氮胁迫对黄瓜幼苗抗氧化酶系统的影响

氮是植物所需的重要营养元素之一,氮缺乏会影响黄瓜的生长发育、营养品质及产量。该研究以黄瓜9930为材料,测定缺氮条件下黄瓜幼苗活性氧和丙二醛含量,抗氧化酶活性及基因表达量的变化。结果表明:缺氮处理6 h后黄瓜叶片内过氧化氢含量和超氧阴离子产生速率均显著上升,处理6 h时分别增长约100%和37%,丙二醛随着处理时间的延长不断累积,处理48 h时上调约25%,说明植物膜系统遭到破坏;植物抗氧化酶系统中的3种抗氧化酶(SOD、POD和CAT)的酶活性在缺氮的黄瓜叶片中均显著上升,处理48h分别上调约37%、24%和26%;这3种抗氧化酶的相关编码基因表达上调,其中SOD2、POD1和CATs上调幅度较大,SOD2上调约5倍,POD1和CATs上调约10倍。因此,该研究发现氮缺乏处理对黄瓜幼苗产生胁迫作用并诱导植株抗氧化酶系统响应,为了解黄瓜在氮胁迫下的抗逆机制提供有价值的线索。     

SOME PROBLEMS BY USE OF BOUNDARY POINT ELEMENT IN BOUNDARY ELEMENT METHOD

Using boundary point element is one of the treatmentsof corner node problem.This paper further discusses some problems byuse of point element.They mainly include the calculation of stresses atpoint elements,the cause and treatment of singularity in boundary usingequations when point elements are used.An example is given.Correctlyboundary point element has certain practical significance for moreobjective simulation of the actual situation of quantities and improvesaccuracy of results.     

干旱和遮光条件下玉米非光化学荧光猝灭的变化和组成的研究

干旱和光照不足是干扰玉米光合作用,进而影响玉米高产的重要限制因素.为了了解玉米叶绿素非光化学荧光猝灭(qN)对干旱和遮光逆境的反应,我们研究了qN的主要叶绿素荧光参数.结果表明:(1) 干旱和遮光处理显著增加了最大值时的qNmax和稳定态时的qNs,降低了PSⅡ电子传递的光量子产量(ΦPSⅡ).(2) qNs与qNmax的比值与逆境的严重程     

Analyses of Interlayer Stresses and Strain Transfer in Smart Laminated Structures

A new model is proposed to analyze the strain/stress transfer relation between host materials and piezoceramic sensors/actuators under bending and axial stress loading. The finite thickness of the adhesive is taken into account. The physical layers of the piezoceramic, adhesive and structure material are further subdivided into thinner layers as fine as necessary in order to improve the accuracy of stress analysis. In each thin layer the in-plane stresses are assumed to vary linearly across the thickness. By satisfying equilibrium equations, constitutive equations and displacement-strain relations, all components of stress, strain and displacement can be expressed as functions of the in-plane forces and the moments of the thin layers. The differential equations governing the in-plane forces and the moments are obtained. Then, this analytical model is used to predict strain transfer from the structure material to the sensor. It is found, both experimentally and theoretically, that the axial strain of the host material is considerably larger than the strain of the sensor, which is directly related to the output voltage. By introducing the so-called strain transfer factor, a relationship between the output voltage of the sensor and the strain of the measured material is derived. The model is used to predict interlayer stress distributions and strain transfer, which are induced by actuator strain. The result was compared with existing experiments and FEM. There is stress concentration between the actuator and adhesive around the edge of the smart structures, which may cause debonding under high stress loading.     

Testing the utility of abiotic surrogates for marine habitat mapping at scales relevant to management

Habitat mapping at the scale at which marine protected areas are designed and managed is essential for assessment of, and design for, representation. Most habitat mapping studies rely solely or in part on abiotic surrogates for patterns of biodiversity. The utility of abiotic variables in predicting biological distributions at the local scale (10 s of km) was tested in a remote video survey of macrobenthos in Moreton Bay, Australia. Habitat classifications of the same set of 41 sites based on 6 abiotic variables and abundances of 89 taxa and bioturbation indicators were compared using correlation, regression and ordination analyses. The concepts of false homogeneity (abiotically similar but biologically distinct) and false heterogeneity (abiotically distinct but biologically similar) were defined to describe types of errors associated with using abiotic surrogates to construct habitat maps, and quantified using two separate methods. Overall, the best prediction by abiotic surrogates explained less than 30% of the pattern of biological similarity. Errors of false homogeneity were between 20% and 62%, depending on the methods of estimation. Predictive capability of abiotic surrogates at the taxon level was poor, with only 6% of taxon/surrogate correlations significant. Abiotic variables did not discriminate sufficiently between different soft bottom communities to be a reliable basis for mapping. These results have implications for the widespread use of abiotic surrogates in marine habitat mapping to plan for, or assess, representation in marine protected areas. Little confidence can be placed in marine habitat classifications based solely or largely on abiotic surrogates without calibration by rigorous biological surveys at the appropriate scale. Therefore, it is questionable whether marine protected areas designed on this basis can have measurable benefits for conservation.     

