Effect of light quality on the biosynthesis of flavonoids and sugars in bilberry (Vaccinium myrtillus L.)

Berries are abundant in bioactive compounds. Bilberry or European blueberry (Vaccinium myrtillus L.) is in particular gaining worldwide attention being one of the best natural sources of antioxidant rich phenolics that accumulate in both skin and flesh during fruit ripening. Alongside, the ubiquitous presence of anthocyanins and related flavonoids, it also contains other compounds such as carotenoids, stilbenes, terpenoids, vitamins and sugars. Especially flavonoids and sugars have major effect of fruit quality. Beside the genetic adaptation by the latitude-based cultivars and ecotypes, altering environmental conditions play a major role in determining the bioavailability of these compounds. Especially, the light quality impacts several secondary metabolic processes, thus by interacting with the number of known positive regulators and repressors of light signaling. The thesis is focused on understanding the biosynthesis and regulatory mechanisms of the key quality compounds, flavonoids and sugars, in bilberry in response to different light qualities from the photosynthetically active radiation (PAR) spectrum. The light quality experiments were carried out in controlled conditions by mimicking single wavelength light spectra of red, blue and far-red using LED-light systems. The promising results showed that indeed supplemental light wavelengths have a positive effect on anthocyanin and sugar biosynthesis in bilberries. Especially, delphinidins were found to be the most reactive class of anthocyanins in response to red light treatments, which increased the concentration several fold in fully ripe berries. The transcriptomic data revealed that the abscisic acid (ABA) biosynthesis and signaling was found to regulate the anthocyanin accumulation, where even the ABA degrading enzyme, ABA-8'-hydroxylase, acted as positive signaling factor. However, the results showed a differential effect or opposite response pattern towards red and blue light in berries which are ripening independently of mother plant to that of naturally attached ripening berries. Interestingly, the blue light influenced the anthocyanin biosynthesis in detached berries to the most, and resulted in highest anthocyanin levels quantified in fully ripe bilberries. The study also showed the effect of light quality on sugar metabolism from the differentially expressed genes (DEGs) data, where both red and blue light influenced the starch and sucrose metabolism. Supplemental red light also increased the amount of sugars in ripe bilberry. The findings of this study will drive-forward the plant research communities towards better understanding on the effect of light on fruit ripening and improving quality. The results can also be further utilized in future commercial breeding programs or cultivation practices of wild Vaccinium berries with improved value-added properties

Insights into sugar metabolism during bilberry (Vaccinium myrtillus L.) fruit development

Bilberry fruit is regarded as one of the best natural sources of anthocyanins and iswidely explored for its health-beneficial compounds. Besides anthocyanins, one of themajor attributes that determine the berry quality is the accumulation of sugars thatprovide sweetness and flavor to ripening fruit. In this study, we have identified 25 sugarmetabolism-related genes in bilberry, including invertases (INVs), hexokinases (HKs),fructokinases (FKs), sucrose synthases (SSs), sucrose phosphate synthases (SPSs), andsucrose phosphate phosphatases (SPPs). The results indicate that isoforms of the identified genes are expressed differentially during berry development, suggesting special-ized functions. The highest sugar content was found in ripe berries, with fructose andglucose dominating accompanied by low sucrose amount. The related enzyme activi-ties during berry development and ripening were further analyzed to understand themolecular mechanism of sugar accumulation. The activity of INVs in the cell wall andvacuole increased toward ripe berries. Amylase activity involved in starch metabolismwas not detected in unripe berries but was found in ripe berries. Sucrose resynthesizing SS enzyme activity was detected upon early ripening and had the highestactivity in ripe berries. Interestingly, our transcriptome data showed that supplementalirradiation with red and blue light triggered upregulation of several sugar metabolism-related genes, including α- and β-amylases. Also, differential expression patterns inresponses to red and blue light were found across sucrose, galactose, and sugar-alcoholmetabolism. Our enzymological and transcriptional data provide new understanding ofthe bilberry fruit sugar metabolism having major effect on fruit quality (20) (PDF) Insights into sugar metabolism during bilberry ( Vaccinium myrtillus L.) fruit development

