蛋鸭骨桥蛋白基因OPN的多态性与蛋品质性状的相关性研究

骨桥蛋白(osteopontin,OPN)是一种分泌型磷酸化蛋白,其可能在蛋壳形成过程中发挥作用。为了分析蛋鸭OPN基因单核甘酸多态性(SNPs)及其与蛋品性状的相关性,本研究以山麻鸭和绍兴鸭(Anas platyrhyncha domestica)各100个个体为研究材料,采用直接测序法进行OPN基因外显子7 SNPs的筛选。结果显示,山麻鸭中共发现8个突变位点,绍兴鸭有9个突变位点。在山麻鸭群体中,G544C、A671G,G672C、T761C和T873C 5处SNPs对部分蛋品性状有极显著或显著作用。而绍兴鸭群体中,A671G、G672C和T761C 3处SNPs对部分蛋品性状有极显著或显著作用。其中,山麻鸭A671G及G672C位点有3种基因型,对蛋壳厚度,BB型个体均值极显著高于其他基因型,对哈氏单位,AA型个体均值显著高于其他基因型。T761C位点有3种基因型,BB基因型对300日龄蛋壳厚度极显著优于AB/AB基因型。T873C位点,BB基因型在300日龄蛋壳厚度和蛋壳强度及500日龄蛋壳厚度、蛋壳强度和蛋壳重均高于其他基因型。因此推断,位点T761C的B等位基因和T873C的B等位基因为改善蛋品性状的有利基因。绍兴鸭A671G和G672C位点在500日龄蛋形指数方面,AB基因型均值极显著高于AA和BB基因型。在T761C位点,BB型和AB型的300日龄蛋壳强度和蛋壳厚度均值显著高于AA基因型,在500日龄蛋形指数、蛋重、蛋壳重和蛋内容物重4个性状上,AB基因型均值略高于AA基因型,极显著高于BB基因型。结果表明,OPN基因可作为蛋品性状分子标记,为蛋鸭的标记辅助选择育种提供基础资料。     

Analysis of SNP Markers for Blue-shelled Gene in Chicken by PCR-SSCP

决定绿壳蛋鸡壳色的Oocyan(O)基因座位位于一号染色体。绿色蛋壳的色素主要有原卟啉、胆绿素以及胆绿素的锌络合物，将上述色素代谢途径中的酶对应的基因在家鸡基因组序列中进行比对，没有发现与O基因座位相符的位点。基于ALEV1周围微卫星标记较少，在家鸡一号染色体基因组序列上选取距离ALEV1上游3.5 cM的位点设计引物进行PCR-SSCP分析，寻找与绿壳基因座位紧密连锁的SNP标记位点，并且分析标记位点基因型与O位点不同基因型之间的相关性。结果表明,一个标记与绿壳基因位点紧密连锁，该标记上发生2个点突变，分别是家鸡Chr1:61754089T->A与Chr1:61754175A->T上的颠换。在纯合绿壳蛋鸡群体中，81%的个体在2个位点均发生突变，标为AA型，杂合绿壳群体中AB型为89%，粉壳蛋鸡群体中93%的个体与红色原鸡序列一致，标为BB型。在绿壳蛋鸡育种中，建议以AA型作为分子标记提高绿壳蛋鸡育种工作的效率。     

二穗短柄草MADS-BOX基因AGL6和FUL1的可变拼接和表达模式分析

MADS-BOX基因家族是一类调控植物发育的重要转录因子,AGAMOUS LIKE 6(AGL6)和FRUITFULL(FUL1)属于其亚家族。本研究克隆了二穗短柄草(Brachypodium distachyon)2个MADS-BOX基因Bd AGL6和Bd FUL1的c DNA序列,分析了这2个基因的可变拼接和表达模式。结果表明,Bd AGL6基因在转录过程中,由于内含子部分保留机制,发生可变拼接,形成了3个转录本(Bd AGL6-1、Bd AGL6-2和Bd AGL6-3);Bd AGL6-3与水稻(Oryza sativa)、玉米(Zea maize)等禾本科植物中的AGL6转录因子序列高度同源;和Bd AGL6-3相比,Bd AGL6-1在C末端结构域插入额外的7个氨基酸;Bd AGL6-2在C末端结构域插入额外的5个氨基酸。q RT-PCR结果显示,Bd AGL6在花中高水平表达,其中Bd AGL6-3表达最强,Bd AGL6-1和Bd AGL6-2表达较弱。Bd FUL1基因的前体m RNA同样发生了可变拼接,产生2个转录本(Bd FUL1-1和Bd FUL1-2);两者的表达模式相似,除了在花和茎中表达之外,在幼苗的叶中也有表达。研究结果为进一步了解MADS-BOX基因家族的生物学功能提供了参考资料。     

