Identification of polymorphic DNA markers in cultivated peanut (Arachis hypogaea L.)

The detection of DNA polymorphism in cultivated peanut (Arachis hypogaea L.) is reported here for the first time. The DNA amplification fingerprinting (DAF) and amplified fragment length polymorphism (AFLP) approaches were tested for their potential to detect genetic variation in peanut. The AFLP approach was more efficient as 43% of the primer combinations detected polymorphic DNA markers in contrast to 3% with the DAF approach. However, the number of polymorphic bands identified using primers selected in both approaches was comparable. In the DAF study, when 559 primers of varying types were screened, 17 (mostly 10-mer types) detected polymorphism producing an average of 3.7 polymorphic bands per primer with a total of 63 polymorphic markers. In the AFLP study, when 64 primer combinations (three selective nucleotides) corresponding to restriction enzymes Eco RI and Mse I were screened, 28 detected polymorphism. On an average, 6.7% of bands obtained from these 28 primer pairs were polymorphic resulting in a total of 111 AFLP markers. Our results demonstrate that both AFLP and DAF approaches can be employed to generate DNA markers in peanut and thus have potential in the marker-assisted genetic improvement and germplasm evaluation of this economically important crop. This revised version was published online in July 2006 with corrections to the Cover Date.     

Tomato: a crop species amenable to improvement by cellular and molecular methods

Summary Tomato is a crop plant with a relatively small DNA content per haploid genome and a well developed genetics. Plant regeneration from explants and protoplasts is feasable which led to the development of efficient transformation procedures.In view of the current data, the isolation of useful mutants at the cellular level probably will be of limited value in the genetic improvement of tomato. Protoplast fusion may lead to novel combinations of organelle and nuclear DNA (cybrids), whereas this technique also provides a means of introducing genetic information from alien species into tomato. Important developments have come from molecular approaches. Following the construction of an RFLP map, these RFLP markers can be used in tomato to tag quantitative traits bred in from related species. Both RFLP's and transposons are in the process of being used to clone desired genes for which no gene products are known. Cloned genes can be introduced and potentially improve specific properties of tomato especially those controlled by single genes. Recent results suggest that, in principle, phenotypic mutants can be created for cloned and characterized genes and will prove their value in further improving the cultivated tomato.     

RFLP mapping of an aphid resistance gene in cowpea (Vigna unguiculata L. Walp)

Summary Restriction fragment length polymorphism (RFLP) analysis has several advantages over traditional methods of genetic linkage mapping, one of these being the starting point for map-based cloning. The recent development of an RFLP map of cowpea (Vigna unguiculata L. Walp) has allowed the investigation of associations between genes of interest and RFLP markers. A cross between an aphid (Aphis craccivora Koch) resistant cultivated cowpea, TT84S-2246-4, and an aphid susceptible wild cowpea, NI 963, was screened for both aphid phenotype and RFLP marker segregation. One RFLP marker, bg4D9b, was found to be tightly linked to the aphid resistance gene (Rac ₁) and several flanking markers in the same linkage group (linkage group 1) were also identified. The close association of Rac ₁ and RFLP bg4D9b presents a real potential for cloning this insect resistance gene.     

Relationships between rock fragment cover and soil hydrological response in a Mediterranean environment

Rock fragments are a key factor for determining erosion rates, particularly in arid and semiarid environments where vegetation cover is very low. However, the effect of rock fragments in non-cultivated bare soils is still not well understood. Currently, there is a need for quantitative information on the effects of rock fragments on hydrological soil processes, in order to improve soil erosion models. The main objective of the present research was to study the influence of rock fragment cover on run-off and interrill soil erosion under simulated rainfall in Mediterranean bare soils in south-western Spain. Thirty-six rainfall simulation experiments were carried out at an intensity of 26.8 mm h⁻¹ over 60 min under three different classes of rock fragment cover (<50%, 50–60% and >60%). Ponding and run-off flow were delayed in soils with high rock fragment cover. In addition, sediment yield and soil erosion rates were higher in soils with a low rock fragment cover. The relationship between soil loss rate and rock fragment cover was described by an exponential function. After this first set of experiments, rock fragments were removed from sites with the highest cover (>60%) and the rainfall simulation experiments were repeated. The steady-state run-off rate and soil loss increased significantly, showing that run-off and soil erosion were partly conditioned by rock fragment cover. These results have significant implications for erosion modelling and soil conservation practices in areas with the same climate and soil characteristics.     

