Using the combined analysis of transcripts and metabolites to propose key genes for differential terpene accumulation across two regions

Abstract

BackgroundTerpenes are of great interest to winemakers because of their extremely low perception thresholds and pleasant floral odors. Even for the same variety, terpene profile can be substantially different for grapevine growing environments. Recently a series of genes required for terpene biosynthesis were biochemically characterized in grape berries. However, the genes that dominate the differential terpene accumulation of grape berries between regions have yet to be identified.MethodsFree and glycosidically-bound terpenes were identified and quantified using gas chromatography-mass spectrometry (GC-MS) technique. The transcription expression profiling of the genes was obtained by RNA sequencing and part of the results were verified by quantitative real time PCR (QPCR). The gene co-expression networks were constructed with the Cytoscape software v 2.8.2 (www.cytoscape.org).Results‘Muscat Blanc a Petits Grains’ berries were collected from two wine-producing regions with strikingly different climates, Gaotai (GT) in Gansu Province and Changli (CL) in Hebei Province in China, at four developmental stages for two consecutive years. GC-MS analysis demonstrated that both free and glycosidically bound terpenes accumulated primarily after veraison and that mature grape berries from CL contained significantly higher concentrations of free and glycosidically bound terpenes than berries from GT. Transcriptome analysis revealed that some key genes involved in terpene biosynthesis were markedly up-regulated in the CL region. Particularly in the MEP pathway, the expression of VviHDR (1-hydroxy-2-methyl-2-butenyl 4-diphosphate reductase) paralleled with the accumulation of terpenes, which can promote the flow of isopentenyl diphosphate (IPP) into the terpene synthetic pathway. The glycosidically bound monoterpenes accumulated differentially along with maturation in both regions, which is synchronous with the expression of a monoterpene glucosyltransferase gene (VviUGT85A2L4 (VviGT14)). Other genes were also found to be related to the differential accumulation of terpenes and monoterpene glycosides in the grapes between regions. Transcription factors that could regulate terpene synthesis were predicted through gene co-expression network analysis. Additionally, the genes involved in abscisic acid (ABA) and ethylene signal responses were expressed at high levels earlier in GT grapes than in CL grapes.ConclusionsDifferential production of free and glycosidically-bound terpenes in grape berries across GT and CL regions should be related at least to the expression of both VviHDR and VviUGT85A2L4 (VviGT14). Considering the expression patterns of both transcription factors and mature-related genes, we infer that less rainfall and stronger sunshine in the GT region could initiate the earlier expression of ripening-related genes and accelerate the berry maturation, eventually limiting the production of terpene volatiles.Electronic supplementary materialThe online version of this article (doi:10.1186/s12870-015-0631-1) contains supple...

Influence of cluster thinning and girdling on aroma composition in ‘Jumeigui’ table grape

“…Similarly, the transcript abundance of VvCSLinNer gene, which was reported as the key gene involved in linalool accumulation 8,12 , was very low throughout the ripening period except the onset of véraison, but was uncorrelated with linalool accumulation. The similar low expression levels of VvCSLinNer gene were found in ripening berries of other cultivars 11,43,44 . Therefore, these inconsistent reports on the same gene might due to the different cultivars and climatic conditions.…”

A sense of place: transcriptomics identifies environmental signatures in Cabernet Sauvignon berry skins in the late stages of ripening

“…Two studies investigated the grape berry transcriptomes during the ripening phase in two different regions of China, a dry region in Western China and a wet region in Eastern China [87,88]. These two locations mirror some of the differences in our conditions in our study, namely moisture, light and elevation, although the dry China western region has higher night temperatures and more rainfall than the very dry RNO location.…”

“…In the second study comparing these two regions in China [88], the effects of the environment on the metabolome and transcriptome of Muscat Blanc à Petits Grains berries were investigated over two seasons; specifically, terpenoid metabolism was targeted. Like in our study, the transcripts in terpenoid were in higher abundance in the wetter location.…”

A Sense of Place: Transcriptomics Identifies Environmental Signatures in Cabernet Sauvignon Berry Skins in the Late Stages of Ripening

“…Two studies investigated the grape berry transcriptomes during the ripening 18 phase in two different regions of China, a dry region in Western China and a 19 wet region in Eastern China [87,88]. These two locations mirror some of the 20 differences in our conditions in our study, namely moisture, light and 21 elevation, although the dry China western region has higher night 22…”

“…In the second study comparing these two regions in China [88], the effects of 8 the environment on the metabolome and transcriptome of Muscat Blanc à 9…”