Influence of Arctic light conditions on crop production and quality

The natural light conditions above the Arctic Circle are unique in terms of annual variation creating special growth conditions for crop production. These include low solar elevations, very long daily photosynthetic light periods, midnight sun/absence of dark nights, and altered spectral distribution depending on solar elevation. All these factors are known to affect the growth and the metabolism of plants, although their influence on northern crop plants has not yet been reviewed. The ongoing global warming is especially affecting the temperature x light interactions in the Arctic, and understanding the impact on crop production and plant metabolism will be important for an Arctic contribution to global food production. Arctic light conditions have a strong influence on the timing of plant development, which together with temperature limits the number of cultivars suitable for Arctic agriculture. This review compiles information from the reports about the effects of light conditions at high latitudes on growth, biomass production, flowering and quality of the crop plants and discusses the gained knowledge and the key gaps to be addressed.Peer reviewe

Red and blue light treatments of ripening bilberry fruits reveal differences in signalling through abscisic acid-regulated anthocyanin biosynthesis

The biosynthesis of anthocyanins has been shown to be influenced by light quality. However, the molecular mechanisms underlying the light-mediated regulation of fruit anthocyanin biosynthesis are not well understood. In this study, we analysed the effects of supplemental red and blue light on the anthocyanin biosynthesis in non-climacteric bilberry (Vaccinium myrtillus L.). After 6 days of continuous irradiation during ripening, both red and blue light elevated concentration of anthocyanins, up to 12- and 4-folds, respectively, compared to the control. Transcriptomic analysis of ripening berries showed that both light treatments up-regulated all the major anthocyanin structural genes, the key regulatory MYB transcription factors and abscisic acid (ABA) biosynthetic genes. However, higher induction of specific genes of anthocyanin and delphinidin biosynthesis alongside ABA signal perception and metabolism were found in red light. The difference in red and blue light signalling was found in 9-cis-epoxycarotenoid dioxygenase (NCED), ABA receptor pyrabactin resistance-like (PYL) and catabolic ABA-8'hydroxylase gene expression. Red light also up-regulated expression of soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) domain transporters, which may indicate involvement of these proteins in vesicular trafficking of anthocyanins during fruit ripening. Our results suggest differential signal transduction and transport mechanisms between red and blue light in ABA-regulated anthocyanin and delphinidin biosynthesis during bilberry fruit ripening.Peer reviewe

Insights into sugar metabolism during bilberry (Vaccinium myrtillus L.) fruit development

Bilberry fruit is regarded as one of the best natural sources of anthocyanins and iswidely explored for its health-beneficial compounds. Besides anthocyanins, one of themajor attributes that determine the berry quality is the accumulation of sugars thatprovide sweetness and flavor to ripening fruit. In this study, we have identified 25 sugarmetabolism-related genes in bilberry, including invertases (INVs), hexokinases (HKs),fructokinases (FKs), sucrose synthases (SSs), sucrose phosphate synthases (SPSs), andsucrose phosphate phosphatases (SPPs). The results indicate that isoforms of the identified genes are expressed differentially during berry development, suggesting special-ized functions. The highest sugar content was found in ripe berries, with fructose andglucose dominating accompanied by low sucrose amount. The related enzyme activi-ties during berry development and ripening were further analyzed to understand themolecular mechanism of sugar accumulation. The activity of INVs in the cell wall andvacuole increased toward ripe berries. Amylase activity involved in starch metabolismwas not detected in unripe berries but was found in ripe berries. Sucrose resynthesizing SS enzyme activity was detected upon early ripening and had the highestactivity in ripe berries. Interestingly, our transcriptome data showed that supplementalirradiation with red and blue light triggered upregulation of several sugar metabolism-related genes, including α- and β-amylases. Also, differential expression patterns inresponses to red and blue light were found across sucrose, galactose, and sugar-alcoholmetabolism. Our enzymological and transcriptional data provide new understanding ofthe bilberry fruit sugar metabolism having major effect on fruit quality (20) (PDF) Insights into sugar metabolism during bilberry ( Vaccinium myrtillus L.) fruit development.Insights into sugar metabolism during bilberry (Vaccinium myrtillus L.) fruit developmentpublishedVersio

