## 1 Introduction  
Norisoprenoids are among the most important grape-derived flavor compounds in wine, especially for non-Muscat cultivars. With very low olfactory perception thresholds and powerful aroma properties, they contribute to the floral and fruity attributes of grapes and wines [1, 2]. Due to the important sensory contribution of norisoprenoids, extensive researches were conducted on the response of these compounds to some treatments such as synthetic auxin application [3], sunlight exposure [4], and partial rootzone drying [5]. Norisoprenoids are carbonyl compounds with 9, 10, 11, or 13 carbon atoms which derived from oxidative degradation of carotenoids, a diverse group of C40 pigments in plant [6]. Previous studies have identified three carotenoid cleavage dioxygenase (CCD) enzyme family members (CCD1, CCD4a, and CCD4b) that can catalyze the cleavage of carotenoid substrates, and then produce norisoprenoids [6; 7]. The expression of these three genes has been found to significantly increase in grape berries at the onset of ripening (veraison), compared to pre-veraison berries [7]. [PERSON] et al. observed that _VviCCD1_ increased from the green stage and peaked at around veraison, while the transcript abundance of _VviCCD4b_ and _VviCCD4a_ started to increase from veraison and after veraison, respectively [8]. They suggested that the higher level of norisoprenoids content in response to distinct climate was related to up-regulated _VviCCD4b_. However, the other regulatory mechanisms of norisoprenoid accumulation like alternative splicing, transcriptional regulation by transcription factors (TFs), and regulatory network with other genes are poorly understood. Alternative splicing (AS), as one important posttranscriptional regulatory mechanism that can affect mRNA stability and increase protein diversity, has recently gained attention in grapevine research. [PERSON] et al. found that 30% (8668) of the grapevine predicted genes undergo AS with 64% of these alternatively spliced genes possess more than two isoforms and produce 32,395 different isoforms in grape berry [9]. They also suggested that AS can affect miRNA target sites, indicating its contribution to the transcriptional complexity and regulation. Furthermore, it was found that AS seems to be conserved among different varieties [10]. Using combined transcriptomic and proteomic analysis, [PERSON] and the colleagues have proven that AS plays an important posttranscriptional regulatory role in the response of grape leaves to high-temperature stimuli [11]. In the aspect of transcriptional regulation, we recently have identified a MADs family transcription factor (TF) _VviMADS4_ directly down-regulating _VviCCD4b_ expression [12], and a _VviWRX740_ transcription factor responsible for monoterepenoid glycosylation [13]. However, to date, there is no report uncovering the potential TFs positively regulating the biosynthesis of norisoprenoids and other volatile organic compounds in grape berry. The norisoprenoids markedly increase at around veraison [8; 14], which is a crucial shift point for grape berries to change from green/immature to ripe/mature, and encompasses physiological and metabolic changes. These changes include berry softening, sugar, anthocyanin, and flavor accumulation, and parallel an increase of abscisic acid (ABA) level and a decrease of auxin level [15; 16; 17]. Hormones are proven to play a major role in controlling several ripening-associated processes like fruit coloration and aroma development [18; 19]. Among the hormones accumulated in grape berry, ABA and auxin are considered critical for the regulation of ripening progression. Several studies confirmed that ABA increase and auxin decline are tightly associated with the initiation of ripening [17; 18; 20]. However, the understanding of the role of the two hormones in regulating norisoprenoid production is limited. One report mentioned that the exogenous application of auxin-like compounds can delay ripening and simultaneously affect the concentration of norisoprenoids in wines [3].