We have developed a new DH mapping population for oilseed rape, named TNDH, using genetically and phenotypically diverse parental lines. We used the population in the construction of a high stringency genetic linkage map, consisting of 277 loci, for use in quantitative genetic analysis. A proportion of the markers had been used previously in the construction of linkage maps for Brassica species, thus permitting the alignment of maps. The map includes 68 newly developed Sequence Tagged Site (STS) markers targeted to the homologues of defined genes of A. thaliana. The use of these markers permits the alignment of our linkage map with the A. thaliana genome sequence. An additional 74 loci (31 newly developed STS markers and 43 loci defined by SSR and RFLP markers that had previously been used in published linkage maps) were added to the map. These markers increased the resolution of alignment of the newly constructed linkage map with existing Brassica linkage maps and the A. thaliana genome sequence. We conducted field trials with the TNDH population at two sites, and over 2 years, and identified reproducible QTL for seed oil content and erucic acid content. The results provide new insights into the genetic control of seed oil and erucic acid content in oilseed rape, and demonstrate the utility of the linkage map and population.

A comparative linkage map of oilseed rape and its use for QTL analysis of seed oil and erucic acid content

Increasing the flow of carbon into seed oil.

Plant oils as feedstock alternatives to petroleum - A short survey of potential oil crop platforms.

The main objective in this research was the genetic analysis of heterosis in rapeseed at the QTL level. A linkage map comprising 235 SSR and 144 AFLP markers covering 2045 cM was constructed in a doubled-haploid population from a cross between the cultivar “Express” and the resynthesized line “R53.” In field experiments at four locations in Germany 250 doubled-haploid (DH) lines and their corresponding testcrosses with Express were evaluated for grain yield and three yield components. The heterosis ranged from 30% for grain yield to 0.7% for kernel weight. QTL were mapped using three different data sets, allowing the estimation of additive and dominance effects as well as digenic epistatic interactions. In total, 33 QTL were detected, of which 10 showed significant dominance effects. For grain yield, mainly complete dominance or overdominance was observed, whereas the other traits showed mainly partial dominance. A large number of epistatic interactions were detected. It was concluded that epistasis together with all levels of dominance from partial to overdominance is responsible for the expression of heterosis in rapeseed.

https://www.genetics.org/content/genetics/179/3/1547.full.pdf

Genetic Analysis of Heterosis for Yield and Yield Components in Rapeseed (Brassica napus L.) by Quantitative Trait Locus Mapping

Oil content in rapeseed (Brassica napus L.) is generally regarded as a character with high heritability that is negatively correlated with protein content and influenced by plant developmental and yield related traits. To evaluate possible genetic interrelationships between these traits and oil content, QTL for oil content were mapped using data on oil content and on oil content conditioned on the putatively interrelated traits. Phenotypic data were evaluated in a segregating doubled haploid population of 282 lines derived from the F1 of a cross between the old German cultivar Sollux and the Chinese cultivar Gaoyou. The material was tested at four locations, two each in Germany and in China. QTLMapper version 1.0 was used for mapping unconditional and conditional QTL with additive (a) and locus pairs with additive × additive epistatic (aa) effects. Clear evidence was found for a strong genetic relationship between oil and protein content. Six QTL and nine epistatic locus pairs were found, which had pleiotropic effects on both traits. Nevertheless, two QTL were also identified, which control oil content independent from protein content and which could be used in practical breeding programs to increase oil content without affecting seed protein content. In addition, six additional QTL with small effects were only identified in the conditional mapping. Some evidence was apparent for a genetic interrelationship between oil content and the number of seeds per silique but no evidence was found for a genetic relationship between oil content and flowering time, grain filling period or single seed weight. The results indicate that for closely correlated traits conditional QTL mapping can be used to dissect the genetic interrelationship between two traits at the level of individual QTL. Furthermore, conditional QTL mapping can reveal additional QTL with small effects that are undetectable in unconditional mapping.

Conditional QTL mapping of oil content in rapeseed with respect to protein content and traits related to plant development and grain yield.

