物积累脯氨酸的作用,重点总结了植物体内脯氨酸合成酶基因吡咯啉-5羧-酸合成酶(P5CS)的克隆、表达和转基因研究进展。研究认为,P5CS是一个逆境胁迫应答基因,通过基因工程方法调节P5CS基因的表达有利于提高植物体脯氨酸的积累量,改善植物的抗逆性。因此,目前可以在大田植物中开展利用提高脯氨酸来改善植物抗逆性的研究。     

Water Pumping Activity of the Root System in the Process of Cross-Adaptation of Sunflower Plants to Hyperthermia and Water Deficiency

To elucidate the mechanisms of cross-adaptation, we investigated the effect of heat shock (HS, for 2 h at 45°C) on leaf tolerance to overheating and exudation by roots detached from 25–30-day old sunflower (Helianthus annuus L.) plants. It was demonstrated that preheating enhanced considerably leaf tolerance and activated root exudation, especially under water deficiency produced by plant transfer to the hypertonic NaCl solution (17 mM). Under water deficiency conditions, the roots of HS-treated plants pumped water against the osmotic pressure (OP) gradient between the exudate and the external solution. Therefore, we concluded that this pumping was realized due to a metabolic (non-osmotic) constituent of root pressure. In the roots of plants that were not treated with HS, the OP gradient became positive. This fact implies that the HS-pretreatment of plants retarded the penetration of sodium and chlorine ions into roots. The data obtained demonstrate that HS induced a cross-adaptation of plants to high temperature and water deficiency. Such cross-adaptation involves, as an important component, an acceleration of water metabolism, including an enhanced water pumping activity of root system.     

Cross-adaptation and molecular modeling study of receptor mechanisms common to four taste stimuli in humans

Psychophysical cross-adaptation experiments were performed with two carbohydrates, sucrose (SUC) and fructose (FRU), and two sweeteners, acesulfame-K (MOD) and dulcin (DUL). Seven subjects were asked to match concentrations that elicited the same intensity as a sucrose reference (30 g/l). Cross-adaptation levels were calculated as the ratio of isointense concentrations measured for a given stimulus before and under adaptation. On average, cross-adaptation between SUC and FRU is low and apparently reciprocal. By contrast, cross-adaptation between SUC and MOD is clearly non-reciprocal: SUC adapts MOD significantly (24%, P < 0.005), but MOD fails to adapt SUC (2%, P < 0.79). Significant and reciprocal cross-enhancement is observed between DUL and MOD (approximately -20%, P < 0.03), and also between SUC and DUL (approximately -15%, P < 0.08). In parallel, molecular modeling of the four tastants was performed in order to look for the 12 common binding motifs that were isolated on 14 other tastants in a previous study. SUC and FRU each display 10 out of the 12 binding motifs, whereas DUL and MOD only display four and five distinct motifs respectively and do not have any motif in common. Experimental cross-adaptation levels seem to correlate well with the number of motifs that molecules have in common. FRU and SUC share a majority of binding motifs and correlatively show mutual cross-adaptation. Four motifs of MOD are found among the 10 motifs of SUC, which may explain why SUC cross-adapts MOD but not vice versa. By contrast, DUL and MOD do not share any motif and do not cross- adapt. The various molecular mechanisms that may be responsible for cross-adaptation and/or cross-enhancement are discussed in light of our results.      

Mechanical Stimulation-Induced Cross-Adaptation in Plants: An Overview

Mechanical stimulation (MS), existing widely but ignored usually in nature, is one of the environmental stress factors. MS not only affects growth, development, morphogenesis, and even survival of plants, but also induces the formation of cross-adaptation. In cross-adaptation, plants make use of common pathways and components to adapt to a range of different stresses after exposure to one specific stress. Here, we summarize current knowledge of MS-induced cross-adaptation to chilling, heat, salt, drought, and pathogen stress, as well as its possible mechanisms.     

