The aim of this research was to determine the effect of development and UV‐B on flavonols and the regulation of gene activity in Vitis vinifera L. var. Sauvignon blanc grapes. Particular emphasis was ...placed on gene activity associated with the low and high fluence UV‐B responses. Flavonols, particularly quercetin and kaempferol glycosides, increased substantially upon fruit exposure due to UV‐B, with spatial analysis locating the changes to the berry skin. Of five VvFLS genes in grapes, two (VvFLS4 and 5) were found to be transcriptionally active, with VvFLS4 also being responsive to UV‐B but VvFLS5 was not. Of the transcription factors known to regulate FLS (VvMYB12, VvMYCA1 and VvWDRs), only VvMYB12 was found to be responsive to UV‐B. A number of candidate genes associated with the low and high UV‐B fluence responses were also studied (VvUVR8, VvHY5, VvCOP1 and VvCHS; PR genes and VvMAPK3; respectively). The genes associated with the low fluence response exhibited transcriptional regulation in line with reports from other species, while the PR genes and VvMAPK3 only appeared to be responsive in a high UV‐B fluence environment. Together, these data supports the view flavonol biosynthesis in grape is stimulated predominantly through the low fluence UV‐B response pathway.
This research investigates the effect of development and UV‐B on flavonols and the regulation of gene activity in Vitis vinifera L. var. Sauvignon blanc grapes. Results suggest flavonol biosynthesis and gene activity are stimulated by UV‐B and the low fluence UV‐B pathway is a major determinant of this response. There is also a strong influence of development on gene expression. This is the first research to analyse signal transduction associated with the recently discovered UV‐B photoreceptor UVR8 and makes a substantial contribution to understanding UV‐B responses in an important commercial species.
Nitrification is a key process of the nitrogen (N) cycle in soil with major environmental implications. The recent discovery of ammonia-oxidizing archaea (AOA) questions the traditional assumption of ...the dominant role of ammonia-oxidizing bacteria (AOB) in nitrification. We investigated AOB and AOA growth and nitrification rate in two different layers of three grassland soils treated with animal urine substrate and a nitrification inhibitor dicyandiamide (DCD). We show that AOB were more abundant in the topsoils than in the subsoils, whereas AOA were more abundant in one of the subsoils. AOB grew substantially when supplied with a high dose of urine substrate, whereas AOA only grew in the Controls without the urine-N substrate. AOB growth and the amoA gene transcription activity were significantly inhibited by DCD. Nitrification rates were much higher in the topsoils than in the subsoils and were significantly related to AOB abundance, but not to AOA abundance. These results suggest that AOB and AOA prefer different soil N conditions to grow: AOB under high ammonia (NH₃) substrate and AOA under low NH₃ substrate conditions.
Abstract
Background
Somatic variation is a valuable source of trait diversity in clonally propagated crops. In grapevine, which has been clonally propagated worldwide for centuries, important ...phenotypes such as white berry colour are the result of genetic changes caused by transposable elements. Additionally, epiallele formation may play a role in determining geo-specific (‘terroir’) differences in grapes and thus ultimately in wine. This genomic plasticity might be co-opted for crop improvement via somatic embryogenesis, but that depends on a species-specific understanding of the epigenetic regulation of transposable element (TE) expression and silencing in these cultures. For this reason, we used whole-genome bisulphite sequencing, mRNA sequencing and small RNA sequencing to study the epigenetic status and expression of TEs in embryogenic callus, in comparison with leaf tissue.
Results
We found that compared with leaf tissue, grapevine embryogenic callus cultures accumulate relatively high genome-wide CHH methylation, particularly across heterochromatic regions. This
de novo
methylation is associated with an abundance of transcripts from highly replicated TE families, as well as corresponding 24 nt heterochromatic siRNAs. Methylation in the TE-specific CHG context was relatively low over TEs located within genes, and the expression of TE loci within genes was highly correlated with the expression of those genes.
Conclusions
This multi-‘omics analysis of grapevine embryogenic callus in comparison with leaf tissues reveals a high level of genome-wide transcription of TEs accompanied by RNA-dependent DNA methylation of these sequences in
trans
. This provides insight into the genomic conditions underlying somaclonal variation and epiallele formation in plants regenerated from embryogenic cultures, which is an important consideration when using these tissues for plant propagation and genetic improvement.
Flowering Process of Vitis vinifera: A Review Vasconcelos, M. Carmo; Greven, Marc; Winefield, Chris S ...
