Growth Of Oilseed Rape Research Articles

Transcriptomic and Metabolomic Analyses Reveal the Differential Regulatory Mechanisms of Compound Material on the Responses of Brassica campestris to Saline and Alkaline Stresses.

Oilseed rape not only has the function of improve saline and alkaline soils, but also alleviate the local feed shortage. However, medium- and high-degree soil salinization and alkalinization always inhibit the growth of oilseed rape. Studies have shown that compound material can improve the tolerance to saline and alkaline stress of crops, but the difference in the regulation mechanism of compound material on oilseed rape in saline and alkaline soils is not clear. This study explored the difference through determining the leaf ion contents, physiological indexes, transcriptomics, and metabolomics of oilseed rape in salinized soil (NaCl 8 g kg−1) and alkalinized soil (Na2CO3 8 g kg−1) at full flowering stage, respectively after the application of compound material. The results showed that in salinized and alkalinized soil, the compound material upregulated the genes related to the regulation of potassium ion transport, and changed the amino acid metabolic pathway, which reduced the contents of Na+, malondialdehyde (MDA), and relative conductivity (REC) in leaves, and increased the contents of K+ and Mg2+ and the activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT). However, there were differences in the regulation mechanism of compound material in salinized and alkalinized soil. In salinized soil, the compound material improved the tolerance of oilseed rape to saline stress by upregulating transcription factors mannose-1-phosphate guanylyltransferase (GPMM) and Glutamine--fructose-6-phosphate transaminase (GFPT) and downregulating phosphomannomutase (PMM) to change nucleotide metabolism pathway and lipid metabolism pathway. In alkalized soil, the compound material improved the tolerance of oilseed rape to alkaline stress by upregulating transcription factors Phenylalanine ammonia lyase (PAL) to change the biosynthesis pathway of other secondary metabolites. Therefore, the compound material can improve the tolerance of oilseed rape to saline and alkaline stress by regulating the genetic adaptability and apparent plasticity, but the mechanisms were different. This study provides a practical method for the ecological environment restoration and the development of animal husbandry.

Co-exposure of sulfur nanoparticles and Cu alleviate Cu stress and toxicity to oilseed rape Brassica napus L.

Experiments were performed to explore the impact of sulfur nanoparticles (SNPs) on growth, Cu accumulation, and physiological and biochemical responses of oilseed rape (Brassica napus L.) inoculated with 5 mg/L Cu-amended MS medium supplemented with or without 300 mg/L SNPs exposure. Cu exerted severe phytotoxicity and inhibited plant growth. SNPs application enhanced the shoot height, root length, and dry weight of shoot and root by 34.6%, 282%, 41.7% and 37.1%, respectively, over Cu treatment alone, while the shoot and root Cu contents and Cu-induced lipid perodixation as the malondialdehyde (MDA) levels in shoots and roots were decreased by 37.6%, 35%, 28.4% and 26.8%. Further, the increases in superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), ascorbate peroxidase (APX), glutathione reductase (GR) and glutathione S-transferase (GST) enzyme activities caused by Cu stress were mitigated in shoots (10.9%–37.1%) and roots (14.6%–35.3%) with SNPs addition. SNPs also positively counteracted the negative effects on shoot K, Ca, P, Mg, Mn, Zn and Fe contents and root K, Ca, Mg and Mn contents from Cu exposure alone, and significantly promoted the nutrients accumulation in plant. Additionally, in comparison with common bulk sulfur particles (BSPs) and sulfate, SNPs showed more positive effects on promoting growth in shoots (6.7% and 19.5%) and roots (10.9% and 15.1%), as well as lowering the shoot Cu content (40.1% and 43.3%) under Cu stress. Thus, SNPs application has potential to be a green and sustainable technology for increasing plant productivity and reducing accumulation of toxic metals in heavy metal polluted soils.

