Multi-Omics Analysis Reveals That Anthocyanin Degradation and Phytohormone Changes Regulate Red Color Fading in Rapeseed (Brassica napus L.) Petals.

Flower color is an important trait for the ornamental value of colored rapeseed (Brassica napus L.), as the plant is becoming more popular. However, the color fading of red petals of rapeseed is a problem for its utilization. Unfortunately, the mechanism for the process of color fading in rapeseed is unknown. In the current study, a red flower line, Zhehuhong, was used as plant material to analyze the alterations in its morphological and physiological characteristics, including pigment and phytohormone content, 2 d before flowering (T1), at flowering (T2), and 2 d after flowering (T3). Further, metabolomics and transcriptomics analyses were also performed to reveal the molecular regulation of petal fading. The results show that epidermal cells changed from spherical and tightly arranged to totally collapsed from T1 to T3, according to both paraffin section and scanning electron microscope observation. The pH value and all pigment content except flavonoids decreased significantly during petal fading. The anthocyanin content was reduced by 60.3% at T3 compared to T1. The content of three phytohormones, 1-aminocyclopropanecarboxylic acid, melatonin, and salicylic acid, increased significantly by 2.2, 1.1, and 30.3 times, respectively, from T1 to T3. However, auxin, abscisic acid, and jasmonic acid content decreased from T1 to T3. The result of metabolomics analysis shows that the content of six detected anthocyanin components (cyanidin, peonidin, pelargonidin, delphinidin, petunidin, and malvidin) and their derivatives mainly exhibited a decreasing trend, which was in accordance with the trend of decreasing anthocyanin. Transcriptomics analysis showed downregulation of genes involved in flavonol, flavonoid, and anthocyanin biosynthesis. Furthermore, genes regulating anthocyanin biosynthesis were preferentially expressed at early stages, indicating that the degradation of anthocyanin is the main issue during color fading. The corresponding gene-encoding phytohormone biosynthesis and signaling, JASMONATE-ZIM-DOMAIN PROTEIN, was deactivated to repress anthocyanin biosynthesis, resulting in fading petal color. The results clearly suggest that anthocyanin degradation and phytohormone regulation play essential roles in petal color fading in rapeseed, which is a useful insight for the breeding of colored rapeseed.

Transcriptomic Analysis of the Reduction in Seed Oil Content through Increased Nitrogen Application Rate in Rapeseed (Brassica napus L.).

Nitrogen is essential for improving the seed oil yield of rapeseed (Brassica napus L.). However, the molecular mechanism by which increased nitrogen rates impact seed oil content is largely unknown. Therefore, a field experiment was conducted to determine how three nitrogen application rates (120, 240, and 360 kg ha-1) regulated seed oil content via transcriptomic analysis. The results showed that the seed yield and the protein and total N contents increased from N1 to N3, with average increases of 57.2%, 16.9%, and 79.5%, respectively. However, the seed oil content significantly decreased from N1 to N3, with an average decrease of 8.6%. These results were repeated over a number of years. The quantity of oil protein bodies observed under a transmission electron microscope was in accordance with the ultimate seed oil and protein contents. As the nitrogen application rate increased, a substantial number of genes involved in the photosynthesis, glycolysis, and phenylpropanoid biosynthesis pathways were up-regulated, as were TF families, such as AP2/ERF, MYB, and NAC. The newly identified genes were mainly involved in carbohydrate, lipid, and amino acid metabolism. Metabolic flux analysis showed that most of the genes involved in glycolysis and fatty acid biosynthesis had higher transcript levels in the early development stages. Our results provide new insights into the molecular regulation of rapeseed seed oil content through increased nitrogen application rates.

MicroRNA-mRNA expression profiles and their potential role in cadmium stress response in Brassica napus.