American journal of enology and viticulture,
01/2009, Letnik:
60, Številka:
4
Journal Article
The effects of UVB radiation on plant growth rate, gene expression and flavonoid content in wild-type, and in transgenic and mutant F3′H deficient
Petunia lines have been studied for the first time. ...In wild-type
Petunia, UVB induced an increase in total levels of flavonols and this was due to an up-regulation of several genes in the phenylpropanoid pathway. Furthermore, UVB induced a higher rate of production of dihydroxylated flavonols than mono-hydroxylated equivalents. Thus, the ratio of quercetin (
ortho-dihydroxylated) to kaempferol (monohydroxylated) increased. In the F3H deficient mutant line, increasing UVB resulted in up-regulation of all of the basic flavonoid biosynthetic genes. Total flavonoids increased to levels significantly higher than in control plants, and the predominant flavonoid was kaempferol. The leaves of these plants grew at a significantly slower rate than comparably treated wild-type plants under ambient or enhanced UVB radiation. This suggests that the predominance of quercetin in the wild-type confers a protective advantage that is not matched in the mutant, even with higher overall flavonoid levels. In contrast, the antisense F3H construct produced an unexpected down-regulation of C4H, CHS and CHI transcription. This resulted in lower total flavonoid production in these plants. The growth rate of these plants was not impaired in UVB to a statistically significant extent, and the Q:K ratio did not change with increasing UVB radiation. This investigation has established a likely correlation between the effect of UVB on plant growth rate, the level of activity of the F3′H gene, and the proposed photoprotection afforded by an increased Q:K ratio.
Transgenic and mutant
Petunia provide a gradient of F3′H removal to establish a likely correlation between the effect of UVB on plant growth rate, the level of activity of the F3′H gene, and the proposed photoprotection afforded by an increased Q:K ratio.
The petals of a number of flowers are shown to contain similar intensely coloured intravacuolar bodies referred to herein as anthocyanic vacuolar inclusions (AVIs). The AVIs in a blue-grey carnation ...and in purple lisianthus have been studied in detail. AVIs occur predominantly in the adaxial epidermal cells and their presence is shown to have a major influence on flower colour by enhancing both intensity and blueness. The latter effect is especially dramatic in the carnation where the normally pink pelargonidin pigments produce a blue-grey colouration. In lisianthus, the presence of large AVIs produces marked colour intensification in the inner zone of the petal by concentrating anthocyanins above levels that would be possible in vacuolar solution. Electron microscopy studies on lisianthus epidermal tissue failed to detect a membrane boundary in AVI bodies. AVIs isolated from lisianthus cells are shown to have a protein matrix. Bound to this matrix are four cyanidin and delphinidin acylated 3,5-diglycosides (three, new to lisianthus), which are relatively minor anthocyanins in whole petal extracts where acylated delphinidin triglycosides predominate. Flavonol glycosides were not bound. A high level of anthocyanin structural specificity in this association is thus implied. The specificity and effectiveness of this anthocyanin “trapping” is confirmed by the presence in the surrounding vacuolar solution of only delphinidin triglycosides, accompanied by the full range of flavonol glycosides. “Trapped” anthocyanins are shown to differ from solution anthocyanins only in that they lack a terminal rhamnose on the 3-linked galactose. The results of this study define for the first time the substantial effect AVIs have on flower colour, and provide insights into their nature and their specificity as vacuolar anthocyanin traps.
Transient Agrobacterium-mediated transformation of plant tissue has become a standard technique for rapid in vivo analysis of gene expression and function. In grapevine, the efficacy of transient ...leaf transformation is limited by the ability of bacterial suspensions to penetrate into the tissue. Current protocols therefore use the temporary application of a vacuum or site-specific syringe infiltration to improve transformation efficiencies. We show that supplementing Agrobacterium suspensions with a commercially available organosilicone surfactant (Pulse®penetrant) elevates transformation efficiency at ambient pressure. The transformation efficiency of leaf tissue of in vitro grown Vitis vinifera ‘Sauvignon blanc’ plantlets submerged in Agrobacterium suspension was increased 65-fold by the addition of Pulse®penetrant at low concentration (0.03 % v/v). A quick and precise determination of transformation efficiency was achieved by measuring red pigmentation of cells transiently transformed with the transcriptional activator of anthocyanin biosynthesis, VvMYBA1. A variable increase in transformation efficiency was also observed in eight commercial wine grape varieties and one rootstock variety. Pulse®penetrant can therefore be used to achieve transient transformation of grapevine by simply dipping in vitro leaf material into bacterial suspension culture.
