Pivotal role of bZIPs in amylose biosynthesis by genome survey and transcriptome analysis in wheat (Triticum aestivum L.) mutants

Abstract

Starch makes up 70% of the wheat grain, and is an important source of calories for humans, however, the overconsumption of wheat starch may contribute to nutrition-associated health problems. The challenge is to develop resistant starch including high amylose wheat varieties with health benefits. Adapting advance genomic approaches in EMS-induced mutant lines differing in amylose content, basic leucine zipper (bZIP) regulatory factors that may play role in controlling amylose biosynthesis were identified in wheat. bZIP transcription factors are key regulators of starch biosynthesis genes in rice and maize, but their role in regulating these genes in wheat is poorly understood. A genome-wide survey identified 370 wheat bZIPs, clustered in 11 groups, showing variations in amino acids composition and predicted physicochemical properties. Three approaches namely, whole transcriptome sequencing, qRT-PCR, and correlation analysis in contrasting high and low amylose mutants and their parent line identified 24 candidate bZIP (positive and negative regulators), suggesting bZIPs role in high amylose biosynthesis. bZIPs positive role in high amylose biosynthesis is not known. In silico interactome studies of candidate wheat bZIP homologs in Arabidopsis and rice identified their putative functional role. The identified bZIPs are involved in stress-related pathways, flower and seed development, and starch biosynthesis. An in-depth analysis of molecular mechanism of novel candidate bZIPs may help in raising and improving high amylose wheat varieties.

Over-Expressing TaSPA-B Reduces Prolamin and Starch Accumulation in Wheat (Triticum aestivum L.) Grains

“…However, the overexpressed TaSPA-B was negatively correlated, TaRSR1 was positively correlated to 27 SSRGs in the TaSPA-B OE-3 lines, showing not completely in line with the previous results [9,25,47]. Other TF genes related to SSRGs, such as the negative regulatory factor genes TabZIP151, TabZIP194.3 and TabZIP229.1 (up-regulated), and the positive regulatory factor gene TabZIP167.2 (down-regulated), were also differentially expressed (Table 2) [13]. A series of TFs, including TaSPA, TaGAMYB, TaFUSCA3, TaSHP, and TaPBF-D, regulate the glutenin genes in wheat [17,19,33,34,36,38].…”

“…Maize O2 regulates a complex gene network, such as genes coding starch synthesis related enzymes, cyPPDK1, cyPPDK2 and PBF, to balance starch and protein synthesis [27,28,35]. The expression of TaRSR1 and TabZIPs is correlated to the expression of SSRGs in wheat [9,13,25,47]. However, the overexpressed TaSPA-B was negatively correlated, TaRSR1 was positively correlated to 27 SSRGs in the TaSPA-B OE-3 lines, showing not completely in line with the previous results [9,25,47].…”

“…The special accumulation of prolamins in the endosperm during grain filling is controlled by several mechanisms. Regulation at the transcriptional level is the primary mode and depends on the interaction of with cis-motifs in the promoters of related genes, which is conserved in most cereals and dicots [6][7][8][9][10][11][12][13]. The bipartite endosperm box is composed of GCN4 motif, which is recognized by basic leucine zipper (bZIP) TFs, and P box, which is recognized by DNA binding with one finger (Dof) TFs [6,14,15].…”

“…Previous researches focused on the modification of the prolamin genes and starch synthesis genes to obtain ideal phenotypes [31,32]. With advances in genomics, the regulatory mechanism underlying the TFs and gene networks becomes a hot topic in wheat grain research [13,17,19,27,33,34]. Maize O2 is a typical TF with a broad influence, especially on starch and protein synthesis [28,35].…”

Genome-wide identification and expression profiling of basic leucine zipper transcription factors following abiotic stresses in potato (Solanum tuberosum L.)

“…In the current study, we mined and functionally annotated the basic leucine zipper family (bZIP) of TFs in potato using its genome information and previous annotation [9][10][11]. Generally, the bZIP proteins contain an essential region that consists of a DNA-binding part and a leucine zipper dimerization motif [9][10][11][12]. Structurally, the bZIP family is highly conserved among the species with signature sequences of the domains (60-80 amino acids long).…”