Circadian oscillatory transcriptional programs in grapevine ripening fruits

Abstract

BackgroundTemperature and solar radiation influence Vitis vinifera L. berry ripening. Both environmental conditions fluctuate cyclically on a daily period basis and the strength of this fluctuation affects grape ripening too. Additionally, a molecular circadian clock regulates daily cyclic expression in a large proportion of the plant transcriptome modulating multiple developmental processes in diverse plant organs and developmental phases. Circadian cycling of fruit transcriptomes has not been characterized in detail despite their putative relevance in the final composition of the fruit. Thus, in this study, gene expression throughout 24 h periods in pre-ripe berries of Tempranillo and Verdejo grapevine cultivars was followed to determine whether different ripening transcriptional programs are activated during certain times of day in different grape tissues and genotypes.ResultsMicroarray analyses identified oscillatory transcriptional profiles following circadian variations in the photocycle and the thermocycle. A higher number of expression oscillating transcripts were detected in samples carrying exocarp tissue including biotic stress-responsive transcripts activated around dawn. Thermotolerance-like responses and regulation of circadian clock-related genes were observed in all studied samples. Indeed, homologs of core clock genes were identified in the grapevine genome and, among them, VvREVEILLE1 (VvRVE1), showed a consistent circadian expression rhythm in every grape berry tissue analysed. Light signalling components and terpenoid biosynthetic transcripts were specifically induced during the daytime in Verdejo, a cultivar bearing white-skinned and aromatic berries, whereas transcripts involved in phenylpropanoid biosynthesis were more prominently regulated in Tempranillo, a cultivar bearing black-skinned berries.ConclusionsThe transcriptome of ripening fruits varies in response to daily environmental changes, which might partially be under the control of circadian clock components. Certain cultivar and berry tissue features could rely on specific circadian oscillatory expression profiles. These findings may help to a better understanding of the progress of berry ripening in short term time scales.

Grape berry position affects the diurnal dynamics of its metabolic profile

“…Contrary to the circadian changes found in the grape transcriptome (Carbonell‐Bejerano et al, ), a lower number of phenylpropanoid metabolites were found to significantly change diurnally compared with primary metabolites (Figure S2). Compounds showing significant diurnal changes clearly differed between contrasting orientations of the same cluster (E vs. EW).…”

The time of the day to harvest affects the degreening, antioxidant compounds, and protein content during postharvest storage of broccoli

“…For example, it has been described that in broccoli and cabbage the antioxidant activity and the content of phenolics decrease toward the end of the day (Soengas, Cartea, Velasco, & Francisco, ). Moreover, in grapes of Tempranillo, a cultivar with black‐skinned berries, the expression of genes related to phenylpropanoid biosynthesis showed a circadian variation (Carbonell‐Bejerano et al, ).…”

The common transcriptional subnetworks of the grape berry skin in the late stages of ripening

“…For example, VviLHY and VviTOC1 did not oscillate, whereas VviRVE1 and VviELF3 of the core clock genes did display a circadian rhythm in grape [84]. The authors attribute the differences in clock gene expression to grape maintaining a simplified clock in ripening fruit.…”