Effect of infrared ray roasting on oxidation stability and flavor of virgin rapeseed oils.

Effects of infrared ray roasting (IRR) on the oxidation stability and flavors of virgin rapeseed oil (VROs) at 110-170°C were investigated and compared with traditional roller roasting (TRR). Results showed that IRR samples showed lower acid and peroxides values, higher oxidation stability index, and 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity than TRR ones. IRR samples displayed better thermal expansion of rapeseed for internal fragmentation from microstructures, which facilitated the release of tocophenols (652.63-748.78 mg/kg) and 4-vinylsyringol (7.54-678.19 mg/kg), compared with TRR ones with tocophenols (652.63-689.28 mg/kg) and 4-vinylsyringol (7.54-524.18 mg/kg) contributing to better oxidation stability. Moreover, important volatile compounds, including pyrazines, isothiocyanates, nitriles and aldehydes, were formed quantitatively more in IRR than TRR samples, which was attributed to better heat transfer efficiency and internal fragmentation promoting complex reactions inside rapeseed. Therefore, IRR has more positive roasting effects on VROs than TRR. PRACTICAL APPLICATION: Virgin rapeseed oil is a massively consumed flavor vegetable oil, but the traditional high-temperature roller seed roasting process can cause serious quality problems. Our work applied a novel roasting technology, infrared ray roasting to rapeseed pretreatment. The results show that this new type of roasting technology is more efficient and stable and has important applications in the production of virgin rapeseed oil with better oxidative stability and flavor.

Effects of supplemental LED light quality and reduced growth temperature on swede (Brassica napus L. ssp. rapifera Metzg.) root vegetable development and contents of glucosinolates and sugars.

BACKGROUND: Low growth temperatures and the special light qualities of midnight sun in northern Scandinavia, have both been shown to improve eating quality of swede root bulbs. To study the combined effect of these factors on root development and sensory-related compounds, plants were grown in phytotron under different 24 h supplemental light-emitting diode (LED) light colours, at constant 15 °C, or reduced end-of-season temperature at 9 °C. RESULTS: Far-red LED (740 nm) light induced longer leaves and produced more roundly shaped bulbs, than the other light quality treatments. At constant 15 °C, supplemental light of far-red LED also produced a stronger purple crown skin colour than the other LED treatments. This difference between light quality treatments disappeared at 9 °C, as all bulb crowns developed a purple colour. There were no significant effects of LED-supplements on sugar concentrations, while the reduced temperature on average did increase concentrations of d-fructose and d-glucose. Total glucosinolate concentrations were not different among treatments, although the most abundant glucosinolate, progoitrin, on average was present in highest concentration under LEDs containing far-red light, and in lower concentration at 9 °C compared to 15 °C. CONCLUSION: The light quality of 24 h photoperiods in combination with temperature appears primarily important for growth and morphological traits in swede root bulbs. Influence of light quality and low temperature on appearance and sensory-related compounds may be utilized in marketing of root vegetables with special quality related to growth conditions of high latitude origin. © 2020 Society of Chemical Industry.

Individual and interactive effects of temperature and light intensity on canola growth, physiological characteristics and methane emissions.

Earlier studies have shown that plants produce methane (CH4) under aerobic conditions, and that this emission is not microbial in nature. However, the precursors of aerobic CH4 remain under debate, and the combined effects of environmental factors on plant-derived CH4 requires further attention. The objective of this study was to determine the interactive effects of temperature and light intensity on CH4 and other relevant plant parameters in canola (Brassica napus L.). Plants were grown under two temperature regimes (22/18 °C and 28/24 °C, 16 h light/8 h dark) and two light intensities (300 and 600 µmol photons m-2 s-1) for 21 days after one week of growth under 22/18 °C (16 h light/8 h dark). In this study, higher temperature had little effects on CH4 emissions from plants, indicating the mitigating effects of higher light intensity. Higher light intensity, however, significantly decreased CH4, which was inversely related to plant dry mass. Higher light intensity decreased stem height, leaf area ratio, chlorophyll, nitrogen balance index, leaf moisture, methionine (Met) and ethylene (C2H4), but increased specific leaf mass, photochemical quenching, flavonoids, epicuticular wax, lysine and tyrosine. The results revealed that increased CH4 emissions from plants could be related to changes in plant physiological activities, which portrayed themselves in increased C2H4 evolution, and methylated amino acids, such as Met. We conclude that higher light intensity reduces Met and, in turn, CH4 and C2H4 emissions, but lower light intensity enhances CH4 formation through cleavage of methyl group of amino acids by reactive oxygen species, as previously suggested.