鸭早期胚胎发育相关基因消减文库的构建与分析

动物胚胎发育受到多个基因的表达调控,为探索鸭早期胚胎发育的分子机制,本实验构建了鸭早期胚胎发育相关基因的消减文库,筛选与鸭早期胚胎发育相关的候选基因.采集两个不同时段的鸭(Anas platyrhynchos)胚(6和20 h)分别作为驱动组(driver)和实验组(tester),通过由双链特异性核酸酶(designatedduplexspecific nuclease,DSN)介导的消减杂交方法,构建鸭早期胚胎发育相关基因的消减文库,并进行生物信息学分析.结果表明,在构建好的文库中随机挑选216个阳性克隆进行测序,最终共得到54条有效序列,平均长度为1 084 bp.将这些序列在GenBank中进行BLAST比对,其中44条有同源基因,基因注释(geneontology,GO)显示,这些基因与代谢、建立细胞定位、生物调节等各种生物途径相关,它们在鸭早期胚胎发育过程中的不同方面(如神经系统发育、免疫调节、转录调节等)都发挥着非常重要的作用.这些差异表达基因的分离与鉴定,有助于家禽早期胚胎发育的相关研究.     

光诱导转录因子MdMYB1对苹果果皮花青苷合成调控的表达分析

MdMYB1是调控苹果(Malus domestica)果皮着色的重要转录因子。黄绿色苹果脱袋后果面现红色,为了研究其花青苷合成表达调控机制,本研究采用Real-time PCR方法分析了光照对4种不同颜色苹果黄绿色品种金冠和陆奥、红色品种富士、深红色品种红星果皮转录因子MdMYB1表达的影响。研究表明,不同颜色苹果品种着色速度、面积和MdMYB1转录表达速度及累积量有关。通过金冠、红星苹果果实套袋处理,研究了果皮着色过程中结构基因苯丙氨酸解氨酶(MdPAL)、花青素合成酶(MdANS)、查尔酮异构酶(MdCHI)和类黄酮糖基转移酶(MdUFGT)的相对表达变化,结果表明,红星处理和对照转录因子MdMYB1及结构基因在着色过程中是持续表达的,而黄绿色品种金冠则没有出现持续表达的态势。金冠苹果转录因子MdMYB1与结构基因MdCHI表达模式相同,与MdPAL相似,经分析MdMYB1和结构基因MdCHI和MdPAL启动子序列,金冠苹果携带等位基因MdMYB1-2,其启动子区域有多个G-box光结合位点,据此推测,光照调控的光敏色素通过结合其启动子区域的G-box位点来调控转录因子MdMYB1-2;MdCHI在启动子区域含有顺式作用元件MBS,MdPAL含有顺式作用元件MBS和MBSⅡ,说明转录因子MdMYB1-2调控结构基因MdCHI表达,并有可能调控基因MdPAL或有密切相关性。结果表明,红星果皮全面着色可能与着色期转录因子及结构基因的持续表达和基因间协调表达有关;而金冠果皮在着红色过程中光诱导的转录因子MdMYB1调控的结构基因起决定性作用。     

兴义鸭MEF2D基因的多态性及组织差异表达研究

肌细胞增强因子2D(myocyte enhancer factor 2D,MEF2D)是属于肌细胞增强因子2(myocyte enhancer factor 2,MEF2)基因家族一员,被认为与骨骼肌生长发育有关。为研究MEF2D基因的多态性对兴义鸭(Anas platyrhynchos domestica)屠宰性状的影响,本研究利用PCR扩增结合测序的方法对90日龄兴义鸭MEF2D基因外显子区域进行SNP位点筛选,同时运用q RT-PCR对0~150日龄兴义鸭不同组织中该基因m RNA表达规律进行探究。结果显示,在MEF2D基因外显子区域共发现6个SNPs,均为同义突变;群体遗传学分析显示,6个多态位点均表现为中度多态(0.25PIC0.5),经χ2检验表明兴义鸭群体在这6个多态位点均处于Hardy-weinberg平衡状态(P0.05);各SNPs与屠宰性状关联分析发现,T16236C位点的不同基因型在活重和屠体重存在显著差异(P0.05),A16305C和A21071G位点对多项屠宰指标存在显著或极显著影响(P0.05或P0.01),G16359C位点的CC基因型个体半净膛重、全净膛重显著高于GG基因型个体(P0.05),其余SNPs对屠宰性状无显著影响(P0.05);单倍型分析结果表明,兴义鸭CGCCCG单倍型的半净膛重和半净膛率显著或极显著高于其他单倍型(P0.05或P0.01);TACCCA单倍型的腿肌重显著高于其他单倍型(P0.05);TATAGA单倍型的全净膛率显著高于其他单倍型(P0.05);q RT-PCR结果显示,在10个组织中均检测到了MEF2D基因的表达,说明该基因的表达具有广谱性,且公母差异显著,母鸭腿肌中的表达量最高,心、肝脏、肺脏、肾脏、十二指肠、大脑、胸肌、腺胃中的表达量较高,而公鸭心肌、肝脏中的表达量最高,十二指肠、大脑、胸肌、腿肌、腺胃中的表达量较高。研究结果可为兴义鸭屠宰性状的分子标记辅助选育提供参考,同时为鸭MEF2D基因结构功能的进一步研究提供理论基础资料。     