BACKGROUND: Oilseed rape is an excellent candidate for phytoremediation of cadmium (Cd) contaminated soils given its advantages of high biomass, fast growth, moderate metal accumulation, ease of harvesting, and metal tolerance, but the cadmium response pathways in this species (Brassica napus) have yet to be fully elucidated. A combined analysis of miRNA and mRNA expression to infer Cd-induced regulation has not been reported in B. napus. RESULTS: We characterized concurrent changes in miRNA and mRNA profiles in the roots and shoots of B. napus seedlings after 10 days of 10 mg/L Cd2+ treatment. Cd treatment significantly affected the expression of 22 miRNAs belonging to 11 families in the root and 29 miRNAs belonging to 14 miRNA families in the shoot. Five miRNA families (MIR395, MIR397, MIR398, MIR408 and MIR858) and three novel miRNAs were differentially expressed in both tissues. A total of 399 differentially expressed genes (DEGs) in the root and 389 DEGs in the shoot were identified, with very little overlap between tissue types. Eight anti-regulation miRNA-mRNA interaction pairs in the root and eight in the shoot were identified in response to Cd and were involved in key plant stress response pathways: for example, four genes targeted by miR398 were involved in a pathway for detoxification of superoxide radicals. Cd stress significantly impacted the photosynthetic pathway. Transcription factor activation, antioxidant response pathways and secondary metabolic processes such as glutathione (GSH) and phenylpropanoid metabolism were identified as major components for Cd-induced response in both roots and shoots. CONCLUSIONS: Combined miRNA and mRNA profiling revealed miRNAs, genes and pathways involved in Cd response which are potentially critical for adaptation to Cd stress in B. napus. Close crosstalk between several Cd-induced miRNAs and mRNAs was identified, shedding light on possible mechanisms for response to Cd stress in underground and aboveground tissues in B. napus. The pathways, genes, and miRNAs identified here will be valuable targets for future improvement of cadmium tolerance in B. napus.

Cytological and Molecular Characterization of a New Ogura Cytoplasmic Male Sterility Restorer of Brassica napus L.

Ogura cytoplasmic male sterility (CMS) is considered the rapeseed (Brassica napus L.) with the most potential to be utilized as a heterosis system worldwide, but it lacks sufficient restorers. In this study, root tip cell (RTC) mitotic and pollen mother cell (PMC) meiosis observations were compared to ensure the number of chromosomes and the formation of a chromosomal bridge using restorer lines R2000, CLR650, and Zhehuhong (a new restorer) as the experimental material. Further, molecular markers of exogenous chromosomal fragments were detected and the sequence and expression differences of restorer genes in the three lines were determined to identify the distinctive characteristics of Zhehuhong. The results showed that the number of chromosomes in Zhehuhong was stable (2n = 38), indicating that the exogenous radish chromosome segment had been integrated into the chromosome of Zhehuhong. Molecular marker detection revealed that Zhehuhong was detected at most loci, with only the RMA05 locus being missed. The exogenous radish chromosome segment of Zhehuhong differed from R2000 and CLR650. The pollen mother cells of Zhehuhong showed chromosome lagging in the meiotic metaphase I, meiotic anaphase I, and meiotic anaphase II, which was consistent with R2000 and CLR650. The restorer gene PPRB in Zhehuhong had 85 SNPs compared with R2000 and 119 SNPs compared with CLR650, indicating the distinctive characteristic of PPRB in Zhehuhong. In terms of the spatial expression of PPRB, the highest level was detected in the anthers in the three restorer lines. In addition, in terms of temporal expression, the PPRB gene expression of Zhehuhong was highest at a bud length of 4 mm. Our results clearly indicated that Zhehuhong is a new restorer line for the Ogura CMS system, which can be used further in rapeseed heterosis utilization.

Elevated ROS Levels Caused by Reductions in GSH and AsA Contents Lead to Grain Yield Reduction in Qingke under Continuous Cropping.