Light induces gene expression to enhance the synthesis of storage reserves in Brassica napus L. embryos.

KEY MESSAGE: In this manuscript, we disclosed the influence of light on the accumulation of storage reserves in B. napus embryos.1.Light induced the gene expression in the developing embryos of B. napus.2.Light promoted the starch synthesis in chloroplasts of B. napus embryos.3.Light enhanced the metabolic activity of storage reserve synthesis in B. napus embryos. Light influences the accumulation of storage reserves in embryos, but the molecular mechanism was not fully understood. Here, we monitored the effects of light on reserve biosynthesis in Brassica napus by comparing embryos from siliques grown in normal light conditions to those that were shaded or masked (i.e., darkened completely). Masked embryos developed more slowly, weighed less, and contained fewer proteins and lipids than control embryos. They also had fewer and smaller oil bodies than control embryos and lacked chloroplasts, where starch grains are usually synthesized. The levels of most amino acids, carbohydrates, and fatty acids were higher in masked embryos than in control or shaded embryos, whereas the levels of these metabolites in the masked endosperms were lower than those in control and shaded endosperm. Transcriptome analysis indicated that genes involved in photosynthesis (42 genes), amino acid biosynthesis (51 genes), lipid metabolism (61 genes), and sugar transport (13 genes) were significantly repressed in masked embryos. Our results suggest that light contributes to reserve accumulation in embryos by inducing the expression of metabolic genes, thereby enhancing the biosynthesis of storage reserves.

Associating transcriptional regulation for rapid germination of rapeseed (Brassica napus L.) under low temperature stress through weighted gene co-expression network analysis.

Slow germination speed caused by low temperature stress intensifies the risk posed by adverse environmental factors, contributing to low germination rate and reduced production of rapeseed. The purpose of this study was to understand the transcriptional regulation mechanism for rapid germination of rapeseed. The results showed that seed components and size do not determine the seed germination speed. Different temporal transcriptomic profiles were generated under normal and low temperature conditions in genotypes with fast and slow germination speeds. Using weight gene co-expression network analysis, 37 823 genes were clustered into 15 modules with different expression patterns. There were 10 233 and 9111 differentially expressed genes found to follow persistent tendency of up- and down-regulation, respectively, which provided the conditions necessary for germination. Hub genes in the continuous up-regulation module were associated with phytohormone regulation, signal transduction, the pentose phosphate pathway, and lipolytic metabolism. Hub genes in the continuous down-regulation module were involved in ubiquitin-mediated proteolysis. Through pairwise comparisons, 1551 specific upregulated DEGs were identified for the fast germination speed genotype under low temperature stress. These DEGs were mainly enriched in RNA synthesis and degradation metabolisms, signal transduction, and defense systems. Transcription factors, including WRKY, bZIP, EFR, MYB, B3, DREB, NAC, and ERF, are associated with low temperature stress in the fast germination genotype. The aquaporin NIP5 and late embryogenesis abundant (LEA) protein genes contributed to the water uptake and transport under low temperature stress during seed germination. The ethylene/H2O2-mediated signal pathway plays an important role in cell wall loosening and embryo extension during germination. The ROS-scavenging system, including catalase, aldehyde dehydrogenase, and glutathione S-transferase, was also upregulated to alleviate ROS toxicity in the fast germinating genotype under low temperature stress. These findings should be useful for molecular assisted screening and breeding of fast germination speed genotypes for rapeseed.

