Functional Characterization of TaFUSCA3, a B3-Superfamily Transcription Factor Gene in the Wheat

Abstract

The end-use quality of wheat, including its unique rheology and viscoelastic properties, is predominantly determined by the composition and concentration of gluten proteins. While, the mechanism regulating expression of the seed storage protein (SSP) genes and other related genes in wheat remains unclear. In this study, we report on the cloning and functional identification of TaFUSCA3, a B3-superfamily transcription factor (TF) gene in wheat. Sequence alignment indicated that wheat and barley FUSCA3 genes are highly conserved. Quantitative reverse-transcription (qRT)-PCR analysis showed that the transcript of TaFUSCA3 was accumulated mostly in the stamens and the endosperms of immature wheat seeds. Yeast-one-hybrid results proved that the full-length TaFUSCA3 and its C-terminal region had transcriptional activities. Yeast-two-hybrid and bimolecular fluorescence complementation assays indicated that TaFUSCA3 could activate the expression of the high molecular weight glutenin subunit gene Glu-1Bx7 and interact with the seed-specific bZIP protein TaSPA. DNA-protein-interaction enzyme-linked immunosorbent assay demonstrated that TaFUSCA3 specifically recognizes the RY-box of the Glu-1Bx7 promoter region. Transient expression results showed that TaFUSCA3 could trans-activate the Glu-1Bx7 promoter, which contains eight RY-box sequences. TaFUSCA3 was unable to activate the downstream transcription when the RY-box was fully mutated. TaFUSCA3 could activate the transcription of the At2S3 gene promoter in a complementation of loss-of-function experiment using the Arabidopsis thaliana line fus3-3, which is a FUSCA3 mutant, demonstrating the evolutionary conservation of the TaFUSCA3 gene. In conclusion, the wheat B3-type TF, TaFUSCA3, is functional conserved between monocot and dicot, and could regulate SSP gene expression by interacting specifically with TaSPA.

The bZIP transcription factor SPA Heterodimerizing Protein represses glutenin synthesis in Triticum aestivum

“…Recently, Sun et al . () identified TaFUSCA3, a B3 TF, which binds an RY motif in the GluB1‐1 promoter, activating the promoter and interacting with SPA protein. TaGamyb binds the AACA motif and activates the GluD1‐2 gene promoter in Arabidopsis (Guo et al ., ).…”

“…Two additional cis ‐elements have been described in barley: 5′‐AACA/TA‐3′ binds GAMYB, a TF of the R2R3MYB family, and 5′‐TATC/GATA‐3′ binds HvMCB1 and HvMYBS3, two regulatory proteins of the R1MYB family (Diaz et al ., ; Rubio‐Somoza et al ., ,b). Another important motif, the RY box (5′‐CATGCATG‐3′), is recognized by FUSCA3, a B3‐type TF in barley and wheat (Moreno‐Risueno et al ., ; Sun et al ., ). Differences in the organization of regulatory cis ‐elements have been noted in wheat GSP promoters.…”

Molecular characterization of gliadins of Chinese Spring wheat in relation to celiac disease elicitors

“…TaFUSCA3 is B3-superfamily transcription factor located on chromosomes 3AL, 3B, and 3DL (Sun et al 2017). It can activate HMW-GS gene expression and interact with SPA (Sun et al 2017). The 2-DE 19 profiles of gliadins were not affected in the aneuploid lines of groups 3 and 5 chromosomes, which these transcription factors locate on.…”

“…Furthermore, the α-gliadin genes located on the chromosome 6D were not amplified by the genomic PCR ( Transcription factors that spatially and temporally regulate the transcription of seed storage protein genes have been reported. In wheat, seed protein activator (SPA), wheat prolamin box binding factor (WPBF), GAMYB, and TaFUSCA3 are known to bind to a specific cis-element in prolamin gene promotors (Albani et al 1997;Haseneyer et al 2008;Ravel et al 2006;Sun et al 2017). Seed protein activator is a homolog of OPAQUE2 (O2), which is a bZIP protein and regulates zein synthesis in maize (Albani et al 1997).…”

“…They are conserved between barley and wheat and are encoded by genes on the chromosome 3 locus (Haseneyer et al 2008). TaFUSCA3 is B3-superfamily transcription factor located on chromosomes 3AL, 3B, and 3DL (Sun et al 2017). It can activate HMW-GS gene expression and interact with SPA (Sun et al 2017).…”