苜蓿重要农艺性状关联分子标记研究进展

将不同品种的优良性状通过品种间的杂交集中到一个品种中是育种工作的主要目标,而利用基因型选择代替传统的表型选择将大大加快育种进程和提高育种效率,其中,DNA标记的获得是进行DNA标记辅助育种的重点。随着作物分子标记辅助育种技术的快速发展,苜蓿（Medicago sativa L．）重要性状关联的分子标记研究也取得了很大进展。本文就苜蓿草产量、抗病（虫）害、抗逆性和繁殖特性等主要农艺性状关联的分子标记研究进展进行了综述,主要包括RFLP（DNA－DNA杂交）、RAPD和SSR（PCR）以及AFLP（PCR与限制性酶切技术结合）等分子标记,最后还就苜蓿分子标记辅助育种（marker assisted selection,MAS）所面临的限制因素及其在苜蓿品种改良中的应用前景进行了探讨。     

分子标记辅助选择在两系不育系选育中的应用

近年来,随着大量水稻关键基因的发现和大量分子标记的开发,分子标记辅助育种已成为培育优良杂交稻亲本的主要手段。概述了分子标记辅助选择(Marker-Assisted Selection,MAS)在两系不育系选育中的应用及取得的主要进展,并探讨了分子标记辅助育种技术在两系杂交稻培育中存在的不足及应用展望。     

短季棉早熟及相关性状的QTL定位北大核心CSCD

短季棉育种是缓解我国当前粮棉争地矛盾、实现粮棉双丰收的有效途径。研究短季棉早熟及相关性状的遗传,寻找与其相关基因紧密连锁的分子标记对于短季棉育种具有重要意义。以百棉2号×TM-1组合构建的F2为作图群体,利用SSR标记构建遗传连锁图,采用复合区间作图法对短季棉早熟及相关性状在F2群体中进行QTL定位,构建了一张含152个SSR标记、40个连锁群、总长1010.3cM、覆盖棉花基因组的22.6%、标记间平均距离为5.91cM的短季棉分子标记遗传连锁图谱,得到的40个连锁群已定位到相应的21条染色体上,为短季棉分子遗传图谱进一步饱和奠定了良好的基础;检测出22个控制早熟及相关性状的QTL,其中检测到的主效QTL可用于短季棉标记辅助选择育种。     

分子标记在油菜育种中的应用

油菜是世界上重要的油料作物之一,为了提高油菜的产量,各国都致力于油菜的育种工作。随着分子生物学的迅速发展,分子标记技术广泛地应用油菜育种。本文从遗传和物理图谱构建、基因的定位与克隆、数量性状位点的遗传分析、遗传多样性的评估、分子标记辅助选择等方面,综述了分子标记在油菜育种中的应用。     

DNA分子标记技术在小麦遗传育种中的应用综述

在简述DNA分子标记的种类和特点的基础上,综述了分子标记技术在小麦遗传育种研究中主要应用于遗传图谱构建、基因标记和定位、品种鉴定和指纹图谱绘制、物种亲缘关系和遗传多样性研究及分子标记辅助育种等方面的现状,并对分子标记技术的发展和应用前景进行了展望。     

我国“应县小黑豆”对SCN4号生理小种抗性的SSR及ISSR分子标记研究

本研究以"应县小黑豆"×"晋豆23"杂交组合F2群体为材料,用塑膜钵柱法进行抗性鉴定,利用分离体分组分析法(BSA)结合SSR和ISSR标记技术对抗性基因进行分子标记筛选和定位,旨在实现大豆孢囊线虫抗性育种中亲本和杂交后代的分子标记辅助选择.筛选到2个与抗SCN基因座位连锁的分子标记Satt038和ISSR811.Satt038片段含180bp和185 bp,为共显性标记,在F2群体中的分离比为121;ISSR标记ISSR811为显性标记,片段长350bp,F2群体分离比为13.2个标记在F2群体中呈孟德尔式遗传.通过JOINMAP分析,微卫星标记Satt038、ISSR标记ISSR811与抗SCN基因座位的遗传距离分别为26.9cM和10.2 cM.还探讨了分子标记Satt038和ISSR811用于大豆抗SCN育种进行分子标记辅助选择的可能性.     

