水胺硫磷在香蕉及土壤中的残留动态

通过田间试验,采用气相色谱法检测水胺硫磷在香蕉及其土壤中的残留消解动态。结果表明,水胺硫磷在香蕉中的原始沉积量及残留量与施药剂量密切相关,施用加倍剂量处理的原始沉积量为推荐剂量的148%。水胺硫磷在香蕉及土壤中的消解规律符合一级动力学关系,在香蕉中的相关系数︱r︱= 0.9465～0.9490(P＜0.01),消解系数(︱k︱) = 0.1606±0.0035,半衰期(T1/2)为4.3～4.5 d,消解99%所需要时间(T0.99)为28.1～29.4 d;在土壤上︱r︱= 0.9552(P＜0.01),︱k︱= 0.2107,T1/2为3.3 d、T0.99为21.9 d。距末次施药后58~65d,在香蕉最终产品及蕉园土壤均未检出水胺硫磷残留。     

茉莉酸甲酯对芽期苦荞黄酮积累及相关基因表达的影响

茉莉酸甲酯(Me JA)是一种新型植物内源激素,该激素可以参与植物黄酮类物质的合成代谢途径。本实验用100μmol/L茉莉酸甲酯溶液对芽期苦荞进行叶面喷施处理,于0~12 h采样。采用Al Cl3法测定处理前后苦荞的总黄酮含量,利用半定量RT-PCR检测苦荞黄酮代谢相关的3个Ft JAZ蛋白基因、3个Ft MYB转录因子以及6个关键酶的基因表达量,并对基因表达量与总黄酮含量进行了相关性分析。结果表明,经茉莉酸甲酯处理后,苦荞芽菜叶片总黄酮含量有所升高,各基因表达模式有所不同,其中Ft JAZ1、Ft JAZ2、Ft JAZ3、Ft MYB2以及Ft PAL基因表达量与总黄酮含量变化趋势相似,而Ft MYB3与Ft F3'H表达量与总黄酮含量变化趋势相反。相关性分析表明,总黄酮含量与Ft MYB2(相关系数为0.864)和Ft JAZ1(相关系数为0.863)显著正相关,与Ft MYB3负相关(相关系数为-0.70),与所有黄酮合成关键酶基因均成正相关。本研究为进一步揭示茉莉酸甲酯参与苦荞黄酮代谢调控的机制奠定了基础。     

ZmJAZ与ZmMYC2的BiFC互作研究

JAZ(jasmonate ZIM-domain)蛋白是茉莉酸(jasmonic acid,JA)信号途径中关键的负调控因子,明确JAZ蛋白和MYC2之间的结合关系对整个JA信号通路至关重要.通过qRT-PCR筛选了在籽粒中较特异表达的ZmJAZ4、生殖器官中高表达的ZmJAZ8以及组成型表达的ZmJAZ12,利用玉米...     

基于图像RGB特征值的甘薯色素与肉色关系初步探讨

为明确甘薯色素、干率与肉色的关系,给图像RGB特征值评估甘薯色素含量提供依据,测定了甘薯240份品系的胡萝卜素含量及234份品系的花青素含量、干率和薯肉RGB颜色特征值。结果表明,甘薯胡萝卜素含量与RGB值的相关系数r=-0.913,偏相关系数为-0.872,花青素含量与RGB值的相关系数r=-0.838,偏相关系数为-0.836,说明甘薯色素含量与肉色是高度正相关的,是肉色的决定因子,但胡萝卜素与肉色关系更紧密。干率与胡萝卜素RGB值的相关系数r=0.597,偏相关系数为0.273,干率与花青素RGB值的相关系数r=-0.273,偏相关系数为0.255,说明干率与对肉色有极明显的负面影响,但是在RGB值≥200的低胡萝卜素(约含量3 mg/100 g·FW以下)群体中,干率与RGB值的偏相关系数为-0.0066(P=0.9426),干率对低胡萝卜素含量品系的肉色没有影响。采用R值、G值、B值、干率的二次多项式回归模型,RGB值≥200的低胡萝卜素群体、RGB值200的较高或高胡萝卜素群体和花青素群体的拟合方程的复相关系数R分别为0.975、0.982和0.937,说明拟合值与实测值关系十分密切。对胡萝卜素含量高于3 mg/100 g·FW的品种,拟合值能达到约90%的精确度,对胡萝卜素含量低于3 mg/100g·FW的品种,也能达到约83%的精确度,对花青素品种能达到约86%的精确度。因此,图像RGB特征值法不仅能够很好地反映甘薯品种间的色素差异,还能较精确地估测甘薯色素含量,可为甘薯早代育种的大批量样品提供便捷、客观的色素含量评估方法。     

