EMS离体诱变及抗草莓灰霉病愈伤组织的筛选

试验用甲基磺酸乙酯（EMS）处理草莓愈伤组织后通过草莓灰霉病病原毒素（Toxin）离体筛选获得抗病愈伤组织并诱导成苗。EMS诱变处理‘幸香’草莓离体叶片产生的愈伤组织,用经毒力检测的草莓灰霉菌毒素粗提液进行离体筛选,通过在愈伤组织继代培养中附加不同浓度毒素粗提液,以确定适宜的抗病选择压,获得抗灰霉病突变体材料。结果表明,将愈伤组织直接进行EMS处理的成活率高于将愈伤组织切割成小块继代培养再经EMS处理的愈伤组织;且0.2% EMS处理1h为最适剂量。在含80%毒素粗提液的培养基培养10 d为抗性筛选的适宜选择压。诱变处理后的867块愈伤组织,在经不连续二次筛选后有195块成活,成活率22.5%,其中有82块再生出了不定芽,再生率为42.1%。不定芽经生根后移栽至田间进一步进行抗性鉴定。     

EMS诱发草莓不同组培材料的耐盐性变异

以全明星草莓花药诱导的愈伤组织以及组培苗叶片为试验材料,用化学诱变剂甲基磺酸乙酯(EMS)进行诱变处理。结果表明,愈伤组织诱变处理的适宜浓度与时间组合为0.1%+1.5h和0.2%+1.0h,而(0.2%~0.4%)+(1.0~2.0h)可作为离体叶片诱变处理的适宜浓度和时间范围。与离体叶片诱变相比,草莓花药的愈伤组织对诱变剂EMS更为敏感。通过对再生植株的耐盐性进行比较发现,愈伤组织诱变筛选植株的盐害率和盐害指数低于离体叶片诱变筛选植株,说明愈伤组织较组培苗叶片更适于作为草莓耐盐诱变育种的起始材料。     

垂吊型矮牵牛叶片培养不定芽发生和微繁研究

以垂吊型矮牵牛叶片为材料 ,建立了垂吊型矮牵牛叶片高效不定芽发生、植株再生和微繁的技术体系。研究了不同激素及其组合对叶片不定芽发生、壮苗和生根的效应。结果显示 ,MS +BA 2mg L +NAA 0 1mg L是叶片不定芽发生的适宜培养基 ;MS +BA 0 5mg L +IBA0 1mg L +GA 0 5mg L是不定芽形成壮苗的适宜培养基 ;MS +IAA 0 1mg L是壮苗生根的适宜培养基 ;草炭珍珠岩基质是生根苗移栽的适宜基质     

EMS诱导太子参抗性突变体及分子检测

为创建太子参突变体库及创造太子参抗叶斑病新种质,用甲基磺酸乙酯(EMS)处理太子参愈伤组织后通过叶斑病粗毒素离体胁迫培养筛选抗病突变体,以愈伤组织0%相对生长量为指标,筛选抗病突变体的粗毒素临界致死浓度选择压,以愈伤组织在粗毒素培养基上50%存活率为指标,筛选EMS半致死处理组合。结果表明:25%粗毒素液培养20 d的处理组合可作为抗性突变体筛选的选择压;0.8%EMS处理2 h,0.8%EMS处理3 h和1%EMS处理2 h,可作为筛选突变体的EMS半致死组合。经EMS处理的愈伤组织提高了在叶斑病粗毒素液临界致死浓度中的存活率。50条RAPD引物PCR检测结果表明,突变体DNA序列发生了变异。突变体苗经田间鉴定,抗性评价为高抗。本研究为建立太子参EMS离体诱变定向改良性状技术体系奠定基础。     

农杆菌介导的洋桔梗遗传转化体系的建立

以洋桔梗叶片为外植体,建立了植株再生体系,并在此基础上,用根癌农杆菌介导法,研究了影响洋桔梗转化的若干因素。结果表明,诱导最佳培养基为MS+6-BA 1.0mg/L+NAA 0.15mg/L,不定芽诱导率达74.5%;不定芽生根培养基为1/2MS+IBA 0.5 mg/L,生根率达90%。不定芽分化阶段和生根阶段的Km筛选浓度分别为45mg/L和15mg/L;根癌农杆菌菌液浓度OD600值为0.6,侵染时间10min,共培养时间3d,有利于抗性芽的产生。Km筛选得到的抗性植株经过PCR和Southern检测表明,八氢番茄红素合成酶基因(PSY)已经整合到洋桔梗基因组中。     