Lipoxygenases (LOXs) are a group of non-haem iron-containing dioxygenases that catalyse oxygenation of polyunsaturated fatty acids (PUFAs) and lipids, and initiate the formation of biologically ...active compounds known as oxylipins. Several plant oxylipins comprise important flavours and aromas in food and beverages. Analysis of the grape (Vitis vinifera L.) genome revealed that the grape LOX family consists of 18 individual members. Phylogenetic analysis places all except one of the identified grape LOXs into either a type II 13-LOX cluster or the type I 9-LOX cluster. Four LOX genes (VvLOXA, VvLOXO, VvLOXC, VvLOXD), representative of the major LOX groupings observed in the phylogenetic analyses, were selected for analysis of patterns of transcript abundance in berry tissues. VvLOXA and VvLOXO represent putative 13-LOXs, while VvLOXC represents a putative 9-LOX. VvLOXD represents a unique LOX that differs significantly from other characterised plant LOXs. All four LOXs exhibited a complex pattern of gene expression. Across all developmental stages, VvLOXA was the most abundant LOX and was expressed predominantly in berry skins. The expression pattern of VvLOXC and -D are more evenly distributed between seeds, pulp and skin, while VvLOXO is mostly expressed in the seed. Mechanical wounding and infection of berries with Botrytis cinerea Pers.: Fr resulted in rapid accumulation of VvLOXC and -O transcripts. VvLOXA expression decreased in diseased berries. Biochemical analysis of VvLOXA and -O recombinant proteins confirmed that these LOX genes encode functional 13-LOXs that exhibit different pH and temperature optima. Both enzymes showed activity with linoleic, linolenic and arachidonic acids.
Purpose
Methanotrophs are an important group of methane (CH
4
)-oxidizing bacteria in the soil, which act as a major sink for the greenhouse gas, CH
4
. In grazed grassland, one of the ecologically ...most sensitive areas is the animal urine patch soil, which is a major source of both nitrate (NO
3
−
) leaching and nitrous oxide (N
2
O) emissions. Nitrification inhibitors, such as dicyandiamide (DCD), have been used to mitigate NO
3
−
leaching and N
2
O emissions in grazed pastures. However, it is not clear if the high nitrogen loading rate in the animal urine patch soil and the use of nitrification inhibitors would have an impact on the abundance of methanotrophs in grazed grassland soils. The purpose of this study was to determine the effect of animal urine and DCD on methanotroph abundance in grazed grassland soils.
Materials and methods
A laboratory incubation study was conducted to determine the effect of urine and DCD applications on the abundance of methanotrophs in six grazed grassland soils sampled from across New Zealand, using real-time PCR targeting the functional
pmoA
gene.
Results and discussion
Results showed that the
pmoA
gene copy numbers were low in these soils, mostly below 2.36 × 10
4
g
−1
soil except in the West Coast soil where
pmoA
gene copy number reached 8.95 × 10
5
g
−1
soil. Most of the clones identified were aligned to the type II methanotrophs. There was no significant effect (
P
< 0.05) on the abundance of methanotrophs by the applications of urine at 1,000 kg N ha
−1
or DCD at 10 kg ha
−1
.
Conclusions
These results suggest that the abundance of methanotrophs is not affected by urine deposition or the application of DCD to mitigate NO
3
−
leaching and N
2
O emissions in grazed grassland soils.
3‐Deoxyanthocyanins provide bright orange‐red colours to flowers of some members of the Gesneriaceae, including sinningia (Sinningia cardinalis). We examined 3‐deoxyanthocyanin biosynthesis in ...sinningia, in particular, the expression of key flavonoid biosynthetic genes and the activities of the encoded proteins. Two abundant 3‐deoxyanthocyanins, luteolinidin 5‐O‐glucoside and apigeninidin 5‐O‐glucoside, three flavone glycosides, luteolin 7‐O‐glucoside, luteolin 7‐O‐glucuronide and apigenin 7‐O‐glucuronide, and the cinnamic acid verbascoside were identified in sinningia petal tissue. Small amounts of a 3‐hydroxyanthocyanin were also detected in a limited region of the petal. cDNA clones for three flavonoid enzymes, flavanone 3‐hydroxylase (F3H), dihydroflavonol 4‐reductase/flavanone 4‐reductase (DFR/FNR) and anthocyanidin synthase (ANS), were isolated from a sinningia cDNA library made from petal RNA and used to measure transcript abundance during petal development. Only very low levels of F3H transcript were detected, while DFR/FNR transcript was highly abundant. ANS transcript levels were intermediate between these two. The F3H cDNA was shown to encode a functional F3H protein by complementation of the phenotype of an Antirrhinum majus F3H mutant. The recombinant DFR/FNR had activity against both flavanone and dihydroflavonol substrates to a comparable extent. The results suggest a mechanism of 3‐deoxyflavonoid biosynthesis in sinningia similar to that reported for Zea mays, in which lack of F3H activity allows action of the DFR/FNR on flavanone substrates and production of flavan‐4‐ols. These are then likely converted to 3‐deoxyanthocyanins through the action of the ANS and subsequent glucosylation.
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