Continuous spring cropping of Qingke (Hordeum viilgare L. var. nudum Hook. f.) results in a reduction in grain yield in the Xizang autonomous region. However, knowledge on the influence of continuous cropping on grain yield caused by reactive oxygen species (ROS)-induced stress remains scarce. A systematic comparison of the antioxidant defensive profile at seedling, tillering, jointing, flowering, and filling stages (T1 to T5) of Qingke was conducted based on a field experiment including 23-year continuous cropping (23y-CC) and control (the first year planted) treatments. The results reveal that the grain yield and superoxide anion (SOA) level under 23y-CC were significantly decreased (by 38.67% and 36.47%), when compared to the control. The hydrogen peroxide content under 23y-CC was 8.69% higher on average than under the control in the early growth stages. The higher ROS level under 23y-CC resulted in membrane lipid peroxidation (LPO) and accumulation of malondialdehyde (MDA) at later stages, with an average increment of 29.67% and 3.77 times higher than that in control plants. Qingke plants accumulated more hydrogen peroxide at early developmental stages due to the partial conversion of SOA by glutathione (GSH) and superoxide dismutase (SOD) and other production pathways, such as the glucose oxidase (GOD) and polyamine oxidase (PAO) pathways. The reduced regeneration ability due to the high oxidized glutathione (GSSG) to GSH ratio resulted in GSH deficiency while the reduction in L-galactono-1,4-lactone dehydrogenase (GalLDH) activity in the AsA biosynthesis pathway, higher enzymatic activities (including ascorbate peroxidase, APX; and ascorbate oxidase, AAO), and lower activities of monodehydroascorbate reductase (MDHAR) all led to a lower AsA content under continuous cropping. The lower antioxidant capacity due to lower contents of antioxidants such as flavonoids and tannins, detected through both physiological measurement and metabolomics analysis, further deteriorated the growth of Qingke through ROS stress under continuous cropping. Our results provide new insights into the manner in which ROS stress regulates grain yield in the context of continuous Qingke cropping.

Design and Realization of Rural Environment Art Construction of Cultural Image and Visual Communication.

The practice of rural construction has been exploring and trying to adapt to the needs of rural development in various periods. In recent years, under the attention and promotion of the central policy, various social forces have joined the ranks of rural construction, and art intervention in rural construction has begun as a new method. Entering the public eye, it deeply intervenes in the construction and development of the countryside in a more gentle way, from the key point of interaction between the social and cultural orientation and the material needs of the countryside. However, most of the art interventions in rural construction practice only unilaterally use artistic techniques to beautify local areas or display works, without realizing the hidden artistic and cultural value of the village and ignoring the participation and role of the villagers in the whole process. After the construction is completed, once the foreign construction forces are withdrawn, the development of the village will stagnate. Therefore, mobilizing the main body of rural construction (original villagers) to participate in the joint construction of the village is an important link to solve the current problems of art intervening in the construction of rural settlements.

Sustainable Development Evaluation on the Landscape Design of Industrial Heritage Park: A Case Study of Tao Sichuan, China.

The sustainable development of the urban environmental landscape is a process that integrates resource utilization, ecological benefit, economy, and society and involves elements of culture, society, politics, economy, and individual residents. Citizen participation is increasingly important for the urban landscape design, and therefore, urban environmental landscape studies must be evaluated objectively by the public to ensure both sustainable development and social justice. In this study, the Tao Sichuan Creative Industry Park (the former "Universe Porcelain Factory") in Jingdezhen, Jiangxi province, China, was taken as example, and the implemented landscape reconstruction was evaluated. The analytical hierarchy process was used to collect both expert and public opinions regarding the cultural landscape; then, the weight coefficient of the value index layer of the industrial heritage park was obtained. A comparison of the two groups (experts and the public) showed that the experts do not exactly agree with the perspective of the public: experts prefer the artistic value far more than any other factors, while the public prefers the artistic value, social value, and economic value. Each group prefers different values of the landscape, suggesting that environmental justice should not be biased toward one of these perspectives. Finally, a design optimization principle is proposed according to the results of this study. This principle strengthens the sustainable development concept in the landscape reconstruction of industrial heritage parks, and suggestions are provided for optimizing the allocation of urban public landscape resources.

How Antioxidants, Osmoregulation, Genes and Metabolites Regulate the Late Seeding Tolerance of Rapeseeds (Brassica napus L.) during Wintering.

