柠檬桉组织培养的初步研究

本文初步研究了柠檬桉（ＥｕｃａｌｙｐｔｕｓｃｉｔｒｉｏｄｏｒａＨｏｏｋ．）茎段培养中腋芽伸长生长、继代增殖及试管苗生根的主要影响因素。在含有６－ＢＡ０．１～２．５ｍｇ／Ｌ、ＮＡＡ０．１～０．５ｍｇ／Ｌ的激素组合的改良ＭＳ培养基上都能诱导柠檬桉茎段腋芽伸长生长，最高诱导率可达７３％。继代增殖以６－ＢＡ０．５～１．０ｍｇ／Ｌ为宜，约２０～３０ｄ，丛生芽可增殖４左右，以每年７代计，年增殖率约１．６×１０４。继代培养基的６－ＢＡ浓度过高会导致丛生芽在形态上产生变异，并对生根产生不利的影响。继代增殖在７代内生活力未见有明显衰退。ＩＢＡ对柠檬桉试管苗生根有良好的促进作用，浓度以０．５～２．０ｍｇ／ｔ较为适宜。生根效果不仅与ＩＢＡ浓度有关，还与继代丛生芽的状态有关。生根的小苗已成功移栽到室内的盆中。本研究结果表明，可以用组织培养技术，快速繁殖经过选优的柠檬桉优良无性系。     

黄脉爵床微体繁殖技术研究

对黄脉爵床（Ｓａｎｃｈｅｚｉａ ｎｏｂｉｌｉｓ Ｈｏｏｋ．ｆ．）微繁技术进行了研究并获成功。研究结果表明,外源植物生长调节剂及营养物质对试管芽苗增殖生长及其不定根诱导均有显著影响。试管芽苗在ＭＳ＋ＢＡ０．５ｍｇ／Ｌ＋ＺＴ０．５ｍｇ／Ｌ＋ＮＡＡ０．０３ｍｇ／Ｌ＋ＩＡＡ０．０３ｍｇ／Ｌ培养基上,可获得最大的单位芽苗数。ＭＳ（大量元素减半,肌醇１／４量）＋ＩＢＡ１．０ｍｇ／Ｌ（或ＮＡＡ０．２ｍｇ／Ｌ）＋     

草莓主栽品种Tudla遗传转化体系的建立

本研究建立起农杆菌介导的草莓主栽品种Ｔｕｄｌａ的转化体系，获得了转化植株，试管苗叶片与携双元载体ｐＭＯＧ４１０的农杆菌菌株ＥＨＡ１０５共培养３天，共培养后叶片在附加止那霉素４０ｍｇ．Ｌ＾－１的再生培养基（ＭＳ＋ＴＤＺ２．０ｍｇ．Ｌ＾－１＋ＩＢＡ０．１ｍｇ．Ｌ＾－１）上选择培养４周后，外植株再生出明显可见的转化芽，转化芽再生频率达４．５％，转化芽在附加卡那霉素２５ｍｇ．Ｌ＾－１草莓继代培养基上分化成     

珠美海棠组培苗繁殖技术的研究

以珠美涨棠为材料,研究了培养基配比、苗龄、琼脂等组培苗工厂化生产关键技术,光照条件和培养容器对组培苗生长发育的影响。结果表明,采用改良型培养基ＭＳ＋６－ＢＡ０．５ｍｇ／Ｌ＋ＩＡＡ０．２ｍｇ／Ｌ用于分化培养、１／２ＭＳ＋ＩＡＡ０．５ｍｇ／Ｌ或１／２ＭＳ＋ＩＢＡ０．５ｍｇ／Ｌ用于生根培养,苗龄３０－４０ｄ,使用接近国际标准的琼脂、光照强度１５００－２０００ｌｘ条例上生产的组培苗繁殖系数最大、有效苗最多     

苄嘧黄隆及甲黄隆的气相色谱分析方法研究

本文研究了苄嘧黄隆和甲黄隆的气相色谱分析方法。采用（１）５％ＯＶ－１０１／Ｃｈｒｏ－ｍｏｓｏｒｂＧＡＷＤＭＣＳ（０．２５～０．１８ｍｍ）；（２）５％新戊二醇己二酸聚酯／ＣｈｒｏｍｏｓｏｒｂＧＡＷＤＭ－ＣＳ（０．２５～０．１８ｍｍ）的两条色谱柱，邻苯二甲酸二戊酯为内标，氢火焰离子化检测器，标准偏差（ＳＤ）≤０．０６４％，变异系数（ＣＶ）≤２．１％，平均回收率为９６．７％～９８．８％。     

