14-3-3 proteins and the response to abiotic and biotic stress

14-3-3 proteins function as regulators of a wide range of target proteins in all eukaryotes by effecting direct protein-protein interactions. Primarily, interactions between 14-3-3 proteins and their targets are mediated by phosphorylation at specific sites on the target protein. Hence, interactions with 14-3-3s are subject to environmental control through signalling pathways which impact on 14-3-3 binding sites. Because 14-3-3 proteins regulate the activities of many proteins involved in signal transduction, there are multiple levels at which 14-3-3 proteins may play roles in stress responses in higher plants. In this article, we review evidence which implicates 14-3-3 proteins in responses to environmental, metabolic and nutritional stresses, as well as in defence responses to wounding and pathogen attack. This evidence includes stress-inducible changes in 14-3-3 gene expression, interactions between 14-3-3 proteins and signalling proteins and interactions between 14-3-3 proteins and proteins with defensive functions.     

Isolation of an osmotin-like protein gene from strawberry and analysis of the response of this gene to abiotic stresses

A strawberry genomic clone containing an osmotin-like protein (OLP) gene, designated FaOLP2, was isolated and sequenced. FaOLP2 is predicted to encode a precursor protein of 229 amino acid residues, and its sequence shares high degrees of homology with a number of other OLPs. Genomic DNA hybridization analysis indicated that FaOLP2 represents a multi-gene family. The expression of FaOP2 in different strawberry organs was analyzed using real-time PCR. The results showed that FaOLP2 expressed at different levels in leaves, crowns, roots, green fruits and ripe red fruits. In addition, the expression of FaOLP2 under different abiotic stresses was analyzed at different time points. All of the three tested abiotic stimuli, abscisic acid, salicylic acid and mechanical wounding, triggered a significant induction of FaOLP2 within 2-6h post-treatment. Moreover, FaOLP2 was more prominently induced by salicylic acid than by abscisic acid or mechanical wounding. The positive responses of FaOLP2 to the three abiotic stimuli suggested that strawberry FaOLP2 may help to protect against osmotic-related environmental stresses and that it may also be involved in plant defense system against pathogens.     

两个小麦14-3-3基因的特征、亚细胞定位及其对非生物胁迫的响应(英文)

为了探讨14-3-3基因在小麦逆境胁迫应答中的调控作用,利用RACE技术克隆了两个包含完整编码框的14-3-3基因(命名为Ta14R1和Ta14R2),其中Ta14R1 cDNA长999 bp,编码262个氨基酸,而Ta14R2 cDNA长897 bp,编码261个氨基酸。Ta14R1/Ta14R2-GFP融合载体瞬时表达结果显示,Ta14R1和Ta14R2蛋白均定位于细胞质和细胞膜,但不在叶绿体中。荧光定量PCR分析表明,Ta14R1和Ta14R2均在萌发1 d的胚芽鞘中表达量最高;在高温、低温、模拟干旱和ABA处理下,两个基因在小麦的根和叶中都受胁迫诱导而且显著上调表达,推测这两个14-3-3基因通过依赖ABA的非生物胁迫响应途径发挥作用,可能参与了小麦中高温、低温和干旱胁迫的耐受调节过程。     

A comparison of the expression patterns of several senescence-associated genes in response to stress and hormone treatment

The expression of several Arabidopsis thaliana senescence-associated genes (SAGs) in attached and/or detached leaves was compared in response to age, dehydration, darkness, abscisic acid, cytokinin, and ethylene treatments. Most of the SAGs responded to most of the treatments in a similar fashion. Detachment in darkness and ethylene were the strongest inducers of both SAGs and visible yellowing. Detachment in light was also a strong inducer of SAGs, but not of visible yellowing. The other treatments varied more in their effects on individual SAGs. Responses were examined in both older and younger leaves, and generally were much stronger in the older ones. Individual SAGs differed from the norms in different ways, however, suggesting that their gene products play a role in overlapping but not identical circumstances. Some SAGs responded quickly to treatments, which may indicate a direct response. Others responded more slowly, which may indicate an indirect response via treatment-induced senescence. Four new SAGs were isolated as part of this work, one of which shows strong similarity to late embryogenesis-abundant (Lea) genes.     

Modulation of enzyme activities and expression of genes related to primary and secondary metabolism in response to UV-B stress in cucumber (Cucumis sativus L.)