Phytotoxic Effects of Selected Herbal Extracts on the Germination, Growth and Metabolism of Mustard and Oilseed Rape

The use of plants that have high allelopathic potential as natural herbicides in the form of aqueous extracts is gaining popularity in environmentally friendly agriculture. Usually, their effect on the germination and growth of weeds is investigated. However, less attention is paid to the effect of the allelopathic compounds from extracts on cultivated plants. Therefore, the aim of this study was to evaluate the impact of herbal extracts that have allelopathic properties on selected physiological and biochemical processes of two plants of great economic importance—white mustard (Sinapis alba L.) and oilseed rape (Brassica napus L. var. oleifera). The extracts were prepared from mountain arnica (Arnica montana L.), ribwort (Plantago lanceolata L.), hypericum (Hypericum perforatum L.), common milfoil (Achillea millefolium L.), sunflower (Helianthus annuus L.) and sage (Salvia officinalis L.). The germination of white mustard and oilseed rape was most inhibited by the extracts that were prepared from sage and sunflower. Additionally, in the germinating plants, the sunflower extracts increased the membrane permeability, which indicates membrane injuries. The metabolic changes in the plants were monitored using isothermal calorimetry and FT-Raman spectroscopy. The total heat production, which provided information about the metabolic activity of the white mustard and oilseed rape, was decreased the most by the sage extract but generally all of the tested extracts disturbed the shape of the heat emission curves compared to the water control. The impact of the allelopathic compounds that are present in the herbal extracts on the metabolism of the seedlings was clearly visible on the FT-Raman spectra—in the fatty acids and flavonoids range, confirmed using a cluster analysis. In conclusion, the herbal extracts from medicinal plants that have herbicidal activity could be used as a natural herbicide for weed control, but since they may also have negative impacts on cultivated plants, preliminary tests are advisable to find the extract from the species that has the least negative effect on a protected crop.

The Impact of Forest Fungi on Promoting Growth and Development of Brassica napus L.

Inoculation of plants with fungi has been shown to increase yields by improving germination, seedling vigor, plant growth, root morphogenesis, photosynthesis, and flowering through direct or indirect mechanisms. These mechanisms include solubilization and mineralization of nutrients, facilitating their uptake by plants, regulation of hormone balance, production of volatile organic compounds and microbial enzymes, suppression of plant pathogens, and mitigation of abiotic stresses. In the presented experiments, the effect of selected forest soil fungi on the growth and development of Brassica napus L. seedlings was investigated. Inoculation was carried out in vivo and in pot experiments with ectomycorrhizal fungi typical for forest soils: Collybia tuberosa, Clitocybe sp., Laccaria laccata, Hebeloma mesophaeum, and Cyathusolla. It was shown that all analyzed fungi produced IAA. In the in vitro experiment, B. napus inoculated with L. laccata showed stimulated root growth and greater number of leaves compared to control plants. A similar stimulatory effect on lateral root formation was observed in cuttings grown in pots in the presence of the C. olla fungus. In the pot experiment, the seedlings inoculated with the L. laccata fungus also showed increased growth of shoots and biomass. The effect of inoculation with the tested fungal strains, especially C. olla, on the growth and development of oilseed rape was probably indirect, as it also contributed to an increase in the number of microorganisms, especially soil bacteria. The expression of the metallothioneins in B. napus (BnMT1-BnMT3) varied depending on the fungal species. The presence of C. olla significantly increased BnMT2 expression in oilseed rape. It was found that BnMT1 expression increased and BnMT3 transcripts decreased in plants growing in the presence of L. laccata. This indicates the involvement of BnMT in the adaptation of oilseed rape to growth in fungi presence.

Oilseed Rape (Brassica napus L.) Phenology Estimation by Averaged Stokes-Related Parameters