鸭PPARs启动子扩增、序列比较及其转录因子表达模式的聚类分析

过氧化物酶体增殖物激活受体(peroxisome proliferators-activated receptors,PPARs)是核激素受体超家族的一员,分α、β/δ、γ3个亚型,是调节细胞生长和分化的重要因子.为了解PPARs各成员在鸭(Anas platyrhynchos)骨骼肌发育中的不同作用,本研究克隆了鸭PPARα、PPARβ和PPARγ基因启动子区,预测其共同转录因子结合位点,用qRT-PCR检测PPARs及共同转录因子在鸭胚及出生后骨骼肌发育过程中的表达,比较表达模式并进行聚类分析.结果表明,扩增出鸭PPARα、PPAEβ和PPARγ启动子序列分别为2 526、1 631和2 942 bp,GenBank登录号分别为KX845431、KX845432和KX845433.鸭PPARs启动子区存在典型的CAAT-box、TATA-box顺式作用元件,预测存在共同的特异性蛋白1(specificity protein 1,Sp1)、核因子κB(nuclear factor kappa B,NF-κB)和CCAAT增强子结合蛋白(CCAAT/enhancer binding protein alpha,C/EBP-α)转录因子结合位点.PPARs成员在鸭胸肌、腿肌组织中均有表达.在胸肌中,转录因子NF-κB与PPARβ基因的表达模式一致;在腿肌中,Sp1、NF-κB、PPARβ和PPARγ的表达模式一致.PPARs各成员均参与了骨骼肌的发育调控,PPARβ作用可能更大;PPAPβ、PPARγ在鸭骨骼肌发育过程中的功能可能相似;此外,NF-κB可能调控PPARβ在骨骼肌中的表达.研究结果为PPARs基因的表达和功能鉴定提供理论依据.     

大麦白化颖壳突变体的转录组学分析

为了探究大麦白化颖壳突变体形成机理,以白化颖壳突变体(AL)和野生型植株(WT)为试验材料,对2份材料抽穗期的颖壳进行转录组测序分析,通过Illumina Hi SeqTM2500高通量转录组测序技术分别从WT和AL中获得2.7 Gb和4.1 Gb有效数据,拼接组装后得到64 634条通用基因(unigenes),其中长度大于1 kb的有23 696条。通过对2份材料间差异基因的筛选,共得到672个差异表达基因(DEGs),其中139个上调表达,533个下调表达。GO功能富集分析发现,在分子功能类型中注释的差异基因主要与叶绿体相关;KEGG显著富集分析发现差异基因广泛涉及碳代谢、光合作用等调控途径。对其中6个相关基因进行了RT-qPCR验证,表达趋势与RNA-Seq测序结果一致。表明AL的形成可能是由于叶绿体形成和发育相关基因的表达受到抑制,进一步导致了光合作用的下降,该研究结果对深入探究大麦的白化形成机理具有重要的参考价值。     

鸭蛋蛋心颜色等级模型研究

应用机器视觉技术，研究出鸭蛋蛋心颜色自动分级系统中的蛋心颜色分级模型。鸭蛋蛋壳颜色与蛋心区域颜色信息有关，可用光密度值进行模糊识别。无论是青壳蛋还是白壳蛋，其蛋心颜色等级G与H，S(色饱和度)，I三个变量间存在着显著的线性相关关系。     

