外源茉莉酸甲酯通过调节相关基因表达诱导光温敏雄性不育小麦BS366离体花药开裂

植物育性与花药开裂性状相关. 茉莉酮酸甲酯(methyl jasmonic acid, MeJA)是一种植物激素,广泛参与植物的胁迫应答和生长发育过程. 植物体内存在6类基因所编码的酶共同维持茉莉酮酸(JA)代谢途径的畅通,并与植物花药开裂有关. 本研究以小麦光温敏不育系BS366为材料,于抽穗期—开花期进行穗部离体48 h的 MeJA外源处理. 分别于0、1、3、6、12、24和48 h时间点收集花药并进行RNA提取. 通过半定量RT-PCR分析发现,在内参基因甘油醛-3-磷酸脱氢酶(glyceraldehyde-3- phosphate dehydrogenase, GAPDH)表达基本一致的情况下,BS366的JA代谢途径中参与调控的6种基因均存在不同程度的诱导表达. 经MeJA 的48 h处理后的离体花药开裂程度明显增大. 本研究获得了BS366离体环境下JA代谢途径基因经MeJA诱导后表达水平的概况,并为诱导BS366花药开裂及人工调控育性,达到高效制种及繁种的目的提供了初步的理论依据.     

Isolation and characterization of novel defence-related genes induced by copper, salicylic acid, methyl jasmonate, abscisic acid and pathogen infection in Brassica carinata

To examine the defence response in Brassica carinata we differentially screened a cDNA library made from CuCl₂-treated (Cu) leaves. The sequence of 17 of the 27 cDNA clones examined that showed Cu-induction had a high similarity to defence genes from other plant species. Among other clones that showed higher expression in the Cu leaves were two cDNAs encoding polypeptides of 351 and 250 amino acids, designated BcCJS1 and BcCJAS1. BcCJS1 had similarity to S-adenosyl-l -methionine: salicylic acid carboxyl methyltransferase from Clarkia breweri. However, the enzyme activity was not found in extracts from E. coli expressing BcCJS1. BcCJAS1 did not show extensive similarity to any genes with known function in the databases but it did contain three regions of amino acid sequence that are frequently found in amidotransferases. A third Cu-induced mRNA, Bcp6PGL, showed very high (86%) similarity to a putative 6-phosphogluconolactonase (6PGL) from Arabidopsis thaliana. In addition to Cu induction, BcCJS1 expression was induced by methyl jasmonate (MeJA) and salicylic acid (SA), BcCJAS1 expression by MeJA, SA and abscisic acid and Bcp6PGL expression by MeJA. The expression of all three genes increased after Alternaria brassicae infection. BcCJS1 and BcCJAS1 were induced within 1 h after MeJA- but not until 3 h after SA-treatment. The expression of both genes was systemically induced after infection with a compatible or incompatible fungal pathogen. SA systemically induced only BcCJAS1. The effects of various inhibitors of signalling pathways on expression of the three genes were studied.     

白桦MYB基因响应激素及盐旱处理的表达研究

转录因子参与到植物激素不同的信号通路中及非生物胁迫的调控中，为研究白桦MYB转录因子家族基因对不同激素信号及非生物胁迫的响应，本研究以野生型白桦（Betula platyphylla）种子为材料，分别用10 μmol·L^-1的茉莉酸甲酯（MeJA）、100 μmol·L^-1的乙烯利（ETH）、20 μmol·L^-1的脱落酸（ABA）、50 μmol·L^-1的细胞激动素（KT）、200 mmol·L^-1 NaCl、100 mmol·L^-1 Mannitol以及水为对照进行处理，对激素处理4周的白桦下胚轴进行表型观察及基因表达分析，结果显示：激素处理能够影响白桦下胚轴及胚根的生长，经过ETH处理的白桦下胚轴和根短于水处理的对照，KT处理过的白桦下胚轴和根长于水处理的对照；MeJA、Ethylene及ABA处理对大部分BpMYBs的表达存在负调控，而BpMYB2，8，12基因上调表达；KT处理后，只有BpMYB11下调表达，其他的BpMYBs基因上调表达；NaCl处理后，大部分基因表现出先下调后上调的表达模式，在48 h被高度诱导；Mannitol模拟干旱处理条件下，大部分基因表现出先微弱上调后下调的表达模式。这些结果说明白桦MYB家族基因能够响应激素、盐和旱的处理，在调控白桦下胚轴及胚根应答外界信号的发育中起作用。本研究为探索激素调控木本植物生长发育的分子机制研究提供了数据和材料。     

三角褐指藻dxs基因克隆与诱导表达

为研究6种外源因素处理对三角褐指藻(Phaeodactylum tricornutum)1-脱氧-D-木酮糖-5-磷酸合成酶(DXS)基因表达的影响,通过高通量转录组测序技术获得三角褐指藻dxs基因cDNA全长序列,并对其进行生物信息学分析。研究结果表明,三角褐指藻dxs基因cDNA全长2476 bp, ORF全长2193 bp,编码730个氨基酸,具有高度保守的ThDP结合位点和转酮醇酶结构域。三角褐指藻DXS蛋白为亲水性稳定蛋白,相对分子质量(M_w)为79.31 kD,理论等电点为6.65,具有信号肽、跨膜区域、卷曲螺旋和TM-螺旋等。系统进化树分析结果表明, DXS蛋白进化树分为高等植物和藻类2个分支,高等植物DXS蛋白进一步分为DXS1和DXS2两支,藻类DXS蛋白聚类为3个分支,分别为硅藻门、红藻门和绿藻门分支,三角褐指藻聚类在硅藻门分支上。诱导表达调控结果表明,三角褐指藻dxs基因受到茉莉酸甲酯(MeJA)、花生四烯酸(AA)、硫酸铈铵(ACS)、光合诱导素(PIF)、光合抑制剂(DCMU)和光质等6种外源因素的诱导调控。在100μmol/L MeJA...     