Influence of different light conditions and time of sprouting on harmful and beneficial aspects of rutabaga sprouts in comparison to their roots and seeds.

BACKGROUND: This study aimed to evaluate the presence and content of selected phytochemicals, namely glucosinolates, fatty acids and phenolic compounds, in rutabaga (Brassica napus L. var. napobrassica) sprouts grown under various light conditions, in comparison to rutabaga seeds and roots. As rutabaga sprouts are likely to become new functional food, special emphasis was placed on the related risks of progoitrin and erucic acid presence - compounds with proven antinutritive properties. RESULTS: Time of sprouting significantly decreased progoitrin content, especially after 10 days (by 91.5%) and 12 days (by 97.5%), as compared to 8 days. In addition, sprouts grown under dark conditions showed 27%, 60% and 17% reduction in progoitrin level in 8, 10 and 12 days after sowing, respectively, as compared to sprouts grown under natural conditions. Progoitrin was found to be the predominant glucosinolate in rutabaga seeds (804.07 ± 60.89 mg 100 g-1 dry weight (DW)), accompanied by glucoerucin (157.82 ± 21.04 mg 100 g-1 DW), also found in the roots (82.20 ± 16.53 mg 100 g-1 DW). Among the unsaturated fatty acids in rutabaga sprouts, erucic, linoleic, linolenic and gondoic acids decreased significantly, and only oleic acid increased as germination days progressed. The amount of harmful erucic acid in rutabaga sprouts was found to vary between 1.8% and 7%, depending on the day of seeding or light conditions, as compared to 42.5% in the seeds. CONCLUSION: The evaluated rutabaga products showed a wide content range of potentially antinutritive compounds, sprouts having the lowest amounts of erucic acid and progoitrin. © 2018 Society of Chemical Industry.

Transcriptional and translational responses of rapeseed leaves to red and blue lights at the rosette stage.

Under different red (R):blue (B) photon flux ratios, the growth performance of rapeseed (Brassica napus L.) is significantly different. Rapeseed under high R ratios shows shade response, while under high B ratios it shows sun-type morphology. Rapeseed under monochromatic red or blue light is seriously stressed. Transcriptomic and proteomic methods were used to analyze the metabolic pathway change of rapeseed (cv. "Zhongshuang 11") leaves under different R:B photon flux ratios (including 100R:0B%, 75R:25B%, 25R:75B%, and 0R:100B%), based on digital gene expression (DGE) and two-dimensional gel electrophoresis (2-DE). For DGE analysis, 2054 differentially expressed transcripts (|log2(fold change)|≥1, q<0.005) were detected among the treatments. High R ratios (100R:0B% and 75R:25B%) enhanced the expression of cellular structural components, mainly the cell wall and cell membrane. These components participated in plant epidermis development and anatomical structure morphogenesis. This might be related to the shade response induced by red light. High B ratios (25R:75B% and 0R:100B%) promoted the expression of chloroplast-related components, which might be involved in the formation of sun-type chloroplast induced by blue light. For 2-DE analysis, 37 protein spots showed more than a 2-fold difference in expression among the treatments. Monochromatic light (ML; 100R:0B% and 0R:100B%) stimulated accumulation of proteins associated with antioxidation, photosystem II (PSII), DNA and ribosome repairs, while compound light (CL; 75R:25B% and 25R:75B%) accelerated accumulation of proteins associated with carbohydrate, nucleic acid, amino acid, vitamin, and xanthophyll metabolisms. These findings can be useful in understanding the response mechanisms of rapeseed leaves to different R:B photon flux ratios.

Germination ecology of turnip weed (Rapistrum rugosum (L.) All.) in the northern regions of Australia.