茉莉酸甲酯对广藿香JA信号转导途径及倍半萜合成途径关键基因表达的影响

分析外源性茉莉酸甲酯对广藿香JA信号转导途径关键基因JAZ2、MYC2、COI1及倍半萜合成途径关键基因PTS、FPPS、SQLE表达的影响,为深入研究茉莉酸甲酯调控广藿香JA信号转导途径及倍半萜合成途径的分子机制奠定基础.该文分别用0.10和0.25 mmol·L-1的MeJA喷施广藿香叶片,于处理后的0、2、6、1...     

转录因子MYC2介导植物抗生物胁迫的研究进展

髓细胞组织增生蛋白(Myelocytomatosis proteins,MYC)类转录因子,是植物激素茉莉酸(JA)响应途径中的激活转录因子,广泛存在于动植物中,MYC2转录因子属于bHLH类转录因子家族,含有bHLH保守结构域,是当前MYC类转录因子中研究最透彻的一个。随着对植物抗生物逆境不断深入研究,对MYC2的研究亦逐渐清晰。本文综述了转录因子MYC2通过与下游靶基因形成一个层级转录级联,放大转录输出,参与调控植物抗生物逆境,着重阐述了水稻OsMYC2转录因子在抗生物逆境中的作用;茉莉酸ZIM结构域蛋白(Jasmonate ZIM-domain,JAZ)作为JA信号的转录抑制因子,抑制MYC2的活性并参与介导JA信号途径,为MYC2功能机制研究提供了参考,并对今后的研究热点与方向进行了展望。     

茉莉酸信号途径中转录抑制因子JAZ蛋白家族的分子进化分析

茉莉酸在植物的生长发育、应激反应和次生代谢过程中起着重要的调控作用。转录抑制因子JAZ（Jasmonate ZIM-domain）蛋白则是茉莉酸信号从SCF^coi1受体复合物向下游茉莉酸应答基因转导的纽带。采用比较基因组学的方法。从多谱系的角度对植物JAZ蛋白家族进行分子进化分析并取得以下研究结果。（1）在藻类植物、苔藓植物、蕨类植物、裸子植物及单、双子叶植物6个不同谱系的15种代表植物基因组中,鉴定了82个JAZ同源基因,其中在低等藻类植物基因组中没有鉴定到JAZ同源基因,提示JAZ家族基因可能起源于陆生植物。（2）系统发育分析表明,在植物基因组中JAZ蛋白家族可分为10个保守的亚家族,而谱系特异扩增尤其是串联重复和区段重复可能是陆生植物JAZ家族基因扩增与进化的主要机制,并导致多个谱系特异的JAZ亚家族产生。（3）基因结构分析表明,JAZ家族基因含有0一7个数目不等、62—4222bp长度不等的内含子,提示在植物基因组进化过程中,JAZ家族基因可能发生内含-丢失或内含子插入缺失,进而导致基因外显子．内含子结构的多样性。该研究结果将为植物JAZ蛋白家族的深入研究提供参考。     

