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。     

Comparative expression profiles of maize genes from a water stress-specific cDNA macroarray in response to high-salinity, cold or abscisic acid

cDNA macroarray has become a useful tool to analyze expression profiles and compare the similarities and differences of various expression patterns. We have prepared a cDNA macroarray containing 190 maize expressed sequence tags (ESTs) specifically induced by water stress to analyze the expression profiles of maize seedlings under abscisic acid (ABA) treatment, high-salinity and cold stress conditions. The results indicated that 48 ESTs in leaves and 111 ESTs in roots were significantly up-regulated by ABA treatment, 36 ESTs in leaves and 41 ESTs in roots by high-salinity stress, 14 ESTs in leaves and 18 ESTs in roots by cold induction, whereas 22 ESTs were induced under all 3 stresses. Results from the hierarchical cluster analysis suggest that the leaves and roots of maize seedlings had different expression profiles after these stresses. The overlap analysis of different stress-induced ESTs indicated that there is more crosstalk between water stress and ABA and high-salinity stress than between water stress and cold stress. It will be helpful to study the precise function of the corresponding overlapping-induced genes for understanding the relationship and crosstalk between different stress signal pathways.     

A novel pathogenesis-related protein (SsPR10) from Solanum surattense with ribonucleolytic and antimicrobial activity is stress- and pathogen-inducible

A cDNA clone (designated as SsPR10, GenBank Accession Number AY660753 ) encoding a PR10 protein from yellow-fruit nightshade (Solanum surattense) was isolated and characterized. SsPR10 encoded a 160-amino-acid polypeptide with a predicted molecular mass of 17.58 kDa and pI of 5.29. Sequence alignments showed that SsPR10 had high identity (68.1%) with CaPR10, but had only about 31.7% identity with JIOsPR10 at the amino acid level. Genomic DNA gel blot analysis indicated that SsPR10 belonged to a multigene family. The constitutively expressed SsPR10 was detected to be the highest in roots of the sterile seedlings cultured in jars, while SsPR10 expression was the highest in old yellow leaves from the seedlings incubated with sap containing TMV. SsPR10 always expressed at slightly higher level in senescent leaves than in tender ones under both conditions. Further expression analysis revealed that the signaling components of defense/stress pathways (MeJA, SA, ABA, GA3, H2O2 and Cu2+) up-regulated significantly the SsPR10 mRNA levels over the control. However, darkness failed to induce SsPR10 expression and its expression was also inhibited by cold treatment. The SsPR10 was successfully expressed in Eschericha coli and the expressed protein was purified to near homogeneity. The dialytically renatured SsPR10 protein without phosphorylation exhibited ribonucleolytic activity against S. surattense leaf total RNA preparations and could inhibit hyphal growth of Pyricularia oryzae. Our findings suggest that the novel stress- and pathogen-inducible SsPR10 with ribonucleolytic and antimicrobial activity participates not only in the defense/stress response pathways but also in plants' growth, development and senescence.     

水杨酸、脱落酸和过氧化氢对镉胁迫小麦幼苗光合及抗氧化酶活性的影响

采用溶液培养方法,用水杨酸(SA)、脱落酸(ABA)或过氧化氢(H2O2)对2叶期小麦进行处理,研究了Cd胁迫下小麦的光合速率及抗氧化酶活性。结果表明:3种处理能不同程度增强叶片和根系中超氧化物歧化酶(SOD)和过氧化物酶(POD)的活性,提高叶片过氧化氢酶(CAT)活性,降低丙二醛(MDA)含量;增加叶片叶绿素含量及其光合速率。说明3种处理能增强小麦对Cd的抗性,其中H2O2预处理的效果最明显。     

大白菜一个冷相关基因的分离与逆境诱导表达(英文)