Rapeseed seeding dates are largely delayed under the rice-rape rotation system, but how rapeseeds adapt to the delayed environment remains unclear. Here, five seeding dates (20 October, 30 October, 10 November, 20 November and 30 November, T1 to T5) were set and the dynamic differences between two late-seeding-tolerant (LST) and two late-seeding-sensitive (LSS) rapeseed cultivars were investigated in a field experiment. The growth was significantly repressed and the foldchange (LST/LSS) of yield increased from 1.50-T1 to 2.64-T5 with the delay in seeding. Both LST cultivars showed higher plant coverage than the LSS cultivars according to visible/hyperspectral imaging and the vegetation index acquired from an unmanned aerial vehicle. Fluorescence imaging, DAB and NBT staining showed that the LSS cultivars suffered more stress damage than the LST cultivars. Antioxidant enzymes (SOD, POD, CAT, APX) and osmoregulation substances (proline, soluble sugar, soluble protein) were decreased with the delay in seeding, while the LST cultivar levels were higher than those of the LSS cultivars. A comparative analysis of transcriptomes and metabolomes showed that 55 pathways involving 123 differentially expressed genes (DEGs) and 107 differentially accumulated metabolites (DAMs) participated in late seeding tolerance regulation, while 39 pathways involving 60 DEGs and 68 DAMs were related to sensitivity. Levanbiose, α-isopropylmalate, s-ribosyl-L-homocysteine, lauroyl-CoA and argino-succinate were differentially accumulated in both cultivars, while genes including isocitrate dehydrogenase, pyruvate kinase, phosphoenolpyruvate carboxykinase and newgene_7532 were also largely regulated. This study revealed the dynamic regulation mechanisms of rapeseeds on late seeding conditions, which showed considerable potential for the genetic improvement of rapeseed.

Tandem Mass Tag-Based Quantitative Proteomics Reveals Implication of a Late Embryogenesis Abundant Protein (BnLEA57) in Seed Oil Accumulation in Brassica napus L.

Enhancing oil content is one of the major goals in Brassica napus breeding; however, genetic regulation of seed oil content in plants is complex and not fully elucidated. In this study, we report proteins that were differentially accumulated in immature seeds of 35 days after anthesis between two recombinant inbred lines with contrasting seed oil content, high oil content line (HOCL) and low oil content line (LOCL) using a multiplex isobaric tandem mass tags (TMT)-based quantitative proteomic approach. Over 4,600 proteins were quantified in seeds of the two lines, and 342 proteins showed differential accumulation between seeds of HOCL and LOCL. Gene Ontology enrichment analysis revealed that the differentially accumulated proteins were enriched in proteins involved in lipid biosynthesis and metabolism, photosynthesis, and nutrient reservoir activity. Western blot confirmed the increased abundance of a late embryogenesis abundant protein (BnLEA57) in HOCL seeds compared with LOCL seeds, and overexpression of either BnLEA57 gene or its homology BnLEA55 in transgenic Arabidopsis thaliana enhanced oil content in Arabidopsis seeds. Our work provides new insights into the molecular regulatory mechanism of seed oil content in B. napus.

Leaf Carbohydrate Metabolism Variation Caused by Late Planting in Rapeseed (Brassica napus L.) at Reproductive Stage.

Delayed planting date of rapeseed is an important factor affecting seed yield. However, regulation of the leaf carbohydrate metabolism in rapeseed by a late planting date at the reproductive stage is scarcely investigated. A two-year field experiment was conducted to assess the effect of planting dates, including early (15 September), optimal (1 October), late (15 October), and very late (30 October), on leaf growth and carbohydrate biosynthetic and catabolic metabolism at the reproductive stage. The results showed that leaf dry matter decreased linearly on average from 7.48 to 0.62 g plant-1 with an early planting date, whereas it increased at first and peaked at 14 days after anthesis (DAA) with other planting dates. Leaf dry matter was the lowest at the very late planting date during the reproductive stage. For leaf chlorophyll content, rapeseed planted at an optimal date maximized at 14 DAA with an average content of 1.51 mg g-1 fresh weight, whereas it kept high and stable at a very late planting date after 28 DAA. For the carbohydrate catabolic system, acid and neutral invertase (AI and NI, respectively) showed higher activity before 14 DAA, whereas both sucrose synthase (SS) and starch phosphorylase (SP) showed higher activity after 14 DAA. For the carbohydrate biosynthetic system, the activity of sucrose phosphate synthase (SPS) was the highest at the late planting date after 14 DAA, whereas it was at the lowest at the very late planting date. However, the activity of ADP-glucose pyrophosphorylase (AGPase) at the late and very late planting dates was significantly higher than that of the early and optimal plant dates after 21 DAA, which is in accordance with the leaf total soluble sugar content, suggesting that leaf carbohydrate metabolism is governed by a biosynthetic system. The current study provides new insights on leaf carbohydrate metabolism regulation by late planting in rapeseed at the reproductive stage.