Virulence systems of Pseudomonas syringae pv. tomato promote bacterial speck disease in tomato by targeting the jasmonate signaling pathway

Pseudomonas syringae pv. tomato strain DC3000 (Pst DC3000) causes bacterial speck disease on tomato. The pathogenicity of Pst DC3000 depends on both the type III secretion system that delivers virulence effector proteins into host cells and the phytotoxin coronatine (COR), which is thought to mimic the action of the plant hormone jasmonic acid (JA). We found that a JA-insensitive mutant (jai1) of tomato was unresponsive to COR and highly resistant to Pst DC3000, whereas host genotypes that are defective in JA biosynthesis were as susceptible to Pst DC3000 as wild-type (WT) plants. Treatment of WT plants with exogenous methyl-JA (MeJA) complemented the virulence defect of a bacterial mutant deficient in COR production, but not a mutant defective in the type III secretion system. Analysis of host gene expression using cDNA microarrays revealed that COR works through Jai1 to induce the massive expression of JA and wound response genes that have been implicated in defense against herbivores. Concomitant with the induction of JA and wound response genes, the type III secretion system and COR repressed the expression of pathogenesis-related (PR) genes in Pst DC3000-infected WT plants. Resistance of jai1 plants to Pst DC3000 was correlated with a high level of PR gene expression and reduced expression of JA/wound response genes. These results indicate that COR promotes bacterial virulence by activating the host's JA signaling pathway, and further suggest that the type III secretion system might also modify host defense by targeting the JA signaling pathway in susceptible tomato plants.     

Molecular cloning and expression analysis of a cytosolic Hsp70 gene from Antarctic ice algae Chlamydomonas sp. ICE-L

A cDNA encoding heat shock protein 70 of Antarctic ice algae Chlamydomonas sp. ICE-L (designated as CiHsp70) was identified by RT-PCR and rapid amplification of cDNA ends approaches. The full-length cDNA of CiHsp70 was 2,232 bp, consisting of a 5′-terminal untranslated region (UTR) of 76 bp, a 3′-terminal UTR of 203 bp with a poly (A) tail, and an open reading frame of 1,953 bp. The CiHsp70 cDNA encoded a polypeptide of 651 amino acids with an ATPase domain of 388 amino acids, the substrate peptide binding domain of 246 amino acids and a C-terminus domain of 17 amino acids. The inducible CiHsp70 cDNA was highly homologous to other plant cytosolic Hsp70 genes and clustered together with green algae and higher plant rather than brown algae, diatom and Cryptophyta. Antarctic ice algae were treated with different stress conditions and messenger RNA (mRNA) expression levels of CiHsp70 were quantified by quantitative RT-PCR. The results showed that both cold and heat shock treatments could stimulate CiHsp70 mRNA expression. Meanwhile, CiHsp70 mRNA expression level increased 2.9-fold in response to UV-B radiation for 6 h, while the expression levels of CiHsp70 were remarkably increased after removing the UV-B radiation and immediately providing additional 6 h visible light. Furthermore, treating with 62 or 93‰ NaCl for 2 h, CiHsp70 mRNA expression level increased 3.0- and 2.1-fold, respectively. Together, our observations revealed that CiHsp70 as a molecular chaperone might play an important role in Antarctic ice algae Chlamydomonas sp. ICE-L acclimatizing to polar environment.     

走马胎三萜皂苷合成相关基因表达分析北大核心CSCD

走马胎是我国华南地区重要的民族药物,其体内的次生代谢物三萜皂苷具有多种药用功效。为了解三萜皂苷含量变化以及生物合成通路相关基因的调控规律,该研究对走马胎在不同组织部位以及不同外源激素处理下所呈现的表达模式进行了比较分析。结果表明:(1)三萜皂苷含量在不同组织部位间和外源激素处理下均存在显著差异,具体表现为根部组织的含量显著高于叶部组织的,而用外源水杨酸(SA)与茉莉酸甲酯(MeJA)喷施处理后其含量低于对照组(CK)。(2)对这两个差异比较组进行qRT-PCR分析结果显示,相比叶部组织,在根部组织中AkPMD、AkHDS、AkSS、AkSM以及与三萜皂苷合成相关的走马胎P450家族、UGT家族基因皆有不同程度的上调;外源SA与MeJA处理会导致合成途径上游的AkPMD、AkHDS、AkSS、AkSM上调,而下游的P450家族、UGT家族基因则有所下调。因此,通过对不同组织部位和不同外源激素处理这两种差异表达模式的比较研究,可推测在这两种表达模式下走马胎三萜皂苷的合成更多地与下游特异化修饰的酶相关。