盐胁迫下柚和橘幼苗体内矿质元素变化的比较研究

采用沙培法,对盐胁迫下坪山柚和福橘幼苗体内矿质元素的变化进行了研究。结果表明,随着NaCl浓度的增加,坪山柚和福橘幼苗根部及地上部Na^＋、Cl-含量增加,且相同浓度下,福橘比坪山柚高。40mmol／L NaCI胁迫下,坪山柚和福橘幼苗地上部的K^＋、Fe含量,根部的Ca^2＋、Mg^2＋、Zn含量显著下降,而根部Fe含量及地上部Zn含量显著增加。随NaCl浓度增大,坪山柚根部K^＋含量,地上部Ca^2＋、Mg^2＋含量变化不明显,而福橘根部、地上部上述离子含量在NaCl浓度≥160mmol／L时均显著下降。因此,根部K^＋含量,地上部Ca^2＋、Mg^2＋含量存在品种问差异,或许可作为耐盐性鉴定指标。NaCl胁迫降低坪山柚和福橘幼苗根部及地上部P、Mn含量,而Cu含量在较高浓度NaCl胁迫下显著增加。NaCl胁迫明显降低坪山柚和福橘幼苗地上部K^＋／Na^＋、Ca^2＋／Na^＋和Mg^2＋／Na^＋值,其中K^＋／Na^＋值的变化可考虑作为柑橘耐盐性鉴定的指标。     

紫花苜蓿光合气体交换和叶绿素荧光特征的时间变异性

气体交换和荧光特性是植物环境适应的重要表征,会随植物生长而变化,但其变化规律尚不明确。以多年生豆科牧草陇东苜蓿为材料,测定了其3茬不同生育时期气体交换和叶绿素荧光、叶绿素组分含量、蔗糖合成酶和蔗糖磷酸合成酶活性等参数,从时间变异性角度探讨紫花苜蓿环境适应的光合作用机制。结果表明:（1）随陇东苜蓿的生长,其地上部分和叶干重在各茬内都呈增加趋势,而平均日増干重在前两茬内呈增加趋势,在第3茬内呈先上升后下降的趋势,符合“S”型生长规律。（2）叶片净光合速率、气孔导度和羧化效率在各茬内呈降低的趋势,而叶片胞间CO₂浓度则相反,水分利用效率和气孔限制值在第一茬内呈下降的趋势而在第二茬和第三茬内则呈增加的趋势。（3）叶片蔗糖合成酶和蔗糖磷酸合成酶活性均不随陇东苜蓿生长而发生明显变化,蔗糖含量则呈增加的趋势。（4）同一茬内,叶片叶绿素含量随陇东苜蓿的生长而呈增加趋势,叶绿素荧光参数只在第一茬初期有较明显的变化,后两茬内变化不明显。研究发现,为适应不同生育时期的环境条件,紫花苜蓿叶片气体交换和叶绿素荧光特性表现出时间变异性,且二者间存在差异。     

以番茄斑萎病毒核蛋白为靶点的荧光偏振药物筛选体系的建立及应用

目的:基于荧光偏振技术建立靶向番茄斑萎病毒(Tomato spotted wilt virus,TSWV)核蛋白(NP)与核酸相互作用的药物筛选体系,并应用该体系展开药物筛选。方法:将目的基因克隆到pGEX-6p-1表达载体上,并采用大肠杆菌表达系统进行目的蛋白的异源表达。建立靶向TSWV NP与核酸相互作用的荧光偏振药物筛选体系,对体系的结合时间、DMSO耐受、变异性和稳定性进行研究,并展开药物筛选。结果:成功构建重组质粒pGEX-6p-1-NP,在大肠杆菌中表达并分离纯化出高质量的核蛋白。基于荧光偏振技术建立了信噪比为8∶1,Z因子为0. 82的稳定的靶向TSWV NP与核酸相互作用的药物筛选体系,并对化合物库中1 000种化合物展开药物筛选,经过初步筛选获得了1种IC_(50)为4. 15μmol/L的化合物。结论:建立了稳定的荧光偏振筛选体系,适用于靶向NP与核酸相互作用的药物的筛选。筛选到的化合物为番茄斑萎病毒的预防和控制提供参考。     

Isolation of paraquat-tolerant mutants from tomato cell cultures

Summary Tomato callus clones selected for the ability to grow at paraquat concentrations lethal to wild-type cells were found at an approximate frequency of 5×10^–8 per viable cell. Diploid plants were regenerated from nine of the nineteen paraquat-tolerant callus clones isolated. Although some of these plants appeared normal, others had altered morphology and reduced vigor and fertility. New callus cultures initiated from these regenerated plants typically had at least a 30-fold increase over the wild type in tolerance to paraquat. Tests on callus from sexual progeny showed that the paraquat-tolerant phenotypes of clones PQT⁴, PQT⁶, and probably also PQT¹³ resulted from dominant nuclear mutations, but the number of loci involved is not yet known. Paraquat spray experiments indicated that slight paraquat-tolerance was expressed at the plant level in PQT¹³, but not in any of the other clones tested.     

