Anthocyanin Content and UVB Sensitivity in Brassica rap

Effects of Supplemental Lighting on Flavonoid and Anthocyanin Biosynthesis in Strawberry Flesh Revealed via Metabolome and Transcriptome Co-Analysis

The spectral composition of light influences the biosynthesis of flavonoids in many plants. However, the detailed composition of flavonoids and anthocyanins and the molecular basis for their biosynthesis in strawberry fruits under two light-quality treatments, red light supplemented with blue light (RB) and ultraviolet B (UVB) irradiation, remain unclear. In this study, the content of flavonoids and anthocyanins was significantly increased in strawberry fruits under RB light and UVB, respectively. The content of flavonoids and anthocyanins in strawberry fruits under UVB light was dramatically higher than that in strawberry fruits irradiated with RB light, and a total of 518 metabolites were detected by means of LC-MS/MS analysis. Among them, 18 phenolic acids, 23 flavonoids, and 8 anthocyanins were differentially accumulated in the strawberry fruits irradiated with red/blue (RB) light compared to 30 phenolic acids, 46 flavonoids, and 9 anthocyanins in fruits irradiated with UVB. The major genes associated with the biosynthesis of flavonoids and anthocyanins, including structural genes and transcription factors (TFs), were differentially expressed in the strawberry fruits under RB and UVB irradiation, as determined through RNA-seq data analysis. A correlation test of transcriptome and metabolite profiling showed that the expression patterns of most genes in the biosynthesis pathway of flavonoids and anthocyanins were closely correlated with the differential accumulation of flavonoids and anthocyanins. Two TFs, bZIP (FvH4_2g36400) and AP2 (FvH4_1g21210), induced by RB and UVB irradiation, respectively, exhibited similar expression patterns to most structural genes, which were closely correlated with six and eight flavonoids, respectively. These results indicated that these two TFs regulated the biosynthesis of flavonoids and anthocyanins in strawberry fruit under RB light and UVB, respectively. These results provide a systematic and comprehensive understanding of the accumulation of flavonoids and anthocyanins and the molecular basis for their biosynthesis in strawberry fruits under RB light and UVB.

Metabolic Analyses and Evaluation of Antioxidant Activity in Purple Kohlrabi Sprouts after Exposed to UVB Radiation

Various metabolites act as plant defense molecules due to their antioxidant abilities. This study aimed to investigate the influence of UVB irradiation on the accumulation of metabolites, including primary metabolites (sugar, sugar alcohols, amino acids, organic acids, and an amine) and secondary metabolites (anthocyanins, fatty acids, and phenolic acids), and its synergistic antioxidant ability, in purple kohlrabi sprouts. Metabolite analyses revealed a total of 92 metabolites in the sprouts. Specifically, the levels of most amino acids increased after 24 h of UVB treatment, and then slightly decreased in the kohlrabi sprouts. The levels of most sugars and sugar alcohols increased after 24 h of UVB treatment and then decreased. The levels of TCA cycle intermediates and phenolic acids gradually increased during the UVB treatment. Furthermore, the levels of some fatty acids gradually increased during the UVB treatment, and the levels of the other fatty acids increased after 6 h of UVB treatment and then decreased. In particular, the levels of most anthocyanins, known to be strong antioxidants, gradually increased after 24 h of UVB treatment. In the in vitro ABTS scavenging assay, UVB-treated purple kohlrabi sprouts showed increased scavenging ability. This may be attributed to the increased accumulation of metabolites acting as antioxidants, in response to UVB treatment. This study confirmed that UVB irradiation induced the alteration of primary and secondary metabolism in the kohlrabi sprouts.