Hydrogen Sulfide: A Novel Gaseous Molecule for Plant Adaptation to Stress

Hydrogen sulfide (H₂S) has emerged as a novel gaseous signal molecule with multifarious effects on seed germination, plant growth, development, and physiological processes. Due to its dominant role in plant stress tolerance and cross-adaptation, it is getting more attention nowadays, although it has been largely referred as toxic and environmental hazardous gas. In this review work, we are highlighting the importance of H₂S as an essential gaseous molecule to help in signaling, metabolism, and stress tolerance in plants. Firstly, production of H₂S from different natural and artificial sources were discussed with its transformation from sulfur (S) to sulfate (SO₄²⁻) and then to sulfite (SO₃²⁻). The importance of different kinds of transporters that helps to take SO₄²⁻ from the soil solution was presented. Mainly, these transporters are SULTRs (H⁺/SO₄²⁻ cotransporters) and multigene family encodes them. Furthermore, these SULTRs have LAST (Low affinity transport proteins), HAST (High affinity transport proteins), vacuole transporters, and plastid transporters. Since it is well known that there is strong relationship between SO₄²⁻ and synthesis of hydrogen sulfide or dihydrogen sulfide or sulfane in plant cells. Thus, cysteine (Cys) metabolism through which H₂S could be generated in plant cell with the role of different enzymes has been presented. Furthermore, H₂S in interaction with other molecules could help to mitigate biotic and abiotic stress. Based on this review work, it can be concluded that H₂S has potential to induce cross-adaptation to biotic and abiotic stress; thus, it is recommended that it should be considered in future studies to answer the questions like what are the receptors of H₂S in plant cell, where in plants the physiological concentration of H₂S is high in response to multiple stress and how it induces cross-adaptation by interaction with other signal molecules.

     

Mutual cross-adaptation of the volatile steroid androstenone and a non-steroid perceptual analog

Self-and cross-adaptation are believed to result from stimulationof the same olfactory sensory channels. These adaptation phenomenawere studied after exposures to 5-androst-16-en-3-one (androstenone)and a synthetic perceptual analog (DMCMC), viz. a racemic mixtureof the isomers 4(R)-(4',4'-dimethyl-cyclohexyl)-2(R)-methylcyclohexanoneand 4(S)-(4',4'-dimethylcyclohexyl)-2(S)-methylcyclohexanone.In Experiment 1, six subjects very sensitive to androstenonereceived four randomized sequences of six concentrations offour ordants (androstenone, DMCMC, amyl acetate, and Galaxolide*;plus blanks) before and following adaptation to either androstenoneor DMCMC. Exposure to each odorant resulted in self-adaptation.Measures of stimulus intensity and identification thresholdrevealed reciprocal cross-adaptation between androstenone andDMCMC, but no cross-adaptation to amyl acetate or Galaxolide.The degree of cross-adaptation was asymmetric; adaptation toDMCMC resulted in more complete adaptation to androstenone thanvice versa. This asymmetry was apparently due to intensity differences;when stimuli were matched for intensity, the asymmetry disappeared(Experiment 2). These results demonstrate cross-adaptation forqualitatively similar, but not dissimilar, odors and suggestthat androstenone and its perceptual analog DMCMC share thesame sensory channels.     

The Role of Perceptual and Structural Similarity in Cross-adaptation

Cross-adaptation, the decrease in sensitivity to one odorantfollowing exposure to a different odorant, is affected by odorantsimilarity, both perceptual and structural, but the preciserelationship is obscure. The present series of studies was designedto explore various aspects of perceptual and structural similarityas they relate to cross-adaptation. In Experiment 1, cross-adaptationwas assessed between androstenone and five odorants that sharea common urinous note with androstenone, but retain unique perceptualcharacteristics; only the compound judged most perceptuallysimilar to androstenone cross-adapted it. In Experiment 2, odorantsboth perceptually and structurally similar (androstenone andandrostanone) displayed significant, mutual cross-adaptation.Furthermore, magnitude estimates for androstanone were significantlyreduced following exposure to 3-methylidene-5a-androstane (3M5A),a structurally similar, perceptually odorless compound. Thisfinding appears to be the first demonstration that an odorlesscompound can affect, via cross-adaptation, the perception ofan odorous compound. Finally, in Experiment 3, significant,asymmetric cross-adaptation was observed between compounds thatare perceptually and structurally dissimilar (4-cyclohexylcyclohexanone[4-CHCH] and androstenone). These findings indicate that therole of similarity in cross-adaptation is difficult to quantifyand emphasize the numerous odorant characteristics that canaffect cross-adaptation. Chem. Senses 21: 223–237, 1996.     

