Molecular genetics of berry colour variation in table grape

Abstract

The genetics and biochemistry of anthocyanins and flavonol biosynthesis and their role in plant organ pigmentation is well established in model species. However, the genetic basis of colour variation is species specific and understanding this variation is very relevant in many fruit and flower crop species. Among grape cultivars, there is a wide genetic variation for berry colour ranging from yellow-green ("white" cultivars) to dark blue berries. Berry colour results from the synthesis and accumulation of anthocyanins in the berry skin, which in plants is commonly regulated by transcription factors belonging to the MYB and bHLH families. In this work, we aimed to identify the major genetic determinants of berry colour variation in a large collection of table grape cultivars and somatic variants. The genetic analyses of berry colour in a few grape segregating progenies had previously identified a single locus on linkage group 2 responsible for colour variation. Furthermore, somatic variation for berry skin colour in cultivar Italia had been associated with the presence of a Gret1 retrotransposon in the promoter region of VvmybA1, a Myb gene whose expression is associated to skin colouration. The results show that VvmybA1 is the gene underlying the mapped locus controlling berry colour in grape. Additionally, the molecular analyses indicate that genetic and somatic berry colour variation can be associated to molecular variation at VvmybA1 in more than 95% of the analyzed cultivars. Thus, VvmybA1 is a major determinant of berry colour variation in table grape and its instability is the major cause of somatic variation for this trait.

Evolution of the VvMybA gene family, the major determinant of berry colour in cultivated grapevine (Vitis vinifera L.)

“…Moreover, the sequencing of the 3 0 -LTR/insertion part of Gret1 showed no variation (data not shown), supporting the hypothesis of a single insertion event that occurred in the B haplogroup. Two other likely paths of the network could alternatively result from Gret1 excision, as observed by Lijavetzky et al (2006).…”

“…Furthermore, most of the antique cultivars have a complete series of coloured mutants such as Pinot or Grenache noir, gris and blanc. The determinants of such variation corresponding to major genomic re-arrangements, such as Gret1 instability (Lijavetzky et al, 2006;Walker et al, 2007), and possibly maintained in chimeric states (Hocquigny et al, 2004) have not been investigated in this study. Multiple Gret1 insertion/excision or recombination events may explain the contrasting pattern of selection in the Rs haplogroup.…”

“…The primary domestication syndromes in grape are hermaphroditism and the size of berries and bunches (Levadoux, 1956). Colour variation is neither considered as a primary target for selection nor correlated with a particular geographic origin (Sefc et al, 2000;Lijavetzky et al, 2006).…”

“…The rise of the white berry genotype was recently demonstrated to be the result of the silencing of the first two functional genes (Kobayashi et al, 2005;Walker et al, 2007). VvMybA1 gene silencing is due to the insertion of Gret1, a gipsy-type retrotransposon in its promoter (Lijavetzky et al, 2006;This et al, 2007). For VvMybA2, the single-nucleotide polymorphism (SNP) K980 in the coding sequence, which modifies a putative a-helix of the R2R3 recognition domain, also led to a nonfunctional gene (Walker et al, 2007).…”

Ecophysiological, Genetic, and Molecular Causes of Variation in Grape Berry Weight and Composition: A Review

“…Anthocyanin concentration is characterized by a high broad sense heritability (from 0.65 to 0.98), and this heritability is stable in different populations (Liang et al 2009). The analyses of mapping populations have indeed identified a single locus on LG2 responsible for the presence or absence of skin color and total anthocyanin content in the skin (Doligez et al 2002, Fischer et al 2004, Fournier-Level et al 2010, Lijavetzky et al 2006, Salmaso et al 2008). This locus accounts for 48 to 62% of the total variation in anthocyanin concentration in a Syrah x Grenache progeny and colocalizes with a cluster of VvMYB genes (VvMYBA1, VvMYBA2, VvMYB3, and VvMYB4) (Fournier-Level et al 2010).…”