A sequential utilization of the UV-A (365 nm) fluence rate for disinfection of water, contaminated with Legionella pneumophila and Legionelladumoffii

Legionella species are the etiological agent of Legionnaires' disease, a pathology easily contracted from water circuits and by the inhalation of aerosol droplets. This bacterium mainly proliferates in water: Legionella pneumophila is the most commonly isolated specie in water environments and consequently in water system, although further Legionella species have frequently been isolated, including Legionella dumoffii. The simultaneous presence of the two species in the water system can therefore lead to the simultaneous infection of several people, giving rise to harmful outbreaks. Ultraviolet inactivation of waterborne microorganisms offers a rapid and effective treatment technique and recently is getting more attention mostly to eliminate unsafe level of contamination. To tackle the issue, the inactivation of the two species of Legionella spp., namely L. pneumophila and L. dumoffii, by means of UV-A light emitting diodes (UV-A LED) system is explored. We used a commercially available UV-A LED at 365 nm wavelength, and the UV-A dose is given incrementally to the Legionellae with a concentration of 106 CFU/mL in 0.9% NaCl (aq) solution. In this study, with a UV-A-dose of 1700 mJ/cm2, the log-reduction of 3-log (99.9% inactivation) for L. pneumophila and 2.1-log (99.1% inactivation) for L. dumoffii of the contaminated water are achieved. The Electrical Energy per Order (EEO) is evaluated and showed this system is more economic and efficient in comparison with UV-C and UV-B LEDs. Following the support of this preliminary study with additional tests, aiming to validate the technology, we expect this device may be installed in water plants such as cooling systems or any water purification station in either industrial or home scales to reduce the risk of this infectious disease, preventing consumers' health.

Genetics and Expression Analysis of Anthocyanin Accumulation in Curd Portion of Sicilian Purple to Facilitate Biofortification of Indian Cauliflower

The present study was undertaken to know the genetics of purple color of cauliflower curds using a Sicilian purple 'PC-1' and a white curding mid-late group genotype of Indian cauliflower. For this, a cross was attempted between 'DC-466' (white curd) and 'PC-1' (purple curd) and observed intermediate level of purple pigmentation on curds in F₁ plants. Segregation of F₂ population (173) revealed that the purple color of the curd was governed by a single gene dominant over white, but the expression of trait was incomplete. It was substantiated by segregation of plants of BC₁ and F_{2:3(intermediate)} generations into 1(white):1(intermediate) and 1(white):2(intermediate):1(intense), respectively. The F₂, B₁, and B₂ generations segregated into purple(intermediate to intense): white curding plants in the ratio of 126: 47, 26:24, and 40:0, respectively fitting well with the Mendelian ratio of single gene for purple curds. However, purple pigmentation on curds ranged from very light to intense, which corroborated with the wide range of anthocyanin content in F₂ (3.81-48.21 mg/100 g fw). Out of three molecular markers from high resolution map of Pr gene in purple color cauliflower 'Graffiti', only BoMYB3 marker could distinguish purple and white curding parents but did not show co-segregation while investigated in F₂ population. Expression of BoMYB1 gene was up regulated in both the purple curd genotypes 'PC-1' and 'Graffiti' in comparison to white curded 'DC-466', while BoMYB2 gene was slightly upregulated in 'PC-1' but down regulated in 'Graffiti'. Occurrence of 'broccoli type' F₂ individuals and their genetic stability in F_2:3 support the intermediate position of 'Sicilian purple' between broccoli (Calabrese) and cauliflower. There was not any correlation between curd coloration and pigmentation on apical leaf and stem portion, indicating difference of expression in 'PC-1' than 'Graffiti'. The information obtained is useful for breeding anthocyanin rich attractive purple curding 'specialty cauliflower' for better consumer health and growers' earnings.

