Direct Factor Analysis With Discrete X-Ray Diffraction Patterns

In this paper,we put forward a method of direct factor analysis with discrete X-ray diffraction patterns, which was supported by the experimental measurement with the mixture containing 2,3,4,5 phases respectively. The detailed discussion was also given to its principles,errors and criterion.     

Genetics and molecular mapping of the naked grains in hexaploid oat

Avena sativa L. subsp. nudisativa has the ability to produce naked grains. Genetic studies on the naked trait of oat began over a century ago, but the genetic and molecular factors associated with the expression of this trait have not been fully clarified. The objectives of this study were to evaluate the naked trait in two oat populations of recombinant inbred lines (RILs), to determine the number of genes, to estimate the heritability, and to map genomic regions associated with the naked trait in hexaploid oat. Parental lines and RILs of each population were screened for the naked trait from plants grown in the field over a 2 year period. Based on the phenotypic data, the oat RILs were classed as naked, partially naked, partially hulled and hulled. In both populations and years, a great number of RILs showed variable expressivity for the naked trait. The genetic analysis indicated the action of a major gene (N1) with the action of modifying genes controlling the formation of naked grains. The results of the estimate of heritability show that environmental conditions do not have a great influence in determining the naked trait. The quantitative trait loci analysis detected a genomic region with a large effect on the naked trait that explained more than 50% of the phenotypic variation. Further studies are needed to validate the use of these molecular markers to assist breeding programs to select high quality and stable naked oat cultivars.     

Resistance screening of breeding lines and commercial tomato cultivars for <Emphasis Type="Italic">Meloidogyne incognita</Emphasis> and <Emphasis Type="Italic">M. javanica</Emphasis> populations (Nematoda) from Ethiopia

Soil and root samples were collected from major tomato growing areas of Ethiopia during the 2012/2013 growing season to identify root-knot nematode problems. DNA-based and isozyme techniques revealed that Meloidogyne incognita and M. javanica were the predominant Meloidogyne species across the sampled areas. The aggressiveness of different populations of these species was assessed on tomato cultivars Marmande and Moneymaker. The two most aggressive populations of each species were selected and further tested on 33 tomato genotypes. The resistance screening and mechanism of resistance was performed after inoculation with 100 freshly hatched (<24 h) second-stage juveniles (J2). Eight weeks after inoculation the number of egg masses produced on each cultivar was assessed. For the resistance mechanism study, J2 penetration and their subsequent development inside the tomato roots were examined at 1, 2, 4 and 6 weeks after inoculation. On both cultivars Marmande and Moneymaker all M. incognita and M. javanica populations formed a high number of egg masses indicating highly aggressive behaviour. Populations from ‘Jittu’ and ‘Babile’ for M. incognita and ‘Jittu’ and ‘Koka’ for M. javanica were selected as most aggressive. None of the 33 tomato genotypes were immune for these M. incognita and M. javanica populations. However, several tomato genotypes were found to have a significant effect on the number of egg masses produced indicating possible resistance. For M. javanica populations there were more plants from cultivars or breeding lines on which no egg masses were found compared to M. incognita populations. The lowest number of egg masses for both populations of M. incognita was produced on cultivars Bridget40, Galilea, and Irma while for M. javanica it was on Assila, Eden, Galilea, Tisey, CLN-2366A, CLN-2366B and CLN-2366C. Tomato genotypes, time (weeks after inoculation) and their interaction were significant sources of variation for J2 penetration and their subsequent development inside the tomato roots. Differential penetration was found in breeding lines such as CLN-2366A, CLN-2366B and CLN-2366C, but many of the selected tomato genotypes resistance for the tested M. incognita and M. javanica populations were expressed by delayed nematode development. Therefore, developing a simple screening technique to be used by local farmers or extension workers is crucial to facilitate selection of a suitable cultivar.     

Characterization of common bean wild populations for their in situ conservation in Northwestern Argentina

In situ conservation of wild species is a method of conservation that allows keeping populations in their natural environments, and set the strategies for maintaining the natural populations. The Active Bank of Northwestern Argentina (BANOA) is in charge of the in situ conservation of wild populations of common bean (Phaseolus vulgaris L.) in Northwestern Argentina (NOA), and has an ex situ collection of 401 landraces and 221 wild accessions from the NOA. We evaluated the phenotypic diversity of 68 common bean wild populations from the NOA both in protected and unprotected areas, finding a moderate variation among them. Ten phenotypic reproductive characteristics related to pod and seed displayed significant differences in the analysis of variance; these traits together with the seed weight were the basis for the multivariate analysis. The cluster analysis ordered the populations in 12 groups but trends in geographical distribution or phenotypical variation were not recognized. For the conservation in situ of the wild bean populations, their diversity should be considered. Two types of populations can be highlighted: (i) candidates for in situ conservation in order to preserve the novel variation generated by convergence with cultivated sympatric germplasm (populations 433, 437, 471, 509, 513 and 517) and (ii) those whose phenotype represents clearly the wild status and should be preserved in situ as such in their current status (populations 480, 495, 496, 525 and 533).     