Accurate and timely knowledge of crop phenology assists in planning and/or triggering appropriate farming activities. The multiple Polarimetric Synthetic Aperture Radar (PolSAR) technique shows great potential in crop phenology retrieval for its characterizations, such as short revisit time, all-weather monitoring and sensitivity to vegetation structure. This study aims to explore the potential of averaged Stokes-related parameters derived from multiple PolSAR data in oilseed rape phenology identification. In this study, the averaged Stokes-related parameters were first computed by two different wave polarimetric states. Then, the two groups of averaged Stokes-related parameters were generated and applied for analyzing averaged Stokes-related parameter sensitivity to oilseed rape phenology changes. At last, decision tree (DT) algorithms trained using 60% of the data were used for oilseed rape phenological stage classification. Four Stokes parameters (g0, g1, g2 and g3) and eight sub parameters (degree of polarization m, entropy H, ellipticity angle χ, orientation angle φ, degree of linear polarization Dolp, degree of circular polarization Docp, linear polarization ratio Lpr and circular polarization ratio Cpr) were extracted from a multi-temporal RADARSAT-2 dataset acquired during the whole oilseed rape growth cycle in 2013. Their sensitivities to oilseed rape phenology were analyzed versus five main rape phenology stages. In two groups (two different wave polarimetric states) of this study, g0, g1, g2, g3, m, H, Dolp and Lpr showed high sensitivity to oilseed rape growth stages while χ, φ, Docp and Cpr showed good performance for phenology classification in previous studies, which were quite noisy during the whole oilseed rape growth circle and showed unobvious sensitivity to the crop’s phenology change. The DT algorithms performed well in oilseed rape phenological stage identification. The results were verified at the parcel level with left 40% of the point dataset. Five phenology intervals of oilseed rape were identified with no more than three parameters by simple but robust decision tree algorithm groups. The identified phenology stages agree well with the ground measurements; the overall identification accuracies were 71.18% and 79.71%, respectively. For each growth stage, the best performance occurred at stage S1 with the accuracy of 95.65% for Group 1 and 94.23% for Group 2, and the worst performance occurred at stage S3 and S5 with the values around 60%. Most of the classification errors may resulted from the indistinguishability of S3 and S5 using Stokes-related parameters.

Oilseed rape (Brassica napus): the importance of aminopeptidases in germination under normal and heavy metals stress conditions.

Oilseed rape is one of the most important oilseed crops worldwide, crucial in the food and feed industries. Different environment and climatic conditions can influence its sustainable cultivation and crop yield. Aminopeptidases are crucial enzymes in many physiological processes in all organisms, including humans, so it is important to learn their behavior in food and feed sources. This study presents, for the first time, a detailed discussion on the importance of aminopeptidases, during the oilseed rape germination process, under standard and stress conditions. During the germination of oilseed rape under standard conditions, a significant increase in aminopeptidases activity toward N-terminal amino acids - phenylalanine (Phe), alanine (Ala), glycine (Gly), leucine (Leu), proline (Pro), methionine (Met) - was observed. The change was substrate specific, with the highest increase being observed for Gly (3.2-fold), followed by Ala (2.9-fold), Pro (2.5-fold), Met (1.5-fold), and Phe (1.3-fold). Generally, N-terminal Phe was preferentially cleaved. Germination under stress conditions, caused by several heavy metal ions (e.g. divalent copper, zinc, cadmium, and lead ions), negatively influenced the plants' growth and quality, but significantly enhanced the expression of genes encoding aminopeptidases (or potentially activated aminopeptidases precursors), which was related to the dramatic increase of their activity. The activity/concentration of aminopeptidases in plants is adjusted to the needs at each stage of development and stress factors occurrence. The most significant increase of activity toward N-terminal Gly and Pro proved the key role of aminopeptidases in the defense mechanisms, by supplying the plants with osmoprotectants and organic nitrogen. The results provide new concepts of oilseed rape growth and cultivation under different conditions. © 2021 Society of Chemical Industry.

The Impact of Growth-Promoting Streptomycetes Isolated from Rhizosphere and Bulk Soil on Oilseed Rape (Brassica napus L.) Growth Parameters