蝴蝶兰类圆球茎的化学诱变试验

用不同浓度的甲基磺酸乙酯(EMS)和叠氮化钠(NaN3)对蝴蝶兰类圆球茎(PLB)作不同时间处理。结果显示:EMS和NaN3均可使部分PLB白化或褐化并逐渐致死。0.4%EMS接近PLB半致死剂量。PLB切片观察发现:用EMS和NaN3处理均可使细胞体积增大,细胞形状改变,细胞质浓缩。较高浓度NaN3处理的PLB细胞中出现晶体物质、双核、畸形核和核仁丢失等现象。较高浓度EMS处理的PLB细胞中出现微核、畸形核、多核、核破裂和核仁丢失等现象。同浓度的同种诱变剂随处理时间的增加材料的变异程度有增大趋势,但不很显著。EMS比NaN3的诱变处理效果好。0.5%EMS可作为创造蝴蝶兰PLB突变体的参考浓度。     

观赏羽衣甘蓝高频再生体系的建立

观赏羽衣甘蓝是一种赏食兼用的耐冻优良景观植物。为了通过基因工程手段赋予其抗虫性,并进一步提高其低温耐受性,获得新的抗性种质,本研究以优良育种品系为试材,详细探讨了影响离体培养不定芽再生的因素,建立了高效再生体系。以8份不同类型羽衣甘蓝基因型的带柄子叶、子叶、下胚轴为外植体,研究了不同基因型、不同外植体、不同的培养基激素浓度配比及添加AgNO3对不定芽诱导的影响。结果表明:无论基因型及使用的培养基,带柄子叶均为最佳外植体;不同的基因型、不同外植体其最佳的芽诱导培养基不同;筛选出两份材料,其带柄子叶分别在L6(MS+6-BA1.0mg/L+NAA0.1mg/L)及L3(MS+6-BA1.5mg/L)培养基中不定芽诱导率为100%,下胚轴诱导率最高也能达88.33%;培养基中添加4mg/L AgNO3不利于羽衣甘蓝的不定芽诱导;再生株生根以MS+NAA0.1mg/L效果好,生根率可达100%。     

多年生黑麦草EMS诱变与耐旱性评价

为构建多年生黑麦草突变体库,本研究采用甲基磺酸乙酯(EMS)对多年生黑麦草品种‘首相’种子进行诱变处理,设置6个诱变浓度(0%、0.4%、0.8%、1.2%、1.6%和2.0%)和3个处理时间(6、12、24 h),分析诱变后种子萌发、幼苗生长及耐旱变异株主要抗旱生理指标的变化。结果表明,1.6%EMS处理12 h与0.8%EMS处理24 h的种子发芽率均接近50%,综合分析结果表明,0.8%EMS处理24 h可作为适宜诱变组合。通过对诱变材料进行抗旱性筛选,共获得15株耐旱变异株,基于丙二醛、脯氨酸、可溶性糖含量、抗氧化酶活性等抗旱生理指标的综合评价表明,变异株B9、B10、B12在干旱胁迫下抗旱性较强,说明EMS诱变可以诱发抗旱变异体。本研究结果为多年生黑麦草的EMS诱变及耐旱育种提供了理论支撑。     

应用组织培养技术进行三倍体毛白杨快繁的研究

应用植物组织培养技术对三倍体毛白杨快速繁殖进行了研究 ,结果表明 ,适宜三倍体毛白杨茎段芽增殖的培养基为MS +BA 0 5mg/L +NAA 0 0 1～ 0 0 2mg/L ,适宜叶切块产生不定芽的最佳培养基为MS +BA 0 15～ 0 5mg/L+NAA 0 0 2～ 0 0 5mg/L +IAA 0～ 0 2 5mg/L ,在此培养基上 ,可建立良好的快速繁殖体系。适宜芽生根的培养基为MS +IBA 0 2mg/L ,生根率在 10 0 %。     