Abstract

Exposure to UV-B at ambient or enhanced levels is known to trigger a variety of responses in all living organisms, including higher plants. Here we show that in Cucumis sativus L. UV-B radiation affects enzyme activity of key oxydative pentose phosphate pathway (OPPP) enzymes glucose-6-phosphate dehydrogenase (G6P-DH) and 6-phosphogluconate dehydrogenase (6-PGlu-DH), of key phenolic compounds enzyme phenylalanine ammonia lyase (PAL) as well as erythrose-4-phosphate, tryptophan and tyrosine levels. Furthermore, we found an increased activity of antioxidant enzymes such as peroxidase (POX) and catalase (CAT) in treated plants, with respect to the controls. In order to confirm the biochemical results, we isolated total RNA from both controls and UV-B treated plants to be used for gene expression analysis. We demonstrated that UV-B increases the gene expression level of peroxidase (POX), catalase (CAT) and phenylalanine ammonia lyase (PAL). Finally, our results are useful for understanding protective strategies against UV-B radiation and for elucidating what components are involved in stress-induced signals within the plant.     

Glutathione reductase from pea leaves: response to abiotic stress and characterization of the peroxisomal isozyme

The glutathione reductase (GR; EC 1.6.4.2) isozyme present in peroxisomes has been purified for the first time, and its unequivocal localization in these organelles, by immunogold electron microscopy, is reported. The enzyme was purified c. 21-fold with a specific activity of 9523 units mg(-1) protein, and a yield of 44 microg protein kg(-1) leaves was obtained. The subunit size of the peroxisomal GR was 56 kDa and the isoelectric point was 5.4. The enzyme was recognized by a polyclonal antibody raised against total GR from pea (Pisum sativum) leaves. The localization of GR in peroxisomes adds to chloroplasts and mitochondria where GR isozymes are also present, and suggests a multiple targeting of this enzyme to distinct cell compartments depending on the metabolism of each organelle under the plant growth conditions. The expression level of GR in several organs of pea plants and under different stress conditions was investigated. The possible role of peroxisomal GR under abiotic stress conditions, such as cadmium toxicity, high light, darkness, high temperature, wounding and low temperature, is discussed.     

Effects of venlafaxine on the expression level and methylation status of genes involved in oxidative stress in rats exposed to a chronic mild stress

Recent human and animal studies indicate that oxidative and nitrosative stress may play a role in the aetiology and pathogenesis of depression. This study investigates the effect of chronic administration of the serotonin-norepinephrine reuptake inhibitor, venlafaxine, on the expression and methylation status of SOD1, SOD2, GPx1, GPx4, CAT, NOS1 and NOS2 in the brain and blood of rats exposed to a chronic mild stress (CMS) model of depression. Separate groups of animals were exposed to CMS for 2 or 7 weeks; the second group received saline or venlafaxine (10 mg/kg/d, IP) for 5 weeks. After completion of both stress conditions and drug administration, the mRNA and protein expression of selected genes and the methylation status of their promoters were measured in peripheral mononuclear blood cells (PBMCs) and in brain structures (hippocampus, amygdala, hypothalamus, midbrain, cortex, basal ganglia) with the use of TaqMan Gene Expression Assay, Western blot and methylation-sensitive high-resolution melting techniques. CMS caused a decrease in sucrose consumption, and this effect was normalized by fluoxetine. In PBMCs, SOD1, SOD2 and NOS2 mRNA expression changed only after venlafaxine administration. In brain, CAT, Gpx1, Gpx4 and NOS1 gene expression changed following CMS or venlafaxine exposure, most prominently in the hippocampus, midbrain and basal ganglia. CMS increased the methylation of the Gpx1 promoter in PBMCs, the second Gpx4 promoter in midbrain and basal ganglia, and SOD1 and SOD2 in hippocampus. The CMS animals treated with venlafaxine displayed a significantly higher CAT level in midbrain and cerebral cortex. CMS caused an elevation of Gpx4 in the hippocampus, which was lowered in cerebral cortex by venlafaxine. The results indicate that CMS and venlafaxine administration affect the methylation of promoters of genes involved in oxidative and nitrosative stress. They also indicate that peripheral and central tissue differ in their response to stress or antidepressant treatments. It is possible that that apart from DNA methylation, a crucial role of expression level of genes may be played by other forms of epigenetic regulation, such as histone modification or microRNA interference. These findings provide strong evidence for thesis that analysis of the level of mRNA and protein expression as well as the status of promoter methylation can help in understanding the pathomechanisms of mental diseases, including depression, and the mechanisms of action of drugs effective in their therapy.     