Inoculation of Streptomyces to improve oilseed rape (Brassica napus L.) yields and minimise the use of chemical fertilisers is a promising sustainable strategy. In this study, we isolated 72 actinobacterial strains from rhizosphere of oilseed rape and maize and from bulk soil for screening and characterising their antimicrobial activity. Nine promising strains, identified as Streptomyces sp. by morphology, physiological characteristics, and 16S rRNA gene sequencing, were selected for their plant growth-promoting traits and in planta experiments. The actinobacterial strains were positive for IAA production, siderophore production, and HCN production. In planta experiments were conducted by soaking the oilseed rape seeds in the actinobacterial suspension, followed by plant growth under controlled conditions in a cultivate chamber (22–28 °C, 8 h dark/16 h light, constant humidity 80%). We recorded root and shoot length (cm) and seedling fresh weight (g). For most of the abovementioned parameters, a significant enhancement was observed with strain KmiRC20A118 treatment. The length of the root increased by 53.14%, the shoot length increased by 65.6%, and the weight of the fresh plant by 60% compared to the control. The integrated application of PGPS (Plant Growth Promoting Streptomyces) from the rhizosphere of oilseed rape is a promising strategy to improve the growth of oilseed rape.

Potassium fertilization reduces silique canopy temperature variation in Brassica napus to enhance seed yield

The seed yield of oilseed rape (Brassica napus), an important edible and industrial oil source, is derived mainly from the photosynthetic products of siliques. High temperatures in the pod-development stage threaten the oilseed rape production. Fertilization promotes the growth and yield of oilseed rape. However, it is unclear whether fertilization can alleviate the effect of the temperature on the yield. During 2017–2019 oilseed rape growing season, two oilseed rape cultivars with different K utilization efficiencies (KUtEs) were grown with four K fertilizer rates (0, 60, 120, and 180 kg ha−1) to study the association between the application of the stress-resistance-related element K and silique canopy temperature of oilseed rape. Infrared imaging was used to determine the canopy temperature of the two cultivars at the silique development stage at different K application rates. Partial least squares path modeling (PLS-PM) was used to analyze the potential physiological mechanism of the increase in crop yield with K fertilization. The K fertilization reduced the canopy temperature, specifically, the canopy temperature variation (CTV), at the silique development stage (reduction of 1.3–3.0°C by 1 % increase in K amount). A reduction of 1°C in CTV increased the seed yield by approximately 417.6 kg ha−1. Nevertheless, the cultivar with a low KUtE required almost twice the K amount, compared with the cultivar with a high KUtE, to achieve the same consequent CTV reduction, and produced a lower seed yield at the same K application rate. The reduction in CTV was induced by an increased stomatal function (transpiration rate), which was accelerated by the K application. PLS-PM showed that the K application promoted seed yield by reducing the CTV and increasing the photosynthetic rate and biomass. The photosynthetic rate and biomass were directly affected by the CTV. Overall, the K fertilization combined with the high KUtE cultivars could efficiently maintain a stable canopy temperature microenvironment to promote oil production.

One-Time Foliar Application and Continuous Resupply via Roots Equally Improved the Growth and Physiological Response of B-Deficient Oilseed Rape.

Oilseed rape (Brassica napus L.) is a high-boron (B)-demanding crop, and initially, normal growing plants might show B deficiency at advanced growth stages on soils with marginal B availability. Hence, we compared the effects of B resupply via roots and leaves on growth and physiological response, and relative expression of B transporters in B-deficient oilseed rape plants. Four-week-old plants initially grown with inadequate B (1 µM B for the first two weeks and 0.25 µM B for the next two weeks) were later grown either as such with 0.25 µM B, with 25 µM B in nutrient solution or foliar sprayed with 7 mL of 30, 60 and 150 mM B solution plant−1 as boric acid. Plants grown with 25 µM B in the nutrient solution from the beginning were included as adequate B treatment. Results showed that B resupply to B-deficient plants via roots and leaves (60 mM B) equally improved root and shoot dry matter, but not to the level of plants grown with adequate B supply. Foliar-applied 150 mM B proved toxic, causing leaf burn but not affecting dry matter. Resupply of B via roots increased B concentration in roots and leaves, while leaf-applied B did so only in leaves. Net carbon assimilation had a positive relationship with dry matter accumulation. Except for the highest foliar B level, B resupply via roots and leaves increased the accumulation of glucose, fructose and sucrose in leaves. Boron-deficient plants showed significant upregulation of BnaNIP5;1 in leaves and roots and of BnaBOR1;2 in roots. Boron resupply via roots reversed the B-deficiency-induced upregulation of BnaNIP5;1 in roots, whereas the expression of BnaBOR1;2 was reversed by both root and foliar B resupply. In leaves, B resupply by both methods reversed the expression of BnaNIP5;1 to the level of B-adequate plants. It is concluded that B resupply to B-deficient plants via roots and leaves equally but partially corrected B deficiency in B. napus grown in hydroponics.