分子标记辅助选择选育高抗性淀粉水稻新品种

为建立高效高抗性淀粉(RS)水稻新品种培育的分子标记辅助选择育种体系,以降糖稻1号为高RS基因供体材料,分别与产量较高的密阳23、秀水123和沪稻55进行杂交,并利用3个杂交群体早世代籽粒垩白特性、直链淀粉含量(AC)及功能标记(CAPS/Spe I)进行高RS水稻辅助选择育种。结果表明,籽粒的垩白特性与RS含量有很高的关联性,早世代通过垩白度和垩白粒率可以淘汰大部分低RS含量单株。利用控制水稻RS合成主效基因sbe3-rs上的一个功能标记(CAPS/Spe I)确定sbe3-rs基因型纯合的高RS单株,经连续自交和辅助选育,最终培育了3个兼具功能性、高产和优质的高RS水稻品系RS23、RS123和RS55。本研究首次提出利用对杂交群体早世代籽粒垩白特性挑选淘汰大部分低RS含量单株,同时结合分子标记辅助选择显著提高选择效率和准确度,建立了高RS水稻品种选育的高效分子标记辅助选择育种体系。本研究可为开展高RS育种提供新的理论依据和基础材料。     

分子标记技术在杉木研究中的应用

综述了分子标记技术在杉木种质资源鉴定、群体遗传多样性研究、遗传连锁图谱构建和数量性状位点(QTL)定位及分子标记辅助选择育种等方面的应用进展,指出目前该方面研究存在的问题,并展望了分子标记技术在杉木研究中的应用前景     

DNA分子标记技术及其在小麦育种及遗传研究中的应用

本文介绍了几种常用的DNA分子标记,如RFLP、RAPD、AFLP、SSR、STS、SNP等,并简要综述了分子标记技术在小麦遗传育种研究中的应用现状,包括基因标记与定位、遗传图谱构建、外源染色体鉴定与标记、种质资源鉴定和辅助育种等。     

普通小麦抗条锈新种质-WT212抗性基因的RAPD标记*

在小麦抗锈病育种中,若利用DNA分子标记辅助选择,可突破传统上利用侵染后表型进行选择的方法,不受环境条件和育种材料中基因背景的影响,可对小麦种质资源及杂种后代中的抗锈病基因进行准确而快速地选择,加快育种的进程（牛永春等,1998）.本实验对高抗条锈流行小种条31号、32号及水源11-6的普通小麦抗条锈新种质-WT212抗性基因进行了初步的RAPD分析,以期确定其抗性基因的来源、类型和差异,为抗条锈新抗源基因在小麦抗病育种及抗条锈分子标记辅助选择中的利用及新抗性基因的分离与转化提供基本资料.     

低氮和干旱胁迫对富士和秦冠生长及氮素利用的影响

【目的】以富士（Fuji）、 秦冠（Qinguan）嫁接在平邑甜茶（Malus hupehensis Rehd.）上的当年生盆栽苗为试验材料,采用砂培方法,研究了缺氮胁迫和干旱对富士和秦冠生长情况、 光合参数、 植株各部位氮磷钾含量及氮素利用效率的影响,分析比较了低氮干旱条件下富士和秦冠生长及氮素利用的差异,以期为果树生产高效肥水利用提供理论指导。【方法】试验共设四个处理: 正常氮正常水（ZZ）、 低氮正常水（DZ）、 正常氮干旱（ZG）、 低氮干旱（DG）。氮素和水分均设置两个水平,分别为正常氮（6 mmol/L NO-3-N）、 低氮（0.3 mmol/LNO-3-N）、 正常供水（保持盆中砂子相对含水量为饱和含水量的80%~85%）、 干旱处理（保持盆中砂子相对含水量为饱和含水量的60%~65%）。【结果】富士和秦冠的生物量（茎和叶）、 株高茎粗等生长指标以及光合速率、 气孔导度、 蒸腾速率均为正常氮正常水（ZZ）＞低氮正常水（DZ）＞正常氮干旱（ZG）＞低氮干旱（DG）,并且相对应处理下秦冠的以上指标均高于富士;正常供水下,缺氮处理使富士、 秦冠的根冠比比正常氮处理均有所增加,富士提高了2.05%,秦冠提高了22.40%。富士和秦冠的氮、 磷、 钾含量均表现出正常氮正常水（ZZ）＞低氮正常水（DZ）＞正常氮干旱（ZG）＞低氮干旱（DG）; 氮、 钾元素含量在植株各部位的分布顺序依次是叶＞根＞茎,磷元素则是根＞叶＞茎;光合氮素利用效率（PNUE）和氮素利用效率表现为秦冠处理之间差异极显著,富士处理之间差异不显著;秦冠的PNUE和NUE明显高于富士,在低氮正常水（DZ）处理下,秦冠氮肥利用率比富士高42.07%,在低氮干旱（DG）处理下高64.14%;低氮胁迫下富士和秦冠的NUE显著提高,并且秦冠提高的幅度高于富士。【结论】施用氮肥能够显著提高富士与秦冠的干物质量,同等水肥条件下,秦冠生长优于富士;水分亏缺会减少叶片对氮的吸收,干旱条件下适度增施氮肥,可提高果树的抗旱能力;低氮干旱胁迫下秦冠的生长指标、 光合指标及氮素利用效率指标均优于富士,表现出较强的抗低氮干旱胁迫的能力。     

