Characterization and diagnostic marker for TTG1 regulating tannin and anthocyanin biosynthesis in faba bean

• Published in: Scientific reports Vol. 9; no. 1; pp. 16174 - 10
• Main Authors: Gutierrez, Natalia, Torres, Ana M.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 07-11-2019; Nature Publishing Group
• Subjects: 38/23; 38/39; 38/43; 45/22; 45/29; 45/41; 45/77; 45/90; 631/208/191/2018; 631/208/8; Alfalfa; Alleles; Anthocyanins - biosynthesis; Anthocyanins - genetics; Biosynthesis; Breeding; Chromosome 2; Cultivars; Feed industry; Flowering; Gene deletion; Gene expression; Gene Expression Regulation, Plant; Genetic Markers; Genotypes; Humanities and Social Sciences; Legumes; Medicago sativa - genetics; Medicago sativa - metabolism; multidisciplinary; Mutation; Phenotypes; Phylogeny; Plant Proteins - biosynthesis; Plant Proteins - genetics; Science; Science (multidisciplinary); Synteny; Tannins; Tannins - biosynthesis; Tannins - genetics; Vicia faba - genetics; Vicia faba - metabolism
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/s41598-019-52575-x

Condensed tannins, found in coloured-flowering varieties of faba bean (
Vicia faba
L) are, after vicine and convicine, one of the major anti-nutritional factors for monogastric animals. The development of tannin-free cultivars is a key goal in breeding to broaden the use of this legume in the animal feed industry. Two recessive genes,
zt-1
and
zt-2
, control the zero-tannin content and promote white-flowered plants. Previous studies exploiting synteny with the model
Medicago truncatula
reported a mutation in
TTG1
, a gene encoding a WD40 transcription factor located in chromosome II, as the responsible for the
zt-1
phenotypes. Here a comprehensive analysis of
VfTTG1
(including phylogenetic relationships, gene structure and gene expression) has been conducted to confirm the identity of the gene and to reveal structural changes that may result in different functional alleles. The results confirmed the identity of the candidate and revealed the existence of two different alleles responsible for the phenotype:
ttg1-a
, probably due to a mutation in the promoter region, and
ttg1-b
caused by a deletion at the 5′end of
VfTTG1
. Based on the sequencing results, an allele-specific diagnostic marker was designed that differentiate zt-1 from wild and zt-2 genotypes and facilitates its deployment in faba bean breeding programs.