A recessive mutation in muscadine grapes causes berry color-loss without influencing anthocyanin pathway

Ahmed Ismail, Pranavkumar Gajjar, Minkyu Park, Abdulla Mahboob, Violeta Tsolova, Jayasankar Subramanian, Ahmed G. Darwish, Islam El-Sharkawy

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)


Anthocyanins, a major class of flavonoids, are important pigments of grape berries. Despite the recent discovery of the genetic cause underlying the loss of color, the metabolomic and molecular responses are unknown. Anthocyanin quantification among diverse berry color muscadines suggests that all genotypes could produce adequate anthocyanin quantities, irrespective of berry color. Transcriptome profiling of contrasting color muscadine genotypes proposes a potential deficiency that occurs within the anthocyanin transport and/or degradation mechanisms and might cause unpigmented berries. Genome-wide association studies highlighted a region on chromosome-4, comprising several genes encoding glutathione S-transferases involved in anthocyanin transport. Sequence comparison among genotypes reveals the presence of two GST4b alleles that differ by substituting the conserved amino acid residue Pro171-to-Leu. Molecular dynamics simulations demonstrate that GST4b2–Leu171 encodes an inactive protein due to modifications within the H-binding site. Population genotyping suggests the recessive inheritance of the unpigmented trait with a GST4b2/2 homozygous. A model defining colorless muscadines’ response to the mutation stimulus, avoiding the impact of trapped anthocyanins within the cytoplasm is established.

Original languageEnglish
Article number1012
JournalCommunications Biology
Issue number1
Publication statusPublished - Dec 2022

ASJC Scopus subject areas

  • Medicine (miscellaneous)
  • General Biochemistry,Genetics and Molecular Biology
  • General Agricultural and Biological Sciences


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