Pseudomonas putida modulates the expression of miRNAs and their target genes in response to drought and salt stresses in chickpea (Cicer arietinum L.)

MicroRNAs are small non-coding regulatory RNA molecules that play an important role in the modulation of gene expression during various environmental stresses. Pseudomonas putida RA, a plant growth promoting rhizobacteria (PGPR) colonizes the root surface of plants improving their growth and development during abiotic stresses modulating the expression of stress-responsive genes; however, the impact of RA on stress responsive-miRNA remains elusive. The present study was an attempt to delineate the role of PGPR in modulating stress responsive-miRNAs in a tolerant desi chickpea genotype exposed to drought and salt stresses. The existence of variable expression patterns of individual miRNAs and their target genes under these stresses at different time points indicate a distinct miRNA-mediated perception and response mechanisms operating under these stresses in the presence or absence of RA in chickpea.     

Cloning and expression pattern of heat shock protein genes from the endoparasitoid wasp, Pteromalus puparum in response to environmental stresses

Six heat shock protein (HSP) genes from five HSP families in the parasitoid, Pteromalus puparum, were evaluated for their response to temperature (-15 ~ 3°C , and 30 ~ 42°C for 1 h), heavy metals (0.5 ~ 5 mM Cd(2+) and Cu(2+) for 24 h and 60 h), and starvation (24 h). Compared with other insect HSPs, all conserved motifs are found in P. puparum HSPs, and they are very similar to those of the recently sequenced ectoparasitoid Nasonia vitripennis. The temporal gene expression patterns indicated that these six HSP genes were all heat-inducible, of which hsp40 was the most inducible. The temperatures for maximal HSP induction at high and low temperature zone were 36 or 39°C and -3°C, respectively. In the hot zone, all HSP genes have the same initial temperature (33°C) for up-regulation. Low concentrations of Cd(2+) for a short-term promoted the expression of all HSP genes, but not high concentrations or long-term treatments. Cu(2+) stress for 24 h increased expression of nearly all HSP. Four HSP genes changed after starvation. We infer that all six HSP genes are sensitive to heat. This may help understand the absence of P. puparum during the summer and winter. The expression profiles of six HSP genes in P. puparum under heavy metal stress indicates that HSP is a short-term response to cellular distress or injury induced by Cd(2+) and Cu(2+).     

Yeast genes involved in response to lactic acid and acetic acid: acidic conditions caused by the organic acids in Saccharomyces cerevisiae cultures induce expression of intracellular metal metabolism genes regulated by Aft1p

Using two types of genome-wide analysis to investigate yeast genes involved in response to lactic acid and acetic acid, we found that the acidic condition affects metal metabolism. The first type is an expression analysis using DNA microarrays to investigate 'acid shock response' as the first step to adapt to an acidic condition, and 'acid adaptation' by maintaining integrity in the acidic condition. The other is a functional screening using the nonessential genes deletion collection of Saccharomyces cerevisiae. The expression analysis showed that genes involved in stress response, such as YGP1, TPS1 and HSP150, were induced under the acid shock response. Genes such as FIT2, ARN1 and ARN2, involved in metal metabolism regulated by Aft1p, were induced under the acid adaptation. AFT1 was induced under acid shock response and under acid adaptation with lactic acid. Moreover, green fluorescent protein-fused Aft1p was localized to the nucleus in cells grown in media containing lactic acid, acetic acid, or hydrochloric acid. Both analyses suggested that the acidic condition affects cell wall architecture. The depletion of cell-wall components encoded by SED1, DSE2, CTS1, EGT2, SCW11, SUN4 and YNL300W and histone acetyltransferase complex proteins encoded by YID21, EAF3, EAF5, EAF6 and YAF9 increased resistance to lactic acid. Depletion of the cell-wall mannoprotein Sed1p provided resistance to lactic acid, although the expression of SED1 was induced by exposure to lactic acid. Depletion of vacuolar membrane H+-ATPase and high-osmolarity glycerol mitogen-activated protein kinase proteins caused acid sensitivity. Moreover, our quantitative PCR showed that expression of PDR12 increased under acid shock response with lactic acid and decreased under acid adaptation with hydrochloric acid.     