以冷处理的大白菜幼叶为材料,采用RT-PCR技术获得1条新的冷相关基因序列(BpCOR,GenBank登录号DQ491005)。该基因编码129个氨基酸的亲水多肽,预测其N端含有叶绿体转运肽序列。多序列比对显示,Bc-COR蛋白与拟南芥及其它植物COR具有较高的相似性。Northern杂交结果显示BcCOR基因能被冷处理强烈诱导表达,而被脱水和盐处理弱诱导;在冷处理下,BcCORmRNA在根中的积累量低于叶片,光照能显著加强该基因在叶片中的表达。研究表明,BcCOR基因可能在大白菜抵抗冷胁迫和其它非生物胁迫的过程中具有重要的作用。     

Expression of ASCORBATE PEROXIDASE 8 in roots of rice (Oryza sativa L.) seedlings in response to NaCl

Reactive oxygen species are thought to play an important role in NaCl stress. Therefore, the expression patterns of the gene family encoding the H(2)O(2)-scavenging enzyme ascorbate peroxidase (APx; EC1.11.1.11) were analysed in roots of etiolated rice (Oryza sativa L.) seedlings in response to NaCl stress. Applying semi-quantitative RT-PCR, the mRNA levels were quantified for two cytosolic (OsAPx1 and OsAPx2), two peroxisomal (OsAPx3 and OsAPx4), and four chloroplastic (OsAPx5, OsAPx6, OsAPx7, and OsAPx8) isoforms identified in the rice genome. NaCl at 150 mM and 200 mM increased the expression of OsAPx8 and the activities of APx, but had no effect on the expression of OsAPx1, OsAPx2, OsAPx3, OsAPx4, OsAPx5, OsAPx6, and OsAPx7 in rice roots. However, NaCl at 300 mM up-regulated OsAPx8 expression, increased APx activity, and down-regulated OsAPx7 expression, but had no effect on the expression of OsAPx1, OsAPx2, OsAPx3, OsAPx4, OsAPx5, and OsAPx6. The accumulation of abscisic acid (ABA) in response to NaCl was observed in rice roots. Exogenously applied ABA also specifically enhanced the expression of OsAPx8 in rice roots. The accumulation of ABA in rice roots in response to NaCl was inhibited by fluridone (Flu), an inhibitor of carotenoid biosynthesis. Flu treatment also suppressed NaCl-enhanced OsAPx8 expression and APx activity. The effect of Flu on the expression of OsAPx8 and increase in APx activity was reversed by the application of ABA. It appears that NaCl-enhanced expression of OsAPx8 in rice roots is mediated through an accumulation of ABA. Evidence is provided to show that Na(+) but not Cl(-) is required for enhancing OsAPx8 expression, APx activity, and ABA accumulation in rice roots treated with NaCl. H(2)O(2) treatment resulted in an enhancement of OsAPx8 induction but no accumulation of ABA. Diphenylene iodonium treatment, which is known to inhibit NaCl-induced accumulation of H(2)O(2) in rice roots, did not suppress OsAPx8 induction and ABA accumulation by NaCl. It appears that H(2)O(2) is not involved in the regulation of NaCl-induced OsAPx8 expression in rice roots.     

Gene expression changes in response to drought stress in <Emphasis Type="Italic">Citrullus colocynthis</Emphasis>

Citrullus colocynthis (L.) Schrad, closely related to watermelon, is a member of the Cucurbitaceae family. This plant is a drought-tolerant species with a deep root system, widely distributed in the Sahara-Arabian deserts in Africa and the Mediterranean region. cDNA amplified fragment length polymorphism (cDNA-AFLP) was used to study differential gene expression in roots of seedlings in response to a 20% polyethylene glycol-(PEG8000) induced drought stress treatment. Eighteen genes which show similarity to known function genes were confirmed by quantitative relative (RQ) real-time RT-PCR to be differentially regulated. These genes are involved in various abiotic and biotic stress and developmental responses. Dynamic changes with tissue-specific pattern were detected between 0 and 48 h of PEG treatment. In general, the highest induction levels in roots occurred earlier than in shoots, because the highest expression was detected in roots following 4 and 12 h, in shoots following 12 and 48 h of drought. These drought-responsive genes were also affected by the plant hormones abscisic acid (ABA), salicylic acid (SA), or jasmonic acid (JA), indicating an extensive cross-talk between drought and plant hormones. Collectively, these results will be useful to explore the functions of these multiple signal-inducible genes for unveiling the relationship and crosstalk between different signaling pathways.     