Bacterial and fungal endophyte communities in healthy and diseased oilseed rape and their potential for biocontrol of Sclerotinia and Phoma disease

Phoma stem canker (caused by the ascomycetes Leptosphaeria maculans and Leptosphaeria biglobosa) is an important disease of oilseed rape. Its effect on endophyte communities in roots and shoots and the potential of endophytes to promote growth and control diseases of oilseed rape (OSR) was investigated. Phoma stem canker had a large effect especially on fungal but also on bacterial endophyte communities. Dominant bacterial genera were Pseudomonas, followed by Enterobacter, Serratia, Stenotrophomonas, Bacillus and Staphylococcus. Achromobacter, Pectobacter and Sphingobacterium were isolated only from diseased plants, though in very small numbers. The fungal genera Cladosporium, Botrytis and Torula were dominant in healthy plants whereas Alternaria, Fusarium and Basidiomycetes (Vishniacozyma, Holtermaniella, Bjerkandera/Thanatephorus) occurred exclusively in diseased plants. Remarkably, Leptosphaeria biglobosa could be isolated in large numbers from shoots of both healthy and diseased plants. Plant growth promoting properties (antioxidative activity, P-solubilisation, production of phytohormones and siderophores) were widespread in OSR endophytes. Although none of the tested bacterial endophytes (Achromobacter, Enterobacter, Pseudomonas, Serratia and Stenotrophomonas) promoted growth of oilseed rape under P-limiting conditions or controlled Phoma disease on oilseed rape cotyledons, they significantly reduced incidence of Sclerotinia disease. In the field, a combined inoculum consisting of Achromobacter piechaudii, two pseudomonads and Stenotrophomonas rhizophila tendencially increased OSR yield and reduced Phoma stem canker.

Optimal temporal-spatial fluorescence techniques for phenotyping nitrogen status in oilseed rape.

Nitrogen (N) fertilizer maximizes the growth of oilseed rape (Brassica napus L.) by improving photosynthetic performance. Elucidating the dynamic relationship between fluorescence and plant N status could provide a non-destructive diagnosis of N status and the breeding of N-efficient cultivars. The aim of this study was to explore the impacts of different N treatments on photosynthesis at a spatial-temporal scale and to evaluate the performance of three fluorescence techniques for the diagnosis of N status. One-way ANOVA and linear discriminant analysis were applied to analyze fluorescence data acquired by a continuous excitation chlorophyll fluorimeter (OJIP transient analysis), pulse amplitude-modulated chlorophyll fluorescence (PAM-ChlF), and multicolor fluorescence (MCF) imaging. The results showed that the maximum quantum efficiency of PSII photochemistry (Fv/Fm) and performance index for photosynthesis (PIABS) of bottom leaves were sensitive to N status at the bolting stage, whereas the red fluorescence/far-red fluorescence ratio of top leaves was sensitive at the early seedling stage. Although the classification of N treatments by the three techniques achieved comparable accuracies, MCF imaging showed the best potential for early diagnosis of N status in field phenotyping because it had the highest sensitivity in the top leaves, at the early seedling stage. The findings of this study could facilitate research on N management and the breeding of N-efficient cultivars.

Planting pattern of oilseed rape (Brassica napus L.) in intercropping systems - A review

Since per capita availability of land is shrinking day by day and there is little scope for horizontal growth of oilseed rape (Brassica napus L.) and thus vertical growth via intercropping can be a viable alternative to reduce the wide gap between the demand and supply of edible oils. Intercropping is an intensive land use system and a profitable venture especially for the small land holders as it fulfills the diversified demands at the farm level itself. Suitable planting pattern for greater light interception and transmission throughout the crop profile is pre-requisite for getting higher productivity. This paper reviews the information regarding role of planting patterns of oilseed rape on various aspects like growth, yield, competitiveness as well as productivity and profitability of intercropping systems. Different oilseed rape cultivars when intercropped with different crops viz., cereals, legumes, fodders or other oilseed crops prove to be more productive and remunerative as compared to their monoculture at different row proportions or spacings, which also varies with locations.