Cloning of heat shock protein genes from the brown planthopper,Nilaparvata lugens,and the small brown planthopper,Laodelphax striatellus,and their expression in relation to thermal stress

Three heat shock protein (HSP) genes (hsp70, hsc70, hsp90) were partially cloned from the brown planthopper Nilaparvata lugens and the small brown planthopper Laodelphax striatellus (Homoptera: Delphacidae), which are serious pests of the rice plant. Sequence comparisons at the deduced amino acid level showed that the three HSPs of planthoppers were most homologous to corresponding HSPs of dipteran and lepi‐dopteran species. Identities of both heat shock cognate 70 and HSP90 were higher than HSP70 in both species. Identity of the HSP70 between the two planthopper species was only 81%, a value much lower than seen among fly and moth groups. Effects of heat and cold shocks were demonstrated on expression of the three hsp genes in the two planthopper species. Heat shock (40 °C) upregulated the hsp90 level but did not change the hsc70 level in either the nymph and adult stages of either species. On the other hand, the hsp70 level was only upregulated in L. striatellus. This heat shock response was prompt and lasted only for 1 h after treatment. In contrast, cold shock at 4°C did not change the expression levels of any hsp in either species.     

Cloning of heat shock protein genes from the brown planthopper,Nilaparvata lugens,and the small brown planthopper,Laodelphax striatellus,and their expression in relation to thermal stress

Three heat shock protein （HSP） genes （hsp70, hsc70, hsp90） were partially cloned from the brown planthopper Nilaparvata lugens and the small brown planthopper Laodelphax striatellus （Homoptera： Delphacidae）, which are serious pests of the rice plant. Sequence comparisons at the deduced amino acid level showed that the three HSPs of planthoppers were most homologous to corresponding HSPs of dipteran and lepidopteran species. Identities of both heat shock cognate 70 and HSP90 were higher than HSP70 in both species. Identity of the HSP70 between the two planthopper species was only 81%, a value much lower than seen among fly and moth groups. Effects of heat and cold shocks were demonstrated on expression of the three hsp genes in the two planthopper species. Heat shock （40 ℃） upregulated the hsp90 level but did not change the hsc70 level in either the nymph and adult stages of either species. On the other hand, the hsp70 level was only upregulated in L. striatellus. This heat shock response was prompt and lasted only for 1 h after treatment. In contrast, cold shock at 4℃ did not change the expression levels of any hsp in either species.     

Structure and expression of glutathione S-transferase genes from the midgut of the Common cutworm, Spodoptera litura (Noctuidae) and their response to xenobiotic compounds and bacteria

Glutathione S-transferases (GSTs) play a pivotal role in detoxifying endogenous and xenobiotic compounds and oxidative stress resistance in cells. In this study, five GST genes, including three Sigma GSTs (SlGSTs1, SlGSTs2, and SlGSTs3), one Omega GST (SlGSTo1) and one un-classified GST (SlGSTu1) were identified from the midgut of the Common cutworm, Spodoptera litura. Structure analyses of the eight (including the previously identified Epsilon GST genes, SlGSTe1, SlGSTe2 and SlGSTe3 from the same insect) SlGSTs genes showed that the Epsilon SlGSTe genes do not contain any intron, while the Sigma SlGSTs contain three introns and the Omega SlGSTo1 and the un-classified SlGSTu1 contain five introns. Analysis of the spatial and temporal expression of these eight SlGSTs indicated that SlGSTe1, SlGSTs2 and SlGSTo1 expressed in all stages of development from the egg to the adult stages. SlGSTe2, SlGSTe3, SlGSTs1, SlGSTs3 and SlGSTu1 had higher expression levels in the larval stages than in other stages and their expression levels in the midgut were higher than in other tissues. SlGSTs1 was expressed in the larval midgut but not in the fat body and could be induced by bacterial infections. The expression of SlGSTe1, SlGSTe3, SlGSTs1 and SlGSTs3 was increased by chlorpyrifos to various degrees, while the expression of SlGSTe1, SlGSTe3, SlGSTs1, SlGSTs3 and SlGSTo1 was increased by xanthotoxin. Levels of malonaldehyde, an indicator of oxidative stress, were higher in the larval midgut than in the pupal midgut. Chlorpyrifos induced the malonaldehyde content in the larvae, whereas xanthotoxin did not. It is hypothesized that high expression levels of the midgut SlGSTs might be due to the increased levels of oxidative stress caused by feeding, bacterial infection and xenobiotic compounds.