## 1 Introduction  
The _Vitis vinifera_ reference genome has been an invaluable resource for the identification of genes involved in metabolic processes of agronomic interest [1]. The genetic basis for various traits associated with flavour and aroma have increasingly been elucidated since the genome became available, as recently reviewed by reference [2]. A major contributor to flavour and aroma profiles are the terpenes, a chemically diverse class of metabolites, mainly associated with floral and Muscat aromas (for example, linaolool, geraniol, merol, or-terpinerol), and notrienol) or a pepper aroma (for example, rotundone) inferred by mono -and sesquiterpenes, respectively [2, 3, 4, 5, 6]. The near-homozygous reference genome PN40024 contains 152 _V. vinifera_ terpen synthase (_VviTPS_)-like loci, of which 69 are predicted to be functional [1, 7]. Thirty of these gene models were subsequently linked to a functional enzyme but were isolated from various genotypes [7]. The _VviTPS_ family annotated on the PN40024 reference genome largely encodes for genes involved in mono- (C10) and sesquiterpene (C15) biosynthesis. These metabolites are biosynthesised via two compartmentalised pathways. The cytosolic mexulonate (MVA) and plastitial 2-C-methyl-D-erythritol 4-phosphate (MEP) pathways both result in the C5 terpene precursors isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP). These isomeric precursors are coupled in a head-to-tail manner by prenyl transferases that result in the mono-TPS substrate geranyl diphosphate (GPP) and sesqui-TPS substrate farnesyl diphosphate (FPP). FPP can be isomerised in a rate-limiting reaction to form the nerolidol diphosphate (NPP) substrate [8; 9; 10; 11]. The array of terpenes produced by a single TPS varies greatly, from a single product to an excess of 40 terpenes [12; 13; 14; 15]. This is due to how the TPS active site interacts with its substrate. Depending on how long the TPS can shield the reaction from being quenched, one will typically see the biosynthesis of acyclic and cyclic terpene structures, with the former usually seen due to premature/early quenching [16; 11; 17; 18]. The added double bond in the C15 FPP/NPP substrates, relative to GPP, allows for more conformational changes to take place, catalysed by a sesqui-TPS, resulting in a more diverse array of chemical structures [14; 19; 20]. The near-homozygosity (\(\
eg\)93%) of the PN40024 reference genome [1; 21] does not reflect the structural complexity associated with commercial heterozygous diploid cultivars [22; 23]. To address this limitation, recent sequencing efforts employed long-read genome sequencing that allows haplotype-aware genome assemblies [24; 25; 26]. Comparative analyses of the genomic landscape for the diploid genomes of Cabernet Sauvignon (CS), Chardonnay (CH), or Carmenere (CR) [24; 25; 26] highlighted extensive genotype-specific structural variations (SV) within the _VviTPS_ family [27]. The extensive duplication of _VviTPS_ genes furthermore resulted in numerous genes having similar functions with various mechanisms potentially involved in these duplication events [7; 20; 28; 29]. The physical proximity of related _VviTPS_ subfamily members on a chromosome are indicative of tandem duplication events, whereas remnants of transposable elements suggest that transposon-mediated duplication allowed for the genome-wide movement of _VviTPS_ genes [7]. Segmental duplications that are highly homologous (94% and \(>\)10 kb in size) contribute to 17% of the PN40024 genome, resulting in large repetitive genomic regions [30]. Domestication-driven introgression between germplasms has furthermore resulted in highly complex genomes that show greater heterozygosity in the domesticated varieties than the wild parent(s) [31; 32; 33; 34]. Tandem _TPS_ duplications often form multi-gene clusters of varying sizes but show similar catalytic mechanisms.