Low concentration of exogenous ethanol promoted biomass and nutrient accumulation in oilseed rape (Brassica napus L.)

ABSTRACTWith hydroponics culture, we monitored the response of the growth and nutrient accumulation of oilseed rape (Brassica napus L.) to five ethanol concentrations: 0 mL•L−1 (control), 0.0125 mL•L−1, 0.025 mL•L−1, 0.05 mL•L−1, and 0.25 mL•L−1, respectively. The results showed that a high concentration of exogenous ethanol (0.25 mL•L−1) significantly inhibited oilseed rape growth by 52.28%. However, the biomass of oilseed rape with a low concentration of exogenous ethanol (0.0125–0.05 mL•L−1) manipulation was raised by 16.62–44.08%. A similar result was found on the total nitrogen, phosphorus, and potassium of the oilseed rape. Results of micro-element determination showed that iron and zinc accumulation in oilseed rape was unchanged, while manganese and copper accumulation was increased first and then decreased with increasing ethanol concentration. This study provided a possibility for improving plant growth with low concentration ethanol application in oilseed rape planting.

Estimating biomass of winter oilseed rape using vegetation indices and texture metrics derived from UAV multispectral images

Monitoring the above ground biomass (AGB) in winter oilseed rape is important for improving the agronomic management efficiency and predicting yield to ensure edible oil and biofuel supplies. The Yangtze River Basin in China accounts for one-fifth of the rapeseed yield in the world. However, the fragmented farming lands in the Yangtze River Basin make it difficult to accurately monitor winter oilseed rape growth at large scale using the medium-resolution satellite data. The low-altitude unmanned aerial vehicle (UAV) provides a feasible way to accurately and non-destructively estimate AGB in winter oilseed rape at the plot level. In this study, we evaluated the contributions of vegetation indices (VIs) and texture metrics, derived from multispectral images captured by the camera mounted on a UAV, to predict the AGB in winter oilseed rape. The AGB was estimated with (1) multiple VIs and (2) multiple VIs and texture metrics. The partial least square regression (PLSR) and random forest (RF) regression models were trained with datasets of the experiment in 2016–2017 and 2017–2018, and then applied to predict AGB of the 2018–2019 growth season. Results demonstrated that the incorporation of texture metrics to both PLSR and RF models provided more accurate estimations of AGB in winter oilseed rape than the models based solely on VIs. The accuracy of the AGB predicted by the RF regression model using VIs and texture metrics (RMSE = 274.18 kg/ha for the validation dataset) was slightly higher than the results of the PLSR model (RMSE = 284.09 kg/ha for the validation dataset). According to the evaluation of the important variables, the red edge chlorophyll index (CIred edge) and ratio vegetation index (RVI) were selected as the most important input features by PLSR and RF regression models. The normalized difference vegetation index (NDVI) contrast was selected as an important texture metrics for the AGB prediction, indicating that NDVI contrast could be a sensitive indicator of the spatial distribution of shadow caused by the different amount of biomass. This study suggested the great potential of UAV in estimating the plot-level AGB by combining VIs and texture metrics.

Effects of 5-aminolevulinic Acid on the Bioactive Compounds and Seedling Growth of Oilseed Rape (Brassica napus L.)