Pasture Vegetation Elemental Analysis by Laser-Induced Breakdown Spectroscopy

Laser-induced breakdown spectroscopy (LIBS) is a new technique for the analysis of plant material. This study investigates the application of LIBS to pasture-based plant samples. The LIBS measurements were obtained from pelletized pasture samples (100 samples) that had been also analyzed by inductively coupled plasma–optical emission spectroscopy (ICP-OES) following microwave digestion for calibration and comparison purposes. Comparisons for elements sodium (Na), potassium (K), magnesium (Mg), calcium (Ca), manganese (Mn), iron (Fe), copper (Cu), zinc (Zn), boron (B), phosphorus (P), and sulfur (S) showed that LIBS could be used for almost all the standard profile total elements with concentrations down to low mg/kg levels (observed error of Na: 0.024 percent, K: 0.18 percent, Mg: 0.016 percent, Ca: 0.073 percent, P: 0.017 percent, Mn: 31 mg/kg, Fe: 150 mg/kg, Zn: 6.6 mg/kg, and B: 1.1 mg/kg). Elemental analysis at less than mg/kg levels was not possible using LIBS. The elements S and Cu were particularly difficult to analyze with reliability using LIBS at the concentration levels found in the plant samples. Replacing microwave digestion and subsequent ICP analysis with a direct analysis of dried plant samples using LIBS has the potential to improve the productivity and reduce the cost of testing.     

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 from individuals who have expertise and a record of accomplishment in research areas related to ecology,agro-hydrology,     

Macroinvertebrates in North American tallgrass prairie soils: effects of fire, mowing, and fertilization on density and biomass

The responses of tallgrass prairie plant communities and ecosystem processes to fire and grazing are well characterized. However, responses of invertebrate consumer groups, and particularly soil-dwelling organisms, to these disturbances are not well known. At Konza Prairie Biological Station, we sampled soil macroinvertebrates in 1994 and 1999 as part of a long-term experiment designed to examine the effects and interactions of annual fire, mowing, and fertilization (N and P) on prairie soil communities and processes. For nearly all taxa, in both years, responses were characterized by significant treatment interactions, but some general patterns were evident. Introduced European earthworms (Aporrectodea spp. and Octolasion spp.) were most abundant in plots where fire was excluded, and the proportion of the total earthworm community consisting of introduced earthworms was greater in unburned, unmowed, and fertilized plots. Nymphs of two Cicada genera were collected (Cicadetta spp. and Tibicen spp.). Cicadetta nymphs were more abundant in burned plots, but mowing reduced their abundance. Tibicen nymphs were collected almost exclusively from unburned plots. Treatment effects on herbivorous beetle larvae (Scarabaeidae, Elateridae, and Curculionidae) were variable, but nutrient additions (N or P) usually resulted in greater densities, whereas mowing usually resulted in lower densities. Our results suggest that departures from historical disturbance regimes (i.e. frequent fire and grazing) may render soils more susceptible to increased numbers of European earthworms, and that interactions between fire, aboveground biomass removal, and vegetation responses affect the structure and composition of invertebrate communities in tallgrass prairie soils.     