水稻中一个新的MYC基因的克隆及其分析

在水稻基因组序列中发现类似MYC序列的同源序列,并设计引物成功克隆了一个水稻OsMYC基因(GenBank登录号：AY398581),并对其进行了分子结构分析。OsMYC基因具有典型的DNA结合结构域：碱性区域／螺旋-环-螺旋(bHLH)基序,与其他MYC类似基因的蛋白序列比对结果表明,OsMYC基因与AtMYC2、MYC7E和PG1等氨基酸序列一致性分别是78%、48％、46％,而在bHLH区的一致性分别为95％、84％、77％,N端保守区的一致性分别为81％、54％、52％;位于bHLH区域内的核定位信号区则完全一致;系统进化树分析结果表明,该基因与AtMYC2、MYC7E和PG1等位于同一亚类。此外,该基因主要在营养器官中表达,茎秆中表达最强,根和叶片中较弱,并且能被外源ABA或Fe^3 所诱导,这与AtMYC2、MYC7E基因的表达模式基本相同。该基因是水稻MYC转录因子家族的一个新成员。     

FmJAZ1基因瞬时侵染水曲柳对 JA通路相关基因表达的影响

该文对水曲柳JAZ蛋白家族的一员FmJAZ1的功能及对其上下游基因影响进行了初步分析。首先,利用无缝克隆的方法构建FmJAZ1-pROK2-GUS过表达载体,利用三亲杂交的方法将载体转入农杆菌;然后,使用农杆菌对水曲柳组培苗进行瞬时侵染,得到FmJAZ1过表达的侵染苗;最后,在侵染后36 h使用茉莉酸合成途径抑制剂(DIECA)对侵染苗进行处理,分别取0、1、3、6、18、21、24 h七个时间点的样品,通过荧光定量PCR对FmJAZ1、FmJAZ2、GL1、EIN3、MYC2 5个基因的表达进行了分析。结果表明:农杆菌瞬时侵染水曲柳幼苗后,FmJAZ1表达显著升高,为空载侵染的3.2倍,说明FmJAZ1瞬时转入水曲柳并完成基因表达,侵染有效。经过DIECA处理的侵染苗FmJAZ1的相对表达量初期下降并出现明显波动,18 h后恢复平稳,证明它是JA通路的作用基因。同时检测了4个JA通路相关基因的表达,在1 h时JAZ2、GL1表达下调,其余均有轻微上调,随后各基因表达均有上调。FmJAZ1瞬时转化水曲柳后FmJAZ1过表达,说明瞬时侵染有效; DIECA处理后FmJAZ1表达显著下调说明FmJAZ1的合成受JA调控。在水曲柳中,FmJAZ1抑制转录因子GL1、EIN3、MYC2、FmJAZ2的表达,且FmJAZ2的合成也受JA调控。综上结果表明,JAZs不仅调节JA通路的关键蛋白,还参与其他信号通路的调节,最终通过体内JA的表达与其他相关信号分子的协同表达来调节植物的生长发育及其对应激的反应。     

MYC、PTEN和TP53表达与哈萨克族食管癌相关性研究

[目的]检测MYC、PTEN、TP53在哈萨克族食管癌组织和远端无癌组织的表达,分析与临床病理因素的关系,探讨它们在哈萨克族食管癌发生发展中可能存在的关系。[方法]Trizol一步法获取组织标本总RNA,逆转录为c DNA,运用半定量RT-PCR技术检测食管癌组织、远端无癌组织中三个基因mRNA表达量及阳性表达率。[结果]1 MYC mRNA表达量在食管癌组织中高于远端无癌组织(P0.01);PTEN、TP53 mRNA表达量在远端无癌组织中高于癌组织(P0.01,P0.05);2 MYC阳性表达率在食管癌组织中高于远端无癌组织(P0.01);PTEN、TP53阳性表达率在远端无癌组织中高于癌组织(P0.01,P0.05));3MYC表达与分化程度(P0.05)、TNM分期(P0.05)、淋巴结转移(P0.01)和侵犯深度(P0.05)有关;PTEN表达与分化程度有关(P0.05);TP53的表达与上述指标无关;4 MYC和PTEN、TP53表达呈负相关(r=-0.494;r=-0.428);PTEN、TP53表达呈正相关(r=0.531)。[结论]哈萨克族食管癌组织中MYC表达上调,PTEN、TP53低表达或不表达。上述结果说明MYC参与哈萨克族食管癌的发生和发展,PTEN、TP53则是阻止食管组织发生癌变的保护性基因。     