QTL mapping and analysis of epistatic interactions for grain yield and yield-related traits in <Emphasis Type="Italic">Triticum turgidum</Emphasis> L. var. <Emphasis Type="Italic">durum</Emphasis>

A quantitative trait loci (QTL) analysis of grain yield and yield-related traits was performed on 93 durum wheat recombinant inbred lines derived from the cross UC1113 × Kofa. The mapping population and parental lines were analyzed considering 19 traits assessed in different Argentine environments, namely grain yield, heading date, flowering time, plant height, biomass per plant, and spikelet number per ear, among others. A total of 224 QTL with logarithm of odds ratio (LOD) ≥ 3 and 47 additional QTL with LOD > 2.0 were detected. These QTL were clustered in 35 regions with overlapping QTL, and 12 genomic regions were associated with only one phenotypic trait. The regions with the highest number of multi-trait and stable QTL were 3BS.1, 3BS.2, 2BS.1, 1BL.1, 3AL.1, 1AS, and 4AL.3. The effects of epistatic QTL and QTL × environment interactions were also analyzed. QTL putatively located at major gene loci (Rht, Vrn, Eps, and Ppd) as well as additional major/minor QTL involved in the complex genetic basis of yield-related traits expressed in Argentine environments were identified. Interestingly, the 3AL.1 region was found to increase yield without altering grain quality or crop phenology.     

Generation and analysis of expressed sequence tag sequences from a soft‐seeded pomegranate cDNA library

The cultivation of soft‐seeded pomegranate is an important direction in pomegranate breeding. To comprehensively understand the molecular mechanisms involved in the formation of soft‐seeded pomegranate (Punica granatum. var. Hongmanaozi), we established an expressed sequence tag (EST) resource. Two thousand valid sequences were generated, from which 907 unigenes were obtained after initial assembly using the clustalx program. Among these unigenes, 51 showed no similarity to any protein in the public databases, 433 matched with proteins of unknown function, and 423 matched with proteins of known or putative functions. The 423 unigenes were further classified into 13 categories. Among these categories, protein synthesis, cell structure, protein destination and storage, secondary metabolism, signal transduction and transporters accounted for 8%, 8%, 4%, 7%, 6% and 17%, respectively. We also successfully developed 10 highly polymorphic expressed sequence tag‐simple sequence repeat (EST‐SSR) markers for pomegranate. The results provide a new tool for future activities in pomegranate breeding.     

Evaluation of carbon sources,gelling agents,growth hormones and additives for efficient callus induction and plant regeneration in Indian wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.) genotypes using mature embryos

Various factors affecting in vitro regeneration like different carbon sources, different gelling agents, and growth additives were assessed comprehensively for callus induction and plant regeneration for five Indian wheat cultivars using mature embryos as the explants for the first time. The tissue culture responses of cultivars WH-1105, HD-2967, and PBW-343 have not been reported earlier. Besides, the effect of different concentrations of the cytokinin, zeatin has also been optimized. Using the optimized factors, the efficiency of five different varieties, i.e., HD 2967, C 306, RAJ 3765, WH 1105, and PBW 343 was evaluated for regeneration. Modified MS basal medium containing dicamba reduced precocious germination of the embryo and induced embryogenic callus more efficiently. Removal of embryogenic calli from non-regenerable structures during early callus phase improved plant regeneration. These calli on zeatin (1.0 mgl^-1) and dicamba (0.1 mgl^-1) containing medium showed the highest regeneration frequency (98%) with a maximum of 8-9 shoots per calli. Maltose had the maximum callusing and regeneration percentage than other carbon sources. Various gelling agents did not have any significant difference on the regeneration. Of all the varieties, C-306 and HD-2967 were found to be more regenerative and can be used in transformation experiments.     

根系分泌物对根际土壤关键氮转化过程的影响

根系分泌物是影响土壤氮素转化、N₂O排放和植株氮肥利用率的重要因素之一,也是土壤学、植物营养学、作物生理生态与耕作栽培学、环境科学等学科的重要关注点。为全面认识根系分泌物在土壤氮循环中的作用,综述了根系分泌物的种类和测定方法,介绍了根系分泌物影响土壤关键氮转化过程及N₂O排放的机理,根系分泌物对土壤硝化和反硝化过程及N₂O排放的抑制作用,并对该领域未来的研究方向进行了展望。为土壤氮素转化的土壤–植物–微生物互作机制研究提供一定参考,以进一步提高氮肥利用率,减少氮肥引起的环境污染。     

一株贝莱斯芽孢杆菌的分离与鉴定

为获得高温高效分解茶渣的菌株。利用高温特殊生境分离方法,从废弃茶渣中分离到有分解茶渣作用的5株菌,其中Fb菌株产生的蛋白酶、纤维素酶的活力均最高。经形态学、生理生化特性以及生长特性等研究,并克隆Fb菌株的16S rDNA基因序列和gyrB基因序列,进行系统发育学分析。结果表明,Fb属贝莱斯芽孢杆菌(Bacillus velezensis),可耐受55℃的高温。最适生长条件为：装液量30 mL、摇床转速分120 r/min、培养温度42~45℃、初始pH 5.0~7.0、培养时间16 h、盐度1.0%~6.0%。本研究首次在茶渣中分离筛选出贝莱斯芽抱杆菌,为茶渣开发研究提供理论依据。