Variation in quality parameters between and within 14 Nordic tree fruit and berry species

Abstract

A 3-year study was carried out to investigate quality parameters in 14 tree fruit and berry species grown in southern Norway. The species were blueberry, apple, aronia, sour cherry, sweet cherry, red raspberry, strawberry, blackcurrant, gooseberry, red currant and elderberry, harvested along with wild bilberry, cloudberry and lingonberry. Significant differences between species were identified for all quality parameters. The coefficient of variation between species was lowest for pH (12.5%), dry matter (18.9%) and soluble solids (25.3%), followed by titratable acids (59.3%), total phenolics (83.8%), antioxidant capacity FRAP (85.7%) and antiradical power by the DPPH-assay (97.8%), total monomeric anthocyanins (132%) and ascorbic acid (137%). Average coefficient of variation within species were lower and ranged from 4 (pH) to 62% (ascorbic acid). Only the FRAP values were significantly affected by harvesting year with lower levels in 2004 than in 2005 and 2006. There were significant interactions between species and harvesting year for dry matter, soluble solids, pH, ascorbic acid and FRAP. The results indicate generic ranges in composition within species independent upon growing location and climate, and the composition of the tree fruits and berries is not likely to deviate from these ranges. It is concluded that desirable composition of tree fruits and berries and their products should primarily be achieved by selection among species rather than searching fors broadened variation within individual species.     

Potassium Fixation and Release Characteristics in Rhizosphere and Nonrhizosphere Soils for a Rapeseed–Rice Cropping Sequence

Potassium (K) fixation and release in soil are important factors in the long-term sustainability of a cropping system. Changes in K concentration and characteristics of K fixation and release in rhizosphere and nonrhizosphere soils in the rapeseed (Brassica napus L.)–rice (Oryza sativa L.) rotation were investigated using a rhizobox system. The concentrations of different forms of K in both rhizosphere and nonrhizosphere soils decreased with plants compared to without plants, regardless of K fertilizer application. Potassium uptake by crops mainly came from the rhizosphere soil. In the treatment without K fertilizer (–K), the main form of K supplied by the soil to the crops was 1.0 mol L^?1 nitric acid (HNO₃) nonextractable K, followed by nonexchangeable K, and then exchangeable K. In the treatment with K fertilizer (+K), the main K forms supplied by the soil to the crops were exchangeable K and nonexchangeable K. The amount and rate of K fixation after one cycle of the rapeseed–rice rotation was greater in rhizosphere soil than in nonrhizosphere soil. The amount and rate of K fixation of soil in the +K treatment were significantly less than in the –K treatment. The cumulative amounts of K released with 1.0 mol L^?1 ammonium acetate (NH₄OAc) and 1.0 mol L^?1 HNO₃ extraction increased with the increasing numbers of extractions, but the K-releasing power of soil by successive extraction decreased gradually and finally became almost constant. The release of K was less in rhizosphere soil than in nonrhizosphere soil. The release of K in the +K treatment was similar to that in the –K treatment in rhizosphere soil, but the K release in nonrhizosphere soil was greater with the +K than the –K treatment. Overall, the information obtained in this study will be helpful in formulating more precise K fertilizer recommendations for certain soils.     

Increase in auxiliary photoprotective photosynthetic pigments in wheat seedlings induced by Azospirillum brasilense

Inoculation of wheat seedlings with the plant growth-promoting bacterium Azospirillum brasilense Cd was immobilized in alginate microbeads and, without applying any stress, significantly increased the quantity of several photosynthetic pigments, such as chlorophyll a, chlorophyll b, and the auxiliary photoprotective pigments violaxanthin, zeaxanthin, antheroxanthin, lutein, neoxanthin, and β-carotene. This resulted in greener plants with no apparent visible stress. After monitoring the quantity of photosynthetic pigments for 4 weeks, we observed that inoculated plants had higher quantities of pigments in shoot and stem. The greatest difference in the quantity of all pigments between inoculated and noninoculated plants occurred in the first week of growth. Regardless of treatment, the quantity of pigments in stems was three to four times less than the quantity of these pigments in shoots. Application of Azospirillum, either as liquid inoculant or as alginate microbeads, did not alter the positive effect of the bacteria on pigment production or the positive response of the plants towards A. brasilense Cd inoculation.     