用Digoxigenin标记重组质粒DNA探针特异性的改良

鸡马立克病病毒基因组DNA的BanHI-K_3片断克隆的重组质粒DNA及从质粒上切下的经电泳和电洗脱提纯的BamHI-K_2DNA片断,在用非放射性Digoxigenin([dig])标记后,分别用作检测马立克病病毒DNA的探针。对两种探针特异性的比较表明,BamHI-K_3克隆的全质粒DNA探针对其它质粒来源的NDA仍表现出很强的交叉反应性,而用经电泳电洗脱提纯的BamHI-K_3DNA片断制备的探针,则仅对含同源DNA片断的质粒提取物或菌苔裂解物产生明显呈色反应,但对不含同源DNA的其它质粒DNA提取物几乎完全不呈现交叉反应。     

甘蔗AFLP分析技术体系的建立

研究目的】为了建立甘蔗AFLP标记技术体系;【方法】本文通过对甘蔗抗、感黑穗病的杂交亲本CP84-1198和科5,以及根据其杂交后代的浸渍接种田间抗性鉴定结果所构建的抗、感黑穗病池的AFLP银染法分析;【结果】建立了甘蔗黑穗病抗性的AFLP分析实验体系,同时将AFLP-银染技术应用于甘蔗近缘植物斑茅抗旱胁迫及其对照材料的cDNA差别筛选,建立了一种mRNA差别显示技术体系。实验过程中还筛选出了四对能在抗、感亲本上扩增出特异条带的引物,以及一对在斑茅水分胁迫和对照中表现良好差异的引物,为下一步的实验工作的开展奠定了基础。【结论】通过本实验建立了甘蔗AFLP分析技术体系、变性聚丙烯酰胺凝胶的快速银染、凝胶简单保存以及聚丙烯酰胺凝胶中的特异条带的高效回收技术。     

Davana： A New Host Plant for Ralstonia solanacearum from India

Ralstonia solanacearum infecting Davana （Artemisia pallens Wall.） from commercial nurseries in India was isolated on modified semi selective media （SMSA）. Here, we report a new host for Ralstonia solanacearum i.e. davana. It has huge demand in medicinal and aromatic industries. Isolate was confirmed as race-l, biovar-3 by morphological, physiological, biochemical and pathogenicity studies. Two sets of primers （OLI 1 ＆ Y2 and Y 1 ＆ Y2） were used in this study. Further, the identity of the isolate was confirmed by serological diagnostic kit obtained from International Potato Research Center, Lima, Peru and single chain variable fragment antibody specific to Ralstonia solanacearum used to confirm the casual organism.     

提取水稻DNA的一种简易方法

水稻染色体RFLP(DNA限制性片段长度多态性)图谱已经构建,RFLP标记正日益广泛地应用于水稻遗传育种的各项研究中。从水稻植株提取一定数量能被各种限制性内切酶完全酶解的DNA是开展这项研究的第一步。目前抽提水稻DNA的一般方法,如Cornell大学Tanksley博士实验室所用的方法,还是比较复杂,而且要使用氯仿和苯酚来提纯DNA,实验过程中就必须使用耐酚的容器和离心管,这给RFLP工作的广泛开展带来     

除草剂抗性基因bar导人烟草叶绿体

将编码Phosphinothricin acetyltrans ferase的bar基因与水稻叶绿体psbA基因的启动子和终止子构建成表达盒,连同烟草叶绿体基因组同源片段rpl2-trnH-psbA和trnK-ORF509A以及选择标记基因aadA一起构建成烟草叶绿体转化载体pTZBA。基因枪法转化烟草叶片,经壮观霉素筛选获得转化再生植株。分别以1.0 kb的叶绿体同源片段trnK-OR     

含碎石土壤的含水量测定误差分析

碎石的存在增加了土壤含水量测定的难度,为便于应用,一些学者将碎石当作细土或不透水介质处理,这在一些情况下可能产生很大误差。本文对忽略碎石或其含水量所引起的土石混合介质和细土含水量的误差进行了分析,并用室内实验验证了所得到的结果与相对误差的关系。结果表明,细土和土石混合介质含水量的相对误差与碎石含量以及碎石与细土含水量的比值有关。当碎石与细土含水量比值很大时,即便碎石含量很低也会产生很大误差;而当碎石与细土含水量比值很小时,高的碎石含量同样导致很大误差。此外,碎石与细土含水量的相对大小并非常数,而是随含水量变化的。因此,对土石混合介质田间水分状况的准确监测,以及水分和溶质迁移过程的定量模拟需要考虑碎石特性的影响。