百合农杆菌介导的遗传转化受体系统的建立

以麝香百合"素雅"(white-Elegance)作为供试材料建立了百合农杆菌介导的受体系统。鳞茎片的诱导分化以MS培养基中添加0.5mg/L6-BA 0.2mg/LNAA为最好;再生苗鳞茎片的不定芽分化以MS培养基中添加1.0mg/L6-BA 0.2mg/LNAA为最好;再生苗小叶柄的诱导以MS培养基中添加1mg/LNAA为佳。确定了再生苗不同部位适宜的抗生素筛选浓度,卡那霉素的筛选浓度小鳞茎块确定为125mg/L,而小叶柄确定为75mg/L;头孢霉素抑菌浓度确定为250mg/L。     

Potential of wild species for genetic enhancement of some semi-arid food crops

Discovery and incorporation of genes from wild species provide means to sustain crop improvement, particularly when levels of resistance in the cultigens are low and virulent strains of pests and pathogens overcome the host plant resistance. The extent of utilization and the potential of the wild genepool for genetic enhancement were reviewed in five important food crops viz. sorghum, pearl millet, chickpea, pigeonpea and groundnut grown in the semi-arid tropics. Introgression from compatible wild germplasm in the primary gene pool resulted in transfer of new cytoplasmic male sterility systems in pearl millet and pigeonpea, development of high protein, cleistogamous flower and dwarf pigeonpea lines and foliar disease resistant groundnut cultivars. Utilization of wild species in secondary and tertiary gene pools has been generally limited due to sterility, restricted recombination or cross incompatibility. Nevertheless, these species are extremely important as they contain high levels of resistance to several important biotic and abiotic stresses. Several of them, like those belonging to the Parasorghum section and the rhizomatous Arachis species are sources of multiple resistances and hold great promise to sustain crop productivity.     

“绿色革命”以来大气CO2浓度升高对C3作物营养品质的影响

自20世纪60年代"绿色革命"以来,育种技术和农耕技术的发展促进了农作物产量的大幅提升,然而作物的营养品质出现下降趋势。在相似的遗传背景下,大气CO_2浓度升高会使单位体积农作物产品的营养元素含量下降,因此"绿色革命"至今,农作物产品的营养元素下降可能受大气CO_2浓度升高影响。通过植物生长箱模拟"绿色革命"初期和目前的大气CO_2浓度水平(310μmol/mol和400μmol/mol),针对主要C_3作物水稻、小麦和大豆,研究"绿色革命"以来大气CO_2浓度升高对其籽粒的C、N、Fe、Zn元素含量的影响,结果表明:CO_2浓度升高对3种作物籽粒的C元素含量几乎没有影响,变化幅度在±1.5%之间;籽粒的N、Fe、Zn元素含量普遍呈现下降趋势,但均未达到显著水平。     

Faculty positions:Center for Agricultural Resources Research,Chinese Academy of Sciences

正The Center for Agricultural Resources Research(CARR),the Institute of Genetics and Developmental Biology(IGDB),Chinese Academy of Sciences,invites applicants for several research group leader positions.CARR is one of the research organizations in Chinese Academy of Sciences(CAS).We seek nominations and applications     

Collection and preliminary evaluation of native turfgrass accessions in Italy

Despite a raising interest on turfs in Italy, all theavailable varieties of this kind in the Country are of foreign origin, and areoften poorly adapted to the prevailing climatic conditions. This prompted tobegin a collection activity of indigenous turfgrass species, with the ultimategoal of identifying promising materials for future breeding based on localgenetic resources. The collection was carried out in three areas of Italy, viz.the northern Po Plain, the coastal region of Liguria, and the island of Sardiniathat are characterised, respectively, by subcontinental, warm temperate, andtypical Mediterranean climate. Altogether, 141 sites were visited, yielding 226accessions belonging to eight species of potential interest for turfs:Poa pratensis, Poa trivialis,Festuca rubra, Festuca arundinacea,Lolium perenne, Agrostis stolonifera,Agrostis tenuis, and Cynodon dactylon,this last being a warm-season grass. Poa pratensis andCynodon dactylon were mostly collected in northern Italyand Sardinia, respectively, whereas Festuca arundinacea andLolium perenne were rather ubiquitous. The collection sitesranged from 0 to 1040 m asl, but sites over 750 m wereonly visited in the inner part of Sardinia. All the accessions, collected aswhole plants, were transplanted at Lodi, northern Italy, where they are beingevaluated. Their preliminary evaluation for traits of importance for turf use,such as sward colour and overall quality, highlighted the great variation andthe occurrence of interesting accessions in all species. Other characters wererecorded, bearing specific importance in individual species, and in all casespromising accessions were identified. The germplasm of Festucarubra, Festuca arundinacea, and Loliumperenne proved highly infected by endophytic (symbiotic) fungi of thegenus Neotyphodium.     