In-situ enrichment and analysis of atrazine-degrading microbial communities using atrazine-containing porous beads

We examined the community composition of microbes that colonized atrazine-containing beads buried in agricultural soils that differed in atrazine treatment history. Bacterial abundance was 5-40-fold greater in atrazine-fortified beads. In beads containing 20 mg atrazine kg⁻¹ buried in soil with a history of atrazine application (conditioned soil), the abundance of Actinobacteria increased approximately 80-fold whereas in control soil, Actinobacteria were enriched only 10-fold and the gamma-Proteobacteria and Planctomycetes increased by 60- and 25-fold, respectively. The gamma-Proteobacteria were enriched by 120- and 230-fold in beads containing 200 mg atrazine kg⁻¹ in conditioned and control soil, respectively. The results demonstrate that BioSep^® beads are a suitable matrix for recruiting a diverse subset of the bacterial community involved in atrazine degradation.     

Genetic similarities among Spanisch populations of Agropyron, Elymus and Thinopyrum, using PCR-based markers

Arbitrary oligonucleotides were used as primers to amplifygenomic DNA of 48 wild Spanish populations of Agropyroncristatum, Elymus hispanicus,E. caninus,E. repens,Thinopyrum curvifolium, Th.junceum and Th.intermedium. Genetic diversity was analysedusing nineteen primers. The number of amplified products ranged from8 to 18 per primer and a total of 240 markers were scored. Differentlevels of intraspecific genetic diversity were found, the allogamousspecies E. repens andTh. intermedium being themost variable. Jaccard's similarity coefficients for internalmeasure within and between populations were used to produce a clusterdiagram. The results demonstrate differences in the degree ofsimilarity between taxonomic units. Interpopulational variability andinterspecific genomic relationships of these species arediscussed.     

Mycorrhizae,biocides, and biocontrol. 4. Response of a mixed culture of arbuscular mycorrhizal fungi and host plant to three fungicides

The effects of three commonly used fungicides on the colonization and sporulation by a mixture of three arbuscular mycorrhizal (AM) fungi consisting of Glomus etunicatum (Becker & Gerd.), Glomus mosseae (Nicol. & Gerd.) Gerd. & Trappe, and Gigaspora rosea (Nicol. & Schenck) in symbiosis with pea plants and the resulting response of the host-plant were examined. Benomyl, PCNB, and captan were applied as soil drenches at a rate of 20 mg active ingredient kg^-1 soil 2 weeks after transplanting pea seedlings in a silty clay-loam soil containing the mixed inocula of AM fungi (AM plants). Effects of fungicides were compared to untreated plants that were inoculated with fungi (AM control). The effect of mycorrhizal inoculation on plant growth was also examined by including nonmycorrhizal, non-fungicide-treated plants (non-AM control). Fungicides or inoculation with AM fungi had only a small effect on the final shoot weights of pea plants, but had greater effects on root length and seed yield. AM control plants had higher seed yields and lower root lengths than the corresponding non-AM plants, and the fungicide-treated AM plants had intermediate yields and root lengths. Seed N and P contents were likewise highest in AM control plants, lowest in non-AM plants, and intermediate in fungicide-treated AM plants. All three fungicides depressed the proportion (%) of root length colonized by AM fungi, but these differences did not translate to reductions in the total root length that was colonized, since roots were longer in the fungicide-treated AM plants. Pea plants apparently compensated for the reduction in AM-fungal metabolism due to fungicides by increasing root growth. Fungicides affected the population of the three fungi as determined by sporulation at the final harvest. Captan significantly reduced the number, relative abundance, and relative volume of G. rosea spores in the final population relative to the controls. The relative volume of G. etunicatum spores was greater in all the fungicide-treated soils, while G. mosseae relative volumes were only greater in the captan-treated soil. These findings show that fungicides can alter the species composition of an AM-fungal community. The results also show that AM fungi can increase seed yield without enhancing the vegetative shoot growth of host plants.