橡胶树茉莉酸信号途径相关基因表达与橡胶产量的相关性

割胶促进橡胶树合成天然橡胶与激活乳管细胞的茉莉酸信号途径密切相关,但茉莉酸信号途径关键环节的基因表达水平与干胶产量的相关性尚不清楚。为了找到与产量相关的分子标记,该研究采用qPCR技术,分析了割胶条件下茉莉酸信号途径关键环节的9个相关基因在5个橡胶树魏克汉种质和5个1981’IRRDB种质乳管细胞中的表达。结果表明:大多魏克汉种质的株次干胶产量显著高于1981’IRRDB种质。在9个基因中,除了HbMYC4和HbMYC5,其余7个基因在大多橡胶树魏克汉种质中的表达量均显著高于1981’IRRDB种质,尤其是HbMYC3基因表达差异性好,与干胶产量相关性高,有望作为橡胶树产量育种的一个分子标记。这对育种周期长的橡胶树产量育种具有实际应用价值。     

橡胶树橡胶生物合成调控相关基因表达丰度比较

蛋白质是构成生命系统的基本元件之一,是大部分生物学功能的执行者.蛋白质丰度与其生物学功能息息相关,其丰度受基因表达过程中各环节严格精密的调控.其中,蛋白质丰度与其相应mRNA丰度存在较强的相关性,蛋白质丰度差异的40％可由mRNA丰度来解释.茉莉酸信号途径调节巴西橡胶树中的天然橡胶生物合成,但相关基因彼此间的表达丰度差...     

Microbial degradation of tyre rubber particles

Degradation of rubber particles from tyre treads, having diameters from 0.8 to 2.3 mm, was achieved using Nocardia sp. 835A-Rc, a mutant strain with strong rubber-degrading ability. The entire surface of the particles was uniformly attacked by the organism either without stirring of the culture medium or at a very low stirring rate of 40 rpm. At a higher rate of stirring, however, a small number of large microbial colonies were formed on the rubber surface and separate deep semi-spherical cavities were observed after the removal of microbial cells by washing. The number of microbial colonies decreased with increasing stirring rate but each one of the colonies became larger at the same time. As the result of these two counteracting effects of stirring on microbial activity, the weight loss of the particles increased when the stirring rate was raised from 0 to 40 rpm but decreased when the rate was increased from 40 to 70 or 150 rpm. At the stirring rate of 40 rpm, the weight losses of the particles with mean diameters of about 0.8, 1.1 and 2.3 mm were 57, 50 and 36%, respectively, after 8 weeks. The rate of microbial degradation increased again when the stirring was raised from 150 to 300 rpm.     

Colletotrichum acutatum is the main cause of Colletotrichum leaf disease of rubber in Sri Lanka

Colletotrichum gloeosporoides has been described as the causal agent of Colletotrichum leaf disease of rubber in Sri Lanka and other parts of the world since 1905. A study carried out on vegetative and reproductive characteristics of 52 isolates from Colletotrichum leaf disease lesions on Hevea brasiliensis in Sri Lanka revealed that only 18 isolates belong to Colletotrichum gloeosporioides. The remaining 34 isolates represented C. aculatum indicating that C. acutatum is the main cause of Colletotrichum leaf disease in Sri Lanka.This revised version was published online in October 2005 with corrections to the Cover Date.     