Leaf position and genotype differences for mineral element concentrations in sorghum grown on tropical acid soil 1

Mineral element deficiencies and toxicities are common problems associated with sorghum [Sorghum bicolor (L.) Moench] production on acid soils. To better understand some of the mineral element problems and the analysis of plant tissue of sorghum plants grown on acid soils, four sorghum genotypes were grown on an acid Oxisol at Carimagua, Colombia limed with dolomite at 2 and 6 Mg ha^‐1.

Samples for mineral element analyses were obtained from leaves at different positions on the four genotypes. Concentrations of P and Mg were highest in the flag leaf (Leaf No. 1) and decreased as the position on the plant declined from the top of the plant for plants grown at 2 Mg lime ha^‐1. Similar decreases in P, Mg, K, and Zn concentrations occurred in plants grown with 6 Mg lime ha^‐1. Concentrations of Ca, S, Si, Mn, Fe, Cu, and Al increased as leaf position declined from the flag leaf for plants grown at 2 and 6 Mg lime ha^‐1. The higher lime supply enhanced Ca and reduced Mn and Fe concentrations in leaves. Differences in mineral element concentrations for the four genotypes used were fairly extensive. The elements to show the greatest range among genotypes were Al and Si and the elements to show the least range among genotypes were P, K, and S. Care should be used in collecting leaf samples for plant analysis and genotypic differences for accumulation of mineral elements should be considered in interpretation of results.     

Short-term variation in the concentration of selected ions within individual tropical rainstorms

Rainwater was collected at the campus of the University of Brunei Darussalam in Bandar Seri Begawan, Brunei Darussalam, using a funnel-in-bottle sampler. Polypropylene bottles were changed at intervals during rainstorm events. The pH and conductivity were determined immediately after collection on aliquots of the sample. Samples were refrigerated at 5°C for subsequent chemical analysis. Analyses for Na, Mg, Ca, Zn and Fe were carried out by means of inductively coupled plasma atomic emission spectroscopy (ICP-AES); Cu and Mn were analysed by graphite furnace atomic absorption spectroscopy (GFAAS); K was analysed using flame atomic emission spectroscopy (FAES); and Cl^–, NO₃ ^– and SO₄ ^2– were analysed by ion chromatography (IC). Concentration versus time profiles are reported for three rainstorm events. All ions exhibited a decrease in concentration during the rainstorm. The first sample contained the highest concentration of ions, consistent with a first-flush effect. The contribution of the initial stages of the shower to the total quantity of ion deposited during the entire rainstorm is quite overwhelming; in many cases 20 to 30% of the mass was deposited in less than 5% of rainstorm duration. On the other hand, the pH and conductivity variation during rainstorms did not exhibit a consistent pattern.     

Leaf litter selection by detritivore and geophagous earthworms

Summary Litterbag experiments with 10 different kinds of leaf litter showed that detritivore (Lumbricus species) and geophagous (Aporrectodea species) earthworms prefer certain litter types over others, since different numbers of worms were found below the litter after 50–52 days of exposure in a pasture. The detritivores preferred Fraxinus, Tilia, and predecomposed Ulmus and Fagus litter to Fagus litter and paper, while geophages preferred Tilia litter to Alnus and Ulmus litter, so that the two groups of earthworms showed different preferences. The detritivores seemed to be more selective than the geophages. The palatability of the litter was examined in relation to the C: N ratio, the lignin concentration and the initial and final polyphenol concentration. The numbers of detritivores were significantly correlated with the C: N ratio and the final polyphenol concentration, so that selection of litter seems to be related to palatability. The numbers of geophages were not significantly correlated with any of the parameters for palatability. The disappearance of litter after 50–52 days appeared to be due to detritivore activity, since the numbers found below the litter were positively and significantly correlated with the litter disappearance. There was no significant correlation with geophage activity. This indicates that detritivores use litter as food, and therefore influence the composition of the litter layer.     