The Effects of Ultraviolet A/B Treatments on Anthocyanin Accumulation and Gene Expression in Dark-Purple Tea Cultivar 'Ziyan' (Camellia sinensis)

‘Ziyan’ is a novel anthocyanin-rich tea cultivar with dark purple young shoots. However, how its anthocyanin accumulation is affected by environmental factors, such as ultraviolet (UV), remains unclear. In this study, we observed that UV light treatments stimulated anthocyanin accumulation in ‘Ziyan’ leaves, and we further analyzed the underlying mechanisms at gene expression and enzyme activity levels. In addition, the catechins and chlorophyll contents of young shoots under different light treatments were also changed. The results showed that the contents of total anthocyanins and three major anthocyanin molecules, i.e., delphinidin, cyanidin, and pelargonidin, were significantly higher in leaves under UV-A, UV-B, and UV-AB treatments than those under white light treatment alone. However, the total catechins and chlorophyll contents in these purple tea plant leaves displayed the opposite trends. The anthocyanin content was the highest under UV-A treatment, which was higher by about 66% than control. Compared with the white light treatment alone, the enzyme activities of chalcone synthase (CHS), flavonoid 3′,5′-hydroxylase (F3′5′H), and anthocyanidin synthase (ANS) under UV treatments increased significantly, whereas the leucoanthocyanidin reductase (LAR) and anthocyanidin reductase (ANR) activities reduced. There was no significant difference in dihydroflavonol 4-reductase (DFR) activity under all treatments. Comparative transcriptome analyses unveiled that there were 565 differentially expressed genes (DEGs) of 29,648 genes in three pair-wise comparisons (white light versus UV-A, W vs. UV-A; white light versus UV-B, W vs. UV-A; white light versus UV-AB, W vs. UV-AB). The structural genes in anthocyanin pathway such as flavanone 3-hydroxylase (F3H), F3′5′H, DFR, and ANS, and regulatory gene TT8 were upregulated under UV-A treatment; F3′5′H, DFR, ANS, and UFGT and regulatory genes EGL1 and TT2 were upregulated under UV-AB treatment. However, most structural genes involved in phenylpropanoid and flavonoid pathways were downregulated under UV-B treatment compared with control. The expression of LAR and ANR were repressed in all UV treatments. Our results indicated that UV-A and UV-B radiations can induce anthocyanin accumulation in tea plant ‘Ziyan’ by upregulating the structural and regulatory genes involved in anthocyanin biosynthesis. In addition, UV radiation repressed the expression levels of LAR, ANR, and FLS, resulting in reduced ANR activity and a metabolic flux shift toward anthocyanin biosynthesis.

Integrative analysis of genome-wide lncRNA and mRNA expression in newly synthesized Brassica hexaploids

Polyploidization, as a significant evolution force, has been considered to facilitate plant diversity. The expression levels of lncRNAs and how they control the expression of protein-coding genes in allopolyploids remain largely unknown. In this study, lncRNA expression profiles were compared between Brassica hexaploid and its parents using a high-throughput sequencing approach. A total of 2,725, 1,672, and 2,810 lncRNAs were discovered in Brassica rapa, Brassica carinata, and Brassica hexaploid, respectively. It was also discovered that 725 lncRNAs were differentially expressed between Brassica hexaploid and its parents, and 379 lncRNAs were nonadditively expressed in this hexaploid. LncRNAs have multiple expression patterns between Brassica hexaploid and its parents and show paternal parent-biased expression. These lncRNAs were found to implement regulatory functions directly in the long-chain form, and acted as precursors or targets of miRNAs. According to the prediction of the targets of differentially expressed lncRNAs, 109 lncRNAs were annotated, and their target genes were involved in the metabolic process, pigmentation, reproduction, exposure to stimulus, biological regulation, and so on. Compared with the paternal parent, differentially expressed lncRNAs between Brassica hexaploid and its maternal parent participated in more regulation pathways. Additionally, 61 lncRNAs were identified as putative targets of known miRNAs, and 15 other lncRNAs worked as precursors of miRNAs. Some conservative motifs of lncRNAs from different groups were detected, which indicated that these motifs could be responsible for their regulatory roles. Our findings may provide a reference for the further study of the function and action mechanisms of lncRNAs during plant evolution.