BnaA03.ANS Identified by Metabolomics and RNA-seq Partly Played Irreplaceable Role in Pigmentation of Red Rapeseed (Brassica napus) Petal.

Colorful flowers of rapeseed (Brassica napus L.) have been a hotspot for researchers, but the underlying mechanisms of pigment formation still need to be clarified. In this study, two stages of unopened rapeseed petals with red, white, and yellow colors were selected to identify the metabolites and genes involved in red pigment formation. Metabolomic analysis showed that flavonoids enriched the most co-differentially accumulated metabolites among all categories, and showed higher accumulation in red petal rapeseed than in white and yellow petal ones. RNA-seq analysis showed that among co-differentially expressed genes involved in red pigment formation, genes involved in anthocyanin (belonging to flavonoids) biosynthesis pathway were largely regulated by ANS, DFR, and UF3GT. The expression of those genes was higher in red petals of rapeseed than in white and yellow petals ones as well. Results of RNA interference of BnaA03.ANS in red rapeseed altered petal colors from raspberry red to beige red and zinc yellow under different interference levels, with the contents of pelargonidin, cyanidin, lutein, neoxanthin, ß-carotene, and lycopene significantly decreased. However, overexpression of BnaA03.ANS in yellow rapeseed petals did not change the color of yellow petals. This study confirmed the important function of flavonoids, especially anthocyanins on red pigment formation, and for the first time, identified the irreplaceable role of BnaA03.ANS on red-flowered rapeseed.

Auxin-regulated timing of transition from vegetative to reproductive growth in rapeseed (Brassica napus L.) under different nitrogen application rates.

Accelerating the differentiation of floral meristem (FM) from shoot apical meristems (SAM) which determines the conversion from vegetative to reproductive growth is of great significance for the production of rapeseed (Brassica napus L.). In this research, the mechanisms of different nitrogen (N) application rates (low N, N1; normal N, N2; and high N, N3) on different FM development stages triggering the regulation of FM differentiation genes through the auxin biosynthetic and signal transduction were investigated. We found that the stage of FM differentiation, which was identified through a stereomicroscope and scanning electron microscope, came 4 and 7 days earlier under high N rate than under normal and low N levels, with the seed yield increased by 11.1 and 22.6%, respectively. Analysis of the auxin and its derivatives contents showed that the main biosynthesis way of auxin was the indole acetaldehyde oxime (IAOx) pathway, with 3-Indole acetonitrile dramatically accumulated during FM differentiation. At the same time, an obvious decrease of IAA contents at each FM differentiation stage was detected, and then gradually rose. Results of the expression of genes involved in auxin biosynthesis, auxin signaling transduction, and FM identification under five FM differentiation stages and three nitrogen application rates showed that genes involved in auxin biosynthesis were regulated before the FM differentiation stage, while the regulation of FM identity genes appeared mainly at the middle and later periods of the five stages, and the regulation level of genes varied under different N rates. Taken together, a high nitrogen rate could accelerate the initiation of FM differentiation, and auxin involved a lot in this regulation.

CRISPR/Cas9-mediated editing of double loci of BnFAD2 increased the seed oleic acid content of rapeseed (Brassica napus L.).

