Nonsense Mutation Inside Anthocyanidin Synthase Gene Controls Pigmentation in Yellow Raspberry (Rubus idaeus L.)

Abstract

Yellow raspberry fruits have reduced anthocyanin contents and offer unique possibility to study the genetics of pigment biosynthesis in this important soft fruit. Anthocyanidin synthase (Ans) catalyzes the conversion of leucoanthocyanidin to anthocyanidin, a key committed step in biosynthesis of anthocyanins. Molecular analysis of the Ans gene enabled to identify an inactive ans allele in a yellow fruit raspberry (“Anne”). A 5 bp insertion in the coding region was identified and designated as ans+5. The insertion creates a premature stop codon resulting in a truncated protein of 264 amino acids, compared to 414 amino acids wild-type ANS protein. This mutation leads to loss of function of the encoded protein that might also result in transcriptional downregulation of Ans gene as a secondary effect, i.e., nonsense-mediated mRNA decay. Further, this mutation results in loss of visible and detectable anthocyanin pigments. Functional characterization of raspberry Ans/ans alleles via complementation experiments in the Arabidopsis thaliana ldox mutant supports the inactivity of encoded protein through ans+5 and explains the proposed block in the anthocyanin biosynthetic pathway in raspberry. Taken together, our data shows that the mutation inside Ans gene in raspberry is responsible for yellow fruit phenotypes.

Structure and contingency determine mutational hotspots for flower color evolution

“…S10), consistent with the ability of ANS to potentially act as a nal bottleneck for overall ux of pathway material toward anthocyanin production. These observations are in line with the occasional involvement of ANS as a target in transitions between pigmented and un-pigmented phenotypes in owers (Keiichi Shimizu 2011) and fruits (Raque et al 2016).…”

Isolation and Analysis of Anthocyanin Pathway Genes from Ribes Genus Reveals MYB Gene with Potent Anthocyanin-Inducing Capabilities

“…Sequence information for ANS is available from many species and, based on the available sequence data, it can be hypothesized that many plant species possess only one functional ANS gene per haploid genome [ 16 , 17 , 18 ]. This hypothesis is indirectly supported by the fact that ANS mutants, such as white pomegranate and yellow raspberry cultivars, as well as an A. thaliana mutant, do not synthesize anthocyanins in any tissues, in any stage of development or in response to any environmental factors [ 24 , 25 , 26 ]. As can be seen in the phylogenetic timetree ( Figure 2 A), Ribes ANS protein sequences are more homologous to the sequences of rosids than to the asterid clade, and sequences inside the asterid branch are more divergent, although that is not true for sequences of all anthocyanin pathway enzymes.…”

Assessment of Genetic Diversity in Differently Colored Raspberry Cultivars Using SSR Markers Located in Flavonoid Biosynthesis Genes

“…The genetic mechanisms for the formation of yellow color in raspberry fruit have not yet been fully studied. Although assumptions on this topic were made back in the 1930s, it was not until 2016 when an inactive anthocyanidin synthase (ANS) allele was identified in yellow raspberry [46]. A 5 bp insertion in the coding region of gene creates a premature stop codon resulting in a truncated amino acid sequence of the defective ANS protein.…”