Evaluation of perennial wild <Emphasis Type="Italic">Cicer</Emphasis> species for drought resistance

About 90% of chickpea (Cicer arietinum L.) in the world is grown under rainfed conditions where drought is one of the major constraints limiting its productivity. Unlike the cultivated chickpea, wild Cicer species possesses sources of resistance to multiple stresses; we therefore evaluated perennial wild Cicer species for resistance to drought. C. anatolicum, C. microphyllum, C. montbretii, C. oxydon and C. songaricum were compared with special checks; C. echinospermum, C. pinnatifidum and C. reticulatum and five cultivated chickpeas. After the cultivated chickpeas were killed, accessions were evaluated using a 1–5 scale, where 1 = highly drought resistant (no visible drought effect and full recovery after three successive wiltings) and 5 = highly drought susceptible (leaves and branches dried out, no recovery at all). All accessions of perennial wild Cicer species were significantly superior to those annual wild species and the cultivated chickpeas including the best drought tolerant chickpea, ICC 4958 under drought conditions. Perennial wild Cicer species did not only recover after wilting and drying out above ground level, they also tolerated high temperatures up to 41.8°C. But, they do not cross with the cultivated chickpeas. C. anatolicum should be taken account in long term breeding programs because it has closer affinities to the first crossability group than the others.     

橡胶树HbWRKY3的克隆及其响应逆境胁迫的表达分析

通过RACE技术扩增获得橡胶树HbWRKY3基因,并对该基因及其所编码氨基酸序列进行生物信息学分析和响应逆境胁迫的表达分析,结果表明：该基因含有2个WRKYGQK结构域和2个C2H2锌指结构,属于WRKY基因家族第Ⅰ类;由4个外显子和3个内含子组成,DNA序列全长3 780 bp;开放阅读框长度为2 211 bp,编码由737个氨基酸组成的多肽。该基因定位于细胞核中,在橡胶树叶片、树皮、花、胶乳等不同组织中都有表达,以花中的表达水平最高。盐、PEG、茉莉酸、水杨酸等非生物胁迫均可诱导HbWRKY3的表达,但干旱、ABA、乙烯和低温胁迫的诱导较为明显。     

The influence of abiotic stress conditions on dough mixing characteristics of two hard red spring wheat cultivars

Two commercial hard red spring wheat cultivars were exposed to high and low temperatures, as well as drought stress when the main tiller kernels were at the soft dough stage. The trial was done in the greenhouse for two consecutive seasons to determine the effects of these stress conditions on protein content, SDS sedimentation and selected Mixsmart characteristics. Heat stress had the largest effect on mixing characteristics. Heat and drought stress caused a significant increase in flour protein content of both cultivars and had similar effects on mixing characteristics. The Mixsmart characteristics associated with dough strength were increased by heat and drought stress. Cold stress caused a slight increase in protein content of the cultivars, but in general caused a reduction in dough strength as measured with Mixsmart characteristics. The reaction of Mixsmart characteristics to heat and drought stress was much larger in Duzi than in Kariega, confirming that there is a large genotype effect in rheological characteristics.     

二穗短柄草FRUITFULL1基因表达分析及RNA干扰和过表达载体的构建

为了揭示BdFUL1的生物学功能,利用生物信息学和分子生物学方法,分析二穗短柄草转录因子FRUITFULL1-2(BdFUL1-2)的结构、序列特征以及与不同植物AP1/FUL的亲缘关系,构建进化树。利用定量RT-PCR等分子生物学方法,分析非生物逆境和外源激素处理条件下两个转录本BdFUL1-1和BdFUL1-2的表达水平。结果表明:BdFUL1属于典型的植物MADS-box基因,与小麦的WFUL1有很近的亲缘关系;在高温、低温、干旱胁迫以及不同激素ABA、6-BA和SA处理下,BdFUL1-1的表达水平显著升高,暗示BdFUL1可能通过激素信号传导而参与响应非生物胁迫。同时,构建BdFUL1-1和BdFUL1-2的RNA干扰和过表达载体。     

植物富含甘氨酸蛋白的研究进展

摘要：植物富含甘氨酸蛋白(Glycine-rich proteins,GRPs)是由富含甘氨酸的高度重复序列组成的蛋白质。此文综述了近年来国内外对植物富含甘氨酸蛋白及其基因的研究进展,系统地介绍了GRPs的结构特点 、GRP基因表达特性及GRP基因功能,旨在为今后的进一步研究提供参考。