猪FUT1基因启动子区的确定及活性分析

F18大肠杆菌(Escherichia coli F18,E.coli F18)是养猪(Susscrofa)业中发生最普遍、危害最大的病原菌之一,球系列鞘糖脂生物合成通路及通路中α-(1,2)岩藻糖转移酶1基因(alpha(1,2)fucose transferase 1,FUT1)对断奶仔猪F18抗性具有重要调控作用.本研究运用生物信息学技术挖掘课题组前期获得的断奶仔猪转录组测序结果,确定FUT1基因的转录起始位点和启动子区.同时对启动子区序列进行CpG岛分析;采用双荧光素酶报告基因以及AliBaba 2.0软件,分别分析启动子区活性和CpG岛序列潜在的转录结合位点.通过比对人类(Homo sapiens)和猪的基因序列信息数据库,结果表明,FUT1基因转录起始区域具有5种可变剪接(AS-1,AS-2,AS-3,AS-4和AS-5)和2个启动子区域(启动子1和启动子2);双荧光素酶报告基因检测结果进一步显示,FUT1基因启动子2的转录活性极显著高于启动子1的转录活性(P＜0.01),启动子2的活性是启动子1的2.75倍,根据结果可以推测启动子2在转录过程中起主导作用;CpG岛分析显示,猪FUT1基因启动子1和启动子2分别存在一个CpG岛.FUT1启动子1扩增片转录因子预测分析表明,FUT1基因启动子1存在20个潜在的转录因子结合位点,并且Sp1出现在多个转录结合位点处.本研究结果为猪FUT1基因的甲基化检测和调控机制分析提供一定的基础和依据.     

“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     

Soil-profile distribution of primary and secondary plant-available nutrients under conventional and no tillage

Nutrient distributions under no tillage (NT) compared with conventional disk-and-bed tillage (CT) management in the warm, humid region of the southeastern USA need to be assessed so that future placement, quantity, and type of fertilizers can be altered, if necessary, to efficiently match crop demands. We determined soil-profile distributions of pH, N, P, S, K, Ca, Mg, Na, Zn, Fe, Mn, and Cu to a depth of 0.9 m at the end of 8.5 years of continuous CT and NT management on a Weswood silty clay loam (fine, mixed, thermic Fluventic Ustochrept) in southcentral Texas. Most dramatic changes occurred within the 0–0.05 m depth, where soil under NT had lower pH, Fe, and Cu than under CT, but greater P, K, Zn, and Mn. Greater P and K under NT than under CT also occurred below the till-zone (0.15–0.3 m). At a depth of 0–0.3 m, soil under NT contained greater amounts of extractable P, K, Zn, Fe, Mn, and Cu than under CT. Nitrogen fertilization had little effect on nutrient distributions, except resulting in greater extractable K at 0–0.05 m and greater nitrate at 0–0.15 m. Few changes in soil-profile distributions were observed for extractable S, Ca, Mg, and Na. Long-term continuous use of NT on this fine-textured, high-fertility (except for N) soil had no apparent adverse effects on nutrient distributions relative to CT, but enhanced conservation and availability of P, K, Zn, Fe, Mn, and Cu near the soil surface where crop roots proliferate.     

Assessing the effectiveness of conservation measures: Resolving the “wicked” problem of the Steller sea lion

“Wicked” problems are those that are complex and that change when solutions are applied. Many conflicts in conservation fall into this category. The study approached the problem of how to constrain the apparent wickedness of a problem in the conservation management of a species by using simple empirical indicators to carry out iterative assessment of the risk to a population and to document how this risk evolves in relation to the addition of new data and the implementation of management actions. Effects of high levels of uncertainty within data and also concerning population structure were examined through stochastic simulation and by exploration of scenarios. Historical trends in the example used, the Steller sea lion, showed rapid declines in abundance in some regions during the 1980s. The current total population is 130,000-150,000 Steller sea lions through Alaska and British Columbia and this number has been stable since about 1990 in spite of regional differences in population dynamics. Regional differences in the sequence of changes in the number of pups and non-pups, suggested that an internal re-distribution of juveniles could have happened between 1980 and 1990. Current productivity also appears close to the long-term mean. Stochastic population projection using various scenarios showed that, based upon this history, the risk of extinction for the population has declined and is below reasonable thresholds for considering the population to be endangered. The trends in risk suggest that management actions taken since 1990 have probably been effective. Consequently, the conservation management objectives for the Steller sea lion are probably being met. The approach provides a mechanism, based upon experience and scenario analysis, for exploring future policy options and may help to constrain the debate amongst stakeholders about the cost-benefit trade-offs associated with different options.     

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.     