In Australia, turnip weed has been rapidly emerging as one of the major weeds in conservation agricultural systems. Germination and emergence of turnip weed were examined for two populations collected from Gatton and St George regions of Australia; two locations with high and low rainfall, respectively. The seeds of turnip weed germinated at all the tested temperatures, but germination was the lowest at 15/5°C, intermediate at 20/10°C and highest at 25/15°C and 30/20°C. The results indicated a high adaptability of turnip weed to warm environmental conditions, although it is a major problem in the winter season. Germination was higher in dark than light/dark regimes except at 30/20°C. Three was a concomitant reduction in germination as the osmotic potential values decreased from 0 to -1.0 MPa. There was 2 and 4% germination at -0.8 MPa for Gatton and St George populations, respectively, and no germination occurred at an osmotic potential of -1.0 MPa. There was a reduction in germination when the sodium chloride (NaCl) concentration was increased from 0 to 150 mM, and no germination was observed at 200 and 250 mM of NaCl. Turnip weed germinated over a broad range of pH (4 to 10). Seedling emergence was higher at 1 cm depth compared to 0.5 cm or at the soil surface. There was 28 and 33% emergence at the surface for the Gatton and St George populations, respectively, compared to 48 and 56% emergence from 1 cm depth for the Gatton and St George populations, respectively and no emergence was observed from 6 cm depth. The results indicated that tillage leading to shallow burial would promote the emergence of turnip weed; on the contrary, tillage that could bury seeds deep into the soil profile might minimise the emergence. Under ideal conditions and lack of integrated weed management programmes, this weed will emerge, set seeds and enrich the soil seed bank and thereby continue to be a problem in the northern grain region of Australia.

Influence of high latitude light conditions on sensory quality and contents of health and sensory-related compounds in swede roots (Brassica napus L. ssp. rapifera Metzg.).

BACKGROUND: Vegetable growers in Arctic areas must increasingly rely on market strategies based on regional origin and product quality. Swede roots (rutabaga) were grown in a phytotron to investigate the effect of high latitude light conditions on sensory quality and some health and sensory-related compounds. Experimental treatments included modifications of 24 h natural day length (69° 39' N) by moving plants at daily intervals to dark chambers with either no light, fluorescent growth light and/or low intensity photoperiod extension. RESULTS: Shortening the photosynthetic light period to 12 h produced smaller roots than 15.7 h and 18 h, with highest scores for bitter and sulfur taste, and lowest scores for sweetness, acidic taste and fibrousness. The photoperiod in combination with the photosynthetic light period also had an influence on glucosinolate (GLS) contents, with lowest concentrations in 24 h natural light and highest in 12 h natural light. Concentrations of vitamin C, glucose, fructose and sucrose were not significantly influenced by any of the treatments. CONCLUSION: High latitude light conditions, with long photosynthetic light periods and 24 h photoperiod, can enhance sweet/less bitter taste and reduce GLS contents in swede roots, compared to growth under short day conditions. This influence of light conditions on eating quality may benefit marketing of regional products from high latitudes. © 2017 Society of Chemical Industry.

Microwave irradiation and citric acid assisted seed germination and phytoextraction of nickel (Ni) by Brassica napus L.: morpho-physiological and biochemical alterations under Ni stress.

The complex bio-geochemistry of soil allows pollutant to persist for a longer period of time which further decreased the fertility and natural composition of land. Nickel, an inorganic pollutant, coming from a wide range of industrial and manufacturing units possesses serious threat to soil degradation and crop productivity around the world. The present study was carried to evaluate the combined role of microwave irradiation (MR) and citric acid (CA) on the phytoextraction potential of Brassica napus L. under Ni stress. An initial seed germination test was conducted to select effective time scale of MR exposure. Highest seed germination was observed at exposure of 2.45 GHz frequency for 30 s. Healthy seeds of B. napus L. genotype Faisal Canola (RBN-03060) treated with MR at 2.45 GHz for 30 s were sown in plastic pots filled with 5 kg of soil. Nickel and CA applied exogenously in solution form with different combinations to both MR-treated and untreated B. napus plants. The MR-treated plants showed higher growth, biomass, photosynthetic pigments (Chl a, b, total, and carotenoids) and activities of antioxidant enzymes (SOD, POD, APX, CAT) as compared to untreated plants who showed higher reactive oxygen species (MDA, H2O2) and electrolyte leakage. Increasing Ni concentration significantly decreased the physiological and biochemical attributes of B. napus both in MR-treated and untreated plants. The addition of CA alleviated Ni-induced toxic effects in both MR-treated and untreated plants by improving antioxidant defense system. The degree of Ni stress mitigation was higher in MR-treated plants. The Ni concentration was higher in root, stem, and leaves of MR-treated plants under CA application as compared to untreated plants. The present study concluded that seeds treated with MR before sowing showed higher accumulation and concentration of Ni from soil, and this phenomenon boosted with the application of CA.