Influence of Arctic light conditions on crop production and quality

The natural light conditions above the Arctic Circle are unique in terms of annual variation creating special growth conditions for crop production. These include low solar elevations, very long daily photosynthetic light periods, midnight sun/absence of dark nights, and altered spectral distribution depending on solar elevation. All these factors are known to affect the growth and the metabolism of plants, although their influence on northern crop plants has not yet been reviewed. The ongoing global warming is especially affecting the temperature × light interactions in the Arctic, and understanding the impact on crop production and plant metabolism will be important for an Arctic contribution to global food production. Arctic light conditions have a strong influence on the timing of plant development, which together with temperature limits the number of cultivars suitable for Arctic agriculture. This review compiles information from the reports about the effects of light conditions at high latitudes on growth, biomass production, flowering and quality of the crop plants and discusses the gained knowledge and the key gaps to be addressed

Flavonoid biosynthesis is differentially altered in detached and attached ripening bilberries in response to spectral light quality

Light spectral quality is known to affect flavonoid biosynthesis during fruit ripening. However, the response of fruits to different light conditions, when ripening autonomously from the parent plant (detached), has been less explored. In this study, we analyzed the effect of light quality on detached and naturally ripening (attached) non-climacteric wild bilberry (Vaccinium myrtillus L.) fruits accumulating high amounts of anthocyanins and flavonols. Our results indicated contrasting responses for the accumulation of phenolic compounds in the berries in response to red and blue light treatments. For detached berries, supplemental blue light resulted in the highest accumulation of anthocyanins, while naturally ripening berries had elevated accumulation under supplemental red light treatment. Both red and blue supplemental light increased the expression levels of all the major structural genes of the flavonoid pathway during ripening. Notably, the key regulatory gene of anthocyanin biosynthesis, VmMYBA1, was found to express fivefold higher under blue light treatment in the detached berries compared to the control. The red light treatment of naturally ripening berries selectively increased the delphinidin branch of anthocyanins, whereas in detached berries, blue light increased other anthocyanin classes along with delphinidins. In addition, red and far-red light had a positive influence on the accumulation of flavonols, especially quercetin and myricetin glycoside derivatives, in both ripening conditions. Our results of differential light effects on attached and detached berries, which lacks signaling from the mother plant, provide new insights in understanding the light-mediated regulatory mechanisms in non-climacteric fruit ripening

Genetic Diversity Studies Based on Morphological Variability, Pathogenicity and Molecular Phylogeny of the Sclerotinia sclerotiorum Population From Indian Mustard (Brassica juncea)

White mold or stem rot disease are ubiquitously distributed throughout the world and the causal organism of this disease Sclerotinia sclerotiorum (Lib.) de Bary, is known to infect over 400 plant species. Sclerotinia stem rot is one of the most devastating fungal diseases and poses a serious threat to the worldwide cultivation of oilseed Brassica including India. S. sclerotiorum pathogen usually infects the stem but in severe cases leaves and pods also affected at different developmental stages that deteriorate not only the oil quality but also causing the seed and oil yield losses up to 90% depending on the severity of the disease infestation. This study investigated the morphological and molecular characterization of pathogenic S. sclerotiorum (Lib) de Bary geographical isolates from oilseed Brassica including Brassica juncea (Indian mustard). The aim of this study was to compare isolates of S. sclerotiorum originated from different agro-climatic conditions and to analyse similarity or differences between them as well as to examine the virulence of this pathogen specifically in Brassica for the first time. The collection of S. sclerotiorum isolates from symptomatic Brassica plants was done and analyzed for morphological features, and molecular characterization. The virulence evaluation test of 65 isolates on four Brassica cultivars has shown 5 of them were highly virulent, 46 were virulent and 14 were moderately virulent. Phylogenetic analysis encompassing all the morphological features, SSR polymorphism, and ITS sequencing has shown the existence of high genetic diversity among the isolates that categorized all the isolates in three evolutionary lineages in the derived dendrogram. Further, genetic variability analysis based on sequences variation in ITS region of all the isolates has shown the existence of either insertions or deletions of the nucleotides in the ITS region has led to the interspecies variability and observed the variation were in a clade-specific manner. Together this analysis observed the existence of higher heterogeneity and genetic variability in S. sclerotiorum isolates collection and indicates the presence of clonal and sexual progenies of the pathogen in the mustard growing regions of India surveyed in this study. With a higher level of genetic variability and diversity among the S. sclerotiorum population needs robust screening approaches to identify the donor parent and utilize them in resistance breeding program for effectively counter the menace of stem rot disease in Brassica

