QTL for phytosterol and sinapate ester content in Brassica napus L. collocate with the two erucic acid genes

Improving oil and protein quality for food and feed purposes is an important goal in rapeseed (Brassica napus L.) breeding programs. Rapeseed contains phytosterols, used to enrich food products, and sinapate esters, which are limiting the utilization of rapeseed proteins in the feed industry. Increasing the phytosterol content of oil and lowering sinapate ester content of meal could increase the value of the oilseed rape crop. The objective of the present study was to identify quantitative trait loci (QTL) for phytosterol and sinapate ester content in a winter rapeseed population of 148 doubled haploid lines, previously found to have a large variation for these two traits. This population also segregated for the two erucic acid genes. A close negative correlation was found between erucic acid and phytosterol content (Spearman’s rank correlation, rs = −0.80**). For total phytosterol content, three QTL were detected, explaining 60% of the genetic variance. The two QTL with the strongest additive effects were mapped on linkage groups N8 and N13 within the confidence intervals of the two erucic acid genes. For sinapate ester content four QTL were detected, explaining 53% of the genetic variance. Again, a close negative correlation was found between erucic acid and sinapate ester content (rs = −0.66**) and the QTL with the strongest additive effects mapped on linkage groups N8 and N13 within the confidence intervals of the two erucic acid genes. The results suggests, that there is a pleiotropic effect of the two erucic acid genes on phytosterol and sinapate ester content; the effect of the alleles for low erucic acid content is to increase phytosterol and sinapate ester content. Possible reasons for this are discussed based on known biosynthetic pathways

Extent and structure of linkage disequilibrium in canola quality winter rapeseed (Brassica napus L.)

Linkage disequilibrium was investigated in canola quality winter rapeseed to analyze (1) the prospects for whole-genome association analyses and (2) the impact of the recent breeding history of rapeseed on linkage disequilibrium. A total of 845 mapped AFLP markers with allele frequencies ≥0.1 were used for the analysis of linkage disequilibrium in a population of 85 canola quality winter rapeseed genotypes. A low overall level of linkage disequilibrium was found with a mean r2 of only 0.027 over all 356,590 possible marker pairs. At a significance threshold of P = 2.8 × 10−7, which was derived by a Bonferroni correction from a global α-level of 0.1, only 0.78% of the marker pairs were in significant linkage disequilibrium. Among physically linked marker pairs, the level of linkage disequilibrium was about five times higher with more than 10% of marker pairs in significant linkage disequilibrium. Linkage disequilibrium decayed rapidly with distance between linked markers with high levels of linkage disequilibrium extending only for about 2 cM. Owing to the rapid decay of linkage disequilibrium with distance association analyses in canola quality rapeseed will have a significantly higher resolution than QTL analyses in segregating populations by interval mapping, but much larger number of markers will be necessary to cover the whole genome. A major impact of the recent breeding history of rapeseed on linkage disequilibrium could not be observed

Induced and recombinative variability of tocopherol content in mutant lines and hybrids of B. napus and wide hybrids B. oleracea var. Botrytis x B. napus