Dynamic metabolic changes in seeds and seedlings of Brassica napus (oilseed rape) suppressing UGT84A9 reveal plasticity and molecular regulation of the phenylpropanoid pathway.

In Brassica napus, suppression of the key biosynthetic enzyme UDP-glucose:sinapic acid glucosyltransferase (UGT84A9) inhibits the biosynthesis of sinapine (sinapoylcholine), the major phenolic component of seeds. Based on the accumulation kinetics of a total of 158 compounds (110 secondary and 48 primary metabolites), we investigated how suppression of the major sink pathway of sinapic acid impacts the metabolome of developing seeds and seedlings. In UGT84A9-suppressing (UGT84A9i) lines massive alterations became evident in late stages of seed development affecting the accumulation levels of 58 secondary and 7 primary metabolites. UGT84A9i seeds were characterized by decreased amounts of various hydroxycinnamic acid (HCA) esters, and increased formation of sinapic and syringic acid glycosides. This indicates glycosylation and ß-oxidation as metabolic detoxification strategies to bypass intracellular accumulation of sinapic acid. In addition, a net loss of sinapic acid upon UGT84A9 suppression may point to a feedback regulation of HCA biosynthesis. Surprisingly, suppression of UGT84A9 under control of the seed-specific NAPINC promoter was maintained in cotyledons during the first two weeks of seedling development and associated with a reduced and delayed transformation of sinapine into sinapoylmalate. The lack of sinapoylmalate did not interfere with plant fitness under UV-B stress. Increased UV-B radiation triggered the accumulation of quercetin conjugates whereas the sinapoylmalate level was not affected.

Responses of wheat (Triticum aestivum) and turnip (Brassica rapa) to the combined exposure of carbaryl and ultraviolet radiation.

The increase of ultraviolet (UV) radiation reaching the Earth's surface as a result of increased ozone layer depletion has affected crop production systems and, in combination with pesticides used in agricultural activities, can lead to greater risks to the environment. The impact of UV radiation and carbaryl singly and in combination on Triticum aestivum (wheat) and Brassica rapa (turnip) was studied. The combined exposure was analyzed using the MixTox tool and was based on the conceptual model of independent action, where possible deviations to synergism or antagonism and dose-ratio or dose-level response pattern were also considered. Compared with the control, carbaryl and UV radiation individually led to reductions in growth, fresh and dry weight, and water content for both species. Combined treatment of UV and carbaryl was more deleterious compared with single exposure. For T. aestivum length, no interaction between the 2 stressors was found (independent action), and a dose-level deviation was the best description for the weight parameters. For B. rapa, dose-ratio deviations from the conceptual model were found when length and dry weight were analyzed, and a higher than expected effect on the fresh weight (synergism) occurred with combined exposure.

Effect of microwave treatment on the efficacy of expeller pressing of Brassica napus rapeseed and Brassica juncea mustard seeds.

