Characterization and expression quantitative trait loci analysis of TaABI4, a pre-harvest sprouting related gene in wheat

Chunsheng Xiao,Calum Watt,Jirui Wang,Zhenzhong Wang,Maolian Li,Jingye Cheng,Zhi Tan,Jian Yang,Yujiao Liu,Wenshuai Chen,Mengping Cheng

doi:10.1017/s0960258521000015

Abstract

AbstractPre-harvest sprouting (PHS) induced by the absence of seed dormancy causes a severe reduction in crop yield and flour quality. In this study, we isolated and characterized TaABI4, an ABA-responsive transcription factor that participates in regulating seed germination in wheat. Sequence analysis revealed that TaABI4 has three homologues, located on chromosomes 1A/1B/1D. TaABI4 contains a conserved AP2 domain, and AP2-associated, LRP and potential PEST motifs. Putative cis-acting regulatory elements (CE1-like box, W-box, ABRE elements and RY elements) were identified in the TaABI4 promoter region that showed high conservation in 17 wheat cultivars and wheat-related species. Expression profiling of TaABI4 indicated that it is a seed-specific gene accumulating during the middle stages of seed development. Transcript accumulation of TaABI4 in wheat cultivar Chuanmai 32 (CM32, PHS susceptible) was 5.07-fold and 1.39-fold higher than that in synthetic hexaploidy wheat SHW-L1 (PHS resistant) at 15 and 20 DPA, respectively. Six expression quantitative trait loci (eQTL) of TaABI4 on chromosomes 2A, 2D, 3B and 4A were characterized based on the accumulated transcripts of TaABI4 in SHW-L1 and CM32-derived recombinant inbred lines. These QTLs explained 10.7 to 46.1% of the trait variation with 4.53–10.59 of LOD scores, which contain genes that may affect the expression of TaABI4.

Highlights

Pre-harvest sprouting (PHS) is the germination of grain prior to ripening in the spike when there is excessive moisture before harvest
ABI4 is indispensable for inhibiting the expression of three family members of Arabidopsis response regulators (ARRs), namely, ARR6/7/15, which are involved in seed dormancy (Huang et al, 2017)
The DNA sequence of ABI4 (AT2G40220) from Arabidopsis was used as a query sequence to carry out BLAST searches in EnsemblPlants

Summary

Introduction

Pre-harvest sprouting (PHS) is the germination of grain prior to ripening in the spike when there is excessive moisture before harvest. The level of wheat grain dormancy partly depends on abscisic acid (ABA) sensitivity before and after the grain reaches physiological maturity (Gubler et al, 2005; Sun et al, 2005; Shu et al, 2016). ABI4 is indispensable for inhibiting the expression of three family members of Arabidopsis response regulators (ARRs), namely, ARR6/7/15, which are involved in seed dormancy (Huang et al, 2017). ABI4 is a primary positive regulator of ABI4, ABI5 and starch branching enzyme 2.2 (SBE2.2), activating transcription by binding the CACCG-box (CE1-like) in the promoter regions during seed development (Bossi et al, 2009). MYELOBLASTOSIS 96 (MYB96) induces ABI4 expression by binding to its promoter during seed germination and seedling development (Lee and Seo, 2015)

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Results

Conclusion