树胡椒的组织培养

树胡椒种子作为外殖体进行微繁殖,不同培养阶段适宜的培养基分别为：（１）愈伤组织诱导：ＭＳ＋ＢＡ１ｍｇ／Ｌ＋ＮＡＡ０．１ｍｇ／Ｌ＋活性碳０．０３％;（２）分化和继代：Ｂ５＋ＫＴ０．５ｍｇ／Ｌ＋ＬＡＡ０．０５ｍｇ／Ｌ和Ｂ５＋ＫＴ２ｍｇ／Ｌ＋ＩＡＡｍｇ／Ｌ;（３）生根：Ｂ５＋ＩＡＡ０．５～２ｍｇ／Ｌ。     

GnRH－A诱导泰和鸡母鸡排卵的生殖内分泌机制

本试验研究了促性腺激素释放激素类似物───［Ｄ－Ｌｅｕ￣６，Ｐｒｏ￣９］－ＧｎＲＨＮ－乙酰胺（ＧｎＲＨ－Ａ）诱导泰和鸡母鸡排卵的生理效应，藉此探讨其生殖内分泌机制。结果表明：（１）ＧｎＲＨ－Ａ具有显著刺激母鸡生殖器官发育的效应，导致母鸡卵巢、输卵管以及肝重增加（Ｐ＜０．０１），但对鸡体重没有显著的影响（Ｐ＜０．０５）；产蛋停止前１周施用ＧｎＲＨ－Ａ可维持母鸡正常产蛋的生殖生理状态。（２）ＧｎＲＨ－Ａ给药后最初２０ｄ诱发出两个鸡血浆促黄体生成素（ＬＨ）释放峰，处理组（ＧｎＲＨ－Ａ组）血浆ＬＨ浓度在此期间显著高于对照组（Ｐ＜０．０１）；然而与对照组相比较，处理组鸡血浆促卵泡素（ＦＳＨ）却没有明显变化（Ｐ＜０．０５）。（３）鸡血浆孕酮（Ｐ４）浓庆在施用ＧｎＲＨ－Ａ后明显上升，显著高于尚处休产期的对照组（Ｐ＜０．０１）。与此相反，给药后的囊初８ｄ内，鸡血浆雌二醇（Ｅ２）浓度明显降低，虽然随后略有回升，但仍低于对照组（Ｐ＜０．０１）。据此可以认为，ＧｎＲＨ－Ａ诱导卵巢和输卵管发育与鸡血浆ＬＨ、Ｐ４以及Ｅ２浓度变化密切相关，ＧｎＲＨ－Ａ是一种有效的制剂，可应用于诱导卵巢和输卵管发育及换羽前产蛋力的改善     

籼稻秋桂矮11叶原生质体的植株再生

以广东籼稻良种秋桂矮１１为材料，切取１１ｄ苗龄的叶基和叶鞘，游离原生质体，以台北３０９悬浮细胞为饲养层，放在饲养层顶部滤膜上培养。用Ｎ６＋２，４－１．５ｍｇ．Ｌ＾－１＋玉米素０．２ｍｇ．Ｌ＾－１＋水解蛋白５００ｍｇ．Ｌ＾－１＋葡萄糖０．５ｍｏｌ．Ｌ＊－１＋Ｃ０．１５％琼脂糖半凝固培养基。     

药用植物甜茶的快速繁殖

将甜茶（ＲｕｂｕｓｓｕａｖｉｓｉｍｕｓＳ．Ｌｅｅ）茎段接种在以ＭＳ和Ｗｈｉｔｅ为基本培养基分别附加不同浓度ＢＡ的培养基上。研究表明,以ＭＳ为基本培养基附加２ｍｇ／Ｌ的ＢＡ和０．５ｍｇ／Ｌ的ＮＡＡ,对芽的增殖和生长效果较显著,增殖率比对照高９１％。将试管苗转入以ＭＳ为基本培养基附加１ｍｇ／Ｌ的ＮＡＡ和２ｍｇ／Ｌ多效唑的培养基中,出根率最高达４３％,根茎粗壮。     

无病毒苹果苗试管微繁技术研究

对经脱毒的优良苹果品种北海道９号、皇家嘎拉和长富２号进行了试管微繁技术的研究。结果表明：适合于３个品种试管苗增殖的培养基为ＭＳ＋６—ＢＡ０．５ｍｇ／Ｌ＋ＮＡＡ０．０５ｍｇ／Ｌ＋蔗糖３０ｇ／Ｌ,增殖率为２５～３,≥３ｃｍ的试管苗率约为５０％。通用的生根培养基为１／２ＭＳ＋ＩＡＡ０．５ｍｇ／Ｌ＋ＩＢＡ０．５ｍｇ／Ｌ＋ＮＡＡ０．１５ｍｇ／Ｌ＋蔗糖２５ｇ／Ｌ－肌醇,平均生根率保持在７５％左右。生根试管苗采用“一步法移栽”,平均成活率在７８％以上。     

“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。     

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.     

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.     

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.     

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.     

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.