A study was conducted to evaluate the effect of microwave heating on the efficacy of expeller pressing of rapeseed and mustard seed and the composition of expeller meals in two types of Brassica napus rapeseed (intermediate- and low-glucosinolate) and in Brassica juncea mustard (high-glucosinolate). Following microwave treatment, the microstructure of rapeseed using transmission electron microscopy showed a significant disappearance of oil bodies and myrosin cells. After 6 min of microwave heating (400 g, 800 W), the oil content of rapeseed expeller meal decreased from 44.9 to 13.5% for intermediate-glucosinolate B. napus rapeseed, from 42.6 to 11.3% for low-glucosinolate B. napus rapeseed, and from 44.4 to 14.1% for B. juncea mustard. The latter values were much lower than the oil contents of the corresponding expeller meals derived from the unheated seeds (i.e., 26.6, 22.6, and 29.8%, respectively). Neutral detergent fiber (NDF) contents showed no differences except for the expeller meal from the intermediate-glucosinolate B. napus rapeseed, which increased from 22.7 to 29.2% after 6 min of microwave heating. Microwave treatment for 4 and 5 min effectively inactivated myrosinase enzyme of intermediate-glucosinolate B. napus rapeseed and B. juncea mustard seed, respectively. In low-glucosinolate B. napus rapeseed the enzyme appeared to be more heat stable, with some activity being present after 6 min of microwave heating. Myrosinase enzyme inactivation had a profound effect on the glucosinolate content of expeller meals and prevented their hydrolysis to toxic breakdown products during the expelling process. It appeared evident from this study that microwave heating for 6 min was an effective method of producing expeller meal without toxic glucosinolate breakdown products while at the same time facilitating high yield of oil during the expelling process.

BrMYB4, a suppressor of genes for phenylpropanoid and anthocyanin biosynthesis, is down-regulated by UV-B but not by pigment-inducing sunlight in turnip cv. Tsuda.

The regulation of light-dependent anthocyanin biosynthesis in Brassica rapa subsp. rapa cv. Tsuda turnip was investigated using an ethyl methanesulfonate (EMS)-induced mutant R30 with light-independent pigmentation. TILLING (targeting induced local lesions in genomes) and subsequent analysis showed that a stop codon was inserted in the R2R3-MYB transcription factor gene BrMYB4 and that the encoded protein (BrMYB4mu) had lost its C-terminal region. In R30, anthocyanin accumulated in the below-ground portion of the storage root of 2-month-old plants. In 4-day-old seedlings and 2-month-old plants, expression of BrMYB4 was similar between R30 and the wild type (WT), but the expression of the cinnamate 4-hydroxylase gene (BrC4H) was markedly enhanced in R30 in the dark. In turnip seedlings, BrMYB4 expression was suppressed by UV-B irradiation in the WT, but this negative regulation was absent in R30. Concomitantly, BrC4H was repressed by UV-B irradiation in the WT, but stayed at high levels in R30. A gel-shift assay revealed that BrMYB4 could directly bind to the promoter region of BrC4H, but BrMYB4mu could not. The BrMYB4-enhanced green fluorescent protein (eGFP) protein could enter the nucleus in the presence of BrSAD2 (an importin ß-like protein) nuclear transporter, but BrMYB4mu-eGFP could not. These results showed that BrMYB4 functions as a negative transcriptional regulator of BrC4H and mediates UV-B-dependent phenylpropanoid biosynthesis, while BrMYB4mu has lost this function. In the storage roots, the expression of anthocyanin biosynthesis genes was enhanced in R30 in the dark and in sunlight in both the WT and R30. However, in the WT, anthocyanin-inducing sunlight did not suppress BrMYB4 expression. Therefore, sunlight-induced anthocyanin biosynthesis does not seem to be regulated by BrMYB4.

Using a non-invasive technique in nutrition: synchrotron radiation infrared microspectroscopy spectroscopic characterization of oil seeds treated with different processing conditions on molecular spectral factors influencing nutrient delivery.