Mapping the anthocyaninless (anl) locus in rapid-cycling Brassica rapa (RBr) to linkage group R9

Background

Anthocyanins are flavonoid pigments that are responsible for purple coloration in the stems and leaves of a variety of plant species. Anthocyaninless (anl) mutants of Brassica rapa fail to produce anthocyanin pigments. In rapid-cycling Brassica rapa, also known as Wisconsin Fast Plants, the anthocyaninless trait, also called non-purple stem, is widely used as a model recessive trait for teaching genetics. Although anthocyanin genes have been mapped in other plants such as Arabidopsis thaliana, the anl locus has not been mapped in any Brassica species.

Results

We tested primer pairs known to amplify microsatellites in Brassicas and identified 37 that amplified a product in rapid-cycling Brassica rapa. We then developed three-generation pedigrees to assess linkage between the microsatellite markers and anl. 22 of the markers that we tested were polymorphic in our crosses. Based on 177 F₂ offspring, we identified three markers linked to anl with LOD scores ≥ 5.0, forming a linkage group spanning 46.9 cM. Because one of these markers has been assigned to a known B. rapa linkage group, we can now assign the anl locus to B. rapa linkage group R9.

Conclusion

This study is the first to identify the chromosomal location of an anthocyanin pigment gene among the Brassicas. It also connects a classical mutant frequently used in genetics education with molecular markers and a known chromosomal location.

Image analysis and in vivo imaging as tools for investigation of productivity dynamics in anthocyanin-producing cell cultures of Daucus carota

An anthocyanin-producing suspension culture of Daucus carota (L.) cv. Flakkese was used as model system to study secondary metabolite production in cell culture at the individual cell level. An approach was set up in which growth and production of anthocyanins were investigated using a combination of biochemical analysis, image (colour) analysis and in vivo imaging. This novel approach was used to segment the culture in different subpopulations and dissect the productive process in the cell culture grown under two different conditions, known to differ mainly for oxygen supply and mixing intensity (volume of 50 ml or 20 ml in 250 ml flasks). The 20 ml batch cultures gave a higher content and yield of anthocyanins, which depended on a complex balance between events that positively or negatively affected anthocyanin production. A model is proposed in which the different ability of cells to respond to environmental stimuli and stress depends on the different amount of anthocyanins accumulated within cells.

Modification of leaf cytology and anatomy in Brassica napus grown under above ambient levels of supplemental UV-B radiation

Plants exposed to natural solar radiation usually show acclimation responses on a daily and seasonal basis. Many of these responses are complex and modified by interactions with acclimation responses to other climatic factors. While changes in photosynthetically active radiation (PAR, 400-700 nm) are the driving force for many acclimation responses in plants, radiation outside the PAR range is also important. Recently, interest has increased in the potential role of UV-A (320-400 nm) and UV-B (280-320 nm) components of sunlight in plant developmental, physiological and daily acclimation processes. In order to explore the role of UV-B further, Brassica napus L. cv Paroll plants were grown to maturity under 13 kJ d(-1) of biologically effective ultraviolet-B radiation (UV-B(BE), 280-320 nm) plus 800 micromol photons m(-2) s(-1) photosynthetically active radiation (PAR, 400-700 nm) or PAR alone. Leaf anatomy and palisade cell structure were quantified using stereological techniques. The leaves of plants grown under UV-B radiation exhibited an increase in overall leaf width, although no change in leaf anatomy was discerned. Palisade cells in UV-B exposed leaves showed a significant decrease in chloroplast, mitochondrial, starch, and microbody volume density (Vv), while the vacuolar Vv increased compared to cells exposed to PAR only. In UV-B exposed leaves, there was an increase in the appressed and non-appressed thylakoid surface area density (Sv) within the chloroplasts. Since the relative proportion of appressed to non-appressed thylakoid surface area did not change, both thylakoid systems changed in concert with each other. Thylakoid stacks were broader and shorter in leaves subjected to UV-B. In general these responses were similar to those which occurred in plants moved from a high to low PAR environment and similar to mature plants exposed to 13 kJ d(-1) UV-B(BE) for only a short period of time. Although UV absorbing pigments increased by 21% in UV-B exposed leaves, there was no significant difference in chlorophyll a,b or carotenoid content compared to plants exposed to only PAR.