Cloning and expression analysis of a water stress-induced gene from Brassica oleracea.

Plant growth and productivity are greatly affected by water stress, such as drought and salinity. Here we report on the cloning and expression analysis of a water stress-induced gene from Brassica oleracea (designated as BoWS, GenBank accession number AY571333) by rapid amplification of cDNA ends (RACE). The full-length cDNA of BoWS consisted of 594 bp and contained a 285 bp open reading frame (ORF) encoding a 95-amino-acid protein. The deduced protein had a calculated molecular mass of 10.53 kDa and an isoelectric point of 6.93. The sequence similarity and comparative analysis showed that BoWS was 84% identical to Arabidopsis thaliana putative water stress-induced protein (GenBank accession number AAM67282). Southern blot analysis indicated that BoWS was a low-copy gene. Northern blot analysis revealed that the expression of BoWS was upregulated by abscisic acid (ABA), mannitol, NaCl, drought, salicylic acid (SA) and hydrogen peroxide (H(2)O(2)). Our results indicate that BoWS is extremely related to the water-deficit stress in B. oleracea.     

Expression of tomato salicylic acid (SA)‐responsive pathogenesis‐related genes in Mi‐1‐mediated and SA‐induced resistance to root‐knot nematodes

The expression pattern of pathogenesis‐related genes PR‐1, PR‐2 and PR‐5, considered as markers for salicylic acid (SA)‐dependent systemic acquired resistance (SAR), was examined in the roots and shoots of tomato plants pre‐treated with SA and subsequently infected with root‐knot nematodes (RKNs) (Meloidogyne incognita). PR‐1 was up‐regulated in both roots and shoots of SA‐treated plants, whereas the expression of PR‐5 was enhanced only in roots. The over‐expression of PR‐1 in the whole plant occurred as soon as 1 day after SA treatment. Up‐regulation of the PR‐1 gene was considered to be the main marker of SAR elicitation. One day after treatment, plants were inoculated with active juveniles (J2s) of M. incognita. The number of J2s that entered the roots and started to develop was significantly lower in SA‐treated than in untreated plants at 5 and 15 days after inoculation. The expression pattern of PR‐1, PR‐2 and PR‐5 was also examined in the roots and shoots of susceptible and Mi‐1‐carrying resistant tomato plants infected by RKNs. Nematode infection produced a down‐regulation of PR genes in both roots and shoots of SA‐treated and untreated plants, and in roots of Mi‐carrying resistant plants. Moreover, in resistant infected plants, PR gene expression, in particular PR‐1 gene expression, was highly induced in shoots. Thus, nematode infection was demonstrated to elicit SAR in shoots of resistant plants. The data presented in this study show that the repression of host defence SA signalling is associated with the successful development of RKNs, and that SA exogenously added as a soil drench is able to trigger a SAR‐like response to RKNs in tomato.     

Inducible Expression of Translation Elongation Factor 1A Gene in Rice Seedlings in Response to Environmental Stresses

Differences of gene expression between salinity-stressed and control rice ( Oryza sativa L. ssp. indica) cultivar "Zhaiyeqing 8" were compared using differential display PCR (DD-PCR) technique. Sequence analysis of one salt-inducible cDNA clone revealed that this clone represented a new member of rice translation elongation factor lA (eEF1A) gene family and was tentatively named REF1A. Northern blot hybridization using REF1A fragment as a probe was performed to investigate the expression of rice translation elongation factor lA gene in response to various environmental factors. It was observed that expression of the eEF1A gene in rice shoots was dramatically induced by salinity stress or exogenous application of abscisic acid (ABA). The induction of this gene by ABA stress occurred more quickly than that by salinity stress. In addition, expression of rice translation elongation factor lA gene was also induced by drought (15% PEG6000), cold (4 ℃ ) or heat-shock (37 ℃ ) stresses. The results suggested that the induction of translation elongation factor lA gene expression by environmental stresses might reflect the general adaptive response of rice plants to the adverse circumstances.