Rapeseed (Brassica napus L.) is one of the most important oilseed crops both in Europe and in China. The objective of this study was to investigate whether the European and the Chinese gene pools of winter oilseed rape contain different alleles for high seed oil content. A linkage map of rapeseed comprising 125 SSR markers and covering 1196-cM genome length was constructed from an F 1 derived doubled haploid (DH) population from a cross between the German cultivar Sollux and the Chinese cultivar Gaoyou, both selected for high oil content. In total, 282 DH lines were evaluated in replicated field experiments in four environments, two each in Germany and in China. QTL were mapped and their additive and epistatic effects as well as interactions with environments were estimated by a mixed model approach implemented in the mapping software QTLMapper. Eight QTL with additive effects and nine pairs of loci with additive × additive epistasis were detected, which together accounted for 80% of the phenotypic variation. The alleles increasing oil content were dispersed between the parents, which explained the transgressive segregation observed: seven DH lines surpassed the better parent by more than 3% oil content. Five of the eight QTL with additive effects showed significant genotype × environment interactions, and 10 additional QTL with genotype × environment interactions, but no significant additive main effect were observed. Epistatic interactions mainly occurred between QTL which also showed additive effects or additive × environment interactions. In conclusion, a marker assisted selection to recombine positive alleles from European and Chinese material is a powerful approach to further increase the oil content of rapeseed, but epistatic effects and genotype × environment interactions have to be considered.

Oil content in a European x Chinese rapeseed population: QTL with additive and epistatic effects and their genotype-environment interactions

The mechanical harvesting of canola seeds requires a suitable plant height. The appropriate time of paclobutrazol application can reduce canola plant height. To evaluate the best application time of paclobutrazol, a field experiment was conducted with the paclobutrazol applied at stalk heights of 10, 20, 30, 40 and 50 cm. Plants without paclobutrazol application were taken as control. The results indicated that the plant height was reduced by 27% with paclobutrazol applied at 10 cm stalk height as compared with the control. The seed yield was significantly improved by mean increment of 21%. The increased branching ability contributed to yield improvement. The total soluble sugar, sucrose, and starch content in the stem, leaf and bud organs were significantly increased by paclobutrazol application at the initial flowering stage. Paclobutrazol enhanced the sucrose synthesis by sucrose phosphate synthase as well as the catalysis via sucrose synthase, neutral invertase, and in particular acid invertase. The amount of carbohydrates during harvesting remained significantly lower in the root after paclobutrazol treatment, thereby indicating the high-efficiency of carbohydrate utilization by the canola plants in comparison with the control plants. Thus, paclobutrazol applied at 10 cm stalk height takes advantages to control plant height and improve seed yield through enhancing carbohydrate utilization efficiency, which is useful in future for canola mechanical harvesting. © 2014 Friends Science Publishers

Paclobutrazol application effects on plant height, seed yield and carbohydrate metabolism in canola

Delayed planting affects seed yield, biomass production, and carbohydrate allocation in canola (Brassica napus).

Radial jet drilling (RJD) technology has been proved to be an economical and efficient stimulation technology for oil and gas, geothermal, hydrate, etc. but conventional RJD technology adopts pure water jet to break rock and form laterals, which has low rock breaking efficiency and is unable to effectively break hard rock such as shale. Swirling abrasive jet is proposed to promote the development of RJD. Here, the characteristics of the flow field of the swirling abrasive jet nozzle and the influence of the key impeller parameters are studied by numerical simulation. The distribution and development of axial velocity, tangential velocity, and radial velocity of water and abrasive are analyzed. The results show that the swirling abrasive jet has no constant velocity core, has stronger diffusivity, and can form a larger impact area than the direct jet. Abrasive particles and water can acquire large tangential and radial velocity which can break rock under the action of shear and tensile stress efficiently. With the increase of the spinning angle, the axial velocity of the fluid decreases, and the tangential velocity increases gradually. With the increase of blade thickness, the axial velocity decreases, and the tangential velocity increases. With the increase of the number of blades, the axial velocity decreases, and the tangential velocity increases. The spinning direction almost has no effect on the flow field. Therefore, the spinning angle is recommended to be no less than 270°, blade thickness is 2.5 mm, and number of blades are 3. The research results provide theoretical guidance for the structural design of swirling abrasive jet nozzles.

/pdf/flow-field-simulation-of-swirling-abrasive-jet-nozzle-for-1nd4yots.pdf

Zhang DongQing

Papers

Oil content in a European x Chinese rapeseed population: QTL with additive and epistatic effects and their genotype-environment interactions

Paclobutrazol application effects on plant height, seed yield and carbohydrate metabolism in canola

Delayed planting affects seed yield, biomass production, and carbohydrate allocation in canola (Brassica napus).

Flow Field Simulation of Swirling Abrasive Jet Nozzle for Hard Rock Breaking

Numerical study of flow establishment process of engine in a shock tunnel