A simple extraction and chromatographic system for the simultaneous analysis of anthocyanins and stilbenes of Vitis species

A separation system has been developed to permit the simultaneous analysis of major anthocyanins and stilbenes from berries of Vitis species in <1 h. The system makes use of separation by HPLC and detection by UV-visible absorption and fluorescence, for anthocyanins and stilbenes, respectively, with the two detection systems linked in series. Monitoring the absorption at 520 nm permits ready identification and quantification of major anthocyanins. Chromatograms derived from fluorescence (330 nm excitation/374 nm emission) produce less clear data for the piceids and resveratrols, which are present in much lower amounts; peaks for these compounds can be verified by means of external or internal standards.

UV-induced DNA damage and repair: a review

Increases in ultraviolet radiation at the Earth's surface due to the depletion of the stratospheric ozone layer have recently fuelled interest in the mechanisms of various effects it might have on organisms. DNA is certainly one of the key targets for UV-induced damage in a variety of organisms ranging from bacteria to humans. UV radiation induces two of the most abundant mutagenic and cytotoxic DNA lesions such as cyclobutane-pyrimidine dimers (CPDs) and 6-4 photoproducts (6-4PPs) and their Dewar valence Isomers. However, cells have developed a number of repair or tolerance mechanism to counteract the DNA damage caused by UV or any other stressors. Photoreactivation with the help of the enzyme photolyase is one of the most important and frequently occurring repair mechanisms in a variety of organisms. Excision repair, which can be distinguished into base excision repair (BER) and nucleotide excision repair (NER), also plays an important role in DNA repair in several organisms with the help of a number of glycosylases and polymerases, respectively. In addition, mechanisms such as mutagenic repair or dimer bypass, recombinational repair, cell-cycle checkpoints, apoptosis and certain alternative repair pathways are also operative in various organisms. This review deals with UV-induced DNA damage and the associated repair mechanisms as well as methods of detecting DNA damage and its future perspectives.

Molybdenum sequestration in Brassica species. A role for anthocyanins?

To elucidate plant mechanisms involved in molybdenum (Mo) sequestration and tolerance, Brassica spp. seedlings were supplied with molybdate, and the effects on plant physiology, morphology, and biochemistry were analyzed. When supplied with (colorless) molybdate Indian mustard (Brassica juncea) seedlings accumulated water-soluble blue crystals in their peripheral cell layers. Energy dispersive x-ray analysis showed that Mo accumulated predominantly in the vacuoles of the epidermal cells. Therefore, the blue crystals are likely to be a Mo compound. The x-ray absorption spectrum of the plant-accumulated Mo was different than that for molybdate, indicating complexation with a plant molecule. Because the blue compound was water soluble and showed a pH-dependent color change, possible involvement of anthocyanins was investigated. An anthocyanin-less mutant of Brassica rapa ("fast plants") was compared with varieties containing normal or high anthocyanin levels. The anthocyanin-less mutant did not show accumulation of a blue compound when supplied with molybdate. In the anthocyanin-containing varieties, the blue compound colocalized with anthocyanins in the peripheral cell layers. Mo accumulation by the three B. rapa varieties was positively correlated with anthocyanin content. Addition of molybdate to purified B. rapa anthocyanin resulted in an in vitro color change from pink to blue. Therefore, Mo appears to be sequestered in vacuoles of the peripheral cell layers of Brassica spp. as a blue compound, probably a Mo-anthocyanin complex.