Seed oleic acid is an important quality trait sought in rapeseed breeding programs. Many methods exist to increase seed oleic acid content, such as the CRISPR/Cas9-mediated genome editing system, yet there is no report on seed oleic acid content improvement via this system's precise editing of the double loci of BnFAD2. Here, a precise CRISPR/Cas9-mediated genome editing of the encoded double loci (A5 and C5) of BnFAD2 was established. The results demonstrated high efficiency of regeneration and transformation, with the rapeseed genotype screened in ratios of 20.18% and 85.46%, respectively. The total editing efficiency was 64.35%, whereas the single locus- and double locus-edited ratios were 21.58% and 78.42%, respectively. The relative proportion of oleic acid with other fatty acids in seed oil of mutants was significantly higher for those that underwent the editing on A5 copy than that on C5 copy, but it was still less than 80%. For double locus-edited mutants, their relative proportion of oleic acid was more than 85% in the T1 and T4 generations. A comparison of the sequences between the double locus-edited mutants and reference showed that no transgenic border sequences were detected from the transformed vector. Analysis of the BnFAD2 sequence on A5 and C5 at the mutated locus of double loci mutants uncovered evidence for base deletion and insertion, and combination. Further, no editing issue of FAD2 on the copy of A1 was detected on the three targeted editing regions. Seed yield, yield component, oil content, and relative proportion of oleic acid between one selected double loci-edited mutant and wild type were also compared. These results showed that although the number of siliques per plant of the wild type was significantly higher than those of the mutant, the differences in seed yield and oil content were not significant between them, albeit with the mutant having a markedly higher relative proportion of oleic acid. Altogether, our results confirmed that the established CRISPR/Cas9-mediated genome editing of double loci (A5 and C5) of the BnFAD2 can precisely edit the targeted genes, thereby enhancing the seed oleic acid content to a far greater extent than can a single locus-editing system.

NBS-Encoding Genes in Brassica napus Evolved Rapidly After Allopolyploidization and Co-localize With Known Disease Resistance Loci.

Genes containing nucleotide-binding sites (NBS) play an important role in pathogen resistance in plants. However, the evolutionary fate of NBS-encoding genes after formation of allotetraploid Brassica napus (AnAnCnCn, 2n = 38) is still unknown. We performed a genome-wide comparison of putatively functional NBS-encoding genes in B. napus and its progenitor species Brassica rapa (ArAr, 2n = 20) and Brassica oleracea (CoCo, 2n = 18), identifying 464, 202, and 146 putatively functional NBS-encoding genes respectively, with genes unevenly distributed in several clusters. The An-subgenome of B. napus possessed similar numbers of NBS-encoding genes (191 genes) to the Ar genome of B. rapa (202 genes) and similar clustering patterns. However, the Cn genome of B. napus had many more genes (273) than the B. oleracea Co genome (146), with different clustering trends. Only 97 NBS-encoding genes (66.4%) in B. oleracea were homologous with NBS-encoding genes in B. napus, while 176 NBS-encoding genes (87.1%) were homologous between B. rapa and B. napus. These results suggest a greater diversification of NBS-encoding genes in the C genome may have occurred after formation of B. napus. Although most NBS-encoding genes in B. napus appeared to derive from the progenitors, the birth and death of several NBS-encoding genes was also putatively mediated by non-homologous recombination. The Ka/Ks values of most homologous pairs between B. napus and the progenitor species were less than 1, suggesting purifying selection during B. napus evolution. The majority of NBS-encoding genes (60% in all species) showed higher expression levels in root tissue (out of root, leaf, stem, seed and flower tissue types). Comparative analysis of NBS-encoding genes with mapped resistance QTL against three major diseases of B. napus (blackleg, clubroot and Sclerotinia stem rot) found 204 NBS-encoding genes in B. napus located within 71 resistance QTL intervals. The majority of NBS-encoding genes were co-located with resistance QTLs against a single disease, while 47 genes were co-located with QTLs against two diseases and 3 genes were co-located with QTLs against all three. Our results revealed significant variation as well as interesting evolutionary trajectories of NBS-encoding genes in the different Brassica subgenomes, while co-localization of NBS-encoding genes and resistance QTL may facilitate resistance breeding in oilseed rape.

Floral Initiation in Response to Planting Date Reveals the Key Role of Floral Meristem Differentiation Prior to Budding in Canola (Brassica napus L.).