The history of tomato: From domestication to biopharming

Imported from the Andean region to Europe in the 16th century, today tomato is widespread throughout the world and represents the most economically important vegetable crop worldwide. Tomato is not only traded in the fresh market but is also used in the processing industry in soups, as paste, concentrate, juice, and ketchup. It is an incredible source of important nutrients such as lycopene, β-carotene and vitamin C, which all have positive impacts on human health. Its production and consumption is increasing with population growth. In this review, we report how tomato was already domesticated by the ancient Incan and Aztec civilizations, and how it came to Europe, where its breeding history started. The development of genetic, molecular biology and plant biotechnology have opened the doors towards the modern genetic engineering of tomato. The different goals of tomato genetic engineering are presented, as well as examples of successfully engineered tomatoes in terms of resistance to biotic and abiotic stresses, and fruit quality. The development of GM tomato for biopharming is also described.     

Phytoavailability of zirconium in relation to its initial added form and soil characteristics

The various uses of zirconium (Zr) in chemical and nuclear industries generate a potential risk of environmental contamination by this element. This study was performed on two agricultural soils, an acidic soil (A) and a clayey calcareous soil (B), collected in the Meuse/Haute Marne experimental site of the French National Agency for radioactive waste management (Andra). Distribution coefficients (K _d), defined as the ratio of Zr concentration in the solid phase (mol/kg) to Zr concentration in the solution (mol/l), were obtained for both soils. Their high values (6,000 < K _d < 30,000 l/kg) suggest a rapid and strong retention of Zr on the soil constituents. Chemical extractions (0.01 M CaCl₂, Calcium chloride, 0.005 M DTPA, Diethylene Triamine Penta Acetic acid, and 0.1 M NaPP, Sodium Pyrophosphate) showed that organic matter had a high affinity for the added Zr. Soil–plant transfer experiments showed low plant uptake. A significant absorption of Zr was, however, observed for the two studied plants, tomato (Lycopersicon esculentum L. cv. St. Pierre) and pea (Pisum sativum L. cv. “express”). For the most available forms of Zr (acetate and oxychloride), concentrations reached from 8 to 57 mg Zr/kg dry weight of roots. Zr is mainly accumulated in plant roots and is more absorbed by tomato than by pea. Zr bound to root cell walls (i.e. apoplastic Zr) concentrations, determined by HCl extraction, are significantly much lower than root absorbed Zr concentrations. Transfer to roots seemed to be more effective in the acidic soil and was strongly dependant on Zr added form.     

Developmentally regulated Arabidopsis thaliana susceptibility to tomato spotted wilt virus infection

Tomato spotted wilt virus (TSWV) is one of the most devastating plant viruses and often causes severe crop losses worldwide. Generally, mature plants become more resistant to pathogens, known as adult plant resistance. In this study, we demonstrated a new phenomenon involving developmentally regulated susceptibility of Arabidopsis thaliana to TSWV. We found that Arabidopsis plants become more susceptible to TSWV as plants mature. Most young 3-week-old Arabidopsis were not infected by TSWV. Infection of TSWV in 4-, 5-, and 6-week-old Arabidopsis increased from 9%, 21%, and 25%, respectively, to 100% in 7- to 8-week-old Arabidopsis plants. Different isolates of TSWV and different tospoviruses show a low rate of infection in young Arabidopsis but a high rate in mature plants. When Arabidopsis dcl2/3/4 or rdr1/2/6 mutant plants were inoculated with TSWV, similar results as observed for the wild-type Arabidopsis plants were obtained. A cell-to-cell movement assay showed that the intercellular movement efficiency of TSWV NSm:GFP fusion was significantly higher in 8-week-old Arabidopsis leaves compared with 4-week-old Arabidopsis leaves. Moreover, the expression levels of pectin methylesterase and β-1,3-glucanase, which play critical roles in macromolecule cell-to-cell trafficking, were significantly up-regulated in 8-week-old Arabidopsis leaves compared with 4-week-old Arabidopsis leaves during TSWV infection. To date, this mature plant susceptibility to pathogen infections has rarely been investigated. Thus, the findings presented here should advance our knowledge on the developmentally regulated mature host susceptibility to plant virus infection.     

Effect of vesicular-arbuscular mycorrhiza on survival,penetration and development of root-knot nematode in tomato

Summary Effect of mycorrhizal colonisation byGlomus fasciculatum on survival, penetration and development of the root knot nematodeMeloidogyne incognita in tomato was studied. The number of giant cells formed in mycorrhizal plants was significantly low. Mycorrhizal roots did not prevent the penetration by nematode larvae. Root extract from the mycorrhizal plants brought about 50% mortality of the nematode larvae in four days time.