Plant regeneration from embryogenic cell suspension-derived protoplasts of rubber

Embryogenic cell suspensions of rubber derived from immature inflorescences and inner integuments of immature fruits released 3.1 ± 0.2 × 10⁷ protoplasts g^-1 f. wt. (mean ± s.e.m, n = 10) and 3.2 ± 0.2 × 10⁷ protoplasts g^-1 f. wt., with mean viabilities of 83 ± 2% and 77 ± 8%, respectively. Sustained mitotic division was observed only when protoplasts were cultured in KPR liquid medium on nitrocellulose membranes overlying the same semi-solid medium containing Lolium multiflorum nurse cells. Protoplast-derived cell colonies were produced within 2 months of culture. Protoplast-derived cell colonies proliferated, upon subculture to MS-based regeneration medium, with 40% of the protoplast-derived calli developing somatic embryos. The latter germinated into plants on the same medium after 3 months of culture. This revised version was published online in June 2006 with corrections to the Cover Date.     

Molecular phylogenetic and morphological analyses of Oidium heveae, a powdery mildew of rubber tree

Powdery mildew of rubber tree caused by Oidium heveae is an important disease of rubber plantations worldwide. Identification and classification of this fungus is still uncertain because there is no authoritative report of its morphology and no record of its teleomorphic stage. In this study, we compared five specimens of the rubber powdery mildew fungus collected in Malaysia, Thailand, and Brazil based on morphological and molecular characteristics. Morphological results showed that the fungus on rubber tree belongs to Oidium subgen. Pseudoidium. Nucleotide sequence analysis of the ribosomal DNA internal transcribed spacer (ITS) region and the large subunit rRNA gene (28S rDNA) were conducted to determine the relationships of the rubber powdery mildew fungus and to link this anamorphic fungus with its allied teleomorph. The results showed that the rDNA sequences of the two specimens from Malaysia were identical to a specimen from Thailand, whereas they differed by three bases from the two Brazilian isolates: one nucleotide position in the ITS2 and two positions in the 28S sequences. The ITS sequences of the two Brazilian isolates were identical to sequences of Erysiphe sp. on Quercus phillyraeoides collected in Japan, although the 28S sequences differed at one base from sequences of this fungus. Phylogenetic trees of both rDNA regions constructed by the distance and parsimony methods showed that the rubber powdery mildew fungus grouped with Erysiphe sp. on Q. phillyraeoides with 100% bootstrap support. Comparisons of the anamorph of two isolates of Erysiphe sp. from Q. phillyraeoides with the rubber mildew did not reveal any obvious differences between the two powdery mildew taxa, which suggests that O. heveae may be an anamorph of Erysiphe sp. on Q. phillyraeoides. Cross-inoculation tests are required to substantiate this conclusion.     

Colonization and degradation of rubber pieces by Nocardia sp.

The growth of a Nocardia sp. occurs essentially on the insoluble rubber substrate and the cells are tightly bound to the rubber in the initial stage of the growth in spite of vigorous stirring of the cultures. The colonization of rubber pieces was followed by staining with Schiff reagent, and it was revealed that not only the thickness of rubber pieces, but also their length and width greatly influenced microbial colonization and degradation of natural rubber products. Among rubber pieces of various shapes, long strips were most rapidly covered by many microbial colonies and experienced the highest rate of rubber degradation. The rate of degradation (expressed by % weight loss) of the long strips of rubber was a linear function of surface area per unit weight of rubber. Thin and wide films of rubber were also rapidly colonized and degraded, while the colonization and degradation of short and narrow pieces were substantially slower and less extensive.     

Silicone rubber membrane bioreactors for bacterial cellulose production

Cellulose production byAcetobacter pasteurianus was investigated in static culture using four bioreactors with silicone rubber membrane submerged in the medium. The shape of the membrane was flat sheet, flat sack, tube and cylindrical balloon. Production rate of cellulose as well as its yield on consumed glucose by the bacteria grown on the flat type membranes was approximately ten-fold greater than those on the non-flat ones in spite of the same membrane thickness. The membrane reactor using flat sacks of silicone rubber membrane as support of bacterial pellicle can supply greater ratio of surface to volume than a conventional liquid surface culture and is promising for industrial production of bacterial cellulose in large scale.