Not Available

Not AvailableWhite mold or stem rot disease are ubiquitously distributed throughout the world and the causal organism of this disease Sclerotinia sclerotiorum (Lib.) de Bary, is known to infect over 400 plant species. Sclerotinia stem rot is one of the most devastating fungal diseases and poses a serious threat to the worldwide cultivation of oilseed Brassica including India. S. sclerotiorum pathogen usually infects the stem but in severe cases leaves and pods also affected at different developmental stages that deteriorate not only the oil quality but also causing the seed and oil yield losses up to 90% depending on the severity of the disease infestation. This study investigated the morphological and molecular characterization of pathogenic S. sclerotiorum (Lib) de Bary geographical isolates from oilseed Brassica including Brassica juncea (Indian mustard). The aim of this study was to compare isolates of S. sclerotiorum originated from different agro-climatic conditions and to analyse similarity or differences between them as well as to examine the virulence of this pathogen specifically in Brassica for the first time. The collection of S. sclerotiorum isolates from symptomatic Brassica plants was done and analyzed for morphological features, and molecular characterization. The virulence evaluation test of 65 isolates on four Brassica cultivars has shown 5 of them were highly virulent, 46 were virulent and 14 were moderately virulent. Phylogenetic analysis encompassing all the morphological features, SSR polymorphism, and ITS sequencing has shown the existence of high genetic diversity among the isolates that categorized all the isolates in three evolutionary lineages in the derived dendrogram. Further, genetic variability analysis based on sequences variation in ITS region of all the isolates has shown the existence of either insertions or deletions of the nucleotides in the ITS region has led to the interspecies variability and observed the variation were in a clade-specific manner. Together this analysis observed the existence of higher heterogeneity and genetic variability in S. sclerotiorum isolates collection and indicates the presence of clonal and sexual progenies of the pathogen in the mustard growing regions of India surveyed in this study. With a higher level of genetic variability and diversity among the S. sclerotiorum population needs robust screening approaches to identify the donor parent and utilize them in resistance breeding program for effectively counter the menace of stem rot disease in Brassica.Not Availabl

Image_6_Genetic Diversity Studies Based on Morphological Variability, Pathogenicity and Molecular Phylogeny of the Sclerotinia sclerotiorum Population From Indian Mustard (Brassica juncea).TIF

<p>White mold or stem rot disease are ubiquitously distributed throughout the world and the causal organism of this disease Sclerotinia sclerotiorum (Lib.) de Bary, is known to infect over 400 plant species. Sclerotinia stem rot is one of the most devastating fungal diseases and poses a serious threat to the worldwide cultivation of oilseed Brassica including India. S. sclerotiorum pathogen usually infects the stem but in severe cases leaves and pods also affected at different developmental stages that deteriorate not only the oil quality but also causing the seed and oil yield losses up to 90% depending on the severity of the disease infestation. This study investigated the morphological and molecular characterization of pathogenic S. sclerotiorum (Lib) de Bary geographical isolates from oilseed Brassica including Brassica juncea (Indian mustard). The aim of this study was to compare isolates of S. sclerotiorum originated from different agro-climatic conditions and to analyse similarity or differences between them as well as to examine the virulence of this pathogen specifically in Brassica for the first time. The collection of S. sclerotiorum isolates from symptomatic Brassica plants was done and analyzed for morphological features, and molecular characterization. The virulence evaluation test of 65 isolates on four Brassica cultivars has shown 5 of them were highly virulent, 46 were virulent and 14 were moderately virulent. Phylogenetic analysis encompassing all the morphological features, SSR polymorphism, and ITS sequencing has shown the existence of high genetic diversity among the isolates that categorized all the isolates in three evolutionary lineages in the derived dendrogram. Further, genetic variability analysis based on sequences variation in ITS region of all the isolates has shown the existence of either insertions or deletions of the nucleotides in the ITS region has led to the interspecies variability and observed the variation were in a clade-specific manner. Together this analysis observed the existence of higher heterogeneity and genetic variability in S. sclerotiorum isolates collection and indicates the presence of clonal and sexual progenies of the pathogen in the mustard growing regions of India surveyed in this study. With a higher level of genetic variability and diversity among the S. sclerotiorum population needs robust screening approaches to identify the donor parent and utilize them in resistance breeding program for effectively counter the menace of stem rot disease in Brassica.</p