Olfactory adaptation as an aspect of odor similarity

Two experiments examined self-adaptation within and cross-adaptationbetween two structurally different substances with almost identicalbitter chocolate odors, trimethyl pyrazine (TMP) and 2-propionyl-3-methylfuran (PMF). The first experiment charted psychophysical functionsfor odor intensity under steady-state self- and cross-adaptationwith adapting concentrations matched in perceived intensityat two different levels. Participants breathed an adapting concentrationcontinuously for 2 min and then rated test concentrations everyminute during momentary respites from the adapting stimulus.Both self-adaptation and cross-adaptation weakened the intensityof low test concentrations proportionally more than higher onesand thereby steepened the psychophysical functions. Adaptingstimuli at matched levels caused equivalent self-adaptation(i.e. altered the functions equivalently) and equivalent, thoughweaker, cross-adaptation (i.e. exhibited symmetry of cross-adaptation).The second experiment examined whether cross-adaptation to TMPand PMF would prove relatively specific. At a matched perceivedintensity of adapting stimulus, adaptation to TPM and PMF againproduced equal amounts of self-adaptation and of cross-adaptationto each other, though not on three other test stimuli: anethole,ethyl butyrate and 2,3 pentanedione. Both TMP and PMF showedsome generality as cross-adapting stimuli, with PMF showinga bit more than TMP. The present protocols and others discussedherein offer opportunities to consider functional criteria forthe relatedness of similar-smelling substances.     

Chemical specificity of short-chain fatty acid-induced electrogenic secretory response in the rat colonic mucosa

1. Luminal additions of normal short-chain fatty acids (SCFA: 3-6 carbons) increased transmural potential difference (PD: lumen negative) across rat everted colon in a dose-dependent manner. 2. The PD response to SCFA adapted rapidly and was not evoked by further cumulative addition of the same acid (self-adaptation) or different acids (cross-adaptation). 3. A broad range of SCFA derivatives were tested as potential stimulators of the PD response and cross-adaptation with propionate: a single carboxyl group and 3-6 carbon-chain were an absolute requirement for recognition. 4. These results suggest that SCFA-reception mechanism of the rat colonic mucosa has some sort of chemical specificity for stimulating electrogenic secretory response.     

Sensitivity to chemically diverse phagostimulants in a single gustatory neuron of a polyphagous caterpillar

Caterpillars of the arctiid moth, Grammia geneura, are polyphagous, but species of Plantago are amongst their preferred food plants. A neuron in the medial styloconic sensillum on the galea has been shown to have a general phagostimulatory function. Experiments with binary mixtures and cross-adaptation have demonstrated that it responds to some sugars, to several amino acids, and also to catalpol. Catalpol is a plant secondary compound in Plantago and a phagostimulant for the caterpillars. The possible significance of combining sensitivity to nutrient compounds with sensitivity to a secondary compound is discussed. Accepted: 7 October 1999     

Gustatory responses of eel palatine receptors to amino acids and carboxylic acids

The gustatory receptors of the eel palate were found to be extremely sensitive to amino acids and carboxylic acids. The results obtained are as follows: (a) 11 amino acids which are among naturally occurring amino acids elicited responses in the palatine nerve, but 9 amino acids did not elicit a response even at a high concentration. The effect of D-amino acids was always much less than that of their corresponding L-isomers. There was no appreciable difference in the effectiveness of an alpha-amino acid (alpha-alanine) and beta-amino acid (beta-alanine). (b) The threshold concentrations of the most potent amino acids (arginine, glycine) were between 10(-8) and 10(-9) M. A linear relation between the magnitude of the response and log stimulus concentration held for a wide concentration range for all the amino acids examined. (c) The palatine receptors responded sensitively to various carboxylic acid solutions whose pH was adjusted to neutral. The threshold concentrations varied between 10(-4) and 10(-7) M. The magnitude of the response at 10(-2) M increased with an increase of carbon chain length. (d) The extent of cross-adaptation was examined with various combinations of amino acids. A variety of the response patterns showing complete cross-adaptation, no cross-adaptation, or synergetic interaction was observed. The synergetic interaction was also observed when one amino acid below its threshold concentration was added to the other amino acid below its threshold concentration was added to the other amino acid. No cross-adaptation was observed between amino acids and fatty acids. (e) The treatment of the palate with papain led to loss of the responses to arginine, glycine, and histidine without affecting those to proline and acetic acid. The treatment with pronase E eliminated selectively the response to proline. The possibility that the eel gustatory receptors are responsible for sensing food at a distance was discussed.