The 5S rRNA gene diversity in the genus <Emphasis Type="Italic">Secale</Emphasis> and determination of its closest haplomes

We analyzed 127 rDNA sequences (5S DNA units) obtained from 23 seed accession samples from more or less 10 taxa in wild and cultivated rye, genus Secale L. The sequences fell into two known groups, here assigned to two unit classes, viz. long R1 and short R1 (designations to reflect on R haplome of rye). The different taxa could not be fully differentiated based on the 5S DNA units. We searched for 5S DNA sequences from known unit classes most closely similar to the long R1 and the short R1. One set with the long R1 unit class contained sequences of the long P1 unit class from Agropyron (P haplome) and from Kengyilia (StYP haplome), long J1 from Thinopyrum (J haplome), whereas the set with the short R1 included the long S1 from Pseudoroegneria (St haplome) and Kengyilia (StYP haplome), the short J1 from Thinopyrum (J haplome) and the short V1 from Dasypyrum (V haplome). Each of the two sets was analyzed separately by maximum likelihood (ML) phylogenetic analysis from which we were able to infer that the 5S DNA units of Secale differentiated in a non-clock fashion and followed the HKY substitution model in the gene tree with the long R1 unit class and the HKY + G in the gene tree with the short R1 unit class. A complementary Bayesian analysis yielded identical tree topologies to the ML ones for each of the two sequence sets. In the tree with the long R1 units the long P1 and long J1 unit classes were closest to the long R1 unit class, whereas in the tree with the short R1 units the long S1 and short J1 unit classes were closest to the short R1 unit class, indicating possibly a close relationship between the St, J and R haplomes.     

Nematode succession and microfauna-microorganism interactions during root residue decomposition

The quality of plant material affects the vigor of the decomposition process and composition of the decomposer biota. Root residues from hairy vetch (Vicia villosa Roth), rye (Secale cereale L.) and vetch+rye, packed in litterbags were placed in pots of soil at 15 C and the content of the bags was analyzed after 2, 4, 8 and 12 weeks. Bacterial biomass did not differ between residues with contrasting composition. Among bacterivores groups of nematodes that require high bacterial production dominated in fast decomposing resources whereas flagellates with smaller requirements prevail in slower decomposing resources. Biomass of bacterial feeding nematodes correlated positively with early phase (0-2 wk) decomposition that increased in the order: rye< vetch+rye<vetch. Bacterial biomass therefore seems to be under top-down (predation) control during early decomposition. In contrast, the fungal biomass differed between resources with highest values for rye. Moreover, this increase in fungal biomass occurred later during succession and was correlated with decomposition activity for rye in that period. Fungal biomass therefore seems to be under bottom-up (resource) control. The composition of the nematode assemblages (composed of 25 taxa) showed a clear relationship to initial plant resource quality as well as decomposition phase. Early successional microbivorous nematodes vary according to resource quality with demanding bacterivores+predators (Neodiplogasteridae) dominating in vetch and less demanding bacterivores (Rhabditidae) and fungivores (Aphelenchus) being equally common in vetch and rye. Later in the succession (2-4 wk) bacterivorous Cephalobidae and fungivorous Aphelenchoides prevailed similarly on the different root materials whereas bacterivorous protozoa and the amoebal fraction thereof dominated in rye. At week 12 no species dominated the nematode assemblages that were similar between the resources. The differences between nematode assemblages among plant resources at 2 week were similar to the results of a field study sampled after 6 weeks with the same soil and plant resources. This lends support to the relevance of the successional patterns observed in this incubation study.     

Cycling of extracellular DNA in the soil environment

Upon entering the soil environment, extracellular DNA is subjected to dynamic biological, physical, and chemical factors that determine its fate. This review concerns the fate of both recombinant and non-recombinant sources of DNA. A schematic of DNA cycling coupled with genetic transformation is presented to understand its behavior in soil. Extracellular DNA may persist through cation bridging onto soil minerals and humic substances, be enzymatically degraded and restricted by DNases of microbial origin, and/or enter the microbial DNA cycle through natural transformation of competent bacteria. Lateral gene transfer may disseminate DNA through the microbial community. An understanding of DNA cycling is fundamental to elucidating the fate of extracellular DNA in the soil environment.