Enhanced establishment and growth of giant cardon cactus in an eroded field in the Sonoran Desert using native legume trees as nurse plants aided by plant growth-promoting microorganisms and compost

To evaluate the feasibility of long-term desert reforestation technology of mixed vegetation, cardon cactus (Pachycereus pringlei) seedlings from indoor and outdoor nurseries were planted in the field adjacent to one seedling of potential legume nurse trees: mesquite amargo (Prosopis articulata), yellow palo verde (Parkinsonia microphylla), and blue palo verde (Parkinsonia florida). Some of the planting holes were also supplemented with common dairy compost. Additionally, the combinations of legume tree–cactus were inoculated with either a consortium of desert arbuscular mycorrhizal (AM) fungi, plant growth promoting bacteria (PGPB; the diazotroph Azospirillum brasilense Cd, and the phosphate solubilizer Paenibacillus sp.), or a mixture of all. The field experiments were evaluated periodically during 30 months for survival and growth. Cardons reared in an outdoor screen house survived better in the field than those reared in a controlled growth chamber and hardened later outdoors. Association with any legume nurse tree increased survival and enhanced growth of untreated cardons. For cardons growing alone, application of either compost, AM fungi, and all the treatments combined increased survival. For these plants, no treatment affected plant growth during the first 3 months after transplanting. Later, all treatments, except for AM fungi, enhanced plant growth. However, only 2 years after transplanting the enhanced growth effect of AM fungi was also significant. In the presence of the legume nurse trees, transient positive effects on cardon growth were recorded. General evaluation after 30 months of cultivation showed that the treatments positively affected cardon growth when growing alone or in combination only with mesquite amargo but not with the other two legume trees. This study proposes that young legume trees have the capacity to enhance survival and growth of cardon cactus, depending on the legume cactus combination. Additional treatments such as compost or PGPB can either amplify the effect or else attenuate it.     

Karyotypic and genome size variation in Cajanus cajan (L.) Millsp. (pigeonpea) and some wild relatives

Detailed karyotypes and 4C DNA amounts have been studied in five cultivars of Cajanus cajan and 20 species belonging to Cajanus, Rhynchosia, Dunbaria, Flemingia and Paracalyx. C. cajan shows intraspecific variability and its karyotype is most similar to that of C. cajanifolius (sect. Cajanus) in the morphology and number of satellite chromosomes and the lack of any correlation between chromosome size within the complement and asymmetry. Karyotypes of C. lineatus and C. sericeus belonging to sect. Atylia are similar with respect to maximum r-index and the ratio of longest and shortest chromosomes in their respective complements. C. acutifolius (sect. Frutocosa) is distinct in having a very low ratio (1.44) between the longest and the shortest chromosomes, while in C. albicans, C. goensis, C. scarabaeoides (sect. Cantharospermum) there is no chromosome pair with r-index >2.0. C. mollis and C. volubilis (sect. Volubilis) show similarity with regard to ratio between the longest and the shortest chromosomes and a distinct chromosome pair with an arm ratio of 2.7 and C. platycarpus is distinct (sect. Rhynchosoides) in having the smallest ratio (1.36) between the longest and the shortest chromosomes. 4C DNA amounts in Cajanus and Rhynchosia vary between 3.28 pg to 11.69 pg and 4.92 pg to 11.13 pg respectively, while in Dunbaria, Flemingia and Paracalyx these vary between 4.70 and 7:06 pg. In the genus Cajanus karyotypic features and 4C DNA amounts agree with the sectional classification and bring out a close relationship between C. cajan and C. cajanifolius. This is supported by studies based on seed protein patterns, isozyme analysis, trypsin and chymotrypsin inhibitor patterns, RFLP and RAPD data and crossability relationships. A clear relation between DNA amount and abnormalities effecting the extent of pairing and recombination in interspecific hybrids shows the importance of this study in developing future breeding programme involving C. cajan and its wild relatives that are of potential value.     

Effect of some fungicide seed treatments on the survival of Bradyrhizobium japonicum and on the nodulation and yield of soybean [Glycine max. (L) Merr.]

Several commercial fungicide seed treatments were evaluated for their possible effect on the survival of Bradyrhizobium japonicum on seeds and on the nodulation and yield of soybeans in a greenhouse and a field experiment. quinolate Pro (carbendazim and oxine copper), Vitavax 200FF (carboxin and thiram), and Monceren (pencycuron) had a small effect or no effect on the survival of B. japonicum and on the nodulation and yield of soybeans. They can thus be considered compatible with soybean seed inoculation. Germipro UFB (carbendazim and iprodione), Apron 35J (metalaxyl), and Tachigaren (hymexazol) decreased B. japonicum survival and the nodulation and yield of soybeans and thus cannot be considered compatible with soybean seed inoculation.     

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.