In Brassica napus, floral development is a decisive factor in silique formation, and it is influenced by many cultivation practices including planting date. However, the effect of planting date on floral initiation in canola is poorly understood at present. A field experiment was conducted using a split plot design, in which three planting dates (early, 15 September, middle, 1 October, and late, 15 October) served as main plot and five varieties differing in maturity (1358, J22, Zhongshuang 11, Zheshuang 8, and Zheyou 50) employed as subplot. The purpose of this study was to shed light on the process of floral meristem (FM) differentiation, the influence of planting date on growth period (GP) and floral initiation, and silique formation. The main stages of FM developments can be divided into four stages: first, the transition from shoot apical meristem to FM; second, flower initiation; third, gynoecium and androecium differentiation; and fourth, bud formation. Our results showed that all genotypes had increased GPs from sowing to FM differentiation as planting date was delayed while the GPs from FM differentiation to budding varied year by year except the very early variety, 1358. Based on the number of flowers present at the different reproductive stages, the flowers produced from FM differentiation to budding closely approximated the final silique even though the FM differentiated continuously after budding and peaked generally at the middle flowering stage. The ratio of siliques to maximum flower number ranged from 48 to 80%. These results suggest that (1) the period from FM differentiation to budding is vital for effective flower and silique formation although there was no significant correlation between the length of the period and effective flowers and siliques, and (2) the increased number of flowers from budding were generally ineffective. Therefore, maximizing flower numbers prior to budding will improve silique numbers, and reducing FM degeneration should also increase final silique formation. From the results of our study, we offer guidelines for planting canola varieties that differ in maturity in order to maximize effective flower numbers.

Chlorophyll and carbohydrate metabolism in developing silique and seed are prerequisite to seed oil content of Brassica napus L.

BACKGROUND: Although the seed oil content in canola is a crucial quality determining trait, the regulatory mechanisms of its formation are not fully discovered. This study compared the silique and seed physiological characteristics including fresh and dry weight, seed oil content, chlorophyll content, and carbohydrate content in a high oil content line (HOCL) and a low oil content line (LOCL) of canola derived from a recombinant inbred line in 2010, 2011, and 2012. The aim of the investigation is to uncover the physiological regulation of silique and seed developmental events on seed oil content in canola. RESULTS: On average, 83% and 86% of silique matter while 69% and 63% of seed matter was produced before 30 days after anthesis (DAA) in HOCL and LOCL, respectively, over three years. Furthermore, HOCL exhibited significantly higher fresh and dry matter at most developmental stages of siliques and seeds. From 20 DAA, lipids were deposited in the seed of HOCL significantly faster than that of LOCL, which was validated by transmission electron microscopy, showing that HOCL accumulates considerable more oil bodies in the seed cells. Markedly higher silique chlorophyll content was observed in HOCL consistently over the three consecutive years, implying a higher potential of photosynthetic capacity in siliques of HOCL. As a consequence, HOCL exhibited significantly higher content of fructose, glucose, sucrose, and starch mainly at 20 to 45 DAA, a key stage of seed lipid deposition. Moreover, seed sugar content was usually higher than silique indicating the importance of sugar transportation from siliques to seeds as substrate for lipid biosynthesis. The much lower silique cellulose content in HOCL was beneficial for lipid synthesis rather than consuming excessive carbohydrate for cell wall. CONCLUSIONS: Superior physiological characteristics of siliques in HOCL showed advantage to produce more photosynthetic assimilates, which were highly correlated to seed oil contents.

A novel method for iodate determination using cadmium sulfide quantum dots as fluorescence probes.

We have developed a novel method for the determination of iodate based on the carboxymethyl cellulose-capped CdS quantum dots (QDs). Factors affecting the iodate detection were investigated, and the optimum conditions were determined. Under the optimum conditions, the relative fluorescence intensity of CdS quantum dots was linearly proportional to IO(3)(-) over a concentration range from 1.0 × 10(-8) to 1.0 × 10(-5) mol L(-1) with a correlation coefficient of 0.9987 and a detection limit of 6.0 nmol L(-1). Iodide, being oxidized by bromine to form iodate, was detected indirectly. The method was successfully applied to the determination of iodate and total amount of iodine in table salt samples. The related mechanism was also discussed.