Application of 5-Aminolevulinic acid (ALA) to plants not only affects their growth, but also influences the nutritional values of plant organs. Oilseed rape (Brassica napus L.) is an important source of vegetable oil and various compounds benefiting human health. However, limited information is available regarding the effect of ALA on the growth of this important crop. Here, we investigated the consequence of ALA application on oilseed rape seedlings. We found that moderate ALA concentrations (0.5 or 1 mg/L) caused an increase in the dry weight of the seedling biomass and the contents of various bioactive compounds, i.e. soluble sugar, phenolic compounds, ascorbate, and glucosinolates etc, and the upregulated expressional levels of the genes encoding RuBisCO, namely, BnRBCL and BnRBCS, and other genes such as BnUGT79B1, BnMYB12 and MYB28 that regulate the synthesis of phenolic compounds and glucosinolates respectively. On the other hand, high ALA concentrations (5 and 10 mg/L) gave rise to oxidative stress that negatively affected oilseed rape growth, and caused deleterious effects by reducing various bioactive compounds, but increasing tocopherols that may serve as a stress mitigatory agent. With the high ALA concentrations, the ultrastructure of chloroplasts was notably damaged, featured with large starch grains and fewer plastoglobules.

Comparative Transcriptome Analysis in Oilseed Rape (Brassica napus) Reveals Distinct Gene Expression Details between Nitrate and Ammonium Nutrition.

Nitrate (NO3−) and ammonium (NH4+) are the main inorganic nitrogen (N) sources absorbed by oilseed rape, a plant that exhibits genotypic differences in N efficiency. In our previous study, the biomass, N accumulation, and root architecture of two oilseed rape cultivars, Xiangyou 15 (high N efficiency, denoted “15”) and 814 (low N efficiency, denoted “814”), were inhibited under NH4+ nutrition, though both cultivars grew normally under NO3− nutrition. To gain insight into the underlying molecular mechanisms, transcriptomic changes were investigated in the roots of 15 and 814 plants subjected to nitrogen-free (control, CK), NO3− (NT), and NH4+ (AT) treatments at the seedling stage. A total of 14,355 differentially expressed genes (DEGs) were identified. Among the enriched Gene Ontology (GO) terms and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway categories of these DEGs, carbohydrate metabolism, lipid metabolism, protein metabolism, and cell wall biogenesis were inhibited by AT treatment. Interestingly, DEGs such as N transporters, genes involved in N assimilation and CESA genes related to cellulose synthase were also mostly downregulated in the AT treatment group. This downregulation of genes related to crucial metabolic pathways resulted in inhibition of oilseed rape growth after AT treatment.

The high-affinity transporter BnPHT1;4 is involved in phosphorus acquisition and mobilization for facilitating seed germination and early seedling growth of Brassica napus

BackgroundSeed germination and seedling establishment are two of the most critical phases in plant development. However, the molecular mechanisms underlying the effect of phosphorus on seed germination and post-germinated growth of oilseed rape are unclear so far. Here, we report the role of BnPHT1;4 in seed germination and early seedling development of Brassica napus.ResultsOur results show that BnPHT1;4 is preferentially expressed in cotyledons of early developing seedlings. Overexpression of BnPHT1;4 in oilseed rape promoted seed germination and seedling growth. Expression levels of the genes related to ABA and GA biosynthesis and signaling were significantly altered in BnPHT1;4 transgenic seedlings. Consequently, active GA level was up-regulated, whereas ABA content was down-regulated in BnPHT1;4 transgenic seedlings. Furthermore, exogenous GA could promote seed germination of wild type, while exogenous ABA could partially recover the advanced-germination phenotype of BnPHT1;4 transgenic seeds. Total phosphorus content in cotyledons of the transgenic seedlings was decreased more rapidly than that in wild type when Pi was supplied or deficient, and Pi contents in shoots and roots of the BnPHT1;4 transgenic plants were higher than those in wild type under high and low Pi conditions.ConclusionsOur data suggest that the high-affinity transporter BnPHT1;4 is involved in phosphorus acquisition and mobilization for facilitating seed germination and seedling growth of Brassica napus by modulating ABA and GA biosynthesis.

Simulated seawater flooding reduces oilseed rape growth, yield and progeny performance.

