AUTHOR=Feng Yumei , Han Yang , Han Bing , Zhao Yongying , Yang Yan , Xing Yanping 

TITLE=A 4 bp InDel in the Promoter of Wheat Gene TaAFP-B Affecting Seed Dormancy Confirmed in Transgenic Rice

JOURNAL=Frontiers in Plant Science

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2022.837805

DOI=10.3389/fpls.2022.837805

ISSN=1664-462X

ABSTRACT=<sec><title>Background</title><p>Wheat (<italic>Triticum aestivum</italic> L.) ABA insensitive five (<italic>ABI5</italic>) binding protein gene (<italic>TaAFP</italic>) is a homologue of the <italic>ABI5</italic> binding protein (AFP) gene in <italic>Arabidopsis thaliana</italic>. It is well documented that <italic>AtAFP</italic> is a negative regulator of ABA signaling that regulates embryo germination and seed dormancy. <italic>TaABI5</italic> was earlier shown to be expressed specifically in seed and its transcript accumulated during wheat grain maturation and acquisition of dormancy. It plays an important role in seed dormancy. In a previous study, we identified two allelic variants <italic>TaAFP-B1a</italic> and <italic>TaAFP-B1b</italic> of <italic>TaAFP</italic> on chromosome arm 2BS in common wheat, designated as, respectively. Sequence analysis revealed a 4 bp insertion in the promoter of <italic>TaAFP-B1a</italic> compared with <italic>TaAFP-B1b</italic> that affected mRNA transcription level, mRNA stability, GUS and tdTomatoER translation level, and GUS activity determining seed dormancy.</p></sec><sec><title>Results</title><p>The transcription and translation levels of <italic>TaAFP-B</italic> were significantly reduced in <italic>TaAFP-Ba</italic> and <italic>TaAFP-Ba-GFP</italic> transgenic plants compared with <italic>TaAFP-Bb</italic> and <italic>TaAFP-Bb-GFP</italic>. The average GI (germination index) values of <italic>TaAFP-Ba</italic> and <italic>TaAFP-Ba-GFP</italic> were significantly lower than those of <italic>TaAFP-Bb</italic> and <italic>TaAFP-Bb-GFP</italic> in T1 and T2 transgenic rice seeds, whereas mature <italic>TaAFP-Ba</italic> and <italic>TaAFP-Ba-GFP</italic> transgenic seeds exhibited increased ABA sensitivity and content of endogenous ABA compared with <italic>TaAFP-Bb</italic> and <italic>TaAFP-Bb-GFP</italic>.</p></sec><sec><title>Conclusion</title><p>The 4 bp insertion in the promoter of <italic>TaAFP-Ba</italic> decreased transcript abundance and translation level in transgenic rice. This insertion increased sensitivity to ABA and content of endogenous ABA in mature seeds, leading to a higher seed dormancy and pre-harvest sprouting tolerance in transgenic rice.</p></sec>