Non-invasive techniques are a key to study nutrition and structure interaction. Fourier transform infrared microspectroscopy coupled with a synchrotron radiation source (SR-IMS) is a rapid, non-invasive, and non-destructive bioanalytical technique. To understand internal structure changes in relation to nutrient availability in oil seed processing is vital to find optimal processing conditions. The objective of this study was to use a synchrotron-based bioanalytical technique SR-IMS as a non-invasive and non-destructive tool to study the effects of heat-processing methods and oil seed canola type on modeled protein structure based on spectral data within intact tissue that were randomly selected and quantify the relationship between the modeled protein structure and protein nutrient supply to ruminants. The results showed that the moisture heat-related processing significantly changed (p<0.05) modeled protein structures compared to the raw canola (control) and those processing by dry heating. The moisture heating increased (p<0.05) spectral intensities of amide I, amide II, α-helices, and ß-sheets but decreased (p<0.05) the ratio of modeled α-helices to ß-sheet spectral intensity. There was no difference (p>0.05) in the protein spectral profile between the raw and dry-heated canola tissue and between yellow- and brown-type canola tissue. The results indicated that different heat processing methods have different impacts on the protein inherent structure. The protein intrinsic structure in canola seed tissue was more sensitive and more response to the moisture heating in comparison to the dry heating. These changes are expected to be related to the nutritive value. However, the current study is based on limited samples, and more large-scale studies are needed to confirm our findings.

Physiological responses of spring rapeseed (Brassica napus) to red/far-red ratios and irradiance during pre- and post-flowering stages.

Early shade signals promote the shade avoidance syndrome (SAS) which causes, among others, petiole and shoot elongation and upward leaf position. In spite of its relevance, these photomorphogenic responses have not been deeply studied in rapeseed (Brassica napus). In contrast to other crops like maize and wheat, rapeseed has a complex developmental phenotypic pattern as it evolves from an initial rosette to the main stem elongation and an indeterminate growth of floral raceme. In this work, we analyzed (1) morphological and physiological responses at individual level due to low red/far-red (R/FR) ratio during plant development, and (2) changes in biomass allocation, grain yield and composition at crop level in response to high R/FR ratio and low irradiance in two modern spring rapeseed genotypes. We carried out pot and field experiments modifying R/FR ratios and irradiance at vegetative or reproductive stages. In pot experiments, low R/FR ratio increased the petiole and lamina length, upward leaf position and also accelerated leaf senescence. Furthermore, low R/FR ratio reduced main floral raceme and increased floral branching with higher remobilization of soluble carbohydrates from the stems. In field experiments, low irradiance during post-flowering reduced grain yield, harvest index and grain oil content, and high R/FR ratio reaching the crop partially alleviated such effects. We conclude that photomorphogenic signals are integrated early during the vegetative growth, and irradiance has stronger effects than R/FR signals at rapeseed crop level.

Cryptochrome 1 regulates growth and development in Brassica through alteration in the expression of genes involved in light, phytohormone and stress signalling.

The blue light photoreceptors cryptochromes are ubiquitous in higher plants and are vital for regulating plant growth and development. In spite of being involved in controlling agronomically important traits like plant height and flowering time, cryptochromes have not been extensively characterized from agriculturally important crops. Here we show that overexpression of CRY1 from Brassica napus (BnCRY1), an oilseed crop, results in short-statured Brassica transgenics, likely to be less prone to wind and water lodging. The overexpression of BnCRY1 accentuates the inhibition of cell elongation in hypocotyls of transgenic seedlings. The analysis of hypocotyl growth inhibition and anthocyanin accumulation responses in BnCRY1 overexpressors substantiates that regulation of seedling photomorphogenesis by cry1 is dependent on light intensity. This study highlights that the photoactivated cry1 acts through coordinated induction and suppression of specific downstream genes involved in phytohormone synthesis or signalling, and those involved in cell wall modification, during de-etiolation of Brassica seedlings. The microarray-based transcriptome profiling also suggests that the overexpression of BnCRY1 alters abiotic/biotic stress signalling pathways; the transgenic seedlings were apparently oversensitive to abscisic acid (ABA) and mannitol.

UV-A light induces anthocyanin biosynthesis in a manner distinct from synergistic blue + UV-B light and UV-A/blue light responses in different parts of the hypocotyls in turnip seedlings.