Of the many threats to global food security, one of the most pressing is the increased incidence of extreme weather events. In addition to extreme rainfall, a combination of global sea level rise and storm surge is likely to result in frequent episodes of seawater flooding in arable systems along low-lying coasts. Our aim was to elucidate the effects of simulated seawater and freshwater flooding on the survival, growth and reproductive potential of four cultivars of the important seed crop, Brassica napus [canola, or oilseed rape (OSR)]. Established plants were exposed to 24 or 96 h freshwater or seawater root zone immersion (with a no immersion 'control'). Initial post-treatment performance over 7 weeks was quantified using dry weight biomass. A second group of plants, cultivated until maturity, were used to quantify reproductive yield (siliqua and seed number, and seed size) and subsequent progeny performance (germination and seedling growth). Oilseed rape growth and reproductive responses were unaffected by freshwater, but seawater negatively affected growth and siliqua number for all cultivars, and seed mass for two ('Agatha' and 'Cubic'). In addition to impacts on crop yield, the growth of seedlings cultivated from seed collected from maternal plants subjected to seawater immersion was also reduced. Our results demonstrate the potential impact of seawater inundation on coastal cropping systems; although OSR may survive acute saline flooding, there are longer term impacts on growth and yield for some cultivars. The threat may necessitate changes in land-use practice and/or the development of salt-tolerant cultivars to maintain economically viable yields. In addition, by evidencing a hitherto unknown effect on reproductive performance (i.e. reduced seed yield) and subsequent seedling growth, our study highlights an important potential impact of coastal flooding on plant community dynamics for (semi-) natural habitats.

Soil Enzyme Activity in Soils Subjected to Flooding and the Effect on Nitrogen and Phosphorus Uptake by Oilseed Rape.

Waterlogging presents one of the greatest constraints for agricultural crops. In order to elucidate the influences of waterlogging stress on the growth of oilseed rape, a pot experiment was performed investigating the impact of waterlogging on nitrogen (N) and phosphorus (P) accumulation in oilseed rape, and mineral N and available P profiles and enzyme activities of soils. The experiment included waterlogging treatments lasting 3 (I), 6 (II), and 9 (III) days, and a control treatment without waterlogging (CK). Results showed that waterlogging lasting 3 or more days significantly depressed the growth of oilseed rape, and prolonged the recovery time of plant growth with the period of flooding. Waterlogging notably influenced the N and P concentrations in plant tissues, and also affected mineral N, available P profiles, and activities of enzymes (including urease, phosphatase, invertase, and catalase) in the soils. With the exception of catalase, flooding suppressed the activity of urease, phosphatase, and invertase to varying degrees, and the longer the flooding time, the greater the suppression. The effect of waterlogging on mineral N and P profiles resulted from the altered proportions of NH4+-N and NO3--N, and the decreased available P concentrations in these soils, respectively. The effect on P was more significant than on N in both soil nutrient profile and plant utilization.

Detection of Sclerotinia Stem Rot on Oilseed Rape (Brassica napus L.) Based on Laser- Induced Breakdown Spectroscopy

Abstract. In this study, a novel approachser-induced breakdown spectroscopy (LIBS) is proposed to rapidly diagnose stem rot (SSR) in oilseed rape ( L.). A rapid diagnostic method is important to prevent this worldwide disease and promote growth of oilseed rape. A total of 120 fresh leaves, including 60 healthy and 60 SSR-infected leaves, were collected to acquire LIBS spectra. Robust baseline estimation (RBE) and wavelet transform (WT) were applied to preprocess the raw LIBS spectra for baseline correction and denoising. K-nearest neighbor (KNN), radial basis function neural network (RBFNN), random forest (RF), and extreme learning machine (ELM) methods combining full LIBS spectra were chosen to establish classification models to identify healthy and SSR-infected leaves, and the ELM model obtained classified accuracy of more than 80.00% in the prediction set. Twenty-four emission lines were selected by second-derivative spectra as the most relevant to distinguish healthy and SSR-infected leaves. The ELM model using the optimal emission lines improved the classified accuracy to more than 85% and the specificity to 95.00%. Compared with full-spectra models, the number of variables in the models based on optimal wavelengths was reduced from 22,036 to 24, a reduction of 99.89%. This study indicates that LIBS combined with appropriate chemometric m. Keywords: Chemometrics, Laser-induced breakdown spectroscopy, Oilseed rape, Sclerotinia stem rot.