Wartość pokarmowa produktów roślin oleistych zależy od zawartości oleju, białka, glukozynolanów, spektrum kwasów tłuszczowych oraz karotenoidów i tokoferoli. Przeciwutleniacze (tokoferole) odgrywają ważną rolę w stabilności oksydacyjnej olejów roślinnych, zwiększając ich wartość odżywczą i trwałość fizjologiczną. Tokoferole wiążą wolne rodniki powstające w procesie metabolizmu różnych składników w organizmie człowieka. Wolne rodniki powodują uszkodzenia w strukturze DNA, które są przyczyną wielu chorób. W związku z tym otrzymanie form z rodzaju Brassica o zwiększonej zawartości i poprawionym spektrum tokoferoli jest ważnym zagadnieniem hodowlanym. Wyselekcjonowane linie mutantów wykazały zwiększony zakres zmienności tokoferoli, która wahała się od 175-362 mg·kg⁻¹, przy czym stwierdzono wyraźny wpływ środowiska (Poznań, Cerekwica) na zawartość badanego składnika. U badanych linii mutantów stwierdzono zwiększony stosunek frakcji α/γ szczególnie w Poznaniu, w porównaniu do linii wyjściowej DH-0120 oraz odmiany Skrzeszowicki. Analiza zawartości tokoferoli w nasionach linii wyjściowej DH-0120 (P1) oraz mutanta M-5N (P2) i mieszańców F₁ z wzajemno-przemiennych krzyżowań P1 x P2 wykazała zmniejszenie zawartości tokoferoli u mieszańców P1 x P2 (282 mg·kg⁻¹) i P2 x Pl (295 mg·kg⁻¹) przy średniej zawartości u form rodzicielskich 314,0 mg·kg⁻¹. Podobny efekt wystąpił u mieszańców F₁ Skrzeszowicki x M3/28 i M-6/14 x Skrzeszowicki. Badane mieszańce F₃B. oleracea var. botrytis x B. napus (27 roślin) wykazały wyraźne zwiększenie zawartości tokoferoli w badanych nasionach, która wahała się od 107-447 mg·kg⁻¹, w porównaniu do średniej zawartości u form rodzicielskich (222 mg·kg⁻¹). Otrzymane wyniki wskazują, że konwencjonalne metody hodowlane (mutageneza, krzyżowanie) są efektywnymi metodami w procesie polepszenia jakości roślin oleistych.Food value of oilseed products depend on: oil, protein, glucosinolate, and tocopherol content, composition of fatty acids and tocopherols. Natural antoxidants play a great role in physiological oxidation of oil increasing food value and physiological stability. Tocopherols bind free radical, which are produced during metabolic process of compounds in the human body. Free radical cause damage in the DNA structure leading to many diseases. Selection of forms of Brassica species with improve tocopherol quality (content and profile) is a very important goal of a breeding program. Selected mutant lines showed an increased range of tocopherol variability, which varied from 175 to 362 mg·kg⁻¹ with a strong effect of the location (Poznań, Cerekwica) environment. Studied mutant lines also showed an increased α/γ ratio, particularly in Poznan location as compared to the initial line DH-0120 and cultivar Skrzeszowicki. Analyses of tocopherol content in parental lines DH-0120 (P1), mutant M-5N (P2) and F, reciprocal hybrids (PI x P2) showed a decrease of tocopherol (282 mg·kg⁻¹ in P1 x P2 and 295 mg·kg⁻¹ in P2 x P1) with the average of 314.0 mg·kg⁻¹ in parental forms. The same effect was observed in F₁ hybrids Skrzeszowicki x M-3/28 and M-6/14 x Skrzeszowicki. The studied hybrids F₃ (B. oleracea x B. napus - 27 plants) produced a markedly increased tocopherol content, which ranged from 107 to 447 mg·kg⁻¹ as compared to the parent average - 222.0 mg·kg⁻¹. The obtained results showed that conventional breeding methods (mutagenesis and crossing) are an effective in the oilseed crop improvement

Improvement to thin film CdTe solar cells with controlled back surface oxidation

Thin film CdTe solar cells were produced by MOCVD, at atmospheric pressure, under a hydrogen atmosphere (i.e. oxygen-free). Window layer alloying with zinc (forming Cd1−xZnxS) and extrinsic p-type doping with arsenic (giving CdTe:As) have been used to improve photovoltaic solar cell performances, but as-grown MOCVD-CdTe PV cells are still typically characterised by low Voc (~620–690 mV). Post-deposition annealing in air for 30 min at low temperature (170 °C) prior to evaporation of the back contacts led to significant increases in Voc and FF. XPS measurements revealed back surface oxidation, resulting in formation of Te–O species. This was also the case for a device aged under ambient laboratory conditions. Extended annealing in air of a fresh device, for up to 180 min, continued to improve both Voc and FF. At longer annealing times the Voc remained relatively stable whilst the FF started to deteriorate. External quantum efficiency showed loss of photocurrent generation after excessive oxidation prior to back contact metallisation. Controlled back surface oxidation resulted in Voc values exceeding 800 mV and a best cell efficiency of 15.3