The effects of irradiating blue, UV-A, UV-B and a combination of the lights on anthocyanin accumulation at different hypocotyl positions were investigated in seedlings of the purple top turnip 'Tsuda'. The location of anthocyanin accumulation varied depending on different light spectra. Stronger accumulation of anthocyanin was induced (i) at the upper hypocotyl positions by blue light; (ii) mainly at the upper position, but also at the middle position by UV-B light; and (iii) at the upper to lower position by UV-A light. There were synergistic effects between blue and UV-B, while such effects were not observed for the other light combinations. Among the six chalcone synthase (CHS) genes identified in the 'Tsuda' turnip, BrCHS1, 4 and 5 exhibited light-dependent expression patterns, while the other three showed no apparent light responses. The expression of BrCHS1, 4 and 5 was increased particularly by UV-A and blue + UV-B irradiation at the middle to lower hypocotyl positions, in accordance with anthocyanin accumulation patterns. The highest induction of gene expression was observed for BrCHS4 upon blue + UV-B co-irradiation. In contrast, CHS expression was induced only slightly at higher hypocotyl positions by blue light. The R2R3-type MYB transcription factor genes PAP1, MYB4, MYB12 and MYB111 exhibited differential expression patterns at different hypocotyl positions; these patterns were unique for different light spectra. These unique anthocyanin accumulation patterns and gene expression profiles depending on hypocotyl positions and light sources demonstrate that there is a distinct UV-A response, blue + UV-B synergistic response and blue/UV-A light response for anthocyanin biosynthesis in turnip. UV-A light-dependent anthocyanin biosynthesis appeared to be regulated in a manner that is distinct from that mediated by cryptochromes and UV-B photoreceptors.

Time and substrate dependent exudation of carboxylates by Lupinus albus L. and Brassica napus L.

Root exudates influence significantly physical, chemical and biological characteristics of rhizosphere soil. Their qualitative and quantitative composition is affected by environmental factors such as pH, soil type, oxygen status, light intensity, soil temperature, plant growth, nutrient availability and microorganisms. The aim of the present study was to assess the influence of growth substrate and plant age on the release of carboxylates from Lupinus albus L. and Brassica napus L. Both plant species were studied in continuously percolated microcosms filled with either sand, soil or sand + soil (1:1) mixture. Soil solution was collected every week at 7, 14, 21, 28 and 35 days after planting (DAP). Carboxylate concentrations were determined by reversed-phase liquid chromatography - electrospray ionization - time of flight mass spectrometry (LC-ESI-TOFMS). Oxalate, citrate, succinate, malate and maleate were detected in soil solutions of both plant species. Their concentrations were correlated with the physiological status of the plant and the growth substrate. Oxalate was the predominant carboxylate detected within the soil solution of B. napus plants while oxalate and citrate were the predominant ones found in the soil solutions of L. albus plants. The sampling determination of carboxylates released by plant roots with continuous percolation systems seems to be promising as it is a non-destructive method and allows sampling and determination of soluble low molecular weight organic compounds derived from root exudation as well as the concentration of soluble nutrients, which both might reflect the nutritional status of plants.

Adaptation of photosystem II to high and low light in wild-type and triazine-resistant Canola plants: analysis by a fluorescence induction algorithm.

Plants of wild-type and triazine-resistant Canola (Brassica napus L.) were exposed to very high light intensities and after 1 day placed on a laboratory table at low light to recover, to study the kinetics of variable fluorescence after light, and after dark-adaptation. This cycle was repeated several times. The fast OJIP fluorescence rise curve was measured immediately after light exposure and after recovery during 1 day in laboratory room light. A fluorescence induction algorithm has been used for resolution and analysis of these curves. This algorithm includes photochemical and photo-electrochemical quenching release components and a photo-electrical dependent IP-component. The analysis revealed a substantial suppression of the photo-electrochemical component (even complete in the resistant biotype), a partial suppression of the photochemical component and a decrease in the fluorescence parameter F (